[llvm-libtool-darwin] Add support for -static option

[sameerarora101]

Summary

Add support for creating static libraries when the input
includes only binaries (and not libraries/archives themselves)
Depends on D82923

[sameerarora101]

llvm/tools/llvm-libtool-darwin/llvm-libtool-darwin.cpp

47–61

5 There are some basic error handling functions available in the Support library which might do all you need them to. Consider using them before rolling your own.

These error functions themselves are using basic error handling functions available in the Support library (e.g logAllUnhandledErrors). If I use createStringError available in the support library, I too would have to pass the error object as an argument to logAllUnhandledErrors. Wouldn't I be doing something similar to this only then (I copied these error functions from llvm-lipo) ? sorry if I missed something. Thanks

[jhenderson]

Out of time. Note to self: finish review of the rest of the source code and tests.

llvm/test/tools/llvm-libtool-darwin/create-static-lib.test

4–5

I assume the idea is that these two YAML files will be used by many different tests in the future? If so, I'd rename them simply to input1.yaml and input2.yaml to emphasise their generality (in particular, the main bit suggests it is significant, which I suspect is not true). I'd probably also rename their symbols to symbol1 and symbol2 for the same reason.

11

t is probably sufficient rather than tv since you don't check the other fields.

15

Use -NEXT suffixes where applicable.

19

--implicit-check-not=T sounds flaky to me, as file paths might start appearing in the output. It also won't indicate that there are no other symbols, merely no other global text symbols. What is the actual output here? Also, are you interested in the archive's symbol table or the symbol table of the members, because I believe this might be printing the latter. There's a --print-armap option to do the former.

26

Nit: one more space of indentation, please.

Again, I think the --implicit-check-not sounds dangerous to me. You might be better off with something like FORMAT-EMPTY: or FORMAT-NOT: {{.}} after the last check line.

28

Add some extra spacing to make this line up:

# FORMAT:      __.SYMDEF
# FORMAT-NEXT: hello.o
# FORMAT-NEXT: main.o

33–37

Similar comments apply here to the lines above.

Also, I feel like showing that the ordering has been reversed is a little subtle. Assuming the tool completely replaces the original archive, I'd add just a single object to the new one, and show that the output only has that one object in it.

46–49

Same comments as above, re. --implicit-check-not, symbol table etc.

llvm/test/tools/llvm-libtool-darwin/invalid-arguments.test

2

I won't review this now, as I think some of it belongs in the first review, plus I'm running low on time for upstream reviewing today!

llvm/tools/llvm-libtool-darwin/llvm-libtool-darwin.cpp

38

Can I confirm that the terminology actually is "statically linked library" in Darwin land? I'd typically use simply "static archive" from my ELF background.

40

Is "shared dynamic library" unnecessarily verbose, or is that the common terminology? I'd expect either "shared library" or "dynamic library" from my background, but am not familiar with Darwin development.

43–45

Can this option be delayed to a later change? I'd tentatively do it by default in this version.

FWIW, I think LLVM tools typically set deterministic to true by default, since it makes testing easier.

47–61

I was referring to the WithColor::defaultErrorHandler function, which does the actual printing of the error message and handles the Error. There's also `createFileError which takes an Error and adds a provided file name. You will still need to convert the string to an error using createStringError, but could then pass that directly to defaultErrorHandler.

68

Nit: incorrect comment format. (Use capital letter/full stop).

69–70

More idiomatic and simpler is:

if (!ObjOrErr)
  reportError(Member.MemberName, ObjOrErr.takeError());

72

Ditto.

100–101

Rather than add this as an unsupported option, I'd just only permit the static mode for now.

[sameerarora101]

llvm/test/tools/llvm-libtool-darwin/create-static-lib.test

19

you are right, --print-armap is what I wanted. It prints:

Archive map
_symbol1 in create-static-lib.test.tmp-input1.o
_symbol2 in create-static-lib.test.tmp-input2.o


/data/users/<complete-path>/create-static-lib.test.tmp.lib(create-static-lib.test.tmp-input1.o):
0000000000000000 T _symbol1

/data/users/<complete-path>/create-static-lib.test.tmp.lib(create-static-lib.test.tmp-input2.o):
0000000000000000 T _symbol2

I have now replaced the check with :

# CHECK-SYMBOLS:      _symbol1 in
# CHECK-SYMBOLS:      _symbol2 in
# CHECK-SYMBOLS-EMPTY:

Would this be fine?
Thanks

33–37

alrighty, replaced the test by adding a single object to it.

llvm/tools/llvm-libtool-darwin/llvm-libtool-darwin.cpp

38

Yup, I took this from the man pages (https://www.unix.com/man-page/osx/1/libtool/):

Libtool can create either dynamically linked shared libraries, with -dynamic, or statically linked (archive) libraries, with -static.

40

For the dynamic option the man page says:

-dynamic
Produce a dynamically linked shared library from the input files.

But I can update our description to something else too ?

(PS: I have removed the dynamic option for this version)

43–45

ok, I'll set it to true for now as well (and pass it as a default instead of creating an option).

69–70

thanks.

100–101

ok, removed dynamic option above.

[sameerarora101]

Updating test and source files as per the comments:

• removing dynamic option
• using createStringError and createFileError
• removing --implicit-check-nots from the test

[jhenderson]

(No time to look at tests today, sorry)

llvm/tools/llvm-libtool-darwin/llvm-libtool-darwin.cpp

62

I'd expect deterministic to be capitalized in the function signature. If that is the case, this comment should match.

76

You probably don't need this blank line.

82

Let's not use auto here, as it's not immediately clear what the type of Member is.

87–90

Same comment as above re. capitalization in the comments.

96

What is ToolName used for?

100

return EXIT_FAILURE maybe? What do other tools typically do?

[sameerarora101]

llvm/tools/llvm-libtool-darwin/llvm-libtool-darwin.cpp

96

Nothing anymore. Previously, it was being used for the error message. I have removed it now

100

llvm-objcopy does return 1. However, llvm-lipo does exit(EXIT_FAILURE) whereas some other tools (llvm-ar, llvm-as) use exit(1). I have replaced it with exit(EXIT_FAILURE) for now. Is it ok?

[sameerarora101]

Rebasing and incorporating inline comments

[sameerarora101]

This comment was removed by sameerarora101.

[jhenderson]

llvm/test/tools/llvm-libtool-darwin/create-static-lib.test

16

Watch out, here and in other cases, this only shows that there is no output AFTER input2.o. It's possible that there's input before input1.o. Also, you'll not catching name corruptions resulting in a prefix/suffix of the name, since FileCheck only does sub-string matching by default, not full line matching. For example, this would fail if the following was emitted:

input-I-really-shouldn't-be-here
input1.osuffix
prefixinput2.o

You probably want to add --implicit-check-not={{.}} to the FileCheck command line, rather than the final CHECK-NAMES-NOT.

20

It would be best to check the symbol is in the right member. You can do this by using FileCheck's -D option, combined with the %t_basename (NB: check the exact name for correctness, but there should be other examples):

# RUN: ... FileCheck %s -D FILE1=%t_basename ...

# CHECK-SYMBOLS: _symbol1 in [[FILE1]]

and so on. This defines a string variable that matches the specified input string, and can be used using the [[VAR]] syntax as shown. Take a look at the FileCheck documentation for details.

Also, you should check the Archive map string to ensure there's no symbol before the first.

23

Use CHECK-SYMBOLS-NEXT here to show there's no symbol in between the two symbols.

42–43

This has the same issue as the earlier comment re. CHECK-NOT/--implicit-check-not

In fact, if you used OVERWRITE-NAMES and OVERWRITE-SYMBOLS instead of CHECK-NAMES/CHECK-SYMBOLS above, the test will still pass.

45–46

Same as above.

55–63

Same comments here as above.

llvm/test/tools/llvm-libtool-darwin/invalid-arguments.test

8

Does the double space match the actual error message?

10–19

These two checks plus the ELF one below probably belong in the invalid input/output arguments test.

21

Does this message use error: as a prefix?

25

Did you mean to use $t.lib? (probably not)

30–35

Only these lines are required to emit a minimal ELF object. Delete everything else. Also, we prefer to use minimal amounts of padding:

--- !ELF
FileHeader:
  Class:   ELFCLASS64
  Data:    ELFDATA2LSB
  Type:    ET_REL
  Machine: EM_X86_64

llvm/tools/llvm-libtool-darwin/llvm-libtool-darwin.cpp

34–38

I'm not really familiar with the Operation type. What does it look like in the help text?

[sameerarora101]

llvm/test/tools/llvm-libtool-darwin/create-static-lib.test

16

Thanks, I added --implicit-check-not. Furthermore, I also added -DPREFIX=create-static-lib.test.tmp as the file names are represented by [[PREFIX]]-input1.o and [[PREFIX]]-input2.o

20

Yup, I now check that the symbol is in the right member using the following:

## Check that symbols are present:
# RUN: llvm-nm --print-armap %t.lib | \
# RUN:   FileCheck %s --check-prefix=CHECK-SYMBOLS -DPREFIX=create-static-lib.test.tmp

# CHECK-SYMBOLS:      Archive map
# CHECK-SYMBOLS-NEXT: _symbol1 in [[PREFIX]]-input1.o
# CHECK-SYMBOLS-NEXT: _symbol2 in [[PREFIX]]-input2.o
# CHECK-SYMBOLS-EMPTY:

Would this be ok?

llvm/test/tools/llvm-libtool-darwin/invalid-arguments.test

8

Yes, the actual error msg also has the double space:

Library Type:  option: must be specified at least once!

10–19

Ok, I have placed all 4 tests into invalid-input-output-args.test now. Please lemme know in case we needed a separate test file for the first test above ## Missing -static option:

21

yup, I added error: in the error message too now, thanks!

llvm/tools/llvm-libtool-darwin/llvm-libtool-darwin.cpp

34–38

this is what help text looks like:

OVERVIEW: llvm-libtool-darwin

USAGE: llvm-libtool-darwin [options] <input files>

OPTIONS:

Color Options:

  --color             - Use colors in output (default=autodetect)

Generic Options:

  --help              - Display available options (--help-hidden for more)
  --help-list         - Display list of available options (--help-list-hidden for more)
  --version           - Display the version of this program

llvm-libtool-darwin options:

  -o                  - Alias for -output
  --output=<filename> - Specify output filename
  Library Type: 
      --static           - Produce a statically linked library from the input files

I created an enum Operation here so that in future we can add support for dynamic operation easily. I can very well make the -static option a boolean flag as well. What do you think?

[sameerarora101]

Updating tests

[sameerarora101]

llvm/tools/llvm-libtool-darwin/llvm-libtool-darwin.cpp

84

@jhenderson Should I replace the type of Member back to auto. clang-tidy raises a warning with StringRef?

[jhenderson]

llvm/test/tools/llvm-libtool-darwin/create-static-lib.test

12

It's not widely used, but there is %basename_t which substitutes for just the file name part of %t. This allows the test to not make assumptions about how %t expands, and also keeps the check independent of the test name. I'd recommend trying that.

19

Mostly fine, but use %basename_t here too.

35

Checking -> Check

38

Here and below, use %basename_t too, to avoid baking in file names.

45

Ditto.

51–53

Ditto.

llvm/test/tools/llvm-libtool-darwin/invalid-arguments.test

8

Okay, bonus marks for fixing it in another patch if you want. Or file a bug against the CommandLine code.

llvm/test/tools/llvm-libtool-darwin/invalid-input-output-args.test

27 ↗

(On Diff #275767)

Maybe make this more generic, e.g. "Missing library type option:"

I don't really know where to put this test. It might want to be its own test case entirely, e.g. "missing-library-type.test"

44 ↗

(On Diff #275767)

Use %basename_t here too.

51 ↗

(On Diff #275767)

Use %basename_t here too.

llvm/tools/llvm-libtool-darwin/llvm-libtool-darwin.cpp

27

Adding the categories sounds like a different change to me? You might want to include it alongside a test case to show that unrelated options aren't incldued.

34–38

Your current approach seems fine. I was just making sure it didn't do anything too weird.

84

Well typically you don't want to use a const & for StringRef because it is already a light-weight construct (much the same as you wouldn't use const & to a pointer or primitive type). That is probably the cause of the problem here.

96

See above re. option category change.

[sameerarora101]

llvm/test/tools/llvm-libtool-darwin/create-static-lib.test

12

thanks, I now have -DPREFIX=%basename_t.tmp as %basename_t substitutes for the last path component of %t but without the .tmp extension

llvm/test/tools/llvm-libtool-darwin/invalid-arguments.test

8

😂I can fix it in another patch.

llvm/test/tools/llvm-libtool-darwin/invalid-input-output-args.test

27 ↗

(On Diff #275767)

Isn't it similar to ## Missing output file? (That's why I thought it would go here). But I have placed it in missing-library-type.test for now.

llvm/tools/llvm-libtool-darwin/llvm-libtool-darwin.cpp

27

yup, I added OptionCategory in order to prevent the general option --safepoint-ir-verifier-print-only from showing up in the help text. Added a test case for it as well. Thanks

84

ok thanks

[sameerarora101]

Use %basename_t and add test for unrelated options.

[smeenai]

llvm/test/tools/llvm-libtool-darwin/create-static-lib.test

19

Might wanna add --match-full-lines here, to ensure there's no unexpected symbol name prefix or member name suffix.

33

You have an underscore instead of a dash :)

Is the purpose to ensure that there's no other members? I assume a -EMPTY would work for that. We should also check for the "Archive : " header, to ensure there's no members before the table of contents member.

48

Might be worth noting that cctools libtool warns in this case, and we don't implement that warning yet.

llvm/test/tools/llvm-libtool-darwin/hide-unrelated-options.test

1 ↗

(On Diff #276081)

This seems unrelated to this diff; perhaps it should be in the previous one?

llvm/test/tools/llvm-libtool-darwin/invalid-input-output-args.test

1 ↗

(On Diff #276081)

Can you add -static to all of the tests in this file, so that the only invalid part of the command line is the aspect being tested?

llvm/tools/llvm-libtool-darwin/llvm-libtool-darwin.cpp

27

Yup, this should either go in the previous diff or be its own diff.

[jhenderson]

Mostly looks good, barring @smeenai's comments.

llvm/test/tools/llvm-libtool-darwin/invalid-input-output-args.test

27 ↗

(On Diff #275767)

Similar in concept, but different behaviour (it's checking the behaviour of the cl::Required on the Library operation option, which is a different thing to the input and output files).

llvm/test/tools/llvm-libtool-darwin/missing-library-type.test

3–5 ↗

(On Diff #276081)

I don't think it's necessary to add --strict-whitespace here, as the exact formatting of the message isn't really the tool's responsibility. I'd get rid of the double space, as if the message was correct, and the option, so that you don't have to modify this test when you fix the command line message.

llvm/tools/llvm-libtool-darwin/llvm-libtool-darwin.cpp

84

You can get rid of the const too if you want. StringRef itself is immutable, so all this does is stop you re-assigning Member.

[sameerarora101]

llvm/test/tools/llvm-libtool-darwin/create-static-lib.test

33

Thanks for catching the underscore.

I added a check for "Archive : " header now. However, using FORMAT-EMPTY would just check that the next line (after 2nd member) has nothing on it. What I thought we wanted to check was that there is nothing at all after the second member. For eg,

Archive : ...
... __.SYMDEF
...<prefix>-input1.o
...<prefix>-input2.o

something here

would pass with FORMAT-EMPTY just below the check for second member, right? But we want it to fail.

llvm/test/tools/llvm-libtool-darwin/hide-unrelated-options.test

1 ↗

(On Diff #276081)

Yup, thanks. Moved it to the previous diff D82923

[sameerarora101]

Updating tests

[smeenai]

llvm/test/tools/llvm-libtool-darwin/create-static-lib.test

33

You're right, that makes sense.

[smeenai]

LGTM, but please wait for @jhenderson too.

[jhenderson]

LGTM, with one optional suggestion.

llvm/test/tools/llvm-libtool-darwin/create-static-lib.test

52

It might be worth adding a 2&>1 and check the output is empty here, to flag up if a warning starts getting emitted. That way, it points to where to add testing for the warning.

[sameerarora101]

llvm/test/tools/llvm-libtool-darwin/create-static-lib.test

52

ok, added

# RUN: llvm-libtool-darwin -static -o %t.lib %t-input1.o %t-input2.o %t-input1.o 2>&1 | \
# RUN:   FileCheck %s --allow-empty --implicit-check-not={{.}}

I hope --alow-empty is the right way to go about empty input files (found it here http://lists.llvm.org/pipermail/llvm-commits/Week-of-Mon-20140804/229905.html). The flag is not there in the documentation

[sameerarora101]

Updating test files

[sameerarora101]

llvm/test/tools/llvm-libtool-darwin/help-message.test

10 ↗

(On Diff #276751)

added --implicit-check-not="--safepoint-ir-verifier-print-only as we know the headers won't be present because of LIST-NOT checks below.

[alexander-shaposhnikov]

llvm/tools/llvm-libtool-darwin/llvm-libtool-darwin.cpp

33

enum class
+ i would add a blank line between the lines 34 and 35

[sameerarora101]

enum -> enum class

[sameerarora101]

As per @alexshap's recommendation, verifyDarwinObject -> verifyMachOObject

[jhenderson]

llvm/test/tools/llvm-libtool-darwin/create-static-lib.test

26

If I'm not mistaken, the canonical name is "Mach-O" (we use MachO for variable and tool names etc, but the file format is technically Mach-O, so we should use that in comments etc).

52

Sounds like a documentation bug. Feel free to update the doc if you get a minute. By default, FileCheck emits an error if the input is empty, but this can be overridden with the use of --allow-empty. That in turn has got me wondering whether --allow-empty should be replaced by a new option that also implies --implicit-check-not. I've raised that on llvm-dev.

llvm/test/tools/llvm-libtool-darwin/help-message.test

10 ↗

(On Diff #276751)

Sounds reasonable, but I'd get rid of the -- bit of the implicit-check-not pattern, so that it doesn't matter whether options are printed in the help with one or two dashes.

llvm/tools/llvm-libtool-darwin/llvm-libtool-darwin.cpp

51

Mach-O (same as mentioned elsewhere).

72

Ditto.

[sameerarora101]

MachO -> Mach-O in comments and update help-message.test

[sameerarora101]

llvm/test/tools/llvm-libtool-darwin/create-static-lib.test

52

ok, I'll create a diff for the doc, thanks!

[sameerarora101]

llvm/test/tools/llvm-libtool-darwin/create-static-lib.test

52

added it here : D83682

[jhenderson]

LGTM again.

[sameerarora101]

Mach-O -> Darwin for archive format in comments

llvm/docs/CommandGuide/llvm-libtool-darwin.rst

 .. option:: --version
 
   Display the version of this program.
 
 .. option:: --output, -o filename
 
  Specify the output file name. Must be specified exactly once.
 
+.. option:: -static
+
+ Produces a static library from the input files.
+
 EXIT STATUS
 -----------
 
 :program:`llvm-libtool-darwin` 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://bugs.llvm.org/>.
 
 SEE ALSO
 --------
 
 :manpage:`llvm-ar(1)`

llvm/test/tools/llvm-libtool-darwin/basic.test

-# This test checks that main exits normally (EC 0) for correct input/output args.
-
-# RUN: yaml2obj %S/Inputs/input1.yaml -o %t-input1.o
-# RUN: yaml2obj %S/Inputs/input2.yaml -o %t-input2.o
-
-## Pass single input:
-# RUN: llvm-libtool-darwin -o %t.lib %t-input1.o
-
-## Pass multiple inputs:
-# RUN: llvm-libtool-darwin -o %t.lib %t-input1.o %t-input2.o

llvm/test/tools/llvm-libtool-darwin/create-static-lib.test

+## This test checks that a correct static library is created.
+
+# RUN: yaml2obj %S/Inputs/input1.yaml -o %t-input1.o
+# RUN: yaml2obj %S/Inputs/input2.yaml -o %t-input2.o
+
+# RUN: rm -rf %t.lib
+# RUN: llvm-libtool-darwin -static -o %t.lib %t-input1.o %t-input2.o
+
+## Check that binaries are present:
+# RUN: llvm-ar t %t.lib | \
+# RUN:   FileCheck %s --check-prefix=CHECK-NAMES
+
+# CHECK-NAMES:      input1.o
+# CHECK-NAMES-NEXT: input2.o
+# CHECK-NAMES-NOT:  {{.}}
+
+## Check that symbols are present:
+# RUN: llvm-nm --print-armap %t.lib | \
+# RUN:   FileCheck %s --check-prefix=CHECK-SYMBOLS
+
+# CHECK-SYMBOLS:      _symbol1 in
+# CHECK-SYMBOLS:      _symbol2 in
+# CHECK-SYMBOLS-EMPTY:
+
+## Check that output archive is in Darwin format:
+# RUN: llvm-objdump --macho --archive-headers %t.lib | \
+# RUN:   FileCheck %s --check-prefix=FORMAT
+
+# FORMAT:      __.SYMDEF
+# FORMAT-NEXT: input1.o
+# FORMAT-NEXT: input2.o
+# FORMAT_NOT:  {{.}}
+
+## Checking that the output file is overwritten:
+# RUN: llvm-libtool-darwin -static -o %t.lib %t-input2.o
+# RUN: llvm-ar t %t.lib | \
+# RUN:   FileCheck %s --check-prefix=OVERWRITE-NAMES
+# RUN: llvm-nm --print-armap %t.lib | \
+# RUN:   FileCheck %s --check-prefix=OVERWRITE-SYMBOLS
+
+# OVERWRITE-NAMES:        input2.o
+# OVERWRITE-NAMES-NOT:    {{.}}
+
+# OVERWRITE-SYMBOLS:      _symbol2 in
+# OVERWRITE-SYMBOLS-EMPTY:
+
+## Duplicate a binary:
+# RUN: llvm-libtool-darwin -static -o %t.lib %t-input1.o %t-input2.o %t-input1.o
+# RUN: llvm-ar t %t.lib | \
+# RUN:   FileCheck %s --check-prefix=DUPLICATE-NAMES
+# RUN: llvm-nm --print-armap %t.lib | \
+# RUN:   FileCheck %s --check-prefix=DUPLICATE-SYMBOLS
+
+# DUPLICATE-NAMES:     input1.o
+# DUPLICATE-NAMES:     input2.o
+# DUPLICATE-NAMES:     input1.o
+# DUPLICATE-NAMES-NOT: {{.}}
+
+# DUPLICATE-SYMBOLS:      _symbol1 in
+# DUPLICATE-SYMBOLS:      _symbol2 in
+# DUPLICATE-SYMBOLS:      _symbol1 in
+# DUPLICATE-SYMBOLS-EMPTY:

llvm/test/tools/llvm-libtool-darwin/invalid-arguments.test

+## This test checks that an error is thrown in case of invalid arguments to -static option
+
+## Missing -static option:
+# RUN: not llvm-libtool-darwin -o %t.lib %t.input 2>&1 | \
+# RUN:   FileCheck %s --check-prefix=MISSING-OPERATION
+
+# MISSING-OPERATION: Library Type:  option: must be specified at least once!
+
+## Input file not found:
+# RUN: not llvm-libtool-darwin -static -o %t.lib %t.missing 2>&1 | \
+# RUN:   FileCheck %s --check-prefix=NO-FILE -DFILE=%t.missing
+
+# NO-FILE: '[[FILE]]': {{[nN]}}o such file or directory
+
+## Input file is not an object file:
+# RUN: touch %t.invalid
+# RUN: not llvm-libtool-darwin -static -o %t.lib %t.invalid 2>&1 | \
+# RUN:   FileCheck %s --check-prefix=NOT-OBJECT
+
+# NOT-OBJECT: The file was not recognized as a valid object file
+
+## Input file is not a MachO object file:
+# RUN: yaml2obj %s -o %t
+# RUN: not llvm-libtool-darwin -static -o $t.lib %t 2>&1 | \
+# RUN:   FileCheck %s --check-prefix=NOT-MACHO
+
+# NOT-MACHO: format not supported
+
+--- !ELF
+FileHeader:
+  Class:           ELFCLASS64
+  Data:            ELFDATA2LSB
+  Type:            ET_REL
+  Machine:         EM_X86_64
+Sections:
+  - Name:            .text
+    Type:            SHT_PROGBITS
+    Flags:           [ SHF_ALLOC, SHF_EXECINSTR ]
+    AddressAlign:    0x0000000000000001
+  - Name:            .data
+    Type:            SHT_PROGBITS
+    Flags:           [ SHF_WRITE, SHF_ALLOC ]
+    AddressAlign:    0x0000000000000001
+  - Name:            .bss
+    Type:            SHT_NOBITS
+    Flags:           [ SHF_WRITE, SHF_ALLOC ]
+    AddressAlign:    0x0000000000000001
+  - Name:            .comment
+    Type:            SHT_PROGBITS
+    Flags:           [ SHF_MERGE, SHF_STRINGS ]
+    AddressAlign:    0x0000000000000001
+    EntSize:         0x0000000000000001
+    Content:         004743433A2028474E552920382E332E3120323031393131323120285265642048617420382E332E312D352900
+  - Name:            .note.GNU-stack
+    Type:            SHT_PROGBITS
+    AddressAlign:    0x0000000000000001
+Symbols:
+  - Name:            foo.c
+    Type:            STT_FILE
+    Index:           SHN_ABS
+  - Name:            .text
+    Type:            STT_SECTION
+    Section:         .text
+  - Name:            .data
+    Type:            STT_SECTION
+    Section:         .data
+  - Name:            .bss
+    Type:            STT_SECTION
+    Section:         .bss
+  - Name:            .note.GNU-stack
+    Type:            STT_SECTION
+    Section:         .note.GNU-stack
+  - Name:            .comment
+    Type:            STT_SECTION
+    Section:         .comment
+...

llvm/tools/llvm-libtool-darwin/CMakeLists.txt

 set(LLVM_LINK_COMPONENTS
+  Object
   Support
   )
 
 add_llvm_tool(llvm-libtool-darwin
   llvm-libtool-darwin.cpp
 )

llvm/tools/llvm-libtool-darwin/LLVMBuild.txt

 ;
 ;   http://llvm.org/docs/LLVMBuild.html
 ;
 ;===------------------------------------------------------------------------===;
 [component_0]
 type = Tool
 name = llvm-libtool-darwin
 parent = Tools
-required_libraries = Support
+required_libraries = Object Support

llvm/tools/llvm-libtool-darwin/llvm-libtool-darwin.cpp

 //===-- llvm-libtool-darwin.cpp - a tool for creating libraries -----------===//
 //
 // 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
 //
 //===----------------------------------------------------------------------===//
 //
 // A utility for creating static and dynamic libraries for Darwin.
 //
 //===----------------------------------------------------------------------===//
 
+#include "llvm/Object/ArchiveWriter.h"
+#include "llvm/Object/MachO.h"
+#include "llvm/Object/ObjectFile.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/InitLLVM.h"
+#include "llvm/Support/WithColor.h"
 
 using namespace llvm;
+using namespace llvm::object;
 
 static cl::opt<std::string> OutputFile("output",
                                        cl::desc("Specify output filename"),
                                        cl::value_desc("filename"),
                                        cl::Required);
 static cl::alias OutputFileShort("o", cl::desc("Alias for --output"),
                                  cl::aliasopt(OutputFile), cl::NotHidden);
 
 static cl::list<std::string>
     InputFiles(cl::Positional, cl::desc("<input files>"), cl::OneOrMore);
 
+enum Operation { Static };
+static cl::opt<Operation> LibraryOperation(
+    cl::desc("Library Type: "),
+    cl::values(
+        clEnumValN(Static, "static",
+                   "Produce a statically linked library from the input files")),
+    cl::Required);
+
+static Error verifyDarwinObject(const NewArchiveMember &Member) {
+  auto MBRef = Member.Buf->getMemBufferRef();
+  Expected<std::unique_ptr<object::ObjectFile>> ObjOrErr =
+      object::ObjectFile::createObjectFile(MBRef);
+
+  // Throw error if not a valid object file.
+  if (!ObjOrErr)
+    return createFileError(Member.MemberName, ObjOrErr.takeError());
+
+  // Throw error if not in darwin format.
+  if (!isa<object::MachOObjectFile>(**ObjOrErr))
+    return createStringError(std::errc::invalid_argument,
+                             "'%s': format not supported",
+                             Member.MemberName.data());
+
+  return Error::success();
+}
+
+static Error addMember(std::vector<NewArchiveMember> &Members,
+                       StringRef FileName) {
+  Expected<NewArchiveMember> NMOrErr =
+      NewArchiveMember::getFile(FileName, /*Deterministic=*/true);
+
+  if (!NMOrErr)
+    return createFileError(FileName, NMOrErr.takeError());
+
+  // For regular archives, use the basename of the object path for the member
+  // name.
+  NMOrErr->MemberName = sys::path::filename(NMOrErr->MemberName);
+
+  // Verify that Member is a darwin object file.
+  if (Error E = verifyDarwinObject(*NMOrErr))
+    return E;
+
+  Members.push_back(std::move(*NMOrErr));
+  return Error::success();
+}
+
+static Error createStaticLibrary() {
+  std::vector<NewArchiveMember> NewMembers;
+  for (const StringRef &Member : InputFiles)
+    if (Error E = addMember(NewMembers, Member))
+      return E;
+
+  if (Error E = writeArchive(OutputFile, NewMembers,
+                             /*WriteSymtab=*/true,
+                             /*Kind=*/object::Archive::K_DARWIN,
+                             /*Deterministic=*/true,
+                             /*Thin=*/false))
+    return E;
+  return Error::success();
+}
+
 int main(int Argc, char **Argv) {
   InitLLVM X(Argc, Argv);
-  cl::ParseCommandLineOptions(Argc, Argv, "llvm-libtool-darwin\n");
+  cl::ParseCommandLineOptions(Argc, Argv, "llvm-libtool\n");
+
+  switch (LibraryOperation) {
+  case Static:
+    if (Error E = createStaticLibrary()) {
+      WithColor::defaultErrorHandler(std::move(E));
+      exit(EXIT_FAILURE);
+    }
+    break;
+  }
 }