[Debuginfo][llvm-dwarfutil] llvm-dwarfutil dsymutil-like tool for ELF.

[avl]

Summary

This patch implements proposal https://lists.llvm.org/pipermail/llvm-dev/2020-August/144579.html
llvm-dwarfutil - is a tool that is used for processing debug info(DWARF) located in built binary files to improve debug info quality, reduce debug info size. The patch currently implements smaller set of command-line options(comparing to the proposal):

./llvm-dwarfutil [options] <input file> <output file>

  --garbage-collection    Do garbage collection for debug info(default)
  -j <value>              Alias for --num-threads
  --no-garbage-collection Don`t do garbage collection for debug info
  --no-odr-deduplication  Don`t do ODR deduplication for debug types
  --no-odr                Alias for --no-odr-deduplication
  --no-separate-debug-file
                          Create single output file, containing debug tables(default)
  --num-threads <threads> Number of available threads for multi-threaded execution. Defaults to the number of cores on the current machine
  --odr-deduplication     Do ODR deduplication for debug types(default)
  --odr                   Alias for --odr-deduplication
  --separate-debug-file   Create two output files: file w/o debug tables and file with debug tables
  --tombstone [bfd,maxpc,exec,universal]
                          Tombstone value used as a marker of invalid address(default: universal)
    =bfd - Zero for all addresses and [1,1] for DWARF v4 (or less) address ranges and exec
    =maxpc - Minus 1 for all addresses and minus 2 for DWARF v4 (or less) address ranges
    =exec - Match with address ranges of executable sections
    =universal - Both: bfd and maxpc

[jhenderson]

llvm/test/tools/llvm-dwarfutil/ELF/verify.test

13–15

Check the error messages.

llvm/tools/llvm-dwarfutil/llvm-dwarfutil.cpp

117–122

Test case?

119

Don't think you need upper-case here.

142

SectionRef is designed to be trivially copyable and doesn't really need the const & bit.

161–164

Not tested.

175

Test case?

183

Test case?

201–208

It's more common to have the public interface first in the class, I find.

221

Do you need the trailing return type?

246

Ditto.

272

Is SmallString really the right answer here for such a large base size?

294

Delete this blank line.

303

Ditto.

333

Is the trailing return type needed?

361

Ditto.

397

Ditto.

407

Test case?

417–418

Test case?

487

Test case?

513

Test case?

[avl]

llvm/lib/DWARFLinker/DWARFLinker.cpp

504–505

right. I used the same style like in the rest of that file. It does not look good to have a mix of styles. I think it should be separate commit for DWARFLinker library changing style of error messages.

llvm/test/tools/llvm-dwarfutil/ELF/copy-itself.test

8

Ok.

9–11

i.e. I need to move this check into the "standard" copy test file. OK.

13–28

It actually does not duplicate coverage. Using combination of these options(--garbage-collection, --no-garbage-collection, --separate-debug-file) leads to crossing different code paths:

llvm-dwwarfutil.cpp:219
llvm-dwwarfutil.cpp:244
llvm-dwwarfutil.cpp:331
llvm-dwwarfutil.cpp:359
llvm-dwwarfutil.cpp:395

Thus it looks good if all of them would be covered.

llvm/test/tools/llvm-dwarfutil/ELF/copy.test

2–3

It seems like gc-default.test covers much of this test's behaviour? Do we need both?

Probably, part for garbage-collection case is doubled and then might be removed. But part for no-garbage-collection looks correct and is not covered by gc-default.test.

18–19

It looks like it does not pass:

diff --git a/llvm/test/tools/llvm-dwarfutil/ELF/copy.test b/llvm/test/tools/llvm-dwarfutil/ELF/copy.test
index 9ca78308f5da..9e9eb8b84750 100644
--- a/llvm/test/tools/llvm-dwarfutil/ELF/copy.test
+++ b/llvm/test/tools/llvm-dwarfutil/ELF/copy.test
@@ -14,7 +14,7 @@
 # RUN: llvm-objdump --headers %t1 | FileCheck -check-prefix=CHECK-NON-DEBUG %s
 # RUN: llvm-dwarfdump -a %t1.debug | FileCheck -check-prefix=CHECK-DEBUG %s
 
-# RUN: llvm-dwarfutil %t.o --separate-debug-file --no-separate-debug-file %t1
+# RUN: llvm-dwarfutil %t.o --separate-debug-file %t1
 # RUN: llvm-dwarfdump -a %t1 | FileCheck -check-prefix=CHECK-DEBUG %s
 
 # RUN: llvm-dwarfutil --no-garbage-collection %t.o %t1

llvm-lit  copy.test 
-- Testing: 1 tests, 1 workers --
FAIL: LLVM :: tools/llvm-dwarfutil/ELF/copy.test (1 of 1)

llvm/test/tools/llvm-dwarfutil/ELF/odr-class.test

11 ↗

(On Diff #420641)

OK

llvm/tools/llvm-dwarfutil/llvm-dwarfutil.cpp

333

I think it is always useful to type it explicitly. It clearly shows return type. Otherwise you need to compile the lambda by itself. If it is against of guideline - then would remove it.

[avl]

addressed comments.

[clayborg]

Right now if any DWARF section isn't supported, or if a DW_FORM is not supported, this patch will still emit a file and return a non-zero exit status.

So if this patch isn't going to support any of the DWARF sections that are required, it must exit with a valid error message and return a non zero exit status. The things that come to mind are:

• anything with an older .debug_types section should return an error stating that debug types support is not supported
• any newer DWARF with type units in the .debug_info section should return an error stating that debug types support is not supported
• If fission is not supported, we need to return an error if we find any fission related sections (".debug_addr", etc)
• if any DWARF section is required for debugging (like ".debug_loclists" or ".debug_rnglists") and not getting re-linked by this tool and if those sections become invalid after the DWARF is changed, then we need to return an error
• if the line tables are too new and the DWARF linker can't update them return an error

All of this stems from Apple not having to support anything but what the Apple compilers emit. Many compilers that emit ELF files and linkers that link ELF have many other options that can be enabled for DWARF. If we aren't going to support them, we can't just emit some warnings and hope the user knows better, we need to return an error and set the exit status to a non zero value. We will need tests to cover these errors as well.

llvm/lib/DWARFLinker/DWARFLinker.cpp

503

Can we improve this check to see if the range already exists and not warn if we try to add the same range that is already in there or if the range is a subrange of an existing range?

[avl]

llvm/tools/llvm-dwarfutil/llvm-dwarfutil.cpp

175

It is quite tricky to create a test case here. Changing this to asserts does not look right. I think it is safe to leave it as is.

272

raw_svector_ostream uses SmallString. If that constant looks too large let`s consider to make it smaller?

[avl]

In D86539#3434419, @clayborg wrote:

Right now if any DWARF section isn't supported, or if a DW_FORM is not supported, this patch will still emit a file and return a non-zero exit status.

So if this patch isn't going to support any of the DWARF sections that are required, it must exit with a valid error message and return a non zero exit status. The things that come to mind are:

• anything with an older .debug_types section should return an error stating that debug types support is not supported
• any newer DWARF with type units in the .debug_info section should return an error stating that debug types support is not supported
• If fission is not supported, we need to return an error if we find any fission related sections (".debug_addr", etc)
• if any DWARF section is required for debugging (like ".debug_loclists" or ".debug_rnglists") and not getting re-linked by this tool and if those sections become invalid after the DWARF is changed, then we need to return an error
• if the line tables are too new and the DWARF linker can't update them return an error

All of this stems from Apple not having to support anything but what the Apple compilers emit. Many compilers that emit ELF files and linkers that link ELF have many other options that can be enabled for DWARF. If we aren't going to support them, we can't just emit some warnings and hope the user knows better, we need to return an error and set the exit status to a non zero value. We will need tests to cover these errors as well.

My intention was to limit first version to functionality presented in current dsymutil/DWARFLinker. And to add improvements incrementally. But If we want to have that extended check in the first version then I will add it.

My own preference is to integrate that first version of the tool and add improvements incrementally. f.e. adding such extended check would require changing interface of DWARFLinker. Use "Error DWARFLinker::link()" instead of "bool DWARFLinker::link()". It would be better to make such change separately.

[clayborg]

In D86539#3434454, @avl wrote:

In D86539#3434419, @clayborg wrote:

Right now if any DWARF section isn't supported, or if a DW_FORM is not supported, this patch will still emit a file and return a non-zero exit status.

So if this patch isn't going to support any of the DWARF sections that are required, it must exit with a valid error message and return a non zero exit status. The things that come to mind are:

• anything with an older .debug_types section should return an error stating that debug types support is not supported
• any newer DWARF with type units in the .debug_info section should return an error stating that debug types support is not supported
• If fission is not supported, we need to return an error if we find any fission related sections (".debug_addr", etc)
• if any DWARF section is required for debugging (like ".debug_loclists" or ".debug_rnglists") and not getting re-linked by this tool and if those sections become invalid after the DWARF is changed, then we need to return an error
• if the line tables are too new and the DWARF linker can't update them return an error

All of this stems from Apple not having to support anything but what the Apple compilers emit. Many compilers that emit ELF files and linkers that link ELF have many other options that can be enabled for DWARF. If we aren't going to support them, we can't just emit some warnings and hope the user knows better, we need to return an error and set the exit status to a non zero value. We will need tests to cover these errors as well.

My intention was to limit first version to functionality presented in current dsymutil/DWARFLinker. And to add improvements incrementally. But If we want to have that extended check in the first version then I will add it.

My own preference is to integrate that first version of the tool and add improvements incrementally. f.e. adding such extended check would require changing interface of DWARFLinker. Use "Error DWARFLinker::link()" instead of "bool DWARFLinker::link()". It would be better to make such change separately.

A little background: I am very interested in this patch and I have been trying to get statistics with the resulting binary from this patch so I can evaluate if we want to use it in production on linked binaries produced by our build system. I'd like to see how long it takes to run and also how much smaller debug info becomes. If I run this currently I have no way to know if we are producing anything valid and wether or not I can log the results since we always produce something and have no exit status. I also can't trust the resulting debug info sizes at all since we might be removing all sorts of extra DWARF sections that the existing DWARF linker doesn't handle, or worse yet we just don't clone an attribute and we are missing inline debug info. So it is hard to evaluate this right now as it is. I do think we should try to return errors for files we can't handle though as it would be great if people trying this out could evaluate it and know if it is working for them or if there are things that aren't handled.

[dblaikie]

In D86539#3434567, @clayborg wrote:

In D86539#3434454, @avl wrote:

In D86539#3434419, @clayborg wrote:

Right now if any DWARF section isn't supported, or if a DW_FORM is not supported, this patch will still emit a file and return a non-zero exit status.

So if this patch isn't going to support any of the DWARF sections that are required, it must exit with a valid error message and return a non zero exit status. The things that come to mind are:

• anything with an older .debug_types section should return an error stating that debug types support is not supported
• any newer DWARF with type units in the .debug_info section should return an error stating that debug types support is not supported
• If fission is not supported, we need to return an error if we find any fission related sections (".debug_addr", etc)
• if any DWARF section is required for debugging (like ".debug_loclists" or ".debug_rnglists") and not getting re-linked by this tool and if those sections become invalid after the DWARF is changed, then we need to return an error
• if the line tables are too new and the DWARF linker can't update them return an error

All of this stems from Apple not having to support anything but what the Apple compilers emit. Many compilers that emit ELF files and linkers that link ELF have many other options that can be enabled for DWARF. If we aren't going to support them, we can't just emit some warnings and hope the user knows better, we need to return an error and set the exit status to a non zero value. We will need tests to cover these errors as well.

My intention was to limit first version to functionality presented in current dsymutil/DWARFLinker. And to add improvements incrementally. But If we want to have that extended check in the first version then I will add it.

My own preference is to integrate that first version of the tool and add improvements incrementally. f.e. adding such extended check would require changing interface of DWARFLinker. Use "Error DWARFLinker::link()" instead of "bool DWARFLinker::link()". It would be better to make such change separately.

A little background: I am very interested in this patch and I have been trying to get statistics with the resulting binary from this patch so I can evaluate if we want to use it in production on linked binaries produced by our build system. I'd like to see how long it takes to run and also how much smaller debug info becomes. If I run this currently I have no way to know if we are producing anything valid and wether or not I can log the results since we always produce something and have no exit status. I also can't trust the resulting debug info sizes at all since we might be removing all sorts of extra DWARF sections that the existing DWARF linker doesn't handle, or worse yet we just don't clone an attribute and we are missing inline debug info. So it is hard to evaluate this right now as it is. I do think we should try to return errors for files we can't handle though as it would be great if people trying this out could evaluate it and know if it is working for them or if there are things that aren't handled.

Sure enough, though that doesn't necessarily have to be in the first version that's committed. It's work in progress - if this gets committed sooner then you can pitch in and help add some of that functionality, which might be more productive. Error handling/ensuring invalid/unsupported inputs don't result in "successful" garbage output is certainly important/something to keep in mind.

[jhenderson]

llvm/lib/DWARFLinker/DWARFLinker.cpp

504–505

Agreed

llvm/test/tools/llvm-dwarfutil/ELF/Inputs/archive.a

1

Why can't this file be generated on the fly? It's also a bit misleading calling it archive.a when it's a thin archive.

llvm/test/tools/llvm-dwarfutil/ELF/copy-itself.test

13–28

I'm not sure what you mean by "crossing different code paths" here exactly, but writeToOutput's behaviour is already tested, and a single test case is sufficient to show that writing to the input file via this method is sufficient, assuming that code calling that function doesn't do anything odd like open the input file again etc. Given that it doesn't currently, a test isn't needed until someone adds that functionality. Your non self-copy tests are sufficient to show that output is written correctly when those options are used.

llvm/test/tools/llvm-dwarfutil/ELF/copy.test

11

Rewording as suggested changes the emphasis slightly to be more natural, namely that the second copy is the thing that is uncertain, and the first is the "correct" version.

16

Shouldn't these cases be in a dedicated test file for --separate-debug-file?

18–19

I somehow completely misread the test (mistaking --no-garbage-collection for --no-separate-debug-file).

23

We already have a test case for the explicit option. The interesting bit here is the last-one-wins behaviour, so just focus on that in this comment.

28–29

31

Use cmp rather than diff for binary files. Applies throughout.

llvm/test/tools/llvm-dwarfutil/ELF/error-corrupted-input-file.test

6

The format would usually be error: 'archive.a': corrupted input file. See createFileError (which you should be using).

That being said, how is this input file "corrupt"? The file itself is a perfectly valid thin archive file. Shouldn't this just be something like "unsupported file format" or similar?

llvm/test/tools/llvm-dwarfutil/ELF/error-separate-file-stdout.test

7

<stdin> is typically used for error messages where the file is read from stdin (please add code and a test case that does this). It makes sense to use the same style for stdout (i.e. <stdout>) where that's relevant, but actually here, I think it would be clearer to say "unable to write to stdout when --separate-debug-file specified" or something equivalent.

llvm/test/tools/llvm-dwarfutil/ELF/gc-class.test

9

I don't think you need to reference "--garbage-collection" in all of these comments in this file, since it's not all that relevant to the test case.

13

Could simplify to "Check --odr alias." No need to say "explicit" here since the use of an alias implies it's explicit anyway.

17–19

I don't think you need to check the "last one wins" behaviour of aliases. It should be sufficient to check that for the primary versions of the options (and I'd do that before the aliases) and then show that aliases produce identical output to their main version.

21

29

llvm/test/tools/llvm-dwarfutil/ELF/verbose.test

10

I'm not convinced you should have a warning here, because otherwise the --verbose option will always produce a warning unless an explicit --num-threads option is specified. I'm not sure though. Perhaps documenting it in the CommandGuide and help text would be sufficient?

llvm/test/tools/llvm-dwarfutil/error-invalid-format.test

9

Not addressed?

llvm/test/tools/llvm-dwarfutil/error-no-input-file.test

7

Not addressed.

Also, this needs to use a lit substitution for the message format. See the %errc* substitutions.

llvm/tools/llvm-dwarfutil/llvm-dwarfutil.cpp

175

Looks like you made a test case after all :-)

272

Yeah, I think smaller may be better. As things stand, this will create a ~100kb string on the stack, which is rather a lot of stack used in one go, but someone with better undersetanding of the code may have a more informed opinion.

333

Otherwise you need to compile the lambda by itself

I don't understand this comment.

If it is against of guideline - then would remove it.

It's because it's superfluous noise - I'm not sure there's a specific coding standard on it though. Since this lambda is being passed directly into a function, you don't need to know what its return type is due to how you use it later. Within the function, it's clear that the return type is Error, so it doesn't really help with readability of the function either, in my opinion. Consequently, the extra code means it's harder for me to read everything.

417–418

Not addressed?

[avl]

In D86539#3434567, @clayborg wrote:

A little background: I am very interested in this patch and I have been trying to get statistics with the resulting binary from this patch so I can evaluate if we want to use it in production on linked binaries produced by our build system. I'd like to see how long it takes to run and also how much smaller debug info becomes. If I run this currently I have no way to know if we are producing anything valid and wether or not I can log the results since we always produce something and have no exit status. I also can't trust the resulting debug info sizes at all since we might be removing all sorts of extra DWARF sections that the existing DWARF linker doesn't handle, or worse yet we just don't clone an attribute and we are missing inline debug info. So it is hard to evaluate this right now as it is. I do think we should try to return errors for files we can't handle though as it would be great if people trying this out could evaluate it and know if it is working for them or if there are things that aren't handled.

Ok, I will prepare followup patch implementing such a behavior.

[avl]

llvm/test/tools/llvm-dwarfutil/ELF/copy-itself.test

13–28

If the implementation would be changed later - and instead of writeToOutput there would be used another code in some places - then we will not have a check that proves everything is working as expected(if we will remove these tests).

llvm/test/tools/llvm-dwarfutil/ELF/copy.test

16

From my point of view there is no difference whether we have dedicated test file for --separate-debug-file or it is tested inside other test cases. If you think we need one - I will do it.

llvm/test/tools/llvm-dwarfutil/ELF/error-corrupted-input-file.test

6

The same error might occur if the source file is corrupted. Possible good message would be :

error: 'archive.a': unsupported or corrupted input file

?

llvm/test/tools/llvm-dwarfutil/ELF/verbose.test

10

If that warning looks annoying - yes we can avoid it and document the behavior. To check my understanding - the warning should not be shown in all cases: in default "llvm-dwarfutil %t.o %t1 --verbose" and in the explicit : "llvm-dwarfutil %t.o %t1 --verbose --num-threads 10", right ?

llvm/test/tools/llvm-dwarfutil/error-invalid-format.test

9

it looks addressed. error-invalid-format.test - is the file name. It probably should be in quotas(using createFileError) like you said in other comment.

llvm/test/tools/llvm-dwarfutil/error-no-input-file.test

7

not-existed - is the file name.

llvm/tools/llvm-dwarfutil/llvm-dwarfutil.cpp

175

no. there is no test case for it still.

333

Otherwise you need to compile the lambda by itself

I don't understand this comment.

I mean that the type of returning value is not clear while someone inspecting the code. Someone need to check types of expressions in the "return" clauses, type of argument where lambda is used, etc...

If it is against of guideline - then would remove it.

It's because it's superfluous noise - I'm not sure there's a specific coding standard on it though. Since this lambda is being passed directly into a function, you don't need to know what its return type is due to how you use it later. Within the function, it's clear that the return type is Error, so it doesn't really help with readability of the function either, in my opinion. Consequently, the extra code means it's harder for me to read everything.

My understanding is opposite. It is not really clear whether return type is Error, or instead it is Expected<something> or something else.. If returning type is hidden it requires less letters but more actions to understand.

so I think the benefit of using explicit return value is more than created noise.

417–418

yep, it is not addressed yet. Returning type of linkDebugInfo is kind of artificial at the moment. I will change it in followup review. Currently it is hard to create a testcase when it returns false.

[avl]

llvm/lib/DWARFLinker/DWARFLinker.cpp

503

@clayborg

Can we improve this check to see if the range already exists and not warn if we try to add the same range that is already in there or if the range is a subrange of an existing range?

I did not get the idea. Every overlapping range is such that "it is already in there or if the range is a subrange of an existing range". Probably you mean: not to report the same range twice ?

[clayborg]

llvm/lib/DWARFLinker/DWARFLinker.cpp

503

The idea here is that the "Ranges" ivar in the CompileUnit class I am assuming is used to create the DW_AT_ranges for a compile unit. If you have two functions that LTO combined into a single address range, you currently will get an "Overlapping address range [0x1000-0x2000), [0x1000, 0x2000). Range will be discarded." warning, which is not true at all in this case and is a bad warning. What is actually happening is that the range is already in the "Ranges" and it won't be discarded and everything is fine.

We also get errors in DWARF a lot of the time due to no smart DWARF linkers out there, and you might have a range that is already inside the "Ranges" like if you have a DW_TAG_subprogram with a range of [0x1000-0x2000) and another with [0x1100-0x1200). In this case "Ranges" will already contain the second range and nothing needs to be added to "Ranges". This is bad DWARF of course, but it happens quite a bit as I have taken part in the "llvm-dwarfdump --verify" patches and we would get a error for overlapping ranges here.

So there are 3 cases I can think of:

• The same range tries to get added to "Ranges" and that is ok since it is already there
• A range that tries to get added is already fully contained within "Ranges", which should also be ok since "Ranges" already contains that range, though it is an indication of bad DWARF.
• You have ranges that intersect with "Ranges" but are not fully contained. like if "Ranges" contained "[0x1000-0x02000) and you tried to add [0xf00-0x1100] or [0x1100-0x2100)

If our goal is to do the best job possible with "CompileUnit::Ranges" so that we can produce a valid DW_AT_ranges attribute, then we should try and do our best to keep it up to date. Right now with the current code, we will happily link the DWARF for the 3rd case above, but we will create in incomplete DW_AT_ranges by ejecting either of the overlapping ranges like [0xf00-0x1100] or [0x1100-0x2100).

[clayborg]

llvm/lib/DWARFLinker/DWARFLinker.cpp

503

Also, I believe "Ranges" will combine sequential ranges from reading the header file, so if "Ranges" already fully contains the range, we do nothing and don't warn, and if a range isn't fully contained but intersects, we should extend the range it overlaps with, and if it doesn't overlap of course we just add it.

[jhenderson]

llvm/test/tools/llvm-dwarfutil/ELF/copy-itself.test

13–28

And at that point, it would be up to the developer to consider the new behaviour and how it needs testing though. Regardless, that code will still be tested by basic testing for each of the different options - the combination of them doesn't change the fact that it gets called ultimately. Combining the options doesn't change the code path of the area under test to something that can't be hit by it. If we followed your logic, we'd write tests for every possible combination of tool options for every tool, which is clearly impractical.

llvm/test/tools/llvm-dwarfutil/ELF/error-corrupted-input-file.test

6

This error can only be hit if the object is a file type supported by Binary that is not an object type. Unless the input file is somehow corrupted to make type identification pass but for the wrong kind of file, then the code wouldn't get to this error - it would fail during Binary construction, which is an earlier error. If it does get corrupted in such a way as to look like another object file kind, I don't think it's unreasonable to assume it is that object file type and state simply "unsupported" (otherwise we have to state "corrupt or unsupported" for every instance where we currently just say "unsupported"). Is there another case you had in mind for "corrupt"?

llvm/test/tools/llvm-dwarfutil/ELF/verbose.test

10

I think default behaviour (no --num-threads specified) should not produce a warning. If --num-threads is specified explicitly, I think a warning makes sense.

llvm/test/tools/llvm-dwarfutil/error-invalid-format.test

9

Sorry, missed that somehow, but see my comment elsewhere about filenames appearing after "error" (use createFileError).

llvm/test/tools/llvm-dwarfutil/error-no-input-file.test

7

Same comment as above - use createFileError (as well as the %errc* substitution).

llvm/tools/llvm-dwarfutil/llvm-dwarfutil.cpp

175

verbose.test line 24 checks "Verifying DWARF..." though?

333

I've created a Discourse thread (https://discourse.llvm.org/t/coding-standard-for-lambda-trailing-return-types/61569) to discuss the general principle, because I don't agree with you, and I think it's clear we need a general standard on this topic.

I mean that the type of returning value is not clear while someone inspecting the code. Someone need to check types of expressions in the "return" clauses, type of argument where lambda is used, etc...

In this particular context, when does somebody need to know the return type? How do return Err; and return Error::success(); not express the return type clearly?

My understanding is opposite. It is not really clear whether return type is Error, or instead it is Expected<something> or something else.

The use of Error::success() rules out Expected<T> as a return type. Instead it would return a concrete value. Again though, my question is, why do you need to know the return type in this context?

I argue the following for this specific case:

1. The lambda is being passed directly into a function so we don't have to worry about capturing it in a variable and ensuring the variable's type matches that of the lambda return value.
2. The function is small. If someone needs to modify it, they'll need to understand what the function does anyway, and it's obvious from what is being returned: the use of Err as a variable name, immediately after assigning it to an Error variable, combined with Error::success().
3. The compiler will tell you if you get something wrong when modifying the code (either the function signature changing or somebody modifying the lambda). If developing in an IDE, this error may even appear as you are typing, without the need to explicitly write the compiler.

417–418

Okay, I take it this isn't the code path that is hit if debug data in the input is malformed?

[avl]

llvm/test/tools/llvm-dwarfutil/ELF/copy-itself.test

13–28

not every possible but every relevant. We have several paths which could lead to writing to the file - it would be good if all of these paths would be covered by test.

But if we want to reduce that level of testing - I will left only one case.

llvm/test/tools/llvm-dwarfutil/ELF/error-corrupted-input-file.test

6

Ok, would use "unsupported file format".

llvm/tools/llvm-dwarfutil/llvm-dwarfutil.cpp

175

my comment was about 181 line :

return createError("unsupported file: '" + FileName + "'");

this line is not covered by test and it is tricky to do it.

333

I've created a Discourse thread (https://discourse.llvm.org/t/coding-standard-for-lambda-trailing-return-types/61569) to discuss the general principle, because I don't agree with you, and I think it's clear we need a general standard on this topic.

Thanks. I will join to this thread.

I mean that the type of returning value is not clear while someone inspecting the code. Someone need to check types of expressions in the "return" clauses, type of argument where lambda is used, etc...

In this particular context, when does somebody need to know the return type? How do return Err; and return Error::success(); not express the return type clearly?

In this particular context it is more or less obvious. But in general it is very subjective - whether it is obvious or not. C++ is very complex language. If you see return true - it does not mean return value is bool. if you see return foo() - it is not seen which type it is. I think it is easier to just have a return type than think whether it is obvious or not.

My understanding is opposite. It is not really clear whether return type is Error, or instead it is Expected<something> or something else.

The use of Error::success() rules out Expected<T> as a return type. Instead it would return a concrete value. Again though, my question is, why do you need to know the return type in this context?

In this particular context it is more or less obvious(Though it still requires to check several places(return Err, Error Err, return Error::success()) instead of one(-> Error)). The thing which does not worth a time, from my opinion -> thinking whether it is enough obvious or not.

I argue the following for this specific case:

1. The lambda is being passed directly into a function so we don't have to worry about capturing it in a variable and ensuring the variable's type matches that of the lambda return value.
2. The function is small. If someone needs to modify it, they'll need to understand what the function does anyway, and it's obvious from what is being returned: the use of Err as a variable name, immediately after assigning it to an Error variable, combined with Error::success().
3. The compiler will tell you if you get something wrong when modifying the code (either the function signature changing or somebody modifying the lambda). If developing in an IDE, this error may even appear as you are typing, without the need to explicitly write the compiler.

My main point is that it would be easier to not waste a time on thinking whether each concrete case is obvious enough or not.

417–418

right. malformed input would not lead to return false here.(Though it looks logical if it is)

[jhenderson]

llvm/test/tools/llvm-dwarfutil/ELF/copy-itself.test

13–28

To be clear, I agree that all call sites for writeToOutput need testing (i.e. the ones you've highlighted above). But I don't think they need testing for the "copy self" case, because that's not significantly different to the "copy to other file" case, as long as there is a test that shows "copy self" in general works.

llvm/test/tools/llvm-dwarfutil/ELF/copy.test

16

Normally, I'd have a dedicated test file per option, with possible additional ones for testing option interactions where needed. --[no-]separate-debug-file is a distinct option, hence I think it should be tested in a separate file, rather than mixing multiple unrelated test axes in one file.

llvm/tools/llvm-dwarfutil/llvm-dwarfutil.cpp

175

Digging into the code some more, the "unsupported file" case can only be hit if the created Binary instance is not an object, but is a recognised Binary type. For this to happen, the output file would have to have been written in an invalid state, no? That seems like an internal error within the program, so possibly should be an llvm_unreachable or similar?

333

My point is less if it's obvious and more whether it matters. In my experience, in 99% of cases, it doesn't with regards to lambdas because of how they are used. Anyway, let's see how that discussion in Discourse pans out. I'm not opposed to trailing return types in some cases where it really isn't obvious and it does matter, but I don't believe that to be the case here. It sounds to me like you're advocating for "always have return types".

[avl]

addressed comments.

not yet addressed comments: overlapped address ranges, returning type of lambda,
check for unsupported debug tables.

[avl]

added comment for overlapping address ranges workaround.

[jhenderson]

llvm/lib/DWARFLinker/DWARFLinker.cpp

506

llvm/test/tools/llvm-dwarfutil/ELF/error-unsupported-input-file.test

5–7 ↗

(On Diff #421775)

Optional to ensure you are checking the file name and not accidentally something else.

llvm/test/tools/llvm-dwarfutil/ELF/gc-class.test

26

llvm/test/tools/llvm-dwarfutil/ELF/reading-from-stdinput.test

4 ↗

(On Diff #421775)

Up to you on this one, but I'd have this in the copy.test file, and then you can do llvm-dwarfutil --no-garbage-collection - %t1 < [input-file] where [input-file] is the same object used in the existing test cases in that file.

24 ↗

(On Diff #421775)

Something to consider if you prefer to keep separate, or indeed more generally: move the YAML into a separate file under an Inputs subdirectory so that it can be referenced by multiple test cases. That saves duplicating identical YAML across different test files.

llvm/test/tools/llvm-dwarfutil/ELF/separate-debug-file.test

1 ↗

(On Diff #421775)

22–23 ↗

(On Diff #421775)

Did you mean cp here and not cmp? If so, I'd move it to where you need it rather than tagging it on the end of this test block, as it makes it look like it is important for the test case it is attached to.

39 ↗

(On Diff #421775)

Nit: too many blank lines (1 is enough).

llvm/tools/llvm-dwarfutil/Error.h

26

If you swap the arguments and make Prefix default to empty, you can avoid the strange empty string at several call sites.

llvm/tools/llvm-dwarfutil/llvm-dwarfutil.cpp

191

I think it might be more useful in the future to explain with a comment why we can't get here, in case something does manage to slip through and a developer needs to investigate. The error message could probably also do with explaining that it's an internal issue, e.g. "tool unexpectedly did not emit a supported object file".

[avl]

addressed comments.

[avl]

llvm/lib/DWARFLinker/DWARFLinker.cpp

503

@clayborg The patch which implements that behavior is D123469.

[jhenderson]

Just to be clear: I don't have the time, or really the knowledge, to review the bulk of the core behaviour of this change. Someone else will need to review that.

llvm/lib/DWARFLinker/DWARFLinker.cpp

506

Apologies, missed one bit in my previous suggestion.

llvm/test/tools/llvm-dwarfutil/ELF/Inputs/common.yaml

8–13 ↗

(On Diff #422029)

Assuming you need a .text section, do you actually need it to have anything other than something like the below?

Name:    .text
Type:    SHT_PROGBITS
Address: 0x1000
Size:    0x10

llvm/tools/llvm-dwarfutil/llvm-dwarfutil.cpp

192–195

Slightly more natural sounding phrasing suggested. Please reflow the comment if needed.

453–454

Could we refactor it out first please? Alternatively, does the behaviour need to be in the initial landing of this patch, or can it be added later?

529

Many tools have the error() function call std::exit(1) to end the program without needing an explicit return EXIT_FAILURE. I'm okay either way with it, but wanted to raise common practice with you here.

[avl]

llvm/test/tools/llvm-dwarfutil/ELF/Inputs/common.yaml

8–13 ↗

(On Diff #422029)

we need Flags and probably AddressAlign:, but Content might be replaced with Size.

llvm/tools/llvm-dwarfutil/llvm-dwarfutil.cpp

453–454

I think it is better to land it in this form. It is useful functionality and it is better to have it from start. As to the refactoring restoreStatOnFile - I am going to create a patch for soon.

529

The reason to not calling std::exit(1) is that error() function is used as a error reporting function for DWARFLinker. DWARFLinker in it`s current state does not stop if any error encountered. As an alternative I can create separate error reporting function for DWARFLinker.

[avl]

addressed comments.

[avl]

In D86539#3434567, @clayborg wrote:

In D86539#3434454, @avl wrote:

In D86539#3434419, @clayborg wrote:

Right now if any DWARF section isn't supported, or if a DW_FORM is not supported, this patch will still emit a file and return a non-zero exit status.

So if this patch isn't going to support any of the DWARF sections that are required, it must exit with a valid error message and return a non zero exit status. The things that come to mind are:

• anything with an older .debug_types section should return an error stating that debug types support is not supported
• any newer DWARF with type units in the .debug_info section should return an error stating that debug types support is not supported
• If fission is not supported, we need to return an error if we find any fission related sections (".debug_addr", etc)
• if any DWARF section is required for debugging (like ".debug_loclists" or ".debug_rnglists") and not getting re-linked by this tool and if those sections become invalid after the DWARF is changed, then we need to return an error
• if the line tables are too new and the DWARF linker can't update them return an error

All of this stems from Apple not having to support anything but what the Apple compilers emit. Many compilers that emit ELF files and linkers that link ELF have many other options that can be enabled for DWARF. If we aren't going to support them, we can't just emit some warnings and hope the user knows better, we need to return an error and set the exit status to a non zero value. We will need tests to cover these errors as well.

My intention was to limit first version to functionality presented in current dsymutil/DWARFLinker. And to add improvements incrementally. But If we want to have that extended check in the first version then I will add it.

My own preference is to integrate that first version of the tool and add improvements incrementally. f.e. adding such extended check would require changing interface of DWARFLinker. Use "Error DWARFLinker::link()" instead of "bool DWARFLinker::link()". It would be better to make such change separately.

A little background: I am very interested in this patch and I have been trying to get statistics with the resulting binary from this patch so I can evaluate if we want to use it in production on linked binaries produced by our build system. I'd like to see how long it takes to run and also how much smaller debug info becomes. If I run this currently I have no way to know if we are producing anything valid and wether or not I can log the results since we always produce something and have no exit status. I also can't trust the resulting debug info sizes at all since we might be removing all sorts of extra DWARF sections that the existing DWARF linker doesn't handle, or worse yet we just don't clone an attribute and we are missing inline debug info. So it is hard to evaluate this right now as it is. I do think we should try to return errors for files we can't handle though as it would be great if people trying this out could evaluate it and know if it is working for them or if there are things that aren't handled.

@clayborg The D123623 implements displaying error messages for unsupported tables. Would you mind to check it, please?

[jhenderson]

llvm/test/tools/llvm-dwarfutil/ELF/Inputs/common.yaml

8–13 ↗

(On Diff #422029)

Is 1b significant as a size? Could it be empty? 1? 0x10?

llvm/tools/llvm-dwarfutil/DebugInfoLinker.cpp

233

Canonical style is as suggested.

llvm/tools/llvm-dwarfutil/llvm-dwarfutil.cpp

193

453–454

As to the refactoring restoreStatOnFile - I am going to create a patch for soon.

Not sure if we're talking past each other hum. I'm simply requesting the restoreStatOnFile patch be created and then this patch rebased on top of it, rather than duplicating code that will be resolved by the other patch.

529

I've got no preference, so do whatever you prefer. The one thing I would say: if you've printed error: xxx to stderr, people will expect the the tool to return with a non-zero exit code.

[avl]

llvm/test/tools/llvm-dwarfutil/ELF/Inputs/common.yaml

8–13 ↗

(On Diff #422029)

It could not be empty. It also should be not less then referenced:

Values:
  - CStr: foo1
  - Value:  0x1000
  - Value:  0x10  <<<<<<<<<

llvm/tools/llvm-dwarfutil/llvm-dwarfutil.cpp

453–454

I understand. This way current patch will depend on the patch for restoreStatOnFile. It looks non practical for me because it would delay review. This restoreStatOnFile is not an important interface thing which will make a lot of problems later. That is why I think it is better to not create patch dependencies and that it might be OK to do both things independently.

But if you prefer to refactor restoreStatOnFile first - will rebase this patch on requested refactoring.

529

that is already done:

inline void error(Error Err, StringRef Prefix = "") {
  handleAllErrors(std::move(Err), [&](ErrorInfoBase &Info) {
    WithColor::error(errs(), Prefix) << Info.message() << '\n';
  });
  std::exit(EXIT_FAILURE);
}

[jhenderson]

llvm/tools/llvm-dwarfutil/llvm-dwarfutil.cpp

453–454

I'd always prefer avoiding incurring technical debt like this when the way forward is not particularly complex. Besides, it's not really delaying this patch, as nobody has given the thumbs up to the core behaviour anyway (and it's not something that I'm prepared to do due to my lack of familiarity and time).

529

Yes, I saw, after I made this comment, but left the comment there as it's still relevant (just information now rather than something you need to change).

[avl]

rebased on top of D123821.

[jhenderson]

llvm/tools/llvm-dwarfutil/llvm-dwarfutil.cpp

499

Similar to how I suggested the class be renamed to FilePermissionsApplier from FilePermissionsCarrier, I think you should use the word "Applier" in the variable name instead of "Carrier". I also think you should add the "OrErr" suffix, like in BinOrErr, so the new name would be PermsApplierOrErr.

[avl]

renamed variable.

[avl]

@aprantl @JDevlieghere Could you take a look at this patch, since it affects dsymutil, please?

[avl]

rebased.

[avl]

rebased.

[avl]

@clayborg Greg, since you`ve already tested this patch, Would you mind setting final approval for this, please?

The dsymutil-specific part is already integrated by separate patches: D125492, D125474, D125469.

The suggestions which you`ve done previously - already have corresponding patches: D123469, D123623.

Also, this patch is reviewed by @jhenderson from the point of view of llvm tools requirements.

[clayborg]

I look forward to using and improving this tool!

[clayborg]

What will this tool do if the "--odr-deduplication" and "--garbage-collection" are not specified?

One other quick suggestion for the "bfd" value for the "--tombstone" option, should we state that the value is zero? Or maybe even change "bfd" to "zero"?

[avl]

@clayborg @jhenderson Thank you and all for the review!

In D86539#3637202, @clayborg wrote:

What will this tool do if the "--odr-deduplication" and "--garbage-collection" are not specified?

The default state for --garbage-collection is enabled.
The default state for --odr-deduplication is enabled.

Thus if above options are not specified the tool would enable them.

One other quick suggestion for the "bfd" value for the "--tombstone" option, should we state that the value is zero? Or maybe even change "bfd" to "zero"?

Following is the description for bfd value from documentation section:

- `bfd`: zero for all addresses and [1,1] for DWARF v4 (or less) address ranges.

Do you think this description should be changed?

[clayborg]

In D86539#3639533, @avl wrote:

@clayborg @jhenderson Thank you and all for the review!

In D86539#3637202, @clayborg wrote:

What will this tool do if the "--odr-deduplication" and "--garbage-collection" are not specified?

The default state for --garbage-collection is enabled.
The default state for --odr-deduplication is enabled.

Ah, these take a value like "--garbage-collection=0" or "--garbage-collection=1"? Then this is ok.

Thus if above options are not specified the tool would enable them.

One other quick suggestion for the "bfd" value for the "--tombstone" option, should we state that the value is zero? Or maybe even change "bfd" to "zero"?

Following is the description for bfd value from documentation section:

- `bfd`: zero for all addresses and [1,1] for DWARF v4 (or less) address ranges.

Do you think this description should be changed?

We currently have:

=bfd                  -   BFD default value.
=maxpc             -   Max PC values(-1/-2).

I was suggesting just adding something like:

=bfd                  -   BFD default value (0).
=maxpc             -   Max PC values (-1/-2).

[MaskRay]

In D86539#3640104, @clayborg wrote:

In D86539#3639533, @avl wrote:

@clayborg @jhenderson Thank you and all for the review!

In D86539#3637202, @clayborg wrote:

What will this tool do if the "--odr-deduplication" and "--garbage-collection" are not specified?

The default state for --garbage-collection is enabled.
The default state for --odr-deduplication is enabled.

Ah, these take a value like "--garbage-collection=0" or "--garbage-collection=1"? Then this is ok.

For user-facing utilities, the convention is --(no-)?foobar. It seems that --(no-)?garbage-collection is implemented in this patch, which is nice.

[avl]

In D86539#3640104, @clayborg wrote:

In D86539#3639533, @avl wrote:

@clayborg @jhenderson Thank you and all for the review!

In D86539#3637202, @clayborg wrote:

What will this tool do if the "--odr-deduplication" and "--garbage-collection" are not specified?

The default state for --garbage-collection is enabled.
The default state for --odr-deduplication is enabled.

Ah, these take a value like "--garbage-collection=0" or "--garbage-collection=1"? Then this is ok.

not exactly. These are in form --[no-]garbage-collection.

Thus if above options are not specified the tool would enable them.

One other quick suggestion for the "bfd" value for the "--tombstone" option, should we state that the value is zero? Or maybe even change "bfd" to "zero"?

Following is the description for bfd value from documentation section:

- `bfd`: zero for all addresses and [1,1] for DWARF v4 (or less) address ranges.

Do you think this description should be changed?

We currently have:

=bfd                  -   BFD default value.
=maxpc             -   Max PC values(-1/-2).

I was suggesting just adding something like:

=bfd                  -   BFD default value (0).
=maxpc             -   Max PC values (-1/-2).

Oh, this is about review summary, which is a bit outdated. Previously, It matched with text shown by --help option. But current llvm-dwarfutil shows shorter variant:

--tombstone [bfd,maxpc,exec,universal]
                        Tombstone value used as a marker of invalid address(default: universal)

I will add descriptions for --tombstone values for 'help' output back and make them match with command line guide(
llvm-dwarfutil.rst) and update review summary:

--tombstone [bfd,maxpc,exec,universal]
                        Tombstone value used as a marker of invalid address(default: universal)

  =bfd            -  zero for all addresses and [1,1] for DWARF v4 (or less) address ranges, and exec.
  =maxpc       -  -1 for all addresses and -2 for DWARF v4 (or less) address ranges.
  =exec          - match with address ranges of executable sections.
  =universal   -   Both: bfd and maxpc.

[avl]

added descriptions for --tombstone option values into help output.

[thakis]

llvm/tools/llvm-dwarfutil/CMakeLists.txt

7

Since you link to this, do you still need the AllTargets* below? Isn't LLVM_TARGETS_TO_BUILD a superset?

[avl]

llvm/tools/llvm-dwarfutil/CMakeLists.txt

7

Indeed. Thank you for the catch! Will remove AllTargets* below.

[thakis]

llvm/tools/llvm-dwarfutil/CMakeLists.txt

7

Did you have a chance to try this? Did it not work?

[avl]

llvm/tools/llvm-dwarfutil/CMakeLists.txt

7

I was busy with other tasks, sorry. Will do this tomorrow.

llvm/docs/CommandGuide/llvm-dwarfutil.rst

+llvm-dwarfutil - A tool to copy and manipulate debug info
+=========================================================
+
+.. program:: llvm-dwarfutil
+
+SYNOPSIS
+--------
+
+:program:`llvm-dwarfutil` [*options*] *input* *output*
+
+DESCRIPTION
+-----------
+
+:program:`llvm-dwarfutil` is a tool to copy and manipulate debug info.
+
+In basic usage, it makes a semantic copy of the input to the output. If any
+options are specified, the output may be modified along the way, e.g.
+by removing unused debug info.
+
+If "-" is specified for the input file, the input is read from the program's
+standard input stream. If "-" is specified for the output file, the output
+is written to the standard output stream of the program.
+
+The tool is still in active development.
+
+COMMAND-LINE OPTIONS
+--------------------
+
+.. option:: --garbage-collection
+
+ Removes pieces of debug information related to discarded sections.
+ When the linker does section garbage collection the abandoned debug info
+ is left behind. Such abandoned debug info references address ranges using
+ tombstone values. Thus, when this option is specified, the tool removes
+ debug info which is marked with the tombstone value.
+
+ That option is enabled by default.
+
+.. option:: --odr-deduplication
+
+ Remove duplicated types (if "One Definition Rule" is supported by source
+ language). Keeps first type definition and removes other definitions,
+ potentially significantly reducing the size of output debug info.
+
+ That option is enabled by default.
+
+.. option:: --help, -h
+
+ Print a summary of command line options.
+
+.. option:: --no-garbage-collection
+
+ Disable :option:`--garbage-collection`.
+
+.. option:: --no-odr-deduplication
+
+ Disable :option:`--odr-deduplication`.
+
+.. option:: --no-separate-debug-file
+
+ Disable :option:`--separate-debug-file`.
+
+.. option:: --num-threads=<n>, -j
+
+ Specifies the maximum number (`n`) of simultaneous threads to use
+ for processing.
+
+.. option:: --separate-debug-file
+
+ Generate separate file containing output debug info. Using
+ :program:`llvm-dwarfutil` with that option equals to the
+ following set of commands:
+
+.. code-block:: console
+
+ :program:`llvm-objcopy` --only-keep-debug in-file out-file.debug
+ :program:`llvm-objcopy` --strip-debug in-file out-file
+ :program:`llvm-objcopy` --add-gnu-debuglink=out-file.debug out-file
+
+.. option:: --tombstone=<value>
+
+ <value> can be one of the following values:
+
+   - `bfd`: zero for all addresses and [1,1] for DWARF v4 (or less) address
+          ranges.
+
+   - `maxpc`: -1 for all addresses and -2 for DWARF v4 (or less) address ranges.
+
+   - `universal`: both `bfd` and `maxpc`.
+
+   - `exec`: match with address ranges of executable sections.
+
+   The value `universal` is used by default.
+
+.. option:: --verbose
+
+ Enable verbose logging.
+
+.. option:: --verify
+
+ Run the DWARF verifier on the output DWARF debug info.
+
+.. option:: --version
+
+ Print the version of this program.
+
+SUPPORTED FORMATS
+-----------------
+
+The following formats are currently supported by :program:`llvm-dwarfutil`:
+
+ELF
+
+EXIT STATUS
+-----------
+
+:program:`llvm-dwarfutil` exits with a non-zero exit code if there is an error.
+Otherwise, it exits with code 0.
+
+BUGS
+----
+
+To report bugs, please visit <https://github.com/llvm/llvm-project/labels/tools:llvm-dwarfutil/>.

llvm/include/llvm/DWARFLinker/DWARFLinker.h

 class DataExtractor;
 class DeclContextTree;
 struct MCDwarfLineTableParams;
 template <typename T> class SmallVectorImpl;
 
 enum class DwarfLinkerClient { Dsymutil, LLD, General };
 
 /// The kind of accelerator tables we should emit.
-enum class AccelTableKind {
+enum class DwarfLinkerAccelTableKind : uint8_t {
+  None,
   Apple,   ///< .apple_names, .apple_namespaces, .apple_types, .apple_objc.
   Dwarf,   ///< DWARF v5 .debug_names.
   Default, ///< Dwarf for DWARF5 or later, Apple otherwise.
   Pub,     ///< .debug_pubnames, .debug_pubtypes
 };
 
 /// Partial address range. Besides an offset, only the
 /// HighPC is stored. The structure is stored in a map where the LowPC is the

 /// AddressesMap represents information about valid addresses used
 /// by debug information. Valid addresses are those which points to
 /// live code sections. i.e. relocations for these addresses point
 /// into sections which would be/are placed into resulting binary.
 class AddressesMap {
 public:
   virtual ~AddressesMap();
 
-  /// Returns true if represented addresses are from linked file.
-  /// Returns false if represented addresses are from not-linked
-  /// object file.
-  virtual bool areRelocationsResolved() const = 0;
-
   /// Checks that there are valid relocations against a .debug_info
   /// section.
   virtual bool hasValidRelocs() = 0;
 
-  /// Checks that the specified DIE has a DW_AT_Location attribute
-  /// that references into a live code section.
-  ///
+  /// Checks that the specified variable \p DIE references live code section.
+  /// Allowed kind of input die: DW_TAG_variable, DW_TAG_constant.
   /// \returns true and sets Info.InDebugMap if it is the case.
-  virtual bool hasLiveMemoryLocation(const DWARFDie &DIE,
-                                     CompileUnit::DIEInfo &Info) = 0;
+  virtual bool isLiveVariable(const DWARFDie &DIE,
 
-  /// Checks that the specified DIE has a DW_AT_Low_pc attribute
-  /// that references into a live code section.
-  ///
+  /// Checks that the specified subprogram \p DIE references live code section.
+  /// Allowed kind of input die: DW_TAG_subprogram, DW_TAG_label.
   /// \returns true and sets Info.InDebugMap if it is the case.
-  virtual bool hasLiveAddressRange(const DWARFDie &DIE,
-                                   CompileUnit::DIEInfo &Info) = 0;
+  virtual bool isLiveSubprogram(const DWARFDie &DIE,
 
   /// Apply the valid relocations to the buffer \p Data, taking into
   /// account that Data is at \p BaseOffset in the .debug_info section.
   ///
   /// \returns true whether any reloc has been applied.
   virtual bool applyValidRelocs(MutableArrayRef<char> Data, uint64_t BaseOffset,
                                 bool IsLittleEndian) = 0;
 
public:
   void setKeepFunctionForStatic(bool KeepFunctionForStatic) {
     Options.KeepFunctionForStatic = KeepFunctionForStatic;
   }
 
   /// Use specified number of threads for parallel files linking.
   void setNumThreads(unsigned NumThreads) { Options.Threads = NumThreads; }
 
   /// Set kind of accelerator tables to be generated.
-  void setAccelTableKind(AccelTableKind Kind) {
+  void setAccelTableKind(DwarfLinkerAccelTableKind Kind) {
     Options.TheAccelTableKind = Kind;
   }
 
   /// Set prepend path for clang modules.
   void setPrependPath(const std::string &Ppath) { Options.PrependPath = Ppath; }
 
   /// Set translator which would be used for strings.
   void
enum class WorklistItemType {
     /// Given a DIE, look for parent DIEs to be kept.
     LookForParentDIEsToKeep,
     /// Given a DIE, update its incompleteness based on whether its children are
     /// incomplete.
     UpdateChildIncompleteness,
     /// Given a DIE, update its incompleteness based on whether the DIEs it
     /// references are incomplete.
     UpdateRefIncompleteness,
+    /// Given a DIE, mark it as ODR Canonical if applicable.
+    MarkODRCanonicalDie,
   };
 
   /// This class represents an item in the work list. The type defines what kind
   /// of work needs to be performed when processing the current item. The flags
   /// and info fields are optional based on the type.
   struct WorklistItem {
     DWARFDie Die;
     WorklistItemType Type;
private:
 
   /// Look at DIEs referenced by the given DIE and decide whether they should be
   /// kept. All DIEs referenced though attributes should be kept.
   void lookForRefDIEsToKeep(const DWARFDie &Die, CompileUnit &CU,
                             unsigned Flags, const UnitListTy &Units,
                             const DWARFFile &File,
                             SmallVectorImpl<WorklistItem> &Worklist);
 
+  /// Mark context corresponding to the specified \p Die as having canonical
+  /// die, if applicable.
+  void markODRCanonicalDie(const DWARFDie &Die, CompileUnit &CU);
+
   /// \defgroup FindRootDIEs Find DIEs corresponding to Address map entries.
   ///
   /// @{
   /// Recursively walk the \p DIE tree and look for DIEs to
   /// keep. Store that information in \p CU's DIEInfo.
   ///
   /// The return value indicates whether the DIE is incomplete.
   void lookForDIEsToKeep(AddressesMap &RelocMgr, RangesTy &Ranges,
struct DWARFLinkerOptions {
     /// Whether we want a static variable to force us to keep its enclosing
     /// function.
     bool KeepFunctionForStatic = false;
 
     /// Number of threads.
     unsigned Threads = 1;
 
     /// The accelerator table kind
-    AccelTableKind TheAccelTableKind = AccelTableKind::Default;
+    DwarfLinkerAccelTableKind TheAccelTableKind =
+        DwarfLinkerAccelTableKind::Default;
 
     /// Prepend path for the clang modules.
     std::string PrependPath;
 
     // warning handler
     messageHandler WarningHandler = nullptr;
 
     // error handler

llvm/include/llvm/DWARFLinker/DWARFLinkerCompileUnit.h

struct DIEInfo {
     /// Was this DIE's entity found in the map?
     bool InDebugMap : 1;
 
     /// Is this a pure forward declaration we can strip?
     bool Prune : 1;
 
     /// Does DIE transitively refer an incomplete decl?
     bool Incomplete : 1;
+
+    /// Is DIE in the clang module scope?
+    bool InModuleScope : 1;
+
+    /// Is ODR marking done?
+    bool ODRMarkingDone : 1;
   };
 
   CompileUnit(DWARFUnit &OrigUnit, unsigned ID, bool CanUseODR,
               StringRef ClangModuleName)
       : OrigUnit(OrigUnit), ID(ID), Ranges(RangeAlloc),
         ClangModuleName(ClangModuleName) {
     Info.resize(OrigUnit.getNumDIEs());
 
public:
   /// Add the low_pc of a label that is relocated by applying
   /// offset \p PCOffset.
   void addLabelLowPc(uint64_t LabelLowPc, int64_t PcOffset);
 
   /// Add a function range [\p LowPC, \p HighPC) that is relocated by applying
   /// offset \p PCOffset.
   void addFunctionRange(uint64_t LowPC, uint64_t HighPC, int64_t PCOffset);
 
+  /// Check whether specified address range \p LowPC \p HighPC
+  /// overlaps with existing function ranges.
+  bool overlapsWithFunctionRanges(uint64_t LowPC, uint64_t HighPC);
+
   /// Keep track of a DW_AT_range attribute that we will need to patch up later.
   void noteRangeAttribute(const DIE &Die, PatchLocation Attr);
 
   /// Keep track of a location attribute pointing to a location list in the
   /// debug_loc section.
   void noteLocationAttribute(PatchLocation Attr, int64_t PcOffset);
 
   /// Add a name accelerator entry for \a Die with \a Name.

llvm/include/llvm/DWARFLinker/DWARFLinkerDeclContext.h

DeclContext(unsigned Hash, uint32_t Line, uint32_t ByteSize, uint16_t Tag,
       : QualifiedNameHash(Hash), Line(Line), ByteSize(ByteSize), Tag(Tag),
         DefinedInClangModule(0), Name(Name), File(File), Parent(Parent),
         LastSeenDIE(LastSeenDIE), LastSeenCompileUnitID(CUId) {}
 
   uint32_t getQualifiedNameHash() const { return QualifiedNameHash; }
 
   bool setLastSeenDIE(CompileUnit &U, const DWARFDie &Die);
 
+  void setHasCanonicalDIE() { HasCanonicalDIE = true; }
+
+  bool hasCanonicalDIE() const { return HasCanonicalDIE; }
+
   uint32_t getCanonicalDIEOffset() const { return CanonicalDIEOffset; }
   void setCanonicalDIEOffset(uint32_t Offset) { CanonicalDIEOffset = Offset; }
 
   bool isDefinedInClangModule() const { return DefinedInClangModule; }
   void setDefinedInClangModule(bool Val) { DefinedInClangModule = Val; }
 
   uint16_t getTag() const { return Tag; }
 
 private:
   friend DeclMapInfo;
 
   unsigned QualifiedNameHash = 0;
   uint32_t Line = 0;
   uint32_t ByteSize = 0;
   uint16_t Tag = dwarf::DW_TAG_compile_unit;
   unsigned DefinedInClangModule : 1;
   StringRef Name;
   StringRef File;
   const DeclContext &Parent;
   DWARFDie LastSeenDIE;
   uint32_t LastSeenCompileUnitID = 0;
   uint32_t CanonicalDIEOffset = 0;
+  bool HasCanonicalDIE = false;
 };
 
 /// This class gives a tree-like API to the DenseMap that stores the
 /// DeclContext objects. It holds the BumpPtrAllocator where these objects will
 /// be allocated.
 class DeclContextTree {
 public:
   /// Get the child of \a Context described by \a DIE in \a Unit. The

llvm/lib/DWARFLinker/DWARFLinker.cpp

struct ContextWorklistItem {
 
   ContextWorklistItem(DWARFDie Die, DeclContext *Context, unsigned ParentIdx,
                       bool InImportedModule)
       : Die(Die), ParentIdx(ParentIdx), Context(Context),
         Type(ContextWorklistItemType::AnalyzeContextInfo),
         InImportedModule(InImportedModule) {}
 };
 
-static bool updatePruning(const DWARFDie &Die, CompileUnit &CU,
-                          uint64_t ModulesEndOffset) {
+static bool updatePruning(const DWARFDie &Die, CompileUnit &CU) {
   CompileUnit::DIEInfo &Info = CU.getInfo(Die);
 
   // Prune this DIE if it is either a forward declaration inside a
   // DW_TAG_module or a DW_TAG_module that contains nothing but
   // forward declarations.
   Info.Prune &= (Die.getTag() == dwarf::DW_TAG_module) ||
                 (isTypeTag(Die.getTag()) &&
                  dwarf::toUnsigned(Die.find(dwarf::DW_AT_declaration), 0));
 
   // Only prune forward declarations inside a DW_TAG_module for which a
   // definition exists elsewhere.
-  if (ModulesEndOffset == 0)
-    Info.Prune &= Info.Ctxt && Info.Ctxt->getCanonicalDIEOffset();
-  else
-    Info.Prune &= Info.Ctxt && Info.Ctxt->getCanonicalDIEOffset() > 0 &&
-                  Info.Ctxt->getCanonicalDIEOffset() <= ModulesEndOffset;
+  Info.Prune &= Info.Ctxt && Info.Ctxt->hasCanonicalDIE();
 
   return Info.Prune;
 }
 
 static void updateChildPruning(const DWARFDie &Die, CompileUnit &CU,
                                CompileUnit::DIEInfo &ChildInfo) {
   CompileUnit::DIEInfo &Info = CU.getInfo(Die);
   Info.Prune &= ChildInfo.Prune;
 }
 
 /// Recursive helper to build the global DeclContext information and
 /// gather the child->parent relationships in the original compile unit.
 ///
 /// This function uses the same work list approach as lookForDIEsToKeep.
 ///
 /// \return true when this DIE and all of its children are only
 /// forward declarations to types defined in external clang modules
 /// (i.e., forward declarations that are children of a DW_TAG_module).
 static bool analyzeContextInfo(
     const DWARFDie &DIE, unsigned ParentIdx, CompileUnit &CU,
     DeclContext *CurrentDeclContext, DeclContextTree &Contexts,
-    uint64_t ModulesEndOffset, swiftInterfacesMap *ParseableSwiftInterfaces,
+    swiftInterfacesMap *ParseableSwiftInterfaces,
     std::function<void(const Twine &, const DWARFDie &)> ReportWarning,
     bool InImportedModule = false) {
   // LIFO work list.
   std::vector<ContextWorklistItem> Worklist;
   Worklist.emplace_back(DIE, CurrentDeclContext, ParentIdx, InImportedModule);
 
   while (!Worklist.empty()) {
     ContextWorklistItem Current = Worklist.back();
     Worklist.pop_back();
 
     switch (Current.Type) {
     case ContextWorklistItemType::UpdatePruning:
-      updatePruning(Current.Die, CU, ModulesEndOffset);
+      updatePruning(Current.Die, CU);
       continue;
     case ContextWorklistItemType::UpdateChildPruning:
       updateChildPruning(Current.Die, CU, *Current.OtherInfo);
       continue;
     case ContextWorklistItemType::AnalyzeContextInfo:
       break;
     }
 
if (Current.Die.getTag() == dwarf::DW_TAG_module &&
         dwarf::toString(Current.Die.find(dwarf::DW_AT_name), "") !=
             CU.getClangModuleName()) {
       Current.InImportedModule = true;
       analyzeImportedModule(Current.Die, CU, ParseableSwiftInterfaces,
                             ReportWarning);
     }
 
     Info.ParentIdx = Current.ParentIdx;
-    bool InClangModule = CU.isClangModule() || Current.InImportedModule;
-    if (CU.hasODR() || InClangModule) {
+    Info.InModuleScope = CU.isClangModule() || Current.InImportedModule;
+    if (CU.hasODR() || Info.InModuleScope) {
       if (Current.Context) {
         auto PtrInvalidPair = Contexts.getChildDeclContext(
-            *Current.Context, Current.Die, CU, InClangModule);
+            *Current.Context, Current.Die, CU, Info.InModuleScope);
         Current.Context = PtrInvalidPair.getPointer();
         Info.Ctxt =
             PtrInvalidPair.getInt() ? nullptr : PtrInvalidPair.getPointer();
         if (Info.Ctxt)
-          Info.Ctxt->setDefinedInClangModule(InClangModule);
+          Info.Ctxt->setDefinedInClangModule(Info.InModuleScope);
       } else
         Info.Ctxt = Current.Context = nullptr;
     }
 
     Info.Prune = Current.InImportedModule;
     // Add children in reverse order to the worklist to effectively process
     // them in order.
     Worklist.emplace_back(Current.Die, ContextWorklistItemType::UpdatePruning);
if (!(Flags & TF_InFunctionScope) &&
     return Flags | TF_Keep;
   }
 
   // See if there is a relocation to a valid debug map entry inside this
   // variable's location. The order is important here. We want to always check
   // if the variable has a valid relocation, so that the DIEInfo is filled.
   // However, we don't want a static variable in a function to force us to keep
   // the enclosing function, unless requested explicitly.
-  const bool HasLiveMemoryLocation =
-      RelocMgr.hasLiveMemoryLocation(DIE, MyInfo);
-  if (!HasLiveMemoryLocation || ((Flags & TF_InFunctionScope) &&
-                                 !LLVM_UNLIKELY(Options.KeepFunctionForStatic)))
+  const bool HasLiveVariable = RelocMgr.isLiveVariable(DIE, MyInfo);
+  if (!HasLiveVariable || ((Flags & TF_InFunctionScope) &&
     return Flags;
 
   if (Options.Verbose) {
     outs() << "Keeping variable DIE:";
     DIDumpOptions DumpOpts;
     DumpOpts.ChildRecurseDepth = 0;
     DumpOpts.Verbose = Options.Verbose;
     DIE.dump(outs(), 8 /* Indent */, DumpOpts);
unsigned DWARFLinker::shouldKeepSubprogramDIE(
     unsigned Flags) {
   Flags |= TF_InFunctionScope;
 
   auto LowPc = dwarf::toAddress(DIE.find(dwarf::DW_AT_low_pc));
   if (!LowPc)
     return Flags;
 
   assert(LowPc.hasValue() && "low_pc attribute is not an address.");
-  if (!RelocMgr.hasLiveAddressRange(DIE, MyInfo))
+  if (!RelocMgr.isLiveSubprogram(DIE, MyInfo))
     return Flags;
 
   if (Options.Verbose) {
     outs() << "Keeping subprogram DIE:";
     DIDumpOptions DumpOpts;
     DumpOpts.ChildRecurseDepth = 0;
     DumpOpts.Verbose = Options.Verbose;
     DIE.dump(outs(), 8 /* Indent */, DumpOpts);
unsigned DWARFLinker::shouldKeepSubprogramDIE(
 
   Optional<uint64_t> HighPc = DIE.getHighPC(*LowPc);
   if (!HighPc) {
     reportWarning("Function without high_pc. Range will be discarded.\n", File,
                   &DIE);
     return Flags;
   }
 
+  if (Unit.overlapsWithFunctionRanges(*LowPc, *HighPc)) {
+    reportWarning(
+        formatv("Overlapping address range [{0:X}, {1:X}]. Range will "
+                "be discarded.\n",
+                *LowPc, *HighPc),
+        File, &DIE);
+    return Flags;
+  }
+
   // Replace the debug map range with a more accurate one.
   Ranges[*LowPc] = ObjFileAddressRange(*HighPc, MyInfo.AddrAdjust);
   Unit.addFunctionRange(*LowPc, *HighPc, MyInfo.AddrAdjust);
   return Flags;
 }
 
 /// Check if a DIE should be kept.
 /// \returns updated TraversalFlags.
for (auto Child : reverse(Die.children())) {
     // after the current child is processed.
     CompileUnit::DIEInfo &ChildInfo = CU.getInfo(Child);
     Worklist.emplace_back(Die, CU, WorklistItemType::UpdateChildIncompleteness,
                           &ChildInfo);
     Worklist.emplace_back(Child, CU, Flags);
   }
 }
 
+static bool isODRCanonicalCandidate(const DWARFDie &Die, CompileUnit &CU) {
+  CompileUnit::DIEInfo &Info = CU.getInfo(Die);
+
+  if (!Info.Ctxt || (Die.getTag() == dwarf::DW_TAG_namespace))
+    return false;
+
+  if (!CU.hasODR() && !Info.InModuleScope)
+    return false;
+
+  return !Info.Incomplete && Info.Ctxt != CU.getInfo(Info.ParentIdx).Ctxt;
+}
+
+void DWARFLinker::markODRCanonicalDie(const DWARFDie &Die, CompileUnit &CU) {
+  CompileUnit::DIEInfo &Info = CU.getInfo(Die);
+
+  Info.ODRMarkingDone = true;
+  if (Info.Keep && isODRCanonicalCandidate(Die, CU) &&
+      !Info.Ctxt->hasCanonicalDIE())
+    Info.Ctxt->setHasCanonicalDIE();
+}
+
 /// Look at DIEs referenced by the given DIE and decide whether they should be
 /// kept. All DIEs referenced though attributes should be kept.
 void DWARFLinker::lookForRefDIEsToKeep(
     const DWARFDie &Die, CompileUnit &CU, unsigned Flags,
     const UnitListTy &Units, const DWARFFile &File,
     SmallVectorImpl<WorklistItem> &Worklist) {
   bool UseOdr = (Flags & DWARFLinker::TF_DependencyWalk)
                     ? (Flags & DWARFLinker::TF_ODR)
if (!Val.isFormClass(DWARFFormValue::FC_Reference) ||
       continue;
     }
 
     Val.extractValue(Data, &Offset, Unit.getFormParams(), &Unit);
     CompileUnit *ReferencedCU;
     if (auto RefDie =
             resolveDIEReference(File, Units, Val, Die, ReferencedCU)) {
       CompileUnit::DIEInfo &Info = ReferencedCU->getInfo(RefDie);
-      bool IsModuleRef = Info.Ctxt && Info.Ctxt->getCanonicalDIEOffset() &&
-                         Info.Ctxt->isDefinedInClangModule();
       // If the referenced DIE has a DeclContext that has already been
       // emitted, then do not keep the one in this CU. We'll link to
       // the canonical DIE in cloneDieReferenceAttribute.
       //
       // FIXME: compatibility with dsymutil-classic. UseODR shouldn't
       // be necessary and could be advantageously replaced by
       // ReferencedCU->hasODR() && CU.hasODR().
       //
       // FIXME: compatibility with dsymutil-classic. There is no
       // reason not to unique ref_addr references.
-      if (AttrSpec.Form != dwarf::DW_FORM_ref_addr && (UseOdr || IsModuleRef) &&
-          Info.Ctxt &&
-          Info.Ctxt != ReferencedCU->getInfo(Info.ParentIdx).Ctxt &&
-          Info.Ctxt->getCanonicalDIEOffset() && isODRAttribute(AttrSpec.Attr))
+      if (AttrSpec.Form != dwarf::DW_FORM_ref_addr &&
+          isODRAttribute(AttrSpec.Attr) && Info.Ctxt &&
+          Info.Ctxt->hasCanonicalDIE())
         continue;
 
       // Keep a module forward declaration if there is no definition.
       if (!(isODRAttribute(AttrSpec.Attr) && Info.Ctxt &&
-            Info.Ctxt->getCanonicalDIEOffset()))
+            Info.Ctxt->hasCanonicalDIE()))
         Info.Prune = false;
       ReferencedDIEs.emplace_back(RefDie, *ReferencedCU);
     }
   }
 
   unsigned ODRFlag = UseOdr ? DWARFLinker::TF_ODR : 0;
 
   // Add referenced DIEs in reverse order to the worklist to effectively
while (!Worklist.empty()) {
     case WorklistItemType::LookForRefDIEsToKeep:
       lookForRefDIEsToKeep(Current.Die, Current.CU, Current.Flags, Units, File,
                            Worklist);
       continue;
     case WorklistItemType::LookForParentDIEsToKeep:
       lookForParentDIEsToKeep(Current.AncestorIdx, Current.CU, Current.Flags,
                               Worklist);
       continue;
+    case WorklistItemType::MarkODRCanonicalDie:
+      markODRCanonicalDie(Current.Die, Current.CU);
+      continue;
     case WorklistItemType::LookForDIEsToKeep:
       break;
     }
 
     unsigned Idx = Current.CU.getOrigUnit().getDIEIndex(Current.Die);
     CompileUnit::DIEInfo &MyInfo = Current.CU.getInfo(Idx);
 
     if (MyInfo.Prune)
       continue;
 
     // If the Keep flag is set, we are marking a required DIE's dependencies.
     // If our target is already marked as kept, we're all set.
     bool AlreadyKept = MyInfo.Keep;
     if ((Current.Flags & TF_DependencyWalk) && AlreadyKept)
       continue;
 
     // We must not call shouldKeepDIE while called from keepDIEAndDependencies,
     // because it would screw up the relocation finding logic.
     if (!(Current.Flags & TF_DependencyWalk))
       Current.Flags = shouldKeepDIE(AddressesMap, Ranges, Current.Die, File,
                                     Current.CU, MyInfo, Current.Flags);
 
+    // We need to mark context for the canonical die in the end of normal
+    // traversing(not TF_DependencyWalk) or after normal traversing if die
+    // was not marked as kept.
+    if (!(Current.Flags & TF_DependencyWalk) ||
+        (MyInfo.ODRMarkingDone && !MyInfo.Keep)) {
+      if (Current.CU.hasODR() || MyInfo.InModuleScope)
+        Worklist.emplace_back(Current.Die, Current.CU,
+                              WorklistItemType::MarkODRCanonicalDie);
+    }
+
     // Finish by looking for child DIEs. Because of the LIFO worklist we need
     // to schedule that work before any subsequent items are added to the
     // worklist.
     Worklist.emplace_back(Current.Die, Current.CU, Current.Flags,
                           WorklistItemType::LookForChildDIEsToKeep);
 
     if (AlreadyKept || !(Current.Flags & TF_Keep))
       continue;
unsigned DWARFLinker::DIECloner::cloneDieReferenceAttribute(
     DIE &Die, const DWARFDie &InputDIE, AttributeSpec AttrSpec,
     unsigned AttrSize, const DWARFFormValue &Val, const DWARFFile &File,
     CompileUnit &Unit) {
   const DWARFUnit &U = Unit.getOrigUnit();
   uint64_t Ref = *Val.getAsReference();
 
   DIE *NewRefDie = nullptr;
   CompileUnit *RefUnit = nullptr;
-  DeclContext *Ctxt = nullptr;
 
   DWARFDie RefDie =
       Linker.resolveDIEReference(File, CompileUnits, Val, InputDIE, RefUnit);
 
   // If the referenced DIE is not found,  drop the attribute.
   if (!RefDie || AttrSpec.Attr == dwarf::DW_AT_sibling)
     return 0;
 
   CompileUnit::DIEInfo &RefInfo = RefUnit->getInfo(RefDie);
 
   // If we already have emitted an equivalent DeclContext, just point
   // at it.
-  if (isODRAttribute(AttrSpec.Attr)) {
-    Ctxt = RefInfo.Ctxt;
-    if (Ctxt && Ctxt->getCanonicalDIEOffset()) {
-      DIEInteger Attr(Ctxt->getCanonicalDIEOffset());
-      Die.addValue(DIEAlloc, dwarf::Attribute(AttrSpec.Attr),
-                   dwarf::DW_FORM_ref_addr, Attr);
-      return U.getRefAddrByteSize();
-    }
-  }
+  if (isODRAttribute(AttrSpec.Attr) && RefInfo.Ctxt &&
+      RefInfo.Ctxt->getCanonicalDIEOffset()) {
+    assert(RefInfo.Ctxt->hasCanonicalDIE() &&
+           "Offset to canonical die is set, but context is not marked");
+    DIEInteger Attr(RefInfo.Ctxt->getCanonicalDIEOffset());
 
   if (!RefInfo.Clone) {
     assert(Ref > InputDIE.getOffset());
     // We haven't cloned this DIE yet. Just create an empty one and
     // store it. It'll get really cloned when we process it.
     RefInfo.Clone = DIE::get(DIEAlloc, dwarf::Tag(RefDie.getTag()));
   }
   NewRefDie = RefInfo.Clone;
if (Ref < InputDIE.getOffset()) {
           RefUnit->getStartOffset() + NewRefDie->getOffset();
       Attr = NewRefOffset;
       Die.addValue(DIEAlloc, dwarf::Attribute(AttrSpec.Attr),
                    dwarf::DW_FORM_ref_addr, DIEInteger(Attr));
     } else {
       // A forward reference. Note and fixup later.
       Attr = 0xBADDEF;
       Unit.noteForwardReference(
-          NewRefDie, RefUnit, Ctxt,
+          NewRefDie, RefUnit, RefInfo.Ctxt,
           Die.addValue(DIEAlloc, dwarf::Attribute(AttrSpec.Attr),
                        dwarf::DW_FORM_ref_addr, DIEInteger(Attr)));
     }
     return U.getRefAddrByteSize();
   }
 
   Die.addValue(DIEAlloc, dwarf::Attribute(AttrSpec.Attr),
                dwarf::Form(AttrSpec.Form), DIEEntry(*NewRefDie));
if (!Die) {
     // (see cloneDieReferenceAttribute()).
     if (!Info.Clone)
       Info.Clone = DIE::get(DIEAlloc, dwarf::Tag(InputDIE.getTag()));
     Die = Info.Clone;
   }
 
   assert(Die->getTag() == InputDIE.getTag());
   Die->setOffset(OutOffset);
-  if ((Unit.hasODR() || Unit.isClangModule()) && !Info.Incomplete &&
-      Die->getTag() != dwarf::DW_TAG_namespace && Info.Ctxt &&
-      Info.Ctxt != Unit.getInfo(Info.ParentIdx).Ctxt &&
-      !Info.Ctxt->getCanonicalDIEOffset()) {
+  if (isODRCanonicalCandidate(InputDIE, Unit) && Info.Ctxt &&
+      (Info.Ctxt->getCanonicalDIEOffset() == 0)) {
+    if (!Info.Ctxt->hasCanonicalDIE())
+      Info.Ctxt->setHasCanonicalDIE();
+
     // We are about to emit a DIE that is the root of its own valid
     // DeclContext tree. Make the current offset the canonical offset
     // for this context.
     Info.Ctxt->setCanonicalDIEOffset(OutOffset + Unit.getStartOffset());
   }
 
   // Extract and clone every attribute.
   DWARFDataExtractor Data = U.getDebugInfoExtractor();
   // Point to the next DIE (generally there is always at least a NULL
   // entry after the current one). If this is a lone
   // DW_TAG_compile_unit without any children, point to the next unit.
   uint64_t NextOffset = (Idx + 1 < U.getNumDIEs())
                             ? U.getDIEAtIndex(Idx + 1).getOffset()
                             : U.getNextUnitOffset();
   AttributesInfo AttrInfo;
 
   // We could copy the data only if we need to apply a relocation to it. After
   // testing, it seems there is no performance downside to doing the copy
   // unconditionally, and it makes the code simpler.
   SmallString<40> DIECopy(Data.getData().substr(Offset, NextOffset - Offset));
   Data =
       DWARFDataExtractor(DIECopy, Data.isLittleEndian(), Data.getAddressSize());
 
   // Modify the copy with relocated addresses.
-  if (ObjFile.Addresses->areRelocationsResolved() &&
-      ObjFile.Addresses->applyValidRelocs(DIECopy, Offset,
+  if (ObjFile.Addresses->applyValidRelocs(DIECopy, Offset,
                                           Data.isLittleEndian())) {
     // If we applied relocations, we store the value of high_pc that was
     // potentially stored in the input DIE. If high_pc is an address
     // (Dwarf version == 2), then it might have been relocated to a
     // totally unrelated value (because the end address in the object
     // file might be start address of another function which got moved
     // independently by the linker). The computation of the actual
     // high_pc value is done in cloneAddressAttribute().
TheDwarfEmitter->emitLineTableForUnit(
         Params, LineData.slice(*StmtList + 4, PrologueEnd),
         LineTable.Prologue.MinInstLength, NewRows,
         Unit.getOrigUnit().getAddressByteSize());
   }
 }
 
 void DWARFLinker::emitAcceleratorEntriesForUnit(CompileUnit &Unit) {
   switch (Options.TheAccelTableKind) {
-  case AccelTableKind::Apple:
+  case DwarfLinkerAccelTableKind::None:
+    // nothing to do.
+    break;
+  case DwarfLinkerAccelTableKind::Apple:
     emitAppleAcceleratorEntriesForUnit(Unit);
     break;
-  case AccelTableKind::Dwarf:
+  case DwarfLinkerAccelTableKind::Dwarf:
     emitDwarfAcceleratorEntriesForUnit(Unit);
     break;
-  case AccelTableKind::Pub:
+  case DwarfLinkerAccelTableKind::Pub:
     emitPubAcceleratorEntriesForUnit(Unit);
     break;
-  case AccelTableKind::Default:
+  case DwarfLinkerAccelTableKind::Default:
     llvm_unreachable("The default must be updated to a concrete value.");
     break;
   }
 }
 
 void DWARFLinker::emitAppleAcceleratorEntriesForUnit(CompileUnit &Unit) {
   // Add namespaces.
   for (const auto &Namespace : Unit.getNamespaces())
if (!registerModuleReference(CUDie, *CU, File, StringPool, ODRContexts,
         // Update the cache entry with the DwoId of the module loaded from disk.
         ClangModules[Filename] = PCMDwoId;
       }
 
       // Add this module.
       Unit = std::make_unique<CompileUnit>(*CU, UnitID++, !Options.NoODR,
                                            ModuleName);
       analyzeContextInfo(CUDie, 0, *Unit, &ODRContexts.getRoot(), ODRContexts,
-                         ModulesEndOffset, Options.ParseableSwiftInterfaces,
+                         Options.ParseableSwiftInterfaces,
                          [&](const Twine &Warning, const DWARFDie &DIE) {
                            reportWarning(Warning, File, &DIE);
                          });
       // Keep everything.
       Unit->markEverythingAsKept();
     }
   }
   assert(Unit && "CompileUnit is not set!");
for (auto &CurrentUnit : CompileUnits) {
              CurrentUnit->computeNextUnitOffset(DwarfVersion));
     }
   }
 
   return OutputDebugInfoSize - StartOutputDebugInfoSize;
 }
 
 void DWARFLinker::updateAccelKind(DWARFContext &Dwarf) {
-  if (Options.TheAccelTableKind != AccelTableKind::Default)
+  if (Options.TheAccelTableKind != DwarfLinkerAccelTableKind::Default)
     return;
 
   auto &DwarfObj = Dwarf.getDWARFObj();
 
   if (!AtLeastOneDwarfAccelTable &&
       (!DwarfObj.getAppleNamesSection().Data.empty() ||
        !DwarfObj.getAppleTypesSection().Data.empty() ||
        !DwarfObj.getAppleNamespacesSection().Data.empty() ||
bool DWARFLinker::link() {
   DeclContextTree ODRContexts;
 
   // If we haven't decided on an accelerator table kind yet, we base ourselves
   // on the DWARF we have seen so far. At this point we haven't pulled in debug
   // information from modules yet, so it is technically possible that they
   // would affect the decision. However, as they're built with the same
   // compiler and flags, it is safe to assume that they will follow the
   // decision made here.
-  if (Options.TheAccelTableKind == AccelTableKind::Default) {
+  if (Options.TheAccelTableKind == DwarfLinkerAccelTableKind::Default) {
     if (AtLeastOneDwarfAccelTable && !AtLeastOneAppleAccelTable)
-      Options.TheAccelTableKind = AccelTableKind::Dwarf;
+      Options.TheAccelTableKind = DwarfLinkerAccelTableKind::Dwarf;
     else
-      Options.TheAccelTableKind = AccelTableKind::Apple;
+      Options.TheAccelTableKind = DwarfLinkerAccelTableKind::Apple;
   }
 
   for (LinkContext &OptContext : ObjectContexts) {
     if (Options.Verbose) {
       if (DwarfLinkerClientID == DwarfLinkerClient::Dsymutil)
         outs() << "DEBUG MAP OBJECT: " << OptContext.File.FileName << "\n";
       else
         outs() << "OBJECT FILE: " << OptContext.File.FileName << "\n";
auto AnalyzeLambda = [&](size_t I) {
 
     // Now build the DIE parent links that we will use during the next phase.
     for (auto &CurrentUnit : Context.CompileUnits) {
       auto CUDie = CurrentUnit->getOrigUnit().getUnitDIE();
       if (!CUDie)
         continue;
       analyzeContextInfo(CurrentUnit->getOrigUnit().getUnitDIE(), 0,
                          *CurrentUnit, &ODRContexts.getRoot(), ODRContexts,
-                         ModulesEndOffset, Options.ParseableSwiftInterfaces,
+                         Options.ParseableSwiftInterfaces,
                          [&](const Twine &Warning, const DWARFDie &DIE) {
                            reportWarning(Warning, Context.File, &DIE);
                          });
     }
   };
 
   // For each object file map how many bytes were emitted.
   StringMap<DebugInfoSize> SizeByObject;
bool DWARFLinker::link() {
   };
 
   auto EmitLambda = [&]() {
     // Emit everything that's global.
     if (!Options.NoOutput) {
       TheDwarfEmitter->emitAbbrevs(Abbreviations, MaxDwarfVersion);
       TheDwarfEmitter->emitStrings(OffsetsStringPool);
       switch (Options.TheAccelTableKind) {
-      case AccelTableKind::Apple:
+      case DwarfLinkerAccelTableKind::None:
+        // nothing to do.
+        break;
+      case DwarfLinkerAccelTableKind::Apple:
         TheDwarfEmitter->emitAppleNames(AppleNames);
         TheDwarfEmitter->emitAppleNamespaces(AppleNamespaces);
         TheDwarfEmitter->emitAppleTypes(AppleTypes);
         TheDwarfEmitter->emitAppleObjc(AppleObjc);
         break;
-      case AccelTableKind::Dwarf:
+      case DwarfLinkerAccelTableKind::Dwarf:
         TheDwarfEmitter->emitDebugNames(DebugNames);
         break;
-      case AccelTableKind::Pub:
+      case DwarfLinkerAccelTableKind::Pub:
         // Already emitted by emitPubAcceleratorEntriesForUnit.
         break;
-      case AccelTableKind::Default:
+      case DwarfLinkerAccelTableKind::Default:
         llvm_unreachable("Default should have already been resolved.");
         break;
       }
     }
   };
 
   auto AnalyzeAll = [&]() {
     for (unsigned I = 0, E = NumObjects; I != E; ++I) {

llvm/lib/DWARFLinker/DWARFLinkerCompileUnit.cpp

 
 void CompileUnit::fixupForwardReferences() {
   for (const auto &Ref : ForwardDIEReferences) {
     DIE *RefDie;
     const CompileUnit *RefUnit;
     PatchLocation Attr;
     DeclContext *Ctxt;
     std::tie(RefDie, RefUnit, Ctxt, Attr) = Ref;
-    if (Ctxt && Ctxt->getCanonicalDIEOffset())
+    if (Ctxt && Ctxt->hasCanonicalDIE()) {
+      assert(Ctxt->getCanonicalDIEOffset() &&
+             "Canonical die offset is not set");
+
       Attr.set(Ctxt->getCanonicalDIEOffset());
-    else
+    } else
       Attr.set(RefDie->getOffset() + RefUnit->getStartOffset());
   }
 }
 
 void CompileUnit::addLabelLowPc(uint64_t LabelLowPc, int64_t PcOffset) {
   Labels.insert({LabelLowPc, PcOffset});
 }
 
 void CompileUnit::addFunctionRange(uint64_t FuncLowPc, uint64_t FuncHighPc,
                                    int64_t PcOffset) {
   //  Don't add empty ranges to the interval map.  They are a problem because
   //  the interval map expects half open intervals. This is safe because they
   //  are empty anyway.
   if (FuncHighPc != FuncLowPc)
     Ranges.insert(FuncLowPc, FuncHighPc, PcOffset);
   this->LowPc = std::min(LowPc, FuncLowPc + PcOffset);
   this->HighPc = std::max(HighPc, FuncHighPc + PcOffset);
 }
 
+bool CompileUnit::overlapsWithFunctionRanges(uint64_t LowPC, uint64_t HighPC) {
+  return Ranges.overlaps(LowPC, HighPC);
+}
+
 void CompileUnit::noteRangeAttribute(const DIE &Die, PatchLocation Attr) {
   if (Die.getTag() != dwarf::DW_TAG_compile_unit)
     RangeAttributes.push_back(Attr);
   else
     UnitRangeAttribute = Attr;
 }
 
 void CompileUnit::noteLocationAttribute(PatchLocation Attr, int64_t PcOffset) {

llvm/test/CMakeLists.txt

set(LLVM_TEST_DEPENDS
           llvm-cxxfilt
           llvm-cxxmap
           llvm-debuginfod-find
           llvm-diff
           llvm-dis
           llvm-dlltool
           dsymutil
           llvm-dwarfdump
+          llvm-dwarfutil
           llvm-dwp
           llvm-exegesis
           llvm-extract
           llvm-gsymutil
           llvm-isel-fuzzer
           llvm-ifs
           llvm-install-name-tool
           llvm-jitlink

llvm/test/lit.cfg.py

tools = [
     ToolSubst('%split-file', FindTool('split-file')),
 ]
 
 # FIXME: Why do we have both `lli` and `%lli` that do slightly different things?
 tools.extend([
     'dsymutil', 'lli', 'lli-child-target', 'llvm-ar', 'llvm-as',
     'llvm-addr2line', 'llvm-bcanalyzer', 'llvm-bitcode-strip', 'llvm-config',
     'llvm-cov', 'llvm-cxxdump', 'llvm-cvtres', 'llvm-debuginfod-find',
-    'llvm-diff', 'llvm-dis', 'llvm-dwarfdump', 'llvm-dlltool', 'llvm-exegesis',
-    'llvm-extract', 'llvm-isel-fuzzer', 'llvm-ifs',
+    'llvm-diff', 'llvm-dis', 'llvm-dwarfdump', 'llvm-dwarfutil', 'llvm-dlltool',
+    'llvm-exegesis', 'llvm-extract', 'llvm-isel-fuzzer', 'llvm-ifs',
     'llvm-install-name-tool', 'llvm-jitlink', 'llvm-opt-fuzzer', 'llvm-lib',
     'llvm-link', 'llvm-lto', 'llvm-lto2', 'llvm-mc', 'llvm-mca',
     'llvm-modextract', 'llvm-nm', 'llvm-objcopy', 'llvm-objdump', 'llvm-otool',
     'llvm-pdbutil', 'llvm-profdata', 'llvm-profgen', 'llvm-ranlib', 'llvm-rc', 'llvm-readelf',
     'llvm-readobj', 'llvm-remark-size-diff', 'llvm-rtdyld', 'llvm-sim',
     'llvm-size', 'llvm-split', 'llvm-stress', 'llvm-strings', 'llvm-strip',
     'llvm-tblgen', 'llvm-tapi-diff', 'llvm-undname', 'llvm-windres',
     'llvm-c-test', 'llvm-cxxfilt', 'llvm-xray', 'yaml2obj', 'obj2yaml',

llvm/test/tools/llvm-dwarfutil/ELF/Inputs/archive.a

+!<thin>
+//                                              20        `
+a-plus-b.a/
+c.txt/
+
+/0              0           0     0     644     202       `
+/12             0           0     0     644     11        `

llvm/test/tools/llvm-dwarfutil/ELF/copy-itself.test

+## This test checks that the debug info contained in the source file
+## is fully copied to the destination file when the source and
+## destination are the same file.
+
+## Check implicit --garbage-collection --no-separate-debug-file case.
+# RUN: yaml2obj %s -o %t1
+# RUN: llvm-dwarfutil %t1 %t1
+# RUN: llvm-dwarfdump -a %t1 | FileCheck --check-prefix=CHECK-DEBUG %s
+
+## Check implicit --garbage-collection and explicit --separate-debug-file.
+# RUN: yaml2obj %s -o %t1
+# RUN: llvm-dwarfutil %t1 --separate-debug-file %t1
+# RUN: llvm-objdump --headers %t1 | FileCheck --check-prefix=CHECK-NON-DEBUG %s
+# RUN: llvm-dwarfdump -a %t1.debug | FileCheck --check-prefix=CHECK-DEBUG %s
+
+## Check explicit --no-garbage-collection and implicit --no-separate-debug-file.
+# RUN: yaml2obj %s -o %t1
+# RUN: llvm-dwarfutil --no-garbage-collection %t4 %t4
+# RUN: llvm-dwarfdump -a %t1 | FileCheck --check-prefix=CHECK-DEBUG %s
+
+## Check explicit --no-garbage-collection and --separate-debug-file.
+# RUN: yaml2obj %s -o %t1
+# RUN: llvm-dwarfutil --no-garbage-collection %t1 --separate-debug-file %t1
+# RUN: llvm-objdump --headers %t1 | FileCheck --check-prefix=CHECK-NON-DEBUG %s
+# RUN: llvm-dwarfdump -a %t1.debug | FileCheck --check-prefix=CHECK-DEBUG %s
+
+# CHECK-NON-DEBUG-NOT: .debug_abbrev
+# CHECK-NON-DEBUG-NOT: .debug_info
+# CHECK-NON-DEBUG: .gnu_debuglink
+# CHECK-NON-DEBUG-NOT: .debug_abbrev
+# CHECK-NON-DEBUG-NOT: .debug_info
+
+
+# CHECK-DEBUG: .debug_abbrev
+# CHECK-DEBUG: DW_TAG_compile_unit
+# CHECK-DEBUG: .debug_info
+# CHECK-DEBUG: DW_TAG_compile_unit
+# CHECK-DEBUG: DW_AT_producer{{.*}}"by_hand"
+# CHECK-DEBUG: DW_AT_language{{.*}}DW_LANG_C_plus_plus
+# CHECK-DEBUG: DW_AT_name{{.*}}"CU1"
+# CHECK-DEBUG: DW_TAG_class_type
+# CHECK-DEBUG: DW_AT_name{{.*}}"class1"
+# CHECK-DEBUG: DW_TAG_base_type
+# CHECK-DEBUG: DW_AT_name{{.*}}"int"
+# CHECK-DEBUG: DW_AT_name{{.*}}"char"
+# CHECK-DEBUG: DW_AT_name{{.*}}"float"
+# CHECK-DEBUG: DW_TAG_pointer_type
+# CHECK-DEBUG: DW_TAG_variable
+# CHECK-DEBUG: DW_AT_name{{.*}}"var1"
+
+--- !ELF
+FileHeader:
+  Class:    ELFCLASS64
+  Data:     ELFDATA2LSB
+  Type:     ET_REL
+  Machine:  EM_X86_64
+Sections:
+  - Name:            .text
+    Type:            SHT_PROGBITS
+    Flags:           [ SHF_ALLOC, SHF_EXECINSTR ]
+    Address:         0x1000
+    AddressAlign:    0x0000000000000010
+    Content:        "FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF"
+DWARF:
+  debug_abbrev:
+    - Table:
+      - Tag:      DW_TAG_compile_unit
+        Children: DW_CHILDREN_yes
+        Attributes:
+          - Attribute: DW_AT_producer
+            Form:      DW_FORM_string
+          - Attribute: DW_AT_language
+            Form:      DW_FORM_data2
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+          - Attribute: DW_AT_low_pc
+            Form:      DW_FORM_addr
+          - Attribute: DW_AT_high_pc
+            Form:      DW_FORM_data8
+      - Tag:      DW_TAG_class_type
+        Children: DW_CHILDREN_yes
+        Attributes:
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+      - Tag:      DW_TAG_member
+        Children: DW_CHILDREN_no
+        Attributes:
+          - Attribute: DW_AT_type
+            Form:      DW_FORM_ref4
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+      - Tag:      DW_TAG_class_type
+        Children: DW_CHILDREN_no
+        Attributes:
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+          - Attribute: DW_AT_declaration
+            Form:      DW_FORM_flag_present
+      - Tag:      DW_TAG_class_type
+        Children: DW_CHILDREN_yes
+        Attributes:
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+          - Attribute: DW_AT_declaration
+            Form:      DW_FORM_flag_present
+      - Tag:      DW_TAG_template_type_parameter
+        Children: DW_CHILDREN_no
+        Attributes:
+          - Attribute: DW_AT_type
+            Form:      DW_FORM_ref4
+      - Tag:      DW_TAG_base_type
+        Children: DW_CHILDREN_no
+        Attributes:
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+      - Tag:      DW_TAG_pointer_type
+        Children: DW_CHILDREN_no
+        Attributes:
+          - Attribute: DW_AT_type
+            Form:      DW_FORM_ref4
+      - Tag:      DW_TAG_variable
+        Children: DW_CHILDREN_no
+        Attributes:
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+          - Attribute: DW_AT_const_value
+            Form:      DW_FORM_data4
+          - Attribute: DW_AT_type
+            Form:      DW_FORM_ref4
+      - Tag:      DW_TAG_subprogram
+        Children: DW_CHILDREN_no
+        Attributes:
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+          - Attribute: DW_AT_low_pc
+            Form:      DW_FORM_addr
+          - Attribute: DW_AT_high_pc
+            Form:      DW_FORM_data8
+          - Attribute: DW_AT_type
+            Form:      DW_FORM_ref4
+  debug_info:
+    - Version: 4
+      Entries:
+        - AbbrCode: 1
+          Values:
+            - CStr: by_hand
+            - Value:  0x04
+            - CStr: CU1
+            - Value:  0x1000
+            - Value:  0x1b
+        - AbbrCode: 2
+          Values:
+            - CStr: class1
+        - AbbrCode: 3
+          Values:
+            - Value:  0x00000052
+            - CStr: member1
+        - AbbrCode: 3
+          Values:
+            - Value:  0x00000058
+            - CStr: member2
+        - AbbrCode: 0
+        - AbbrCode: 7
+          Values:
+            - CStr: int
+        - AbbrCode: 7
+          Values:
+            - CStr: char
+        - AbbrCode: 7
+          Values:
+            - CStr: float
+        - AbbrCode: 8
+          Values:
+            - Value:  0x0000002a
+        - AbbrCode: 9
+          Values:
+            - CStr: var1
+            - Value:  0x00000000
+            - Value:  0x0000005f
+        - AbbrCode: 10
+          Values:
+            - CStr: foo1
+            - Value:  0x1000
+            - Value:  0x10
+            - Value:  0x0000002a
+        - AbbrCode: 0
+...

llvm/test/tools/llvm-dwarfutil/ELF/copy.test

+## This test checks that debug info contained in the source file
+## is fully copied to the destination file in case --no-garbage-collection
+## is specified.
+
+# RUN: yaml2obj %s -o %t.o
+
+## Check that the resulting file contains debug info from source file.
+# RUN: llvm-dwarfutil --no-garbage-collection %t.o %t1
+# RUN: llvm-dwarfdump -a %t1 | FileCheck --check-prefix=CHECK-DEBUG %s
+
+## Check that the first copy matches with the second.
+# RUN: llvm-dwarfutil --no-garbage-collection %t1 %t2
+# RUN: llvm-dwarfdump -a %t2 | FileCheck --check-prefix=CHECK-DEBUG %s
+# RUN: diff %t1 %t2
+
+## Check that debug info is stored in separate file.
+# RUN: llvm-dwarfutil --no-garbage-collection %t.o --separate-debug-file %t3
+# RUN: llvm-objdump --headers %t3 | FileCheck --check-prefix=CHECK-NON-DEBUG %s
+# RUN: llvm-dwarfdump -a %t3.debug | FileCheck --check-prefix=CHECK-DEBUG %s
+# RUN: cp %t3 %t4
+# RUN: cp %t3.debug %t4.debug
+
+## Check that debug info is stored in separate file (last --separate-debug-file wins).
+# RUN: llvm-dwarfutil %t.o --no-garbage-collection --no-separate-debug-file --separate-debug-file %t3
+# RUN: diff %t4 %t3
+# RUN: diff %t4.debug %t3.debug
+
+## Check that the resulting file contains debug info from source file.
+## (last --no-separate-debug-file wins)
+# RUN: llvm-dwarfutil %t.o --no-garbage-collection --separate-debug-file --no-separate-debug-file %t5
+# RUN: diff %t1 %t5
+
+# CHECK-NON-DEBUG-NOT: .debug_abbrev
+# CHECK-NON-DEBUG-NOT: .debug_info
+# CHECK-NON-DEBUG: .gnu_debuglink
+# CHECK-NON-DEBUG-NOT: .debug_abbrev
+# CHECK-NON-DEBUG-NOT: .debug_info
+
+
+# CHECK-DEBUG: .debug_abbrev
+# CHECK-DEBUG: DW_TAG_compile_unit
+# CHECK-DEBUG: .debug_info
+# CHECK-DEBUG: DW_TAG_compile_unit
+# CHECK-DEBUG: DW_AT_producer{{.*}}"by_hand"
+# CHECK-DEBUG: DW_AT_language{{.*}}DW_LANG_C_plus_plus
+# CHECK-DEBUG: DW_AT_name{{.*}}"CU1"
+# CHECK-DEBUG: DW_TAG_class_type
+# CHECK-DEBUG: DW_AT_name{{.*}}"class1"
+# CHECK-DEBUG: DW_TAG_base_type
+# CHECK-DEBUG: DW_AT_name{{.*}}"int"
+# CHECK-DEBUG: DW_AT_name{{.*}}"char"
+# CHECK-DEBUG: DW_AT_name{{.*}}"float"
+# CHECK-DEBUG: DW_TAG_pointer_type
+# CHECK-DEBUG: DW_TAG_variable
+# CHECK-DEBUG: DW_AT_name{{.*}}"var1"
+
+--- !ELF
+FileHeader:
+  Class:    ELFCLASS64
+  Data:     ELFDATA2LSB
+  Type:     ET_REL
+  Machine:  EM_X86_64
+Sections:
+  - Name:            .text
+    Type:            SHT_PROGBITS
+    Flags:           [ SHF_ALLOC, SHF_EXECINSTR ]
+    Address:         0x1000
+    AddressAlign:    0x0000000000000010
+    Content:        "FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF"
+DWARF:
+  debug_abbrev:
+    - Table:
+      - Tag:      DW_TAG_compile_unit
+        Children: DW_CHILDREN_yes
+        Attributes:
+          - Attribute: DW_AT_producer
+            Form:      DW_FORM_string
+          - Attribute: DW_AT_language
+            Form:      DW_FORM_data2
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+          - Attribute: DW_AT_low_pc
+            Form:      DW_FORM_addr
+          - Attribute: DW_AT_high_pc
+            Form:      DW_FORM_data8
+      - Tag:      DW_TAG_class_type
+        Children: DW_CHILDREN_yes
+        Attributes:
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+      - Tag:      DW_TAG_member
+        Children: DW_CHILDREN_no
+        Attributes:
+          - Attribute: DW_AT_type
+            Form:      DW_FORM_ref4
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+      - Tag:      DW_TAG_class_type
+        Children: DW_CHILDREN_no
+        Attributes:
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+          - Attribute: DW_AT_declaration
+            Form:      DW_FORM_flag_present
+      - Tag:      DW_TAG_class_type
+        Children: DW_CHILDREN_yes
+        Attributes:
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+          - Attribute: DW_AT_declaration
+            Form:      DW_FORM_flag_present
+      - Tag:      DW_TAG_template_type_parameter
+        Children: DW_CHILDREN_no
+        Attributes:
+          - Attribute: DW_AT_type
+            Form:      DW_FORM_ref4
+      - Tag:      DW_TAG_base_type
+        Children: DW_CHILDREN_no
+        Attributes:
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+      - Tag:      DW_TAG_pointer_type
+        Children: DW_CHILDREN_no
+        Attributes:
+          - Attribute: DW_AT_type
+            Form:      DW_FORM_ref4
+      - Tag:      DW_TAG_variable
+        Children: DW_CHILDREN_no
+        Attributes:
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+          - Attribute: DW_AT_const_value
+            Form:      DW_FORM_data4
+          - Attribute: DW_AT_type
+            Form:      DW_FORM_ref4
+      - Tag:      DW_TAG_subprogram
+        Children: DW_CHILDREN_no
+        Attributes:
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+          - Attribute: DW_AT_low_pc
+            Form:      DW_FORM_addr
+          - Attribute: DW_AT_high_pc
+            Form:      DW_FORM_data8
+          - Attribute: DW_AT_type
+            Form:      DW_FORM_ref4
+  debug_info:
+    - Version: 4
+      Entries:
+        - AbbrCode: 1
+          Values:
+            - CStr: by_hand
+            - Value:  0x04
+            - CStr: CU1
+            - Value:  0x1000
+            - Value:  0x1b
+        - AbbrCode: 2
+          Values:
+            - CStr: class1
+        - AbbrCode: 3
+          Values:
+            - Value:  0x00000052
+            - CStr: member1
+        - AbbrCode: 3
+          Values:
+            - Value:  0x00000058
+            - CStr: member2
+        - AbbrCode: 0
+        - AbbrCode: 7
+          Values:
+            - CStr: int
+        - AbbrCode: 7
+          Values:
+            - CStr: char
+        - AbbrCode: 7
+          Values:
+            - CStr: float
+        - AbbrCode: 8
+          Values:
+            - Value:  0x0000002a
+        - AbbrCode: 9
+          Values:
+            - CStr: var1
+            - Value:  0x00000000
+            - Value:  0x0000005f
+        - AbbrCode: 10
+          Values:
+            - CStr: foo1
+            - Value:  0x1000
+            - Value:  0x10
+            - Value:  0x0000002a
+        - AbbrCode: 0
+        - AbbrCode: 0
+...

llvm/test/tools/llvm-dwarfutil/ELF/error-corrupted-input-file.test

+## This test checks the error message displayed if input file
+## has wrong format.
+
+# RUN: not llvm-dwarfutil --garbage-collection %p/Inputs/archive.a - 2>&1 | FileCheck %s
+
+# CHECK: archive.a: error: corrupted input file

llvm/test/tools/llvm-dwarfutil/ELF/error-separate-file-stdout.test

+## This test checks the error message displayed if the destination
+## is stdout and separate debug info file is requested.
+
+# RUN: yaml2obj %s -o %t.o
+# RUN: not llvm-dwarfutil --separate-debug-file %t.o - 2>&1 | FileCheck --check-prefix CHECK %s
+
+# CHECK: error: writing to stdout. --separate-debug-file should be disabled
+
+--- !ELF
+FileHeader:
+  Class:    ELFCLASS64
+  Data:     ELFDATA2LSB
+  Type:     ET_REL
+  Machine:  EM_X86_64
+DWARF:
+  debug_abbrev:
+    - Table:
+      - Tag:      DW_TAG_compile_unit
+        Children: DW_CHILDREN_yes
+        Attributes:
+          - Attribute: DW_AT_producer
+            Form:      DW_FORM_string
+          - Attribute: DW_AT_language
+            Form:      DW_FORM_data2
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+          - Attribute: DW_AT_low_pc
+            Form:      DW_FORM_addr
+          - Attribute: DW_AT_high_pc
+            Form:      DW_FORM_data8
+      - Tag:      DW_TAG_subprogram
+        Children: DW_CHILDREN_no
+        Attributes:
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+          - Attribute: DW_AT_low_pc
+            Form:      DW_FORM_addr
+          - Attribute: DW_AT_high_pc
+            Form:      DW_FORM_data8
+          - Attribute: DW_AT_type
+            Form:      DW_FORM_ref4
+      - Tag:      DW_TAG_class_type
+        Children: DW_CHILDREN_yes
+        Attributes:
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+      - Tag:      DW_TAG_member
+        Children: DW_CHILDREN_no
+        Attributes:
+          - Attribute: DW_AT_type
+            Form:      DW_FORM_ref4
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+      - Tag:      DW_TAG_class_type
+        Children: DW_CHILDREN_no
+        Attributes:
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+          - Attribute: DW_AT_declaration
+            Form:      DW_FORM_flag_present
+      - Tag:      DW_TAG_class_type
+        Children: DW_CHILDREN_yes
+        Attributes:
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+          - Attribute: DW_AT_declaration
+            Form:      DW_FORM_flag_present
+      - Tag:      DW_TAG_template_type_parameter
+        Children: DW_CHILDREN_no
+        Attributes:
+          - Attribute: DW_AT_type
+            Form:      DW_FORM_ref4
+      - Tag:      DW_TAG_base_type
+        Children: DW_CHILDREN_no
+        Attributes:
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+  debug_info:
+    - Version: 4
+      Entries:
+        - AbbrCode: 1
+          Values:
+            - CStr: by_hand
+            - Value:  0x04
+            - CStr: CU1
+            - Value:  0x1000
+            - Value:  0x100
+        - AbbrCode: 3
+          Values:
+            - CStr: class1
+        - AbbrCode: 4
+          Values:
+            - Value:  0x0000006c
+            - CStr: member1
+        - AbbrCode: 0
+        - AbbrCode: 3
+          Values:
+            - CStr: class2
+        - AbbrCode: 4
+          Values:
+            - Value:  0x0000006c
+            - CStr: member1
+        - AbbrCode: 0
+        - AbbrCode: 3
+          Values:
+            - CStr: class3
+        - AbbrCode: 4
+          Values:
+            - Value:  0x0000006c
+            - CStr: member1
+        - AbbrCode: 0
+        - AbbrCode: 8
+          Values:
+            - CStr: int
+        - AbbrCode: 2
+          Values:
+            - CStr: foo1
+            - Value:  0x1000
+            - Value:  0x10
+            - Value:  0x0000002a
+        - AbbrCode: 2
+          Values:
+            - CStr: foo2
+            - Value:  0x0
+            - Value:  0x100
+            - Value:  0x00000040
+        - AbbrCode: 2
+          Values:
+            - CStr: foo3
+            - Value:  0x0
+            - Value:  0x100
+            - Value:  0x00000040
+        - AbbrCode: 0
+...

llvm/test/tools/llvm-dwarfutil/ELF/gc-bfd.test

+## This test checks that debug info related to deleted code (marked with
+## tombstone=bfd) is removed.
+
+# RUN: yaml2obj %s -o %t.o
+
+# RUN: llvm-dwarfutil --tombstone=bfd --garbage-collection %t.o - | llvm-dwarfdump -a - | FileCheck %s
+# RUN: llvm-dwarfutil --tombstone=universal --garbage-collection %t.o - | llvm-dwarfdump -a - | FileCheck %s
+
+# CHECK: DW_TAG_compile_unit
+# CHECK: DW_AT_name{{.*}}"CU1"
+# CHECK: DW_TAG_class_type
+# CHECK: DW_AT_name{{.*}}"class1"
+# CHECK-NOT: DW_TAG_class_type
+# CHECK-NOT: "class2"
+# CHECK-NOT: "class3"
+# CHECK: DW_TAG_subprogram
+# CHECK: DW_AT_name{{.*}}"foo1"
+# CHECK: DW_AT_low_pc{{.*}}0x0000000000001000
+# CHECK: DW_AT_high_pc{{.*}}0x0000000000001010
+# CHECK: DW_AT_type{{.*}}"class1"
+# CHECK-NOT: DW_TAG_subprogram
+# CHECK-NOT: "foo2"
+
+
+--- !ELF
+FileHeader:
+  Class:    ELFCLASS64
+  Data:     ELFDATA2LSB
+  Type:     ET_REL
+  Machine:  EM_X86_64
+Sections:
+  - Name:            .text
+    Type:            SHT_PROGBITS
+    Flags:           [ SHF_ALLOC, SHF_EXECINSTR ]
+    Address:         0x1000
+    AddressAlign:    0x0000000000000010
+    Content:        "FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF"
+DWARF:
+  debug_abbrev:
+    - Table:
+      - Tag:      DW_TAG_compile_unit
+        Children: DW_CHILDREN_yes
+        Attributes:
+          - Attribute: DW_AT_producer
+            Form:      DW_FORM_string
+          - Attribute: DW_AT_language
+            Form:      DW_FORM_data2
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+          - Attribute: DW_AT_low_pc
+            Form:      DW_FORM_addr
+          - Attribute: DW_AT_high_pc
+            Form:      DW_FORM_data8
+      - Tag:      DW_TAG_subprogram
+        Children: DW_CHILDREN_no
+        Attributes:
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+          - Attribute: DW_AT_low_pc
+            Form:      DW_FORM_addr
+          - Attribute: DW_AT_high_pc
+            Form:      DW_FORM_data8
+          - Attribute: DW_AT_type
+            Form:      DW_FORM_ref4
+      - Tag:      DW_TAG_class_type
+        Children: DW_CHILDREN_yes
+        Attributes:
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+      - Tag:      DW_TAG_member
+        Children: DW_CHILDREN_no
+        Attributes:
+          - Attribute: DW_AT_type
+            Form:      DW_FORM_ref4
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+      - Tag:      DW_TAG_class_type
+        Children: DW_CHILDREN_no
+        Attributes:
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+          - Attribute: DW_AT_declaration
+            Form:      DW_FORM_flag_present
+      - Tag:      DW_TAG_class_type
+        Children: DW_CHILDREN_yes
+        Attributes:
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+          - Attribute: DW_AT_declaration
+            Form:      DW_FORM_flag_present
+      - Tag:      DW_TAG_template_type_parameter
+        Children: DW_CHILDREN_no
+        Attributes:
+          - Attribute: DW_AT_type
+            Form:      DW_FORM_ref4
+      - Tag:      DW_TAG_base_type
+        Children: DW_CHILDREN_no
+        Attributes:
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+  debug_info:
+    - Version: 4
+      Entries:
+        - AbbrCode: 1
+          Values:
+            - CStr: by_hand
+            - Value:  0x04
+            - CStr: CU1
+            - Value:  0x1000
+            - Value:  0x1b
+        - AbbrCode: 3
+          Values:
+            - CStr: class1
+        - AbbrCode: 4
+          Values:
+            - Value:  0x0000006c
+            - CStr: member1
+        - AbbrCode: 0
+        - AbbrCode: 3
+          Values:
+            - CStr: class2
+        - AbbrCode: 4
+          Values:
+            - Value:  0x0000006c
+            - CStr: member1
+        - AbbrCode: 0
+        - AbbrCode: 3
+          Values:
+            - CStr: class3
+        - AbbrCode: 4
+          Values:
+            - Value:  0x0000006c
+            - CStr: member1
+        - AbbrCode: 0
+        - AbbrCode: 8
+          Values:
+            - CStr: int
+        - AbbrCode: 2
+          Values:
+            - CStr: foo1
+            - Value:  0x1000
+            - Value:  0x10
+            - Value:  0x0000002a
+        - AbbrCode: 2
+          Values:
+            - CStr: foo2
+            - Value:  0x0
+            - Value:  0x100
+            - Value:  0x00000040
+        - AbbrCode: 0
+...

llvm/test/tools/llvm-dwarfutil/ELF/gc-class.test

+## This test checks debug info for the case when one compilation unit
+## contains a definition of a type and another compilation unit
+## contains a definition of the same type. When --garbage-collection
+## is enabled the result should contain the original definition in CU1
+## and the definition from CU2 should have been removed.
+
+# RUN: yaml2obj %s -o %t.o
+
+## Check implicit --garbage-collection and --odr-deduplication.
+# RUN: llvm-dwarfutil %t.o %t1
+# RUN: llvm-dwarfdump -a %t1 | FileCheck %s --check-prefixes=CHECK,CHECK-ODR
+
+## Check implicit --garbage-collection and explicit alias for --odr-deduplication.
+# RUN: llvm-dwarfutil --odr %t.o %t2
+# RUN: diff %t1 %t2
+
+## Check implicit --garbage-collection and explicit alias for --no-odr (last option wins).
+# RUN: llvm-dwarfutil --odr --no-odr %t.o %t3
+# RUN: llvm-dwarfdump -a %t3 | FileCheck %s --check-prefixes=CHECK,CHECK-NOODR
+
+## Check implicit --garbage-collection and explicit --no-odr-deduplication (last option wins).
+# RUN: llvm-dwarfutil --odr-deduplication --no-odr-deduplication %t.o %t4
+# RUN: diff %t3 %t4
+
+## Check implicit --garbage-collection and explicit alias for --odr-deduplication (last option wins).
+# RUN: llvm-dwarfutil --no-odr --odr %t.o %t5
+# RUN: diff %t1 %t5
+
+## Check implicit --garbage-collection and explicit --odr-deduplication (last option wins).
+# RUN: llvm-dwarfutil --no-odr-deduplication --odr-deduplication %t.o %t6
+# RUN: diff %t1 %t6
+
+## CU1:
+##
+## class class1 {
+##   char member1;
+##   float member2;
+## };
+##
+## class1 *var1;
+##
+## CU2:
+##
+## class class1 {
+##   char member1;
+##   float member2;
+## };
+##
+## class1 *var1;
+
+# CHECK: file format elf64-x86-64
+# CHECK: .debug_info contents:
+
+# CHECK: DW_TAG_compile_unit
+# CHECK: DW_AT_name{{.*}}"CU1"
+
+# CHECK: 0x[[CU1_CLASS1:[0-9a-f]*]]: DW_TAG_class_type{{.*[[:space:]].*}}DW_AT_name{{.*}}"class1"
+# CHECK: DW_TAG_member
+# CHECK-ODR: DW_AT_type{{.*}}0x00000000[[CU1_CHAR:[0-9a-f]*]] "char"
+# CHECK-NOODR: DW_AT_type{{.*}}0x[[CU1_CHAR:[0-9a-f]*]] "char"
+# CHECK: DW_AT_name{{.*}}"member1"
+
+# CHECK: DW_TAG_member
+# CHECK-ODR: DW_AT_type{{.*}}0x00000000[[CU1_FLOAT:[0-9a-f]*]] "float"
+# CHECK-NOODR: DW_AT_type{{.*}}0x[[CU1_FLOAT:[0-9a-f]*]] "float"
+# CHECK: DW_AT_name{{.*}}"member2"
+
+# CHECK: 0x[[CU1_INT:[0-9a-f]*]]: DW_TAG_base_type
+# CHECK: DW_AT_name{{.*}}"int"
+
+# CHECK: 0x[[CU1_CHAR]]: DW_TAG_base_type
+# CHECK: DW_AT_name{{.*}}"char"
+
+# CHECK: 0x[[CU1_FLOAT]]: DW_TAG_base_type
+# CHECK: DW_AT_name{{.*}}"float"
+
+# CHECK-ODR: 0x[[CU1_PTR_CLASS1:[0-9a-f]*]]: DW_TAG_pointer_type{{.*[[:space:]].*}}DW_AT_type{{.*}}0x00000000[[CU1_CLASS1]] "class1"
+# CHECK-NOODR: 0x[[CU1_PTR_CLASS1:[0-9a-f]*]]: DW_TAG_pointer_type{{.*[[:space:]].*}}DW_AT_type{{.*}}0x[[CU1_CLASS1]] "class1"
+
+# CHECK: DW_TAG_variable
+# CHECK: DW_AT_name{{.*}}"var1"
+# CHECK-ODR: DW_AT_type{{.*}}0x00000000[[CU1_PTR_CLASS1]] "class1 *"
+# CHECK-NOODR: DW_AT_type{{.*}}0x[[CU1_PTR_CLASS1]] "class1 *"
+
+# CHECK: DW_TAG_compile_unit
+# CHECK: DW_AT_name{{.*}}"CU2"
+
+# CHECK-ODR-NOT: DW_TAG_class_type
+# CHECK-ODR-NOT: "class1"
+
+# CHECK-ODR: 0x[[CU2_PTR_CLASS1:[0-9a-f]*]]: DW_TAG_pointer_type{{.*[[:space:]].*}}DW_AT_type{{.*}}0x00000000[[CU1_CLASS1]] "class1"
+
+# CHECK-ODR: DW_TAG_variable
+# CHECK-ODR: DW_AT_name{{.*}}"var1"
+# CHECK-ODR: DW_AT_type{{.*}}0x00000000[[CU2_PTR_CLASS1]] "class1 *"
+
+
+# CHECK-NOODR: 0x[[CU2_CLASS1:[0-9a-f]*]]: DW_TAG_class_type{{.*[[:space:]].*}}DW_AT_name{{.*}}"class1"
+# CHECK-NOODR: DW_TAG_member
+# CHECK-NOODR: DW_AT_type{{.*}}0x[[CU2_CHAR:[0-9a-f]*]] "char"
+# CHECK-NOODR: DW_AT_name{{.*}}"member1"
+
+# CHECK-NOODR: DW_TAG_member
+# CHECK-NOODR: DW_AT_type{{.*}}0x[[CU2_FLOAT:[0-9a-f]*]] "float"
+# CHECK-NOODR: DW_AT_name{{.*}}"member2"
+
+# CHECK-NOODR: 0x[[CU2_INT:[0-9a-f]*]]: DW_TAG_base_type
+# CHECK-NOODR: DW_AT_name{{.*}}"int"
+
+# CHECK-NOODR: 0x[[CU2_CHAR]]: DW_TAG_base_type
+# CHECK-NOODR: DW_AT_name{{.*}}"char"
+
+# CHECK-NOODR: 0x[[CU2_FLOAT]]: DW_TAG_base_type
+# CHECK-NOODR: DW_AT_name{{.*}}"float"
+
+# CHECK-NOODR: 0x[[CU2_PTR_CLASS1:[0-9a-f]*]]: DW_TAG_pointer_type{{.*[[:space:]].*}}DW_AT_type{{.*}}0x[[CU2_CLASS1]] "class1"
+
+# CHECK-NOODR: DW_TAG_variable
+# CHECK-NOODR: DW_AT_name{{.*}}"var1"
+# CHECK-NOODR: DW_AT_type{{.*}}0x[[CU2_PTR_CLASS1]] "class1 *"
+
+--- !ELF
+FileHeader:
+  Class:    ELFCLASS64
+  Data:     ELFDATA2LSB
+  Type:     ET_REL
+  Machine:  EM_X86_64
+Sections:
+  - Name:            .text
+    Type:            SHT_PROGBITS
+    Flags:           [ SHF_ALLOC, SHF_EXECINSTR ]
+    Address:         0x1000
+    AddressAlign:    0x0000000000000010
+    Content:        "FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF"
+  - Name:            .text2
+    Type:            SHT_PROGBITS
+    Flags:           [ SHF_ALLOC, SHF_EXECINSTR ]
+    Address:         0x2000
+    AddressAlign:    0x0000000000000010
+    Content:        "FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF"
+DWARF:
+  debug_abbrev:
+    - Table:
+      - Tag:      DW_TAG_compile_unit
+        Children: DW_CHILDREN_yes
+        Attributes:
+          - Attribute: DW_AT_producer
+            Form:      DW_FORM_string
+          - Attribute: DW_AT_language
+            Form:      DW_FORM_data2
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+          - Attribute: DW_AT_low_pc
+            Form:      DW_FORM_addr
+          - Attribute: DW_AT_high_pc
+            Form:      DW_FORM_data8
+      - Tag:      DW_TAG_class_type
+        Children: DW_CHILDREN_yes
+        Attributes:
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+      - Tag:      DW_TAG_member
+        Children: DW_CHILDREN_no
+        Attributes:
+          - Attribute: DW_AT_type
+            Form:      DW_FORM_ref4
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+      - Tag:      DW_TAG_class_type
+        Children: DW_CHILDREN_no
+        Attributes:
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+          - Attribute: DW_AT_declaration
+            Form:      DW_FORM_flag_present
+      - Tag:      DW_TAG_class_type
+        Children: DW_CHILDREN_yes
+        Attributes:
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+          - Attribute: DW_AT_declaration
+            Form:      DW_FORM_flag_present
+      - Tag:      DW_TAG_template_type_parameter
+        Children: DW_CHILDREN_no
+        Attributes:
+          - Attribute: DW_AT_type
+            Form:      DW_FORM_ref4
+      - Tag:      DW_TAG_base_type
+        Children: DW_CHILDREN_no
+        Attributes:
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+      - Tag:      DW_TAG_pointer_type
+        Children: DW_CHILDREN_no
+        Attributes:
+          - Attribute: DW_AT_type
+            Form:      DW_FORM_ref4
+      - Tag:      DW_TAG_variable
+        Children: DW_CHILDREN_no
+        Attributes:
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+          - Attribute: DW_AT_const_value
+            Form:      DW_FORM_data4
+          - Attribute: DW_AT_type
+            Form:      DW_FORM_ref4
+    - Table:
+      - Tag:      DW_TAG_compile_unit
+        Children: DW_CHILDREN_yes
+        Attributes:
+          - Attribute: DW_AT_producer
+            Form:      DW_FORM_string
+          - Attribute: DW_AT_language
+            Form:      DW_FORM_data2
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+          - Attribute: DW_AT_low_pc
+            Form:      DW_FORM_addr
+          - Attribute: DW_AT_high_pc
+            Form:      DW_FORM_data8
+      - Tag:      DW_TAG_class_type
+        Children: DW_CHILDREN_yes
+        Attributes:
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+      - Tag:      DW_TAG_member
+        Children: DW_CHILDREN_no
+        Attributes:
+          - Attribute: DW_AT_type
+            Form:      DW_FORM_ref4
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+      - Tag:      DW_TAG_class_type
+        Children: DW_CHILDREN_no
+        Attributes:
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+          - Attribute: DW_AT_declaration
+            Form:      DW_FORM_flag_present
+      - Tag:      DW_TAG_class_type
+        Children: DW_CHILDREN_yes
+        Attributes:
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+          - Attribute: DW_AT_declaration
+            Form:      DW_FORM_flag_present
+      - Tag:      DW_TAG_template_type_parameter
+        Children: DW_CHILDREN_no
+        Attributes:
+          - Attribute: DW_AT_type
+            Form:      DW_FORM_ref4
+      - Tag:      DW_TAG_base_type
+        Children: DW_CHILDREN_no
+        Attributes:
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+      - Tag:      DW_TAG_pointer_type
+        Children: DW_CHILDREN_no
+        Attributes:
+          - Attribute: DW_AT_type
+            Form:      DW_FORM_ref4
+      - Tag:      DW_TAG_variable
+        Children: DW_CHILDREN_no
+        Attributes:
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+          - Attribute: DW_AT_const_value
+            Form:      DW_FORM_data4
+          - Attribute: DW_AT_type
+            Form:      DW_FORM_ref4
+  debug_info:
+    - Version: 4
+      Entries:
+        - AbbrCode: 1
+          Values:
+            - CStr: by_hand
+            - Value:  0x04
+            - CStr: CU1
+            - Value:  0x1000
+            - Value:  0x1b
+        - AbbrCode: 2
+          Values:
+            - CStr: class1
+        - AbbrCode: 3
+          Values:
+            - Value:  0x00000052
+            - CStr: member1
+        - AbbrCode: 3
+          Values:
+            - Value:  0x00000058
+            - CStr: member2
+        - AbbrCode: 0
+        - AbbrCode: 7
+          Values:
+            - CStr: int
+        - AbbrCode: 7
+          Values:
+            - CStr: char
+        - AbbrCode: 7
+          Values:
+            - CStr: float
+        - AbbrCode: 8
+          Values:
+            - Value:  0x0000002a
+        - AbbrCode: 9
+          Values:
+            - CStr: var1
+            - Value:  0x00000000
+            - Value:  0x0000005f
+        - AbbrCode: 0
+    - Version: 4
+      Entries:
+        - AbbrCode: 1
+          Values:
+            - CStr: by_hand
+            - Value:  0x04
+            - CStr: CU2
+            - Value:  0x2000
+            - Value:  0x1b
+        - AbbrCode: 2
+          Values:
+            - CStr: class1
+        - AbbrCode: 3
+          Values:
+            - Value:  0x00000052
+            - CStr: member1
+        - AbbrCode: 3
+          Values:
+            - Value:  0x00000058
+            - CStr: member2
+        - AbbrCode: 0
+        - AbbrCode: 7
+          Values:
+            - CStr: int
+        - AbbrCode: 7
+          Values:
+            - CStr: char
+        - AbbrCode: 7
+          Values:
+            - CStr: float
+        - AbbrCode: 8
+          Values:
+            - Value:  0x0000002a
+        - AbbrCode: 9
+          Values:
+            - CStr: var1
+            - Value:  0x00000000
+            - Value:  0x0000005f
+        - AbbrCode: 0
+...

llvm/test/tools/llvm-dwarfutil/ELF/gc-default.test

+## This test checks that debug info related to deleted code (marked with
+## default tombstone value) is removed.
+
+# RUN: yaml2obj %s -o %t.o
+
+# RUN: llvm-dwarfutil %t.o - | llvm-dwarfdump -a - | FileCheck %s --check-prefixes=CHECK,CHECK-GC
+
+# RUN: llvm-dwarfutil --garbage-collection %t.o - | llvm-dwarfdump -a - | FileCheck %s --check-prefixes=CHECK,CHECK-GC
+
+# RUN: llvm-dwarfutil --no-garbage-collection --garbage-collection %t.o - | llvm-dwarfdump -a - | FileCheck %s --check-prefixes=CHECK,CHECK-GC
+
+# RUN: llvm-dwarfutil --garbage-collection --no-garbage-collection %t.o - | llvm-dwarfdump -a - | FileCheck %s --check-prefixes=CHECK,CHECK-NOGC
+
+# RUN: llvm-dwarfutil %t.o --tombstone=universal - | llvm-dwarfdump -a - | FileCheck %s --check-prefixes=CHECK,CHECK-GC
+
+# CHECK: DW_TAG_compile_unit
+# CHECK: DW_AT_name{{.*}}"CU1"
+# CHECK: DW_TAG_class_type
+# CHECK: DW_AT_name{{.*}}"class1"
+# CHECK-GC-NOT: DW_TAG_class_type
+# CHECK-GC-NOT: "class2"
+# CHECK-GC-NOT: "class3"
+# CHECK-NOGC: DW_TAG_class_type
+# CHECK-NOGC: "class2"
+# CHECK-NOGC: "class3"
+# CHECK: DW_TAG_subprogram
+# CHECK: DW_AT_name{{.*}}"foo1"
+# CHECK: DW_AT_low_pc{{.*}}0x0000000000001000
+# CHECK: DW_AT_high_pc{{.*}}0x0000000000001010
+# CHECK: DW_AT_type{{.*}}"class1"
+# CHECK-GC-NOT: DW_TAG_subprogram
+# CHECK-GC-NOT: "foo2"
+# CHECK-NOGC: DW_TAG_subprogram
+# CHECK-NOGC: "foo2"
+
+
+--- !ELF
+FileHeader:
+  Class:    ELFCLASS64
+  Data:     ELFDATA2LSB
+  Type:     ET_REL
+  Machine:  EM_X86_64
+Sections:
+  - Name:            .text
+    Type:            SHT_PROGBITS
+    Flags:           [ SHF_ALLOC, SHF_EXECINSTR ]
+    Address:         0x1000
+    AddressAlign:    0x0000000000000010
+    Content:        "FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF"
+DWARF:
+  debug_abbrev:
+    - Table:
+      - Tag:      DW_TAG_compile_unit
+        Children: DW_CHILDREN_yes
+        Attributes:
+          - Attribute: DW_AT_producer
+            Form:      DW_FORM_string
+          - Attribute: DW_AT_language
+            Form:      DW_FORM_data2
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+          - Attribute: DW_AT_low_pc
+            Form:      DW_FORM_addr
+          - Attribute: DW_AT_high_pc
+            Form:      DW_FORM_data8
+      - Tag:      DW_TAG_subprogram
+        Children: DW_CHILDREN_no
+        Attributes:
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+          - Attribute: DW_AT_low_pc
+            Form:      DW_FORM_addr
+          - Attribute: DW_AT_high_pc
+            Form:      DW_FORM_data8
+          - Attribute: DW_AT_type
+            Form:      DW_FORM_ref4
+      - Tag:      DW_TAG_class_type
+        Children: DW_CHILDREN_yes
+        Attributes:
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+      - Tag:      DW_TAG_member
+        Children: DW_CHILDREN_no
+        Attributes:
+          - Attribute: DW_AT_type
+            Form:      DW_FORM_ref4
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+      - Tag:      DW_TAG_class_type
+        Children: DW_CHILDREN_no
+        Attributes:
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+          - Attribute: DW_AT_declaration
+            Form:      DW_FORM_flag_present
+      - Tag:      DW_TAG_class_type
+        Children: DW_CHILDREN_yes
+        Attributes:
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+          - Attribute: DW_AT_declaration
+            Form:      DW_FORM_flag_present
+      - Tag:      DW_TAG_template_type_parameter
+        Children: DW_CHILDREN_no
+        Attributes:
+          - Attribute: DW_AT_type
+            Form:      DW_FORM_ref4
+      - Tag:      DW_TAG_base_type
+        Children: DW_CHILDREN_no
+        Attributes:
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+  debug_info:
+    - Version: 4
+      Entries:
+        - AbbrCode: 1
+          Values:
+            - CStr: by_hand
+            - Value:  0x04
+            - CStr: CU1
+            - Value:  0x1000
+            - Value:  0x1b
+        - AbbrCode: 3
+          Values:
+            - CStr: class1
+        - AbbrCode: 4
+          Values:
+            - Value:  0x0000006c
+            - CStr: member1
+        - AbbrCode: 0
+        - AbbrCode: 3
+          Values:
+            - CStr: class2
+        - AbbrCode: 4
+          Values:
+            - Value:  0x0000006c
+            - CStr: member1
+        - AbbrCode: 0
+        - AbbrCode: 3
+          Values:
+            - CStr: class3
+        - AbbrCode: 4
+          Values:
+            - Value:  0x0000006c
+            - CStr: member1
+        - AbbrCode: 0
+        - AbbrCode: 8
+          Values:
+            - CStr: int
+        - AbbrCode: 2
+          Values:
+            - CStr: foo1
+            - Value:  0x1000
+            - Value:  0x10
+            - Value:  0x0000002a
+        - AbbrCode: 2
+          Values:
+            - CStr: foo2
+            - Value:  0x0
+            - Value:  0x100
+            - Value:  0x00000040
+        - AbbrCode: 0
+...

llvm/test/tools/llvm-dwarfutil/ELF/gc-exec.test

+## This test checks that debug info related to deleted code (marked with
+## tombstone=exec) is removed.
+
+# RUN: yaml2obj %s -o %t.o
+
+# RUN: llvm-dwarfutil --tombstone=exec --garbage-collection %t.o - | llvm-dwarfdump -a - | FileCheck %s
+# RUN: llvm-dwarfutil --tombstone=universal --garbage-collection %t.o - | llvm-dwarfdump -a - | FileCheck %s
+
+# CHECK: DW_TAG_compile_unit
+# CHECK: DW_AT_name{{.*}}"CU1"
+# CHECK: DW_TAG_class_type
+# CHECK: DW_AT_name{{.*}}"class1"
+# CHECK-NOT: DW_TAG_class_type
+# CHECK-NOT: "class2"
+# CHECK-NOT: "class3"
+# CHECK: DW_TAG_subprogram
+# CHECK: DW_AT_name{{.*}}"foo1"
+# CHECK: DW_AT_low_pc{{.*}}0x0000000000001000
+# CHECK: DW_AT_high_pc{{.*}}0x0000000000001010
+# CHECK: DW_AT_type{{.*}}"class1"
+# CHECK-NOT: DW_TAG_subprogram
+# CHECK-NOT: "foo2"
+
+
+--- !ELF
+FileHeader:
+  Class:    ELFCLASS64
+  Data:     ELFDATA2LSB
+  Type:     ET_REL
+  Machine:  EM_X86_64
+Sections:
+  - Name:            .text
+    Type:            SHT_PROGBITS
+    Flags:           [ SHF_ALLOC, SHF_EXECINSTR ]
+    Address:         0x1000
+    AddressAlign:    0x0000000000000010
+    Content:        "FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF"
+DWARF:
+  debug_abbrev:
+    - Table:
+      - Tag:      DW_TAG_compile_unit
+        Children: DW_CHILDREN_yes
+        Attributes:
+          - Attribute: DW_AT_producer
+            Form:      DW_FORM_string
+          - Attribute: DW_AT_language
+            Form:      DW_FORM_data2
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+          - Attribute: DW_AT_low_pc
+            Form:      DW_FORM_addr
+          - Attribute: DW_AT_high_pc
+            Form:      DW_FORM_data8
+      - Tag:      DW_TAG_subprogram
+        Children: DW_CHILDREN_no
+        Attributes:
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+          - Attribute: DW_AT_low_pc
+            Form:      DW_FORM_addr
+          - Attribute: DW_AT_high_pc
+            Form:      DW_FORM_data8
+          - Attribute: DW_AT_type
+            Form:      DW_FORM_ref4
+      - Tag:      DW_TAG_class_type
+        Children: DW_CHILDREN_yes
+        Attributes:
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+      - Tag:      DW_TAG_member
+        Children: DW_CHILDREN_no
+        Attributes:
+          - Attribute: DW_AT_type
+            Form:      DW_FORM_ref4
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+      - Tag:      DW_TAG_class_type
+        Children: DW_CHILDREN_no
+        Attributes:
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+          - Attribute: DW_AT_declaration
+            Form:      DW_FORM_flag_present
+      - Tag:      DW_TAG_class_type
+        Children: DW_CHILDREN_yes
+        Attributes:
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+          - Attribute: DW_AT_declaration
+            Form:      DW_FORM_flag_present
+      - Tag:      DW_TAG_template_type_parameter
+        Children: DW_CHILDREN_no
+        Attributes:
+          - Attribute: DW_AT_type
+            Form:      DW_FORM_ref4
+      - Tag:      DW_TAG_base_type
+        Children: DW_CHILDREN_no
+        Attributes:
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+  debug_info:
+    - Version: 4
+      Entries:
+        - AbbrCode: 1
+          Values:
+            - CStr: by_hand
+            - Value:  0x04
+            - CStr: CU1
+            - Value:  0x1000
+            - Value:  0x1b
+        - AbbrCode: 3
+          Values:
+            - CStr: class1
+        - AbbrCode: 4
+          Values:
+            - Value:  0x0000006c
+            - CStr: member1
+        - AbbrCode: 0
+        - AbbrCode: 3
+          Values:
+            - CStr: class2
+        - AbbrCode: 4
+          Values:
+            - Value:  0x0000006c
+            - CStr: member1
+        - AbbrCode: 0
+        - AbbrCode: 3
+          Values:
+            - CStr: class3
+        - AbbrCode: 4
+          Values:
+            - Value:  0x0000006c
+            - CStr: member1
+        - AbbrCode: 0
+        - AbbrCode: 8
+          Values:
+            - CStr: int
+        - AbbrCode: 2
+          Values:
+            - CStr: foo1
+            - Value:  0x1000
+            - Value:  0x10
+            - Value:  0x0000002a
+        - AbbrCode: 2
+          Values:
+            - CStr: foo2
+            - Value:  0x0
+            - Value:  0x100
+            - Value:  0x00000040
+        - AbbrCode: 0
+...

llvm/test/tools/llvm-dwarfutil/ELF/gc-func-overlapping-address-ranges.test

+## This test checks that overlapping function address ranges
+## are ignored (i.e. left unchanged) by --garbage-collection
+## optimisation. "Overlapped address range" warning should
+## be displayed.
+
+# RUN: yaml2obj %s -o %t.o
+# RUN: llvm-dwarfutil --garbage-collection %t.o %t1 2>&1 | FileCheck --check-prefix=CHECK-WARNING %s
+# RUN: llvm-dwarfdump -a %t1 | FileCheck %s
+
+# CHECK-WARNING: warning: {{.*}}: Overlapping address range [0x1004, 0x100B]. Range will be discarded.
+
+# CHECK: DW_TAG_compile_unit
+# CHECK: DW_AT_name{{.*}}"CU1"
+# CHECK: DW_TAG_class_type
+# CHECK: DW_AT_name{{.*}}"class1"
+# CHECK: DW_TAG_class_type
+# CHECK: "class2"
+# CHECK: DW_TAG_subprogram
+# CHECK: DW_AT_name{{.*}}"foo1"
+# CHECK: DW_AT_low_pc{{.*}}0x0000000000001000
+# CHECK: DW_AT_high_pc{{.*}}0x0000000000001010
+# CHECK: DW_AT_type{{.*}}"class1"
+# CHECK: DW_TAG_subprogram
+# CHECK: "foo2"
+# CHECK: DW_AT_low_pc{{.*}}0x0000000000001004
+# CHECK: DW_AT_high_pc{{.*}}0x000000000000100b
+# CHECK: DW_AT_type{{.*}}"class2"
+
+--- !ELF
+FileHeader:
+  Class:    ELFCLASS64
+  Data:     ELFDATA2LSB
+  Type:     ET_REL
+  Machine:  EM_X86_64
+Sections:
+  - Name:            .text
+    Type:            SHT_PROGBITS
+    Flags:           [ SHF_ALLOC, SHF_EXECINSTR ]
+    Address:         0x1000
+    AddressAlign:    0x0000000000000010
+    Content:        "FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF"
+DWARF:
+  debug_abbrev:
+    - Table:
+      - Tag:      DW_TAG_compile_unit
+        Children: DW_CHILDREN_yes
+        Attributes:
+          - Attribute: DW_AT_producer
+            Form:      DW_FORM_string
+          - Attribute: DW_AT_language
+            Form:      DW_FORM_data2
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+          - Attribute: DW_AT_low_pc
+            Form:      DW_FORM_addr
+          - Attribute: DW_AT_high_pc
+            Form:      DW_FORM_data8
+      - Tag:      DW_TAG_subprogram
+        Children: DW_CHILDREN_no
+        Attributes:
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+          - Attribute: DW_AT_low_pc
+            Form:      DW_FORM_addr
+          - Attribute: DW_AT_high_pc
+            Form:      DW_FORM_data8
+          - Attribute: DW_AT_type
+            Form:      DW_FORM_ref4
+      - Tag:      DW_TAG_class_type
+        Children: DW_CHILDREN_yes
+        Attributes:
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+      - Tag:      DW_TAG_member
+        Children: DW_CHILDREN_no
+        Attributes:
+          - Attribute: DW_AT_type
+            Form:      DW_FORM_ref4
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+      - Tag:      DW_TAG_class_type
+        Children: DW_CHILDREN_no
+        Attributes:
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+          - Attribute: DW_AT_declaration
+            Form:      DW_FORM_flag_present
+      - Tag:      DW_TAG_class_type
+        Children: DW_CHILDREN_yes
+        Attributes:
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+          - Attribute: DW_AT_declaration
+            Form:      DW_FORM_flag_present
+      - Tag:      DW_TAG_template_type_parameter
+        Children: DW_CHILDREN_no
+        Attributes:
+          - Attribute: DW_AT_type
+            Form:      DW_FORM_ref4
+      - Tag:      DW_TAG_base_type
+        Children: DW_CHILDREN_no
+        Attributes:
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+  debug_info:
+    - Version: 4
+      Entries:
+        - AbbrCode: 1
+          Values:
+            - CStr: by_hand
+            - Value:  0x04
+            - CStr: CU1
+            - Value:  0x1000
+            - Value:  0x1b
+        - AbbrCode: 3
+          Values:
+            - CStr: class1
+        - AbbrCode: 4
+          Values:
+            - Value:  0x00000056
+            - CStr: member1
+        - AbbrCode: 0
+        - AbbrCode: 3
+          Values:
+            - CStr: class2
+        - AbbrCode: 4
+          Values:
+            - Value:  0x00000056
+            - CStr: member1
+        - AbbrCode: 0
+        - AbbrCode: 8
+          Values:
+            - CStr: int
+        - AbbrCode: 2
+          Values:
+            - CStr: foo1
+            - Value:  0x1000
+            - Value:  0x10
+            - Value:  0x0000002a
+        - AbbrCode: 2
+          Values:
+            - CStr: foo2
+            - Value:  0x1004
+            - Value:  0x7
+            - Value:  0x00000040
+        - AbbrCode: 0
+...

llvm/test/tools/llvm-dwarfutil/ELF/gc-maxpc.test

+## This test checks that debug info related to deleted code (marked with
+## tombstone=maxpc) is removed.
+
+## RUN: yaml2obj %s -o %t.o
+
+# RUN: llvm-dwarfutil --tombstone=maxpc --garbage-collection %t.o - | llvm-dwarfdump -a - | FileCheck %s
+# RUN: llvm-dwarfutil --tombstone=universal --garbage-collection %t.o - | llvm-dwarfdump -a - | FileCheck %s
+
+# CHECK: DW_TAG_compile_unit
+# CHECK: DW_AT_name{{.*}}"CU1"
+# CHECK: DW_TAG_class_type
+# CHECK: DW_AT_name{{.*}}"class1"
+# CHECK-NOT: DW_TAG_class_type
+# CHECK-NOT: "class2"
+# CHECK-NOT: "class3"
+# CHECK: DW_TAG_subprogram
+# CHECK: DW_AT_name{{.*}}"foo1"
+# CHECK: DW_AT_low_pc{{.*}}0x0000000000001000
+# CHECK: DW_AT_high_pc{{.*}}0x0000000000001010
+# CHECK: DW_AT_type{{.*}}"class1"
+# CHECK-NOT: DW_TAG_subprogram
+# CHECK-NOT: "foo2"
+
+
+--- !ELF
+FileHeader:
+  Class:    ELFCLASS64
+  Data:     ELFDATA2LSB
+  Type:     ET_REL
+  Machine:  EM_X86_64
+Sections:
+  - Name:            .text
+    Type:            SHT_PROGBITS
+    Flags:           [ SHF_ALLOC, SHF_EXECINSTR ]
+    Address:         0x1000
+    AddressAlign:    0x0000000000000010
+    Content:        "FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF"
+DWARF:
+  debug_abbrev:
+    - Table:
+      - Tag:      DW_TAG_compile_unit
+        Children: DW_CHILDREN_yes
+        Attributes:
+          - Attribute: DW_AT_producer
+            Form:      DW_FORM_string
+          - Attribute: DW_AT_language
+            Form:      DW_FORM_data2
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+          - Attribute: DW_AT_low_pc
+            Form:      DW_FORM_addr
+          - Attribute: DW_AT_high_pc
+            Form:      DW_FORM_data8
+      - Tag:      DW_TAG_subprogram
+        Children: DW_CHILDREN_no
+        Attributes:
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+          - Attribute: DW_AT_low_pc
+            Form:      DW_FORM_addr
+          - Attribute: DW_AT_high_pc
+            Form:      DW_FORM_data8
+          - Attribute: DW_AT_type
+            Form:      DW_FORM_ref4
+      - Tag:      DW_TAG_class_type
+        Children: DW_CHILDREN_yes
+        Attributes:
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+      - Tag:      DW_TAG_member
+        Children: DW_CHILDREN_no
+        Attributes:
+          - Attribute: DW_AT_type
+            Form:      DW_FORM_ref4
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+      - Tag:      DW_TAG_class_type
+        Children: DW_CHILDREN_no
+        Attributes:
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+          - Attribute: DW_AT_declaration
+            Form:      DW_FORM_flag_present
+      - Tag:      DW_TAG_class_type
+        Children: DW_CHILDREN_yes
+        Attributes:
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+          - Attribute: DW_AT_declaration
+            Form:      DW_FORM_flag_present
+      - Tag:      DW_TAG_template_type_parameter
+        Children: DW_CHILDREN_no
+        Attributes:
+          - Attribute: DW_AT_type
+            Form:      DW_FORM_ref4
+      - Tag:      DW_TAG_base_type
+        Children: DW_CHILDREN_no
+        Attributes:
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+  debug_info:
+    - Version: 4
+      Entries:
+        - AbbrCode: 1
+          Values:
+            - CStr: by_hand
+            - Value:  0x04
+            - CStr: CU1
+            - Value:  0x1000
+            - Value:  0x1b
+        - AbbrCode: 3
+          Values:
+            - CStr: class1
+        - AbbrCode: 4
+          Values:
+            - Value:  0x0000006c
+            - CStr: member1
+        - AbbrCode: 0
+        - AbbrCode: 3
+          Values:
+            - CStr: class2
+        - AbbrCode: 4
+          Values:
+            - Value:  0x0000006c
+            - CStr: member1
+        - AbbrCode: 0
+        - AbbrCode: 3
+          Values:
+            - CStr: class3
+        - AbbrCode: 4
+          Values:
+            - Value:  0x0000006c
+            - CStr: member1
+        - AbbrCode: 0
+        - AbbrCode: 8
+          Values:
+            - CStr: int
+        - AbbrCode: 2
+          Values:
+            - CStr: foo1
+            - Value:  0x1000
+            - Value:  0x10
+            - Value:  0x0000002a
+        - AbbrCode: 2
+          Values:
+            - CStr: foo2
+            - Value:  0xFFFFFFFFFFFFFFFF
+            - Value:  0x100
+            - Value:  0x00000040
+        - AbbrCode: 0
+...

llvm/test/tools/llvm-dwarfutil/ELF/gc-no-garbage.test

+## This test checks that debug info removal optimization (--garbage-collection)
+## does not affect files which do not have dead debug info.
+
+# RUN: yaml2obj %s -o %t.o
+# RUN: llvm-dwarfutil --tombstone=maxpc --garbage-collection %t.o - | llvm-dwarfdump -a - | FileCheck %s
+
+# CHECK: DW_TAG_compile_unit
+# CHECK: DW_AT_name{{.*}}"CU1"
+# CHECK: DW_TAG_class_type
+# CHECK: DW_AT_name{{.*}}"class1"
+# CHECK: DW_TAG_class_type
+# CHECK: "class2"
+# CHECK: DW_TAG_subprogram
+# CHECK: DW_AT_name{{.*}}"foo1"
+# CHECK: DW_AT_low_pc{{.*}}0x0000000000001000
+# CHECK: DW_AT_high_pc{{.*}}0x0000000000001010
+# CHECK: DW_AT_type{{.*}}"class1"
+# CHECK: DW_TAG_subprogram
+# CHECK: "foo2"
+# CHECK: DW_AT_low_pc{{.*}}0x0000000000001010
+# CHECK: DW_AT_high_pc{{.*}}0x000000000000101b
+# CHECK: DW_AT_type{{.*}}"class2"
+
+
+--- !ELF
+FileHeader:
+  Class:    ELFCLASS64
+  Data:     ELFDATA2LSB
+  Type:     ET_REL
+  Machine:  EM_X86_64
+Sections:
+  - Name:            .text
+    Type:            SHT_PROGBITS
+    Flags:           [ SHF_ALLOC, SHF_EXECINSTR ]
+    Address:         0x1000
+    AddressAlign:    0x0000000000000010
+    Content:        "FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF"
+DWARF:
+  debug_abbrev:
+    - Table:
+      - Tag:      DW_TAG_compile_unit
+        Children: DW_CHILDREN_yes
+        Attributes:
+          - Attribute: DW_AT_producer
+            Form:      DW_FORM_string
+          - Attribute: DW_AT_language
+            Form:      DW_FORM_data2
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+          - Attribute: DW_AT_low_pc
+            Form:      DW_FORM_addr
+          - Attribute: DW_AT_high_pc
+            Form:      DW_FORM_data8
+      - Tag:      DW_TAG_subprogram
+        Children: DW_CHILDREN_no
+        Attributes:
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+          - Attribute: DW_AT_low_pc
+            Form:      DW_FORM_addr
+          - Attribute: DW_AT_high_pc
+            Form:      DW_FORM_data8
+          - Attribute: DW_AT_type
+            Form:      DW_FORM_ref4
+      - Tag:      DW_TAG_class_type
+        Children: DW_CHILDREN_yes
+        Attributes:
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+      - Tag:      DW_TAG_member
+        Children: DW_CHILDREN_no
+        Attributes:
+          - Attribute: DW_AT_type
+            Form:      DW_FORM_ref4
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+      - Tag:      DW_TAG_class_type
+        Children: DW_CHILDREN_no
+        Attributes:
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+          - Attribute: DW_AT_declaration
+            Form:      DW_FORM_flag_present
+      - Tag:      DW_TAG_class_type
+        Children: DW_CHILDREN_yes
+        Attributes:
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+          - Attribute: DW_AT_declaration
+            Form:      DW_FORM_flag_present
+      - Tag:      DW_TAG_template_type_parameter
+        Children: DW_CHILDREN_no
+        Attributes:
+          - Attribute: DW_AT_type
+            Form:      DW_FORM_ref4
+      - Tag:      DW_TAG_base_type
+        Children: DW_CHILDREN_no
+        Attributes:
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+  debug_info:
+    - Version: 4
+      Entries:
+        - AbbrCode: 1
+          Values:
+            - CStr: by_hand
+            - Value:  0x04
+            - CStr: CU1
+            - Value:  0x1000
+            - Value:  0x1b
+        - AbbrCode: 3
+          Values:
+            - CStr: class1
+        - AbbrCode: 4
+          Values:
+            - Value:  0x00000056
+            - CStr: member1
+        - AbbrCode: 0
+        - AbbrCode: 3
+          Values:
+            - CStr: class2
+        - AbbrCode: 4
+          Values:
+            - Value:  0x00000056
+            - CStr: member1
+        - AbbrCode: 0
+        - AbbrCode: 8
+          Values:
+            - CStr: int
+        - AbbrCode: 2
+          Values:
+            - CStr: foo1
+            - Value:  0x1000
+            - Value:  0x10
+            - Value:  0x0000002a
+        - AbbrCode: 2
+          Values:
+            - CStr: foo2
+            - Value:  0x1010
+            - Value:  0xb
+            - Value:  0x00000040
+        - AbbrCode: 0
+...

llvm/test/tools/llvm-dwarfutil/ELF/gc-unit-overlapping-address-ranges.test

+## This test checks that overlapping compile unit address ranges
+## are ignored (i.e. left unchanged) by --garbage-collection
+## optimisation.
+
+# RUN: yaml2obj %s -o %t.o
+# RUN: llvm-dwarfutil --garbage-collection %t.o %t1
+# RUN: llvm-dwarfdump -a %t1 | FileCheck %s
+
+# CHECK: DW_TAG_compile_unit
+# CHECK: DW_AT_name{{.*}}"CU1"
+# CHECK: DW_TAG_class_type
+# CHECK: DW_AT_name{{.*}}"class1"
+# CHECK: DW_TAG_subprogram
+# CHECK: DW_AT_name{{.*}}"foo1"
+# CHECK: DW_AT_low_pc{{.*}}0x0000000000001000
+# CHECK: DW_AT_high_pc{{.*}}0x0000000000001010
+# CHECK: DW_TAG_subprogram
+# CHECK: DW_AT_name{{.*}}"foo2"
+# CHECK: DW_AT_low_pc{{.*}}0x0000000000001000
+# CHECK: DW_AT_high_pc{{.*}}0x0000000000001010
+# CHECK: DW_AT_type{{.*}}"class2"
+
+--- !ELF
+FileHeader:
+  Class:    ELFCLASS64
+  Data:     ELFDATA2LSB
+  Type:     ET_REL
+  Machine:  EM_X86_64
+Sections:
+  - Name:            .text
+    Type:            SHT_PROGBITS
+    Flags:           [ SHF_ALLOC, SHF_EXECINSTR ]
+    Address:         0x1000
+    AddressAlign:    0x0000000000000010
+    Content:        "FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF"
+DWARF:
+  debug_abbrev:
+    - Table:
+      - Tag:      DW_TAG_compile_unit
+        Children: DW_CHILDREN_yes
+        Attributes:
+          - Attribute: DW_AT_producer
+            Form:      DW_FORM_string
+          - Attribute: DW_AT_language
+            Form:      DW_FORM_data2
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+          - Attribute: DW_AT_low_pc
+            Form:      DW_FORM_addr
+          - Attribute: DW_AT_high_pc
+            Form:      DW_FORM_data8
+      - Tag:      DW_TAG_subprogram
+        Children: DW_CHILDREN_no
+        Attributes:
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+          - Attribute: DW_AT_low_pc
+            Form:      DW_FORM_addr
+          - Attribute: DW_AT_high_pc
+            Form:      DW_FORM_data8
+          - Attribute: DW_AT_type
+            Form:      DW_FORM_ref4
+      - Tag:      DW_TAG_class_type
+        Children: DW_CHILDREN_yes
+        Attributes:
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+      - Tag:      DW_TAG_member
+        Children: DW_CHILDREN_no
+        Attributes:
+          - Attribute: DW_AT_type
+            Form:      DW_FORM_ref4
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+      - Tag:      DW_TAG_class_type
+        Children: DW_CHILDREN_no
+        Attributes:
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+          - Attribute: DW_AT_declaration
+            Form:      DW_FORM_flag_present
+      - Tag:      DW_TAG_class_type
+        Children: DW_CHILDREN_yes
+        Attributes:
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+          - Attribute: DW_AT_declaration
+            Form:      DW_FORM_flag_present
+      - Tag:      DW_TAG_template_type_parameter
+        Children: DW_CHILDREN_no
+        Attributes:
+          - Attribute: DW_AT_type
+            Form:      DW_FORM_ref4
+      - Tag:      DW_TAG_base_type
+        Children: DW_CHILDREN_no
+        Attributes:
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+    - Table:
+      - Tag:      DW_TAG_compile_unit
+        Children: DW_CHILDREN_yes
+        Attributes:
+          - Attribute: DW_AT_producer
+            Form:      DW_FORM_string
+          - Attribute: DW_AT_language
+            Form:      DW_FORM_data2
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+          - Attribute: DW_AT_low_pc
+            Form:      DW_FORM_addr
+          - Attribute: DW_AT_high_pc
+            Form:      DW_FORM_data8
+      - Tag:      DW_TAG_subprogram
+        Children: DW_CHILDREN_no
+        Attributes:
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+          - Attribute: DW_AT_low_pc
+            Form:      DW_FORM_addr
+          - Attribute: DW_AT_high_pc
+            Form:      DW_FORM_data8
+          - Attribute: DW_AT_type
+            Form:      DW_FORM_ref4
+      - Tag:      DW_TAG_class_type
+        Children: DW_CHILDREN_yes
+        Attributes:
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+      - Tag:      DW_TAG_member
+        Children: DW_CHILDREN_no
+        Attributes:
+          - Attribute: DW_AT_type
+            Form:      DW_FORM_ref4
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+      - Tag:      DW_TAG_class_type
+        Children: DW_CHILDREN_no
+        Attributes:
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+          - Attribute: DW_AT_declaration
+            Form:      DW_FORM_flag_present
+      - Tag:      DW_TAG_class_type
+        Children: DW_CHILDREN_yes
+        Attributes:
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+          - Attribute: DW_AT_declaration
+            Form:      DW_FORM_flag_present
+      - Tag:      DW_TAG_template_type_parameter
+        Children: DW_CHILDREN_no
+        Attributes:
+          - Attribute: DW_AT_type
+            Form:      DW_FORM_ref4
+      - Tag:      DW_TAG_base_type
+        Children: DW_CHILDREN_no
+        Attributes:
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+  debug_info:
+    - Version: 4
+      Entries:
+        - AbbrCode: 1
+          Values:
+            - CStr: by_hand
+            - Value:  0x04
+            - CStr: CU1
+            - Value:  0x1000
+            - Value:  0x1b
+        - AbbrCode: 3
+          Values:
+            - CStr: class1
+        - AbbrCode: 4
+          Values:
+            - Value:  0x0000006c
+            - CStr: member1
+        - AbbrCode: 0
+        - AbbrCode: 3
+          Values:
+            - CStr: class2
+        - AbbrCode: 4
+          Values:
+            - Value:  0x0000006c
+            - CStr: member1
+        - AbbrCode: 0
+        - AbbrCode: 3
+          Values:
+            - CStr: class3
+        - AbbrCode: 4
+          Values:
+            - Value:  0x0000006c
+            - CStr: member1
+        - AbbrCode: 0
+        - AbbrCode: 8
+          Values:
+            - CStr: int
+        - AbbrCode: 2
+          Values:
+            - CStr: foo1
+            - Value:  0x1000
+            - Value:  0x10
+            - Value:  0x0000002a
+        - AbbrCode: 0
+    - Version: 4
+      Entries:
+        - AbbrCode: 1
+          Values:
+            - CStr: by_hand
+            - Value:  0x04
+            - CStr: CU1
+            - Value:  0x1000
+            - Value:  0x1b
+        - AbbrCode: 3
+          Values:
+            - CStr: class1
+        - AbbrCode: 4
+          Values:
+            - Value:  0x0000006c
+            - CStr: member1
+        - AbbrCode: 0
+        - AbbrCode: 3
+          Values:
+            - CStr: class2
+        - AbbrCode: 4
+          Values:
+            - Value:  0x0000006c
+            - CStr: member1
+        - AbbrCode: 0
+        - AbbrCode: 3
+          Values:
+            - CStr: class3
+        - AbbrCode: 4
+          Values:
+            - Value:  0x0000006c
+            - CStr: member1
+        - AbbrCode: 0
+        - AbbrCode: 8
+          Values:
+            - CStr: int
+        - AbbrCode: 2
+          Values:
+            - CStr: foo2
+            - Value:  0x1000
+            - Value:  0x10
+            - Value:  0x00000040
+        - AbbrCode: 0
+...

llvm/test/tools/llvm-dwarfutil/ELF/odr-fwd-declaration.test

+## This test checks debug info for the case when one compilation unit
+## contains a forward declaration of a type and another compilation unit
+## contains a definition for that type. The result should contain
+## the original definition and the declaration without modifications.
+
+# RUN: yaml2obj %s -o %t.o
+# RUN: llvm-dwarfutil %t.o - | llvm-dwarfdump -a - | FileCheck %s
+
+## CU1:
+##
+## class class1;
+## template<int> class class2;
+##
+## class1 *var1;
+## class2<int> *var2;
+##
+## CU2:
+##
+## class class1 {
+##   char member1;
+##   float member2;
+## };
+##
+## template<int> class class2 {
+##   char member1;
+## };
+##
+## class1 *var1;
+## class2<int> *var2;
+
+# CHECK: file format elf64-x86-64
+# CHECK: .debug_info contents:
+
+# CHECK: DW_TAG_compile_unit
+# CHECK: DW_AT_name{{.*}}"CU1"
+
+# CHECK: 0x[[CU1_CLASS1:[0-9a-f]*]]: DW_TAG_class_type{{.*[[:space:]].*}}DW_AT_name{{.*}}"class1"
+# CHECK: DW_AT_declaration (true)
+
+# CHECK: 0x[[CU1_CLASS2:[0-9a-f]*]]: DW_TAG_class_type{{.*[[:space:]].*}}DW_AT_name{{.*}}"class2"
+# CHECK: DW_AT_declaration (true)
+# CHECK: DW_TAG_template_type_parameter{{.*[[:space:]].*}}DW_AT_type{{.*}}0x00000000[[CU1_INT:[0-9a-f]*]] "int"
+
+# CHECK: 0x[[CU1_INT]]: DW_TAG_base_type
+# CHECK: DW_AT_name{{.*}}"int"
+
+# CHECK: 0x[[CU1_PTR_CLASS1:[0-9a-f]*]]: DW_TAG_pointer_type{{.*[[:space:]].*}}DW_AT_type{{.*}}0x00000000[[CU1_CLASS1]] "class1"
+
+# CHECK: 0x[[CU1_PTR_CLASS2:[0-9a-f]*]]: DW_TAG_pointer_type{{.*[[:space:]].*}}DW_AT_type{{.*}}0x00000000[[CU1_CLASS2]] "class2<int>"
+
+# CHECK: DW_TAG_variable
+# CHECK: DW_AT_name{{.*}}"var1"
+# CHECK: DW_AT_type{{.*}}0x00000000[[CU1_PTR_CLASS1]] "class1 *"
+# CHECK: DW_TAG_variable
+# CHECK: DW_AT_name{{.*}}"var2"
+# CHECK: DW_AT_type{{.*}}0x00000000[[CU1_PTR_CLASS2]] "class2<int> *"
+
+# CHECK: DW_TAG_compile_unit
+# CHECK: DW_AT_name{{.*}}"CU2"
+
+# CHECK: 0x[[CU2_CLASS1:[0-9a-f]*]]: DW_TAG_class_type{{.*[[:space:]].*}}DW_AT_name{{.*}}"class1"
+# CHECK: DW_TAG_member
+# CHECK: DW_AT_type{{.*}}0x00000000[[CU2_CHAR:[0-9a-f]*]] "char"
+# CHECK: DW_AT_name{{.*}}"member1"
+
+# CHECK: DW_TAG_member
+# CHECK: DW_AT_type{{.*}}0x00000000[[CU2_FLOAT:[0-9a-f]*]] "float"
+# CHECK: DW_AT_name{{.*}}"member2"
+
+# CHECK: 0x[[CU2_CLASS2:[0-9a-f]*]]: DW_TAG_class_type{{.*[[:space:]].*}}DW_AT_name{{.*}}"class2"
+# CHECK: DW_TAG_template_type_parameter{{.*[[:space:]].*}}DW_AT_type{{.*}}0x00000000[[CU2_INT:[0-9a-f]*]] "int"
+# CHECK: DW_TAG_member
+# CHECK: DW_AT_type{{.*}}0x00000000[[CU2_CHAR]] "char"
+# CHECK: DW_AT_name{{.*}}"member1"
+
+# CHECK: 0x[[CU2_INT]]: DW_TAG_base_type
+# CHECK: DW_AT_name{{.*}}"int"
+
+# CHECK: 0x[[CU2_CHAR]]: DW_TAG_base_type
+# CHECK: DW_AT_name{{.*}}"char"
+
+# CHECK: 0x[[CU2_FLOAT]]: DW_TAG_base_type
+# CHECK: DW_AT_name{{.*}}"float"
+
+# CHECK: 0x[[CU2_PTR_CLASS1:[0-9a-f]*]]: DW_TAG_pointer_type{{.*[[:space:]].*}}DW_AT_type{{.*}}0x00000000[[CU2_CLASS1]] "class1"
+
+# CHECK: 0x[[CU2_PTR_CLASS2:[0-9a-f]*]]: DW_TAG_pointer_type{{.*[[:space:]].*}}DW_AT_type{{.*}}0x00000000[[CU2_CLASS2]] "class2<int>"
+
+# CHECK: DW_TAG_variable
+# CHECK: DW_AT_name{{.*}}"var1"
+# CHECK: DW_AT_type{{.*}}0x00000000[[CU2_PTR_CLASS1]] "class1 *"
+# CHECK: DW_TAG_variable
+# CHECK: DW_AT_name{{.*}}"var2"
+# CHECK: DW_AT_type{{.*}}0x00000000[[CU2_PTR_CLASS2]] "class2<int> *"
+
+--- !ELF
+FileHeader:
+  Class:    ELFCLASS64
+  Data:     ELFDATA2LSB
+  Type:     ET_REL
+  Machine:  EM_X86_64
+Sections:
+  - Name:            .text
+    Type:            SHT_PROGBITS
+    Flags:           [ SHF_ALLOC, SHF_EXECINSTR ]
+    Address:         0x1000
+    AddressAlign:    0x0000000000000010
+    Content:        "FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF"
+  - Name:            .text2
+    Type:            SHT_PROGBITS
+    Flags:           [ SHF_ALLOC, SHF_EXECINSTR ]
+    Address:         0x2000
+    AddressAlign:    0x0000000000000010
+    Content:        "FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF"
+DWARF:
+  debug_abbrev:
+    - Table:
+      - Tag:      DW_TAG_compile_unit
+        Children: DW_CHILDREN_yes
+        Attributes:
+          - Attribute: DW_AT_producer
+            Form:      DW_FORM_string
+          - Attribute: DW_AT_language
+            Form:      DW_FORM_data2
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+          - Attribute: DW_AT_low_pc
+            Form:      DW_FORM_addr
+          - Attribute: DW_AT_high_pc
+            Form:      DW_FORM_data8
+      - Tag:      DW_TAG_class_type
+        Children: DW_CHILDREN_yes
+        Attributes:
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+      - Tag:      DW_TAG_member
+        Children: DW_CHILDREN_no
+        Attributes:
+          - Attribute: DW_AT_type
+            Form:      DW_FORM_ref_addr
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+      - Tag:      DW_TAG_class_type
+        Children: DW_CHILDREN_no
+        Attributes:
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+          - Attribute: DW_AT_declaration
+            Form:      DW_FORM_flag_present
+      - Tag:      DW_TAG_class_type
+        Children: DW_CHILDREN_yes
+        Attributes:
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+          - Attribute: DW_AT_declaration
+            Form:      DW_FORM_flag_present
+      - Tag:      DW_TAG_template_type_parameter
+        Children: DW_CHILDREN_no
+        Attributes:
+          - Attribute: DW_AT_type
+            Form:      DW_FORM_ref_addr
+      - Tag:      DW_TAG_base_type
+        Children: DW_CHILDREN_no
+        Attributes:
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+      - Tag:      DW_TAG_pointer_type
+        Children: DW_CHILDREN_no
+        Attributes:
+          - Attribute: DW_AT_type
+            Form:      DW_FORM_ref_addr
+      - Tag:      DW_TAG_variable
+        Children: DW_CHILDREN_no
+        Attributes:
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+          - Attribute: DW_AT_const_value
+            Form:      DW_FORM_data4
+          - Attribute: DW_AT_type
+            Form:      DW_FORM_ref_addr
+    - Table:
+      - Tag:      DW_TAG_compile_unit
+        Children: DW_CHILDREN_yes
+        Attributes:
+          - Attribute: DW_AT_producer
+            Form:      DW_FORM_string
+          - Attribute: DW_AT_language
+            Form:      DW_FORM_data2
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+          - Attribute: DW_AT_low_pc
+            Form:      DW_FORM_addr
+          - Attribute: DW_AT_high_pc
+            Form:      DW_FORM_data8
+      - Tag:      DW_TAG_class_type
+        Children: DW_CHILDREN_yes
+        Attributes:
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+      - Tag:      DW_TAG_member
+        Children: DW_CHILDREN_no
+        Attributes:
+          - Attribute: DW_AT_type
+            Form:      DW_FORM_ref_addr
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+      - Tag:      DW_TAG_class_type
+        Children: DW_CHILDREN_no
+        Attributes:
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+          - Attribute: DW_AT_declaration
+            Form:      DW_FORM_flag_present
+      - Tag:      DW_TAG_class_type
+        Children: DW_CHILDREN_yes
+        Attributes:
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+          - Attribute: DW_AT_declaration
+            Form:      DW_FORM_flag_present
+      - Tag:      DW_TAG_template_type_parameter
+        Children: DW_CHILDREN_no
+        Attributes:
+          - Attribute: DW_AT_type
+            Form:      DW_FORM_ref_addr
+      - Tag:      DW_TAG_base_type
+        Children: DW_CHILDREN_no
+        Attributes:
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+      - Tag:      DW_TAG_pointer_type
+        Children: DW_CHILDREN_no
+        Attributes:
+          - Attribute: DW_AT_type
+            Form:      DW_FORM_ref_addr
+      - Tag:      DW_TAG_variable
+        Children: DW_CHILDREN_no
+        Attributes:
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+          - Attribute: DW_AT_const_value
+            Form:      DW_FORM_data4
+          - Attribute: DW_AT_type
+            Form:      DW_FORM_ref_addr
+  debug_info:
+    - Version: 4
+      Entries:
+        - AbbrCode: 1
+          Values:
+            - CStr: by_hand
+            - Value:  0x04
+            - CStr: CU1
+            - Value:  0x1000
+            - Value:  0x1b
+        - AbbrCode: 4
+          Values:
+            - CStr: class1
+        - AbbrCode: 5
+          Values:
+            - CStr: class2
+        - AbbrCode: 6
+          Values:
+            - Value:  0x00000040
+        - AbbrCode: 0
+        - AbbrCode: 7
+          Values:
+            - CStr: int
+        - AbbrCode: 8
+          Values:
+            - Value:  0x0000002a
+        - AbbrCode: 8
+          Values:
+            - Value:  0x00000032
+        - AbbrCode: 9
+          Values:
+            - CStr: var1
+            - Value:  0x00000000
+            - Value:  0x00000045
+        - AbbrCode: 9
+          Values:
+            - CStr: var2
+            - Value:  0x00000000
+            - Value:  0x0000004a
+        - AbbrCode: 0
+    - Version: 4
+      Entries:
+        - AbbrCode: 1
+          Values:
+            - CStr: by_hand
+            - Value:  0x04
+            - CStr: CU2
+            - Value:  0x2000
+            - Value:  0x1b
+        - AbbrCode: 2
+          Values:
+            - CStr: class1
+        - AbbrCode: 3
+          Values:
+            - Value:  0x000000d9
+            - CStr: member1
+        - AbbrCode: 3
+          Values:
+            - Value:  0x000000df
+            - CStr: member2
+        - AbbrCode: 0
+        - AbbrCode: 2
+          Values:
+            - CStr: class2
+        - AbbrCode: 6
+          Values:
+            - Value:  0x000000d4
+        - AbbrCode: 3
+          Values:
+            - Value:  0x000000d9
+            - CStr: member1
+        - AbbrCode: 0
+        - AbbrCode: 7
+          Values:
+            - CStr: int
+        - AbbrCode: 7
+          Values:
+            - CStr: char
+        - AbbrCode: 7
+          Values:
+            - CStr: float
+        - AbbrCode: 8
+          Values:
+            - Value:  0x00000096
+        - AbbrCode: 8
+          Values:
+            - Value:  0x000000b9
+        - AbbrCode: 9
+          Values:
+            - CStr: var1
+            - Value:  0x00000000
+            - Value:  0x000000e6
+        - AbbrCode: 9
+          Values:
+            - CStr: var2
+            - Value:  0x00000000
+            - Value:  0x000000eb
+        - AbbrCode: 0
+...

llvm/test/tools/llvm-dwarfutil/ELF/verbose.test

+## This test checks output of llvm-dwarfutil when verbose mode
+## is enabled.
+
+# RUN: yaml2obj %s -o %t.o
+
+## Check verbose output.
+# RUN: llvm-dwarfutil %t.o %t1 -j 1 --verbose 2>&1 | FileCheck %s
+
+## Check warning displayed in multi-thread mode.
+# RUN: llvm-dwarfutil %t.o %t1 --verbose 2>&1 | FileCheck %s --check-prefix=CHECK-THREAD-WARNING
+
+## Check warning displayed in multi-thread mode (--num-threads set explicitly).
+# RUN: llvm-dwarfutil %t.o %t1 --verbose --num-threads 10 2>&1 | FileCheck %s --check-prefix=CHECK-THREAD-WARNING
+
+## Check warning displayed in multi-thread mode (use alias of --num-threads).
+# RUN: llvm-dwarfutil %t.o %t1 --verbose -j 10 2>&1 | FileCheck %s --check-prefix=CHECK-THREAD-WARNING
+
+## Check verbose output.
+# RUN: llvm-dwarfutil %t.o %t1 -j 1 --verbose --verify 2>&1 | FileCheck %s --check-prefixes=CHECK,CHECK-VERIFY
+
+# CHECK-NOT: warning: --num-threads set to 1 because verbose mode is specified
+# CHECK: Do garbage collection for debug info ...
+# CHECK-THREAD-WARNING: warning: --num-threads set to 1 because verbose mode is specified
+# CHECK-VERIFY: Verifying DWARF...
+
+--- !ELF
+FileHeader:
+  Class:    ELFCLASS64
+  Data:     ELFDATA2LSB
+  Type:     ET_REL
+  Machine:  EM_X86_64
+DWARF:
+  debug_abbrev:
+    - Table:
+      - Tag:      DW_TAG_compile_unit
+        Children: DW_CHILDREN_yes
+        Attributes:
+          - Attribute: DW_AT_producer
+            Form:      DW_FORM_string
+          - Attribute: DW_AT_language
+            Form:      DW_FORM_data2
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+          - Attribute: DW_AT_low_pc
+            Form:      DW_FORM_addr
+          - Attribute: DW_AT_high_pc
+            Form:      DW_FORM_data8
+      - Tag:      DW_TAG_subprogram
+        Children: DW_CHILDREN_no
+        Attributes:
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+          - Attribute: DW_AT_low_pc
+            Form:      DW_FORM_addr
+          - Attribute: DW_AT_high_pc
+            Form:      DW_FORM_data8
+          - Attribute: DW_AT_type
+            Form:      DW_FORM_ref4
+      - Tag:      DW_TAG_class_type
+        Children: DW_CHILDREN_yes
+        Attributes:
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+      - Tag:      DW_TAG_member
+        Children: DW_CHILDREN_no
+        Attributes:
+          - Attribute: DW_AT_type
+            Form:      DW_FORM_ref4
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+      - Tag:      DW_TAG_class_type
+        Children: DW_CHILDREN_no
+        Attributes:
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+          - Attribute: DW_AT_declaration
+            Form:      DW_FORM_flag_present
+      - Tag:      DW_TAG_class_type
+        Children: DW_CHILDREN_yes
+        Attributes:
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+          - Attribute: DW_AT_declaration
+            Form:      DW_FORM_flag_present
+      - Tag:      DW_TAG_template_type_parameter
+        Children: DW_CHILDREN_no
+        Attributes:
+          - Attribute: DW_AT_type
+            Form:      DW_FORM_ref4
+      - Tag:      DW_TAG_base_type
+        Children: DW_CHILDREN_no
+        Attributes:
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+  debug_info:
+    - Version: 4
+      Entries:
+        - AbbrCode: 1
+          Values:
+            - CStr: by_hand
+            - Value:  0x04
+            - CStr: CU1
+            - Value:  0x1000
+            - Value:  0x100
+        - AbbrCode: 3
+          Values:
+            - CStr: class1
+        - AbbrCode: 4
+          Values:
+            - Value:  0x0000006c
+            - CStr: member1
+        - AbbrCode: 0
+        - AbbrCode: 3
+          Values:
+            - CStr: class2
+        - AbbrCode: 4
+          Values:
+            - Value:  0x0000006c
+            - CStr: member1
+        - AbbrCode: 0
+        - AbbrCode: 3
+          Values:
+            - CStr: class3
+        - AbbrCode: 4
+          Values:
+            - Value:  0x0000006c
+            - CStr: member1
+        - AbbrCode: 0
+        - AbbrCode: 8
+          Values:
+            - CStr: int
+        - AbbrCode: 2
+          Values:
+            - CStr: foo1
+            - Value:  0x1000
+            - Value:  0x10
+            - Value:  0x0000002a
+        - AbbrCode: 2
+          Values:
+            - CStr: foo2
+            - Value:  0x0
+            - Value:  0x100
+            - Value:  0x00000040
+        - AbbrCode: 2
+          Values:
+            - CStr: foo3
+            - Value:  0x0
+            - Value:  0x100
+            - Value:  0x00000040
+        - AbbrCode: 0
+...

llvm/test/tools/llvm-dwarfutil/ELF/verify.test

+## This test checks that debug info contained in the source file is properly
+## verified by --verify after copying. If --no-garbage-collection is
+## specified then the verification should fail, otherwise the verification
+## should succeed.
+
+# RUN: yaml2obj %s -o %t.o
+
+## Verify resulting debug info after --garbage-collection optimisation.
+# RUN: llvm-dwarfutil %t.o %t1 --verify
+
+## Verify separate debug file after --garbage-collection optimisation.
+# RUN: llvm-dwarfutil %t.o --separate-debug-file %t1 --verify
+
+## Verify not optimised resulting debug info.
+# RUN: not llvm-dwarfutil --no-garbage-collection %t.o %t1 --verify 2>&1 | FileCheck %s
+
+## Verify not optimised resulting separate debug file.
+# RUN: not llvm-dwarfutil --no-garbage-collection %t.o --separate-debug-file %t1 --verify 2>&1 | FileCheck %s
+
+## Check that verification is disabled when destination is stdout.
+# RUN: llvm-dwarfutil %t.o - --verify 2>&1 | FileCheck %s --check-prefix=CHECK-STDOUT
+
+# CHECK: error: output verification failed
+# CHECK-STDOUT: warning: verification skipped because writing to stdout
+
+--- !ELF
+FileHeader:
+  Class:    ELFCLASS64
+  Data:     ELFDATA2LSB
+  Type:     ET_REL
+  Machine:  EM_X86_64
+DWARF:
+  debug_abbrev:
+    - Table:
+      - Tag:      DW_TAG_compile_unit
+        Children: DW_CHILDREN_yes
+        Attributes:
+          - Attribute: DW_AT_producer
+            Form:      DW_FORM_string
+          - Attribute: DW_AT_language
+            Form:      DW_FORM_data2
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+          - Attribute: DW_AT_low_pc
+            Form:      DW_FORM_addr
+          - Attribute: DW_AT_high_pc
+            Form:      DW_FORM_data8
+      - Tag:      DW_TAG_subprogram
+        Children: DW_CHILDREN_no
+        Attributes:
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+          - Attribute: DW_AT_low_pc
+            Form:      DW_FORM_addr
+          - Attribute: DW_AT_high_pc
+            Form:      DW_FORM_data8
+          - Attribute: DW_AT_type
+            Form:      DW_FORM_ref4
+      - Tag:      DW_TAG_class_type
+        Children: DW_CHILDREN_yes
+        Attributes:
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+      - Tag:      DW_TAG_member
+        Children: DW_CHILDREN_no
+        Attributes:
+          - Attribute: DW_AT_type
+            Form:      DW_FORM_ref4
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+      - Tag:      DW_TAG_class_type
+        Children: DW_CHILDREN_no
+        Attributes:
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+          - Attribute: DW_AT_declaration
+            Form:      DW_FORM_flag_present
+      - Tag:      DW_TAG_class_type
+        Children: DW_CHILDREN_yes
+        Attributes:
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+          - Attribute: DW_AT_declaration
+            Form:      DW_FORM_flag_present
+      - Tag:      DW_TAG_template_type_parameter
+        Children: DW_CHILDREN_no
+        Attributes:
+          - Attribute: DW_AT_type
+            Form:      DW_FORM_ref4
+      - Tag:      DW_TAG_base_type
+        Children: DW_CHILDREN_no
+        Attributes:
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+  debug_info:
+    - Version: 4
+      Entries:
+        - AbbrCode: 1
+          Values:
+            - CStr: by_hand
+            - Value:  0x04
+            - CStr: CU1
+            - Value:  0x1000
+            - Value:  0x100
+        - AbbrCode: 3
+          Values:
+            - CStr: class1
+        - AbbrCode: 4
+          Values:
+            - Value:  0x0000006c
+            - CStr: member1
+        - AbbrCode: 0
+        - AbbrCode: 3
+          Values:
+            - CStr: class2
+        - AbbrCode: 4
+          Values:
+            - Value:  0x0000006c
+            - CStr: member1
+        - AbbrCode: 0
+        - AbbrCode: 3
+          Values:
+            - CStr: class3
+        - AbbrCode: 4
+          Values:
+            - Value:  0x0000006c
+            - CStr: member1
+        - AbbrCode: 0
+        - AbbrCode: 8
+          Values:
+            - CStr: int
+        - AbbrCode: 2
+          Values:
+            - CStr: foo1
+            - Value:  0x1000
+            - Value:  0x10
+            - Value:  0x0000002a
+        - AbbrCode: 2
+          Values:
+            - CStr: foo2
+            - Value:  0x0
+            - Value:  0x100
+            - Value:  0x00000040
+        - AbbrCode: 2
+          Values:
+            - CStr: foo3
+            - Value:  0x0
+            - Value:  0x100
+            - Value:  0x00000040
+        - AbbrCode: 0
+...

llvm/test/tools/llvm-dwarfutil/error-invalid-format.test

+## This test checks that llvm-dwarfutil displays an error message
+## if an input file of unsupported format was specified.
+
+# RUN: not llvm-dwarfutil %s - 2>&1 | FileCheck %s
+
+# CHECK: error-invalid-format.test: error: The file was not recognized as a valid object file

llvm/test/tools/llvm-dwarfutil/error-no-gc-odr.test

+## This test checks the error message displayed if ODR deduplication
+## is enabled while debug info garbage collection is disabled.
+
+# RUN: not llvm-dwarfutil --no-garbage-collection --odr-deduplication - - 2>&1 | FileCheck --check-prefix CHECK %s
+
+# CHECK: error: cannot use --odr-deduplication without --garbage-collection

llvm/test/tools/llvm-dwarfutil/error-no-input-file.test

+## This test checks the error message displayed if
+## an input file does not exist.
+
+# RUN: not llvm-dwarfutil not-existed not-existed 2>&1 | FileCheck %s
+
+# CHECK: not-existed: error: {{[Nn]}}o such file or directory

llvm/test/tools/llvm-dwarfutil/error-positional-args.test

+## This test checks the error message displayed if an incorrect
+## number of positional arguments is specified.
+
+# RUN: not llvm-dwarfutil - 2>&1 | FileCheck --check-prefix CHECK1 %s
+# RUN: not llvm-dwarfutil - - - 2>&1 | FileCheck --check-prefix CHECK3 %s
+
+# CHECK1: error: exactly two positional arguments expected, 1 provided
+# CHECK3: error: exactly two positional arguments expected, 3 provided

llvm/test/tools/llvm-dwarfutil/error-unknown-option.test

+## This test checks the error message displayed if an unknown
+## option is specified.
+
+# RUN: not llvm-dwarfutil --unknown-option 2>&1 | FileCheck %s
+
+# CHECK: error: unknown option: --unknown-option

llvm/test/tools/llvm-dwarfutil/error-unknown-tombstone.test

+## This test checks the error message diplayed if an incorrect
+## tombstone value is specified.
+
+# RUN: not llvm-dwarfutil --tombstone=unknown - - 2>&1 | FileCheck --check-prefix CHECK %s
+
+# CHECK: error: unknown tombstone value: 'unknown'

llvm/test/tools/llvm-dwarfutil/help.test

+## This test checks the help message of llvm-dwarfutil.
+
+# RUN: llvm-dwarfutil | FileCheck %s
+# RUN: llvm-dwarfutil -h | FileCheck %s
+# RUN: llvm-dwarfutil --help | FileCheck %s
+
+# CHECK: OVERVIEW: llvm-dwarfutil is a tool to copy and manipulate debug info
+# CHECK: USAGE: {{.*}}llvm-dwarfutil{{.*}} [options] <input file> <output file>
+# CHECK: OPTIONS:
+# CHECK:   --garbage-collection
+# CHECK:   --help
+# CHECK:   -h
+# CHECK:   -j
+# CHECK:   --no-garbage-collection
+# CHECK:   --no-odr-deduplication
+# CHECK:   --no-odr
+# CHECK:   --no-separate-debug-file
+# CHECK:   --num-threads
+# CHECK:   --odr-deduplication
+# CHECK:   --separate-debug-file
+# CHECK:   --tombstone
+# CHECK:   --verbose
+# CHECK:   --verify
+# CHECK:   --version
+# CHECK:   -V

llvm/tools/dsymutil/DwarfLinkerForBinary.h

AddressManager(DwarfLinkerForBinary &Linker, const object::ObjectFile &Obj,
         if (Mapping.Size && Mapping.ObjectAddress)
           AddressRanges[*Mapping.ObjectAddress] = ObjFileAddressRange(
               *Mapping.ObjectAddress + Mapping.Size,
               int64_t(Mapping.BinaryAddress) - *Mapping.ObjectAddress);
       }
     }
     virtual ~AddressManager() override { clear(); }
 
-    virtual bool areRelocationsResolved() const override { return true; }
-
     bool hasValidRelocs() override {
       return !ValidDebugInfoRelocs.empty() || !ValidDebugAddrRelocs.empty();
     }
 
     /// \defgroup FindValidRelocations Translate debug map into a list
     /// of relevant relocations
     ///
     /// @{
public:
     /// Checks that there is a relocation in the \p Relocs array against a
     /// debug map entry between \p StartOffset and \p NextOffset.
     ///
     /// \returns true and sets Info.InDebugMap if it is the case.
     bool hasValidRelocationAt(const std::vector<ValidReloc> &Relocs,
                               uint64_t StartOffset, uint64_t EndOffset,
                               CompileUnit::DIEInfo &Info);
 
-    bool hasLiveMemoryLocation(const DWARFDie &DIE,
-                               CompileUnit::DIEInfo &Info) override;
-    bool hasLiveAddressRange(const DWARFDie &DIE,
-                             CompileUnit::DIEInfo &Info) override;
+    bool isLiveVariable(const DWARFDie &DIE,
+    bool isLiveSubprogram(const DWARFDie &DIE,
 
     bool applyValidRelocs(MutableArrayRef<char> Data, uint64_t BaseOffset,
                           bool IsLittleEndian) override;
 
     llvm::Expected<uint64_t> relocateIndexedAddr(uint64_t StartOffset,
                                                  uint64_t EndOffset) override;
 
     RangesTy &getValidAddressRanges() override { return AddressRanges; }

llvm/tools/dsymutil/DwarfLinkerForBinary.cpp

getAttributeOffsets(const DWARFAbbreviationDeclaration *Abbrev, unsigned Idx,
 
   uint64_t End = Offset;
   DWARFFormValue::skipValue(Abbrev->getFormByIndex(Idx), Data, &End,
                             Unit.getFormParams());
 
   return std::make_pair(Offset, End);
 }
 
-bool DwarfLinkerForBinary::AddressManager::hasLiveMemoryLocation(
+bool DwarfLinkerForBinary::AddressManager::isLiveVariable(
     const DWARFDie &DIE, CompileUnit::DIEInfo &MyInfo) {
   const auto *Abbrev = DIE.getAbbreviationDeclarationPtr();
 
   Optional<uint32_t> LocationIdx =
       Abbrev->findAttributeIndex(dwarf::DW_AT_location);
   if (!LocationIdx)
     return false;
 
   uint64_t Offset = DIE.getOffset() + getULEB128Size(Abbrev->getCode());
   uint64_t LocationOffset, LocationEndOffset;
   std::tie(LocationOffset, LocationEndOffset) =
       getAttributeOffsets(Abbrev, *LocationIdx, Offset, *DIE.getDwarfUnit());
 
   // FIXME: Support relocations debug_addr.
   return hasValidRelocationAt(ValidDebugInfoRelocs, LocationOffset,
                               LocationEndOffset, MyInfo);
 }
 
-bool DwarfLinkerForBinary::AddressManager::hasLiveAddressRange(
+bool DwarfLinkerForBinary::AddressManager::isLiveSubprogram(
     const DWARFDie &DIE, CompileUnit::DIEInfo &MyInfo) {
   const auto *Abbrev = DIE.getAbbreviationDeclarationPtr();
 
   Optional<uint32_t> LowPcIdx = Abbrev->findAttributeIndex(dwarf::DW_AT_low_pc);
   if (!LowPcIdx)
     return false;
 
   dwarf::Form Form = Abbrev->getFormByIndex(*LowPcIdx);

 /// in the debug_info section.
 ///
 /// Like for findValidRelocs(), this function must be called with
 /// monotonic \p BaseOffset values.
 ///
 /// \returns whether any reloc has been applied.
 bool DwarfLinkerForBinary::AddressManager::applyValidRelocs(
     MutableArrayRef<char> Data, uint64_t BaseOffset, bool IsLittleEndian) {
-  assert(areRelocationsResolved());
   std::vector<ValidReloc> Relocs = getRelocations(
       ValidDebugInfoRelocs, BaseOffset, BaseOffset + Data.size());
 
   for (const ValidReloc &CurReloc : Relocs) {
     assert(CurReloc.Offset - BaseOffset < Data.size());
     assert(CurReloc.Offset - BaseOffset + CurReloc.Size <= Data.size());
     char Buf[8];
     uint64_t Value = relocate(CurReloc);

llvm/tools/dsymutil/LinkUtils.h

struct LinkOptions {
 
   /// Number of threads.
   unsigned Threads = 1;
 
   // Output file type.
   OutputFileType FileType = OutputFileType::Object;
 
   /// The accelerator table kind
-  AccelTableKind TheAccelTableKind;
+  DwarfLinkerAccelTableKind TheAccelTableKind;
 
   /// -oso-prepend-path
   std::string PrependPath;
 
   /// The -object-prefix-map.
   std::map<std::string, std::string> ObjectPrefixMap;
 
   /// The Resources directory in the .dSYM bundle.

llvm/tools/dsymutil/dsymutil.cpp

if (!Options.ReproducerPath.empty() &&
       Options.ReproMode != ReproducerMode::Use)
     return make_error<StringError>(
         "cannot combine --gen-reproducer and --use-reproducer.",
         errc::invalid_argument);
 
   return Error::success();
 }
 
-static Expected<AccelTableKind> getAccelTableKind(opt::InputArgList &Args) {
+static Expected<DwarfLinkerAccelTableKind>
+getAccelTableKind(opt::InputArgList &Args) {
   if (opt::Arg *Accelerator = Args.getLastArg(OPT_accelerator)) {
     StringRef S = Accelerator->getValue();
     if (S == "Apple")
-      return AccelTableKind::Apple;
+      return DwarfLinkerAccelTableKind::Apple;
     if (S == "Dwarf")
-      return AccelTableKind::Dwarf;
+      return DwarfLinkerAccelTableKind::Dwarf;
     if (S == "Pub")
-      return AccelTableKind::Pub;
+      return DwarfLinkerAccelTableKind::Pub;
     if (S == "Default")
-      return AccelTableKind::Default;
+      return DwarfLinkerAccelTableKind::Default;
     return make_error<StringError>(
         "invalid accelerator type specified: '" + S +
             "'. Support values are 'Apple', 'Dwarf', 'Pub' and 'Default'.",
         inconvertibleErrorCode());
   }
-  return AccelTableKind::Default;
+  return DwarfLinkerAccelTableKind::Default;
 }
 
 static Expected<DWARFVerify> getVerifyKind(opt::InputArgList &Args) {
   if (Args.hasArg(OPT_verify))
     return DWARFVerify::Output;
   if (opt::Arg *Verify = Args.getLastArg(OPT_verify_dwarf)) {
     StringRef S = Verify->getValue();
     if (S == "input")
static Expected<DsymutilOptions> getOptions(opt::InputArgList &Args) {
   if (opt::Arg *ReproducerPath = Args.getLastArg(OPT_use_reproducer)) {
     Options.ReproMode = ReproducerMode::Use;
     Options.ReproducerPath = ReproducerPath->getValue();
   }
 
   if (Args.hasArg(OPT_gen_reproducer))
     Options.ReproMode = ReproducerMode::Generate;
 
-  if (Expected<AccelTableKind> AccelKind = getAccelTableKind(Args)) {
+  if (Expected<DwarfLinkerAccelTableKind> AccelKind = getAccelTableKind(Args)) {
     Options.LinkOpts.TheAccelTableKind = *AccelKind;
   } else {
     return AccelKind.takeError();
   }
 
   if (opt::Arg *SymbolMap = Args.getLastArg(OPT_symbolmap))
     Options.SymbolMap = SymbolMap->getValue();
 

llvm/tools/llvm-dwarfutil/CMakeLists.txt

+set(LLVM_TARGET_DEFINITIONS Options.td)
+tablegen(LLVM Options.inc -gen-opt-parser-defs)
+add_public_tablegen_target(DwarfutilTableGen)
+
+set(LLVM_LINK_COMPONENTS
+  ${LLVM_TARGETS_TO_BUILD}
+  DebugInfoDWARF
+  DWARFLinker
+  MC
+  ObjCopy
+  Object
+  Option
+  Support
+  Target
+  AllTargetsCodeGens
+  AllTargetsDescs
+  AllTargetsInfos
+  )
+
+add_llvm_tool(llvm-dwarfutil
+  llvm-dwarfutil.cpp
+  DebugInfoLinker.cpp
+
+  DEPENDS
+  intrinsics_gen
+  ${tablegen_deps}
+  )

llvm/tools/llvm-dwarfutil/DebugInfoLinker.h

+//===- DebugInfoLinker.h ----------------------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_TOOLS_LLVM_DWARFUTIL_DEBUGINFOLINKER_H
+#define LLVM_TOOLS_LLVM_DWARFUTIL_DEBUGINFOLINKER_H
+
+#include "Options.h"
+#include "llvm/Object/Archive.h"
+#include "llvm/Object/ELFObjectFile.h"
+#include "llvm/Object/ObjectFile.h"
+
+namespace llvm {
+namespace dwarfutil {
+
+bool linkDebugInfo(object::ObjectFile &file, const Options &Options,
+                   raw_pwrite_stream &OutStream);
+
+} // end of namespace dwarfutil
+} // end of namespace llvm
+
+#endif // LLVM_TOOLS_LLVM_DWARFUTIL_DEBUGINFOLINKER_H

llvm/tools/llvm-dwarfutil/DebugInfoLinker.cpp

+//=== DebugInfoLinker.cpp -------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "DebugInfoLinker.h"
+#include "Error.h"
+#include "llvm/DWARFLinker/DWARFLinker.h"
+#include "llvm/DWARFLinker/DWARFStreamer.h"
+#include "llvm/DebugInfo/DWARF/DWARFContext.h"
+#include "llvm/DebugInfo/DWARF/DWARFExpression.h"
+#include "llvm/Object/ObjectFile.h"
+#include <memory>
+#include <vector>
+
+namespace llvm {
+namespace dwarfutil {
+
+// ObjFileAddressMap allows to check whether specified DIE referencing
+// dead addresses. It uses tombstone values to determine dead addresses.
+// The concrete values of tombstone constants were discussed in
+// https://reviews.llvm.org/D81784 and https://reviews.llvm.org/D84825.
+// So we use following values as indicators of dead addresses:
+//
+// bfd: (LowPC == 0) or (LowPC == 1 and HighPC == 1 and  DWARF v4 (or less))
+//      or ([LowPC, HighPC] is not inside address ranges of .text sections).
+//
+// maxpc: (LowPC == -1) or (LowPC == -2 and  DWARF v4 (or less))
+//        That value is assumed to be compatible with
+//        http://www.dwarfstd.org/ShowIssue.php?issue=200609.1
+//
+// exec: [LowPC, HighPC] is not inside address ranges of .text sections
+//
+// universal: maxpc and bfd
+class ObjFileAddressMap : public AddressesMap {
+public:
+  ObjFileAddressMap(DWARFContext &Context, const Options &Options,
+                    object::ObjectFile &ObjFile)
+      : Opts(Options) {
+    // Remember addresses of existing text sections.
+    for (const object::SectionRef &Sect : ObjFile.sections()) {
+      if (!Sect.isText())
+        continue;
+      const uint64_t Size = Sect.getSize();
+      if (Size == 0)
+        continue;
+      const uint64_t StartAddr = Sect.getAddress();
+      TextAddressRanges[{StartAddr}] = {StartAddr + Size, 0};
+    }
+
+    // Check CU address ranges for tombstone value.
+    for (std::unique_ptr<DWARFUnit> &CU : Context.compile_units()) {
+      Expected<llvm::DWARFAddressRangesVector> ARanges =
+          CU->getUnitDIE().getAddressRanges();
+      if (ARanges) {
+        for (auto &Range : *ARanges) {
+          if (!isDeadAddressRange(Range.LowPC, Range.HighPC, CU->getVersion(),
+                                  Options.Tombstone, CU->getAddressByteSize()))
+            DWARFAddressRanges[{Range.LowPC}] = {Range.HighPC, 0};
+        }
+      }
+    }
+  }
+
+  // should be renamed into has valid address ranges
+  bool hasValidRelocs() override { return !DWARFAddressRanges.empty(); }
+
+  bool isLiveSubprogram(const DWARFDie &DIE,
+                        CompileUnit::DIEInfo &Info) override {
+    assert((DIE.getTag() == dwarf::DW_TAG_subprogram ||
+            DIE.getTag() == dwarf::DW_TAG_label) &&
+           "Wrong type of input die");
+
+    if (Optional<uint64_t> LowPC =
+            dwarf::toAddress(DIE.find(dwarf::DW_AT_low_pc))) {
+      if (!isDeadAddress(*LowPC, DIE.getDwarfUnit()->getVersion(),
+                         Opts.Tombstone,
+                         DIE.getDwarfUnit()->getAddressByteSize())) {
+        Info.AddrAdjust = 0;
+        Info.InDebugMap = true;
+        return true;
+      }
+    }
+
+    return false;
+  }
+
+  bool isLiveVariable(const DWARFDie &DIE,
+                      CompileUnit::DIEInfo &Info) override {
+    assert((DIE.getTag() == dwarf::DW_TAG_variable ||
+            DIE.getTag() == dwarf::DW_TAG_constant) &&
+           "Wrong type of input die");
+
+    if (Expected<DWARFLocationExpressionsVector> Loc =
+            DIE.getLocations(dwarf::DW_AT_location)) {
+      DWARFUnit *U = DIE.getDwarfUnit();
+      for (const auto &Entry : *Loc) {
+        DataExtractor Data(toStringRef(Entry.Expr),
+                           U->getContext().isLittleEndian(), 0);
+        DWARFExpression Expression(Data, U->getAddressByteSize(),
+                                   U->getFormParams().Format);
+        bool HasLiveAddresses =
+            any_of(Expression, [&](const DWARFExpression::Operation &Op) {
+              // TODO: add handling of dwarf::DW_OP_addrx
+              return !Op.isError() &&
+                     (Op.getCode() == dwarf::DW_OP_addr &&
+                      !isDeadAddress(Op.getRawOperand(0), U->getVersion(),
+                                     Opts.Tombstone,
+                                     DIE.getDwarfUnit()->getAddressByteSize()));
+            });
+
+        if (HasLiveAddresses) {
+          Info.AddrAdjust = 0;
+          Info.InDebugMap = true;
+          return true;
+        }
+      }
+    } else {
+      // FIXME: missing DW_AT_location is OK here, but other errors should be
+      // reported to the user.
+      consumeError(Loc.takeError());
+    }
+
+    return false;
+  }
+
+  bool applyValidRelocs(MutableArrayRef<char>, uint64_t, bool) override {
+    // no need to apply relocations to the linked binary.
+    return false;
+  }
+
+  RangesTy &getValidAddressRanges() override { return DWARFAddressRanges; };
+
+  void clear() override { DWARFAddressRanges.clear(); }
+
+  llvm::Expected<uint64_t> relocateIndexedAddr(uint64_t, uint64_t) override {
+    // should not be called.
+    return object::createError("no relocations in linked binary");
+  }
+
+protected:
+  // returns true if specified address range is inside address ranges
+  // of executable sections.
+  bool isInsideExecutableSectionsAddressRange(uint64_t LowPC,
+                                              Optional<uint64_t> HighPC) {
+    auto Range = TextAddressRanges.lower_bound(LowPC);
+    if ((Range == TextAddressRanges.end() || Range->first != LowPC) &&
+        Range != TextAddressRanges.begin())
+      --Range;
+
+    if (Range != TextAddressRanges.end() && Range->first <= LowPC &&
+        (HighPC ? Range->second.HighPC >= HighPC
+                : Range->second.HighPC >= LowPC))
+      return true;
+
+    return false;
+  }
+
+  uint64_t isBFDDeadAddressRange(uint64_t LowPC, Optional<uint64_t> HighPC,
+                                 uint16_t Version) {
+    if (LowPC == 0)
+      return true;
+
+    if ((Version <= 4) && HighPC && (LowPC == 1 && *HighPC == 1))
+      return true;
+
+    return !isInsideExecutableSectionsAddressRange(LowPC, HighPC);
+  }
+
+  uint64_t isMAXPCDeadAddressRange(uint64_t LowPC, Optional<uint64_t> HighPC,
+                                   uint16_t Version, uint8_t AddressByteSize) {
+    if (Version <= 4 && HighPC) {
+      if (LowPC == (dwarf::computeTombstoneAddress(AddressByteSize) - 1))
+        return true;
+    } else if (LowPC == dwarf::computeTombstoneAddress(AddressByteSize))
+      return true;
+
+    if (!isInsideExecutableSectionsAddressRange(LowPC, HighPC))
+      warning("Address referencing invalid text section is not marked with "
+              "tombstone value");
+
+    return false;
+  }
+
+  bool isDeadAddressRange(uint64_t LowPC, Optional<uint64_t> HighPC,
+                          uint16_t Version, TombstoneKind Tombstone,
+                          uint8_t AddressByteSize) {
+    switch (Tombstone) {
+    case TombstoneKind::BFD:
+      return isBFDDeadAddressRange(LowPC, HighPC, Version);
+    case TombstoneKind::MaxPC:
+      return isMAXPCDeadAddressRange(LowPC, HighPC, Version, AddressByteSize);
+    case TombstoneKind::Universal:
+      return isBFDDeadAddressRange(LowPC, HighPC, Version) ||
+             isMAXPCDeadAddressRange(LowPC, HighPC, Version, AddressByteSize);
+    case TombstoneKind::Exec:
+      return !isInsideExecutableSectionsAddressRange(LowPC, HighPC);
+    }
+
+    llvm_unreachable("Unknown tombstone value");
+  }
+
+  bool isDeadAddress(uint64_t LowPC, uint16_t Version, TombstoneKind Tombstone,
+                     uint8_t AddressByteSize) {
+    return isDeadAddressRange(LowPC, None, Version, Tombstone, AddressByteSize);
+  }
+
+private:
+  RangesTy DWARFAddressRanges;
+  RangesTy TextAddressRanges;
+  const Options &Opts;
+};
+
+bool linkDebugInfo(object::ObjectFile &File, const Options &Options,
+                   raw_pwrite_stream &OutStream) {
+
+  auto ReportWarn = [&](const Twine &Message, StringRef Context,
+                        const DWARFDie *) {
+    if (Context.empty())
+      warning(Message);
+    else
+      warning(Context + ": " + Message);
+  };
+
+  // Create output streamer.
+  DwarfStreamer OutStreamer(OutputFileType::Object, OutStream, nullptr,
+                            ReportWarn, ReportWarn);
+  if (!OutStreamer.init(File.makeTriple(), ""))
+    return false;
+
+  // Create DWARF linker.
+  DWARFLinker DebugInfoLinker(&OutStreamer, DwarfLinkerClient::LLD);
+
+  DebugInfoLinker.setEstimatedObjfilesAmount(1);
+  DebugInfoLinker.setAccelTableKind(DwarfLinkerAccelTableKind::None);
+  DebugInfoLinker.setErrorHandler(ReportWarn);
+  DebugInfoLinker.setWarningHandler(ReportWarn);
+  DebugInfoLinker.setNumThreads(Options.NumThreads);
+  DebugInfoLinker.setNoODR(!Options.DoODRDeduplication);
+  DebugInfoLinker.setVerbosity(Options.Verbose);
+  DebugInfoLinker.setUpdate(!Options.DoGarbageCollection);
+
+  std::vector<std::unique_ptr<DWARFFile>> ObjectsForLinking(1);
+  std::vector<std::unique_ptr<AddressesMap>> AddresssMapForLinking(1);
+  std::vector<std::string> EmptyWarnings;
+
+  std::unique_ptr<DWARFContext> Context = DWARFContext::create(File);
+
+  // Add object files to the DWARFLinker.
+  AddresssMapForLinking[0] =
+      std::make_unique<ObjFileAddressMap>(*Context, Options, File);
+
+  ObjectsForLinking[0] = std::make_unique<DWARFFile>(
+      File.getFileName(), &*Context, AddresssMapForLinking[0].get(),
+      EmptyWarnings);
+
+  for (size_t I = 0; I < ObjectsForLinking.size(); I++)
+    DebugInfoLinker.addObjectFile(*ObjectsForLinking[I]);
+
+  // Link debug info.
+  DebugInfoLinker.link();
+  OutStreamer.finish();
+  return true;
+}
+
+} // end of namespace dwarfutil
+} // end of namespace llvm

llvm/tools/llvm-dwarfutil/Error.h

+//===- Error.h --------------------------------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_TOOLS_LLVM_DWARFUTIL_ERROR_H
+#define LLVM_TOOLS_LLVM_DWARFUTIL_ERROR_H
+
+#include "llvm/ADT/STLExtras.h"
+#include "llvm/ADT/StringRef.h"
+#include "llvm/ADT/StringSet.h"
+#include "llvm/ADT/Triple.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/Error.h"
+#include "llvm/Support/Format.h"
+#include "llvm/Support/WithColor.h"
+#include "llvm/Support/raw_ostream.h"
+
+namespace llvm {
+namespace dwarfutil {
+
+inline void error(StringRef Prefix, Error Err) {
+  handleAllErrors(std::move(Err), [&](ErrorInfoBase &Info) {
+    WithColor::error(errs(), Prefix) << Info.message() << '\n';
+  });
+}
+
+inline void error(StringRef Prefix, const Twine &Message) {
+  WithColor::error(errs(), Prefix) << Message << '\n';
+}
+
+inline void warning(const Twine &Message) {
+  WithColor::warning(errs()) << Message << '\n';
+}
+
+inline void verbose(const Twine &Message, bool Verbose) {
+  if (Verbose)
+    outs() << Message << '\n';
+}
+
+} // end of namespace dwarfutil
+} // end of namespace llvm
+
+#endif // LLVM_TOOLS_LLVM_DWARFUTIL_ERROR_H

llvm/tools/llvm-dwarfutil/Options.h

+//===- Options.h ------------------------------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_TOOLS_LLVM_DWARFUTIL_OPTIONS_H
+#define LLVM_TOOLS_LLVM_DWARFUTIL_OPTIONS_H
+
+#include "llvm/ADT/SmallString.h"
+#include "llvm/ADT/StringRef.h"
+
+namespace llvm {
+namespace dwarfutil {
+
+/// The kind of tombstone value.
+enum class TombstoneKind {
+  BFD,       /// 0/[1:1]. Bfd default.
+  MaxPC,     /// -1/-2. Assumed to match with
+             /// http://www.dwarfstd.org/ShowIssue.php?issue=200609.1.
+  Universal, /// both: BFD + MaxPC
+  Exec,      /// match with address range of executable sections.
+};
+
+struct Options {
+  std::string InputFileName;
+  std::string OutputFileName;
+  bool DoGarbageCollection = false;
+  bool DoODRDeduplication = false;
+  bool BuildSeparateDebugFile = false;
+  TombstoneKind Tombstone = TombstoneKind::Universal;
+  bool Verbose = false;
+  int NumThreads = 0;
+  bool Verify = false;
+
+  std::string getSeparateDebugFileName() const {
+    return OutputFileName + ".debug";
+  }
+};
+
+} // namespace dwarfutil
+} // namespace llvm
+
+#endif // LLVM_TOOLS_LLVM_DWARFUTIL_OPTIONS_H

llvm/tools/llvm-dwarfutil/Options.td

+include "llvm/Option/OptParser.td"
+
+multiclass BB<string name, string help1, string help2> {
+  def NAME: Flag<["--"], name>, HelpText<help1>;
+  def no_ # NAME: Flag<["--"], "no-" # name>, HelpText<help2>;
+}
+
+def help : Flag<["--"], "help">,
+  HelpText<"Prints this help output">;
+
+def h : Flag<["-"], "h">,
+  Alias<help>,
+  HelpText<"Alias for --help">;
+
+defm odr_deduplication : BB<"odr-deduplication",
+  "Do ODR deduplication for debug types(default)",
+  "Don`t do ODR deduplication for debug types">;
+
+def odr : Flag<["--"], "odr">,
+  Alias<odr_deduplication>,
+  HelpText<"Alias for --odr-deduplication">;
+
+def no_odr : Flag<["--"], "no-odr">,
+  Alias<no_odr_deduplication>,
+  HelpText<"Alias for --no-odr-deduplication">;
+
+defm garbage_collection : BB<"garbage-collection",
+  "Do garbage collection for debug info(default)",
+  "Don`t do garbage collection for debug info">;
+
+defm separate_debug_file : BB<"separate-debug-file",
+  "Create two output files: file w/o debug tables and file with debug tables",
+  "Create single output file, containing debug tables(default)">;
+
+def tombstone: Separate<["--", "-"], "tombstone">,
+  MetaVarName<"[bfd,maxpc,text,universal]">,
+  HelpText<"Tombstone value used as a marker of invalid address(default: universal)">;
+def: Joined<["--", "-"], "tombstone=">, Alias<tombstone>;
+
+def threads: Separate<["--", "-"], "num-threads">,
+  MetaVarName<"<threads>">,
+  HelpText<"Number of available threads for multi-threaded execution. Defaults to the number of cores on the current machine">;
+
+def: Separate<["-"], "j">,
+  Alias<threads>,
+  HelpText<"Alias for --num-threads">;
+
+def verbose : Flag<["--"], "verbose">,
+  HelpText<"Enable verbose logging">;
+
+def verify : Flag<["--"], "verify">,
+  HelpText<"Run the DWARF verifier on the resulting debug info">;
+
+def version : Flag<["--"], "version">,
+  HelpText<"Print the version and exit">;
+
+def V : Flag<["-"], "V">,
+  Alias<version>,
+  HelpText<"Alias for --version">;

llvm/tools/llvm-dwarfutil/llvm-dwarfutil.cpp

+//=== llvm-dwarfutil.cpp --------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "DebugInfoLinker.h"
+#include "Error.h"
+#include "Options.h"
+#include "llvm/DebugInfo/DWARF/DWARFContext.h"
+#include "llvm/DebugInfo/DWARF/DWARFVerifier.h"
+#include "llvm/MC/MCTargetOptionsCommandFlags.h"
+#include "llvm/ObjCopy/CommonConfig.h"
+#include "llvm/ObjCopy/ConfigManager.h"
+#include "llvm/ObjCopy/ObjCopy.h"
+#include "llvm/Option/Arg.h"
+#include "llvm/Option/ArgList.h"
+#include "llvm/Option/Option.h"
+#include "llvm/Support/CRC.h"
+#include "llvm/Support/CommandLine.h"
+#include "llvm/Support/InitLLVM.h"
+#include "llvm/Support/PrettyStackTrace.h"
+#include "llvm/Support/Signals.h"
+#include "llvm/Support/TargetSelect.h"
+
+using namespace llvm;
+using namespace object;
+
+namespace {
+enum ID {
+  OPT_INVALID = 0, // This is not an option ID.
+#define OPTION(PREFIX, NAME, ID, KIND, GROUP, ALIAS, ALIASARGS, FLAGS, PARAM,  \
+               HELPTEXT, METAVAR, VALUES)                                      \
+  OPT_##ID,
+#include "Options.inc"
+#undef OPTION
+};
+
+#define PREFIX(NAME, VALUE) const char *const NAME[] = VALUE;
+#include "Options.inc"
+#undef PREFIX
+
+const opt::OptTable::Info InfoTable[] = {
+#define OPTION(PREFIX, NAME, ID, KIND, GROUP, ALIAS, ALIASARGS, FLAGS, PARAM,  \
+               HELPTEXT, METAVAR, VALUES)                                      \
+  {                                                                            \
+      PREFIX,      NAME,      HELPTEXT,                                        \
+      METAVAR,     OPT_##ID,  opt::Option::KIND##Class,                        \
+      PARAM,       FLAGS,     OPT_##GROUP,                                     \
+      OPT_##ALIAS, ALIASARGS, VALUES},
+#include "Options.inc"
+#undef OPTION
+};
+
+class DwarfutilOptTable : public opt::OptTable {
+public:
+  DwarfutilOptTable() : OptTable(InfoTable) {}
+};
+} // namespace
+
+namespace llvm {
+namespace dwarfutil {
+
+std::string ToolName;
+
+static mc::RegisterMCTargetOptionsFlags MOF;
+
+static bool isDebugSection(StringRef SecName) {
+  return SecName.startswith(".debug") || SecName.startswith(".zdebug") ||
+         SecName == ".gdb_index";
+}
+
+static Error validateAndSetOptions(opt::InputArgList &Args, Options &Options) {
+  auto UnknownArgs = Args.filtered(OPT_UNKNOWN);
+  if (!UnknownArgs.empty())
+    return createError("unknown option: " +
+                       (*UnknownArgs.begin())->getSpelling());
+
+  std::vector<std::string> InputFiles = Args.getAllArgValues(OPT_INPUT);
+  if (InputFiles.size() != 2)
+    return createError(formatv("exactly two positional arguments expected, "
+                               "{0} provided",
+                               InputFiles.size()));
+
+  Options.InputFileName = InputFiles[0];
+  Options.OutputFileName = InputFiles[1];
+
+  Options.BuildSeparateDebugFile =
+      Args.hasFlag(OPT_separate_debug_file, OPT_no_separate_debug_file, false);
+  Options.DoODRDeduplication =
+      Args.hasFlag(OPT_odr_deduplication, OPT_no_odr_deduplication, true);
+  Options.DoGarbageCollection =
+      Args.hasFlag(OPT_garbage_collection, OPT_no_garbage_collection, true);
+  Options.Verbose = Args.hasArg(OPT_verbose);
+  Options.Verify = Args.hasArg(OPT_verify);
+
+  if (opt::Arg *NumThreads = Args.getLastArg(OPT_threads))
+    Options.NumThreads = atoi(NumThreads->getValue());
+  else
+    Options.NumThreads = 0; // Use all available hardware threads
+
+  if (opt::Arg *Tombstone = Args.getLastArg(OPT_tombstone)) {
+    StringRef S = Tombstone->getValue();
+    if (S == "bfd")
+      Options.Tombstone = TombstoneKind::BFD;
+    else if (S == "maxpc")
+      Options.Tombstone = TombstoneKind::MaxPC;
+    else if (S == "universal")
+      Options.Tombstone = TombstoneKind::Universal;
+    else if (S == "exec")
+      Options.Tombstone = TombstoneKind::Exec;
+    else
+      return createError("unknown tombstone value: '" + S + "'");
+  }
+
+  if (Options.Verbose) {
+    if (Options.NumThreads != 1)
+      warning("--num-threads set to 1 because verbose mode is specified");
+
+    Options.NumThreads = 1;
+  }
+
+  if (Options.DoODRDeduplication && Args.hasArg(OPT_odr_deduplication) &&
+      !Options.DoGarbageCollection)
+    return createError(
+        "cannot use --odr-deduplication without --garbage-collection");
+
+  if (Options.BuildSeparateDebugFile && Options.OutputFileName == "-")
+    return createError(
+        "writing to stdout. --separate-debug-file should be disabled");
+
+  return Error::success();
+}
+
+static Error setConfigToAddNewDebugSections(objcopy::ConfigManager &Config,
+                                            ObjectFile &ObjFile) {
+  // Add new debug sections.
+  for (SectionRef Sec : ObjFile.sections()) {
+    Expected<StringRef> SecName = Sec.getName();
+    if (!SecName)
+      return SecName.takeError();
+
+    if (isDebugSection(*SecName)) {
+      Expected<StringRef> SecData = Sec.getContents();
+      if (!SecData)
+        return SecData.takeError();
+
+      Config.Common.AddSection.emplace_back(objcopy::NewSectionInfo(
+          *SecName, MemoryBuffer::getMemBuffer(*SecData, *SecName, false)));
+    }
+  }
+
+  return Error::success();
+}
+
+static Expected<bool> verifyOutput(const Options &Opts) {
+  if (Opts.OutputFileName == "-") {
+    warning("verification skipped because writing to stdout");
+    return true;
+  }
+
+  std::string FileName = Opts.BuildSeparateDebugFile
+                             ? Opts.getSeparateDebugFileName()
+                             : Opts.OutputFileName;
+  Expected<OwningBinary<Binary>> BinOrErr = createBinary(FileName);
+  if (!BinOrErr)
+    return BinOrErr.takeError();
+
+  if (BinOrErr->getBinary()->isObject()) {
+    if (ObjectFile *Obj = static_cast<ObjectFile *>(BinOrErr->getBinary())) {
+      verbose("Verifying DWARF...", Opts.Verbose);
+      std::unique_ptr<DWARFContext> DICtx = DWARFContext::create(*Obj);
+      DIDumpOptions DumpOpts;
+      return DICtx->verify(Opts.Verbose ? outs() : nulls(),
+                           DumpOpts.noImplicitRecursion());
+    }
+  }
+
+  return createError("unsupported file: '" + FileName + "'");
+}
+
+class raw_crc_ostream : public raw_ostream {
+public:
+  explicit raw_crc_ostream(raw_ostream &O) : OS(O) { SetUnbuffered(); }
+
+  void reserveExtraSpace(uint64_t ExtraSize) override {
+    OS.reserveExtraSpace(ExtraSize);
+  }
+
+  uint32_t getCRC32() { return CRC32; }
+
+protected:
+  raw_ostream &OS;
+  uint32_t CRC32 = 0;
+
+  /// See raw_ostream::write_impl.
+  void write_impl(const char *Ptr, size_t Size) override {
+    CRC32 = crc32(
+        CRC32, ArrayRef<uint8_t>(reinterpret_cast<const uint8_t *>(Ptr), Size));
+    OS.write(Ptr, Size);
+  }
+
+  /// Return the current position within the stream, not counting the bytes
+  /// currently in the buffer.
+  uint64_t current_pos() const override { return OS.tell(); }
+};
+
+static Expected<uint32_t> saveSeparateDebugInfo(const Options &Opts,
+                                                ObjectFile &InputFile) {
+  objcopy::ConfigManager Config;
+  std::string OutputFilename = Opts.getSeparateDebugFileName();
+  Config.Common.InputFilename = Opts.InputFileName;
+  Config.Common.OutputFilename = OutputFilename;
+  Config.Common.OnlyKeepDebug = true;
+  uint32_t WrittenFileCRC32 = 0;
+
+  if (Error Err = writeToOutput(
+          Config.Common.OutputFilename, [&](raw_ostream &OutFile) -> Error {
+            raw_crc_ostream CRCBuffer(OutFile);
+            if (Error Err = objcopy::executeObjcopyOnBinary(Config, InputFile,
+                                                            CRCBuffer))
+              return Err;
+
+            WrittenFileCRC32 = CRCBuffer.getCRC32();
+            return Error::success();
+          }))
+    return std::move(Err);
+
+  return WrittenFileCRC32;
+}
+
+static Error saveNonDebugInfo(const Options &Opts, ObjectFile &InputFile,
+                              uint32_t GnuDebugLinkCRC32) {
+  objcopy::ConfigManager Config;
+  Config.Common.InputFilename = Opts.InputFileName;
+  Config.Common.OutputFilename = Opts.OutputFileName;
+  Config.Common.StripDebug = true;
+  Config.Common.AddGnuDebugLink =
+      sys::path::filename(Opts.getSeparateDebugFileName());
+  Config.Common.GnuDebugLinkCRC32 = GnuDebugLinkCRC32;
+
+  if (Error Err = writeToOutput(
+          Config.Common.OutputFilename, [&](raw_ostream &OutFile) -> Error {
+            if (Error Err =
+                    objcopy::executeObjcopyOnBinary(Config, InputFile, OutFile))
+              return Err;
+
+            return Error::success();
+          }))
+    return Err;
+
+  return Error::success();
+}
+
+static Error splitDebugIntoSeparateFile(const Options &Opts,
+                                        ObjectFile &InputFile) {
+  Expected<uint32_t> SeparateDebugFileCRC32OrErr =
+      saveSeparateDebugInfo(Opts, InputFile);
+  if (!SeparateDebugFileCRC32OrErr)
+    return SeparateDebugFileCRC32OrErr.takeError();
+
+  if (Error Err =
+          saveNonDebugInfo(Opts, InputFile, *SeparateDebugFileCRC32OrErr))
+    return Err;
+
+  return Error::success();
+}
+
+using DebugInfoBits = SmallString<100000>;
+
+static Error addSectionsFromLinkedData(objcopy::ConfigManager &Config,
+                                       ObjectFile &InputFile,
+                                       DebugInfoBits &LinkedDebugInfoBits) {
+  if (dyn_cast<ELFObjectFile<ELF32LE>>(&InputFile)) {
+    Expected<ELFObjectFile<ELF32LE>> MemFile = ELFObjectFile<ELF32LE>::create(
+        MemoryBufferRef(LinkedDebugInfoBits, ""));
+    if (!MemFile)
+      return MemFile.takeError();
+
+    if (Error Err = setConfigToAddNewDebugSections(Config, *MemFile))
+      return Err;
+  } else if (dyn_cast<ELFObjectFile<ELF64LE>>(&InputFile)) {
+    Expected<ELFObjectFile<ELF64LE>> MemFile = ELFObjectFile<ELF64LE>::create(
+        MemoryBufferRef(LinkedDebugInfoBits, ""));
+    if (!MemFile)
+      return MemFile.takeError();
+
+    if (Error Err = setConfigToAddNewDebugSections(Config, *MemFile))
+      return Err;
+  } else if (dyn_cast<ELFObjectFile<ELF32BE>>(&InputFile)) {
+    Expected<ELFObjectFile<ELF32BE>> MemFile = ELFObjectFile<ELF32BE>::create(
+        MemoryBufferRef(LinkedDebugInfoBits, ""));
+    if (!MemFile)
+      return MemFile.takeError();
+
+    if (Error Err = setConfigToAddNewDebugSections(Config, *MemFile))
+      return Err;
+  } else if (dyn_cast<ELFObjectFile<ELF64BE>>(&InputFile)) {
+    Expected<ELFObjectFile<ELF64BE>> MemFile = ELFObjectFile<ELF64BE>::create(
+        MemoryBufferRef(LinkedDebugInfoBits, ""));
+    if (!MemFile)
+      return MemFile.takeError();
+
+    if (Error Err = setConfigToAddNewDebugSections(Config, *MemFile))
+      return Err;
+  } else
+    return createError("unsupported file format");
+
+  return Error::success();
+}
+
+static Expected<uint32_t>
+saveSeparateLinkedDebugInfo(const Options &Opts, ObjectFile &InputFile,
+                            DebugInfoBits LinkedDebugInfoBits) {
+  objcopy::ConfigManager Config;
+  std::string OutputFilename = Opts.getSeparateDebugFileName();
+  Config.Common.InputFilename = Opts.InputFileName;
+  Config.Common.OutputFilename = OutputFilename;
+  Config.Common.StripDebug = true;
+  Config.Common.OnlyKeepDebug = true;
+  uint32_t WrittenFileCRC32 = 0;
+
+  if (Error Err =
+          addSectionsFromLinkedData(Config, InputFile, LinkedDebugInfoBits))
+    return std::move(Err);
+
+  if (Error Err = writeToOutput(
+          Config.Common.OutputFilename, [&](raw_ostream &OutFile) -> Error {
+            raw_crc_ostream CRCBuffer(OutFile);
+
+            if (Error Err = objcopy::executeObjcopyOnBinary(Config, InputFile,
+                                                            CRCBuffer))
+              return Err;
+
+            WrittenFileCRC32 = CRCBuffer.getCRC32();
+            return Error::success();
+          }))
+    return std::move(Err);
+
+  return WrittenFileCRC32;
+}
+
+static Error saveSingleLinkedDebugInfo(const Options &Opts,
+                                       ObjectFile &InputFile,
+                                       DebugInfoBits LinkedDebugInfoBits) {
+  objcopy::ConfigManager Config;
+
+  Config.Common.InputFilename = Opts.InputFileName;
+  Config.Common.OutputFilename = Opts.OutputFileName;
+  Config.Common.StripDebug = true;
+  if (Error Err =
+          addSectionsFromLinkedData(Config, InputFile, LinkedDebugInfoBits))
+    return Err;
+
+  if (Error Err = writeToOutput(
+          Config.Common.OutputFilename, [&](raw_ostream &OutFile) -> Error {
+            return objcopy::executeObjcopyOnBinary(Config, InputFile, OutFile);
+          }))
+    return Err;
+
+  return Error::success();
+}
+
+static Error saveLinkedDebugInfo(const Options &Opts, ObjectFile &InputFile,
+                                 DebugInfoBits LinkedDebugInfoBits) {
+  if (Opts.BuildSeparateDebugFile) {
+    Expected<uint32_t> SeparateDebugFileCRC32OrErr =
+        saveSeparateLinkedDebugInfo(Opts, InputFile,
+                                    std::move(LinkedDebugInfoBits));
+    if (!SeparateDebugFileCRC32OrErr)
+      return SeparateDebugFileCRC32OrErr.takeError();
+
+    if (Error Err =
+            saveNonDebugInfo(Opts, InputFile, *SeparateDebugFileCRC32OrErr))
+      return Err;
+  } else {
+    if (Error Err = saveSingleLinkedDebugInfo(Opts, InputFile,
+                                              std::move(LinkedDebugInfoBits)))
+      return Err;
+  }
+
+  return Error::success();
+}
+
+static Error saveCopyOfFile(const Options &Opts, ObjectFile &InputFile) {
+  objcopy::ConfigManager Config;
+
+  Config.Common.InputFilename = Opts.InputFileName;
+  Config.Common.OutputFilename = Opts.OutputFileName;
+
+  if (Error Err = writeToOutput(
+          Config.Common.OutputFilename, [&](raw_ostream &OutFile) -> Error {
+            return objcopy::executeObjcopyOnBinary(Config, InputFile, OutFile);
+          }))
+    return Err;
+
+  return Error::success();
+}
+
+static Error applyCLOptions(const struct Options &Opts, ObjectFile &InputFile) {
+  if (Opts.DoGarbageCollection) {
+    verbose("Do garbage collection for debug info ...", Opts.Verbose);
+
+    DebugInfoBits LinkedDebugInfo;
+    raw_svector_ostream OutStream(LinkedDebugInfo);
+
+    if (linkDebugInfo(InputFile, Opts, OutStream)) {
+      if (Error Err =
+              saveLinkedDebugInfo(Opts, InputFile, std::move(LinkedDebugInfo)))
+        return Err;
+    } else
+      return createStringError(std::errc::invalid_argument,
+                               "possible broken debug info");
+
+    return Error::success();
+  } else if (Opts.BuildSeparateDebugFile) {
+    if (Error Err = splitDebugIntoSeparateFile(Opts, InputFile))
+      return Err;
+  } else {
+    if (Error Err = saveCopyOfFile(Opts, InputFile))
+      return Err;
+  }
+
+  return Error::success();
+}
+
+} // end of namespace dwarfutil
+} // end of namespace llvm
+
+int main(int Argc, char const *Argv[]) {
+  using namespace dwarfutil;
+
+  InitLLVM X(Argc, Argv);
+  ToolName = Argv[0];
+
+  // Parse arguments.
+  DwarfutilOptTable T;
+  unsigned MAI;
+  unsigned MAC;
+  ArrayRef<const char *> ArgsArr = makeArrayRef(Argv + 1, Argc - 1);
+  opt::InputArgList Args = T.ParseArgs(ArgsArr, MAI, MAC);
+
+  if (Args.hasArg(OPT_help) || Args.size() == 0) {
+    T.printHelp(
+        outs(), (ToolName + " [options] <input file> <output file>").c_str(),
+        "llvm-dwarfutil is a tool to copy and manipulate debug info", false);
+    return EXIT_SUCCESS;
+  }
+
+  if (Args.hasArg(OPT_version)) {
+    cl::PrintVersionMessage();
+    return EXIT_SUCCESS;
+  }
+
+  Options Opts;
+  if (Error Err = validateAndSetOptions(Args, Opts)) {
+    error(dwarfutil::ToolName, std::move(Err));
+    return EXIT_FAILURE;
+  }
+
+  InitializeAllTargets();
+  InitializeAllTargetMCs();
+  InitializeAllTargetInfos();
+  InitializeAllAsmPrinters();
+  InitializeAllAsmParsers();
+
+  ErrorOr<std::unique_ptr<MemoryBuffer>> BuffOrErr =
+      MemoryBuffer::getFileOrSTDIN(Opts.InputFileName);
+  if (BuffOrErr.getError()) {
+    error(Opts.InputFileName, BuffOrErr.getError().message().c_str());
+    return EXIT_FAILURE;
+  }
+
+  Expected<std::unique_ptr<Binary>> BinOrErr =
+      object::createBinary(**BuffOrErr);
+  if (!BinOrErr) {
+    error(Opts.InputFileName, BinOrErr.takeError());
+    return EXIT_FAILURE;
+  }
+
+  if (!(*BinOrErr)->isObject()) {
+    error(Opts.InputFileName, "corrupted input file");
+    return EXIT_FAILURE;
+  }
+
+  if (Error Err =
+          applyCLOptions(Opts, *static_cast<ObjectFile *>((*BinOrErr).get()))) {
+    error(Opts.InputFileName, std::move(Err));
+    return EXIT_FAILURE;
+  }
+
+  // TODO: Refactor restoreStatOnFile function out of llvm-objcopy and use it
+  //       here.
+  // static Error restoreStatOnFile(StringRef OutFilename,
+  //   const sys::fs::file_status &Stat,
+  //   const ConfigManager &ConfigMgr);
+  BinOrErr->release();
+  BuffOrErr->release();
+
+  if (Opts.Verify) {
+    Expected<bool> IsCorrect = verifyOutput(Opts);
+    if (!IsCorrect) {
+      error(Opts.InputFileName, IsCorrect.takeError());
+      return EXIT_FAILURE;
+    }
+
+    if (!*IsCorrect) {
+      error(Opts.InputFileName, "output verification failed");
+      return EXIT_FAILURE;
+    }
+  }
+
+  return EXIT_SUCCESS;
+}