[XCOFF][llvm-dwarfdump] support llvm-dwarfdump for XCOFF DWARF

[shchenz]

Summary

Add support for XCOFF DWARF for llvm-dwarfdump tool.

The patch is made by @hubert.reinterpretcast

[shchenz]

gentle ping

[jasonliu]

I think what we usually do for test case is to upstream some pre-compiled binaries for testing purpose. But that's not the way community preferred anyway because those binaries are baked, and might be hard to reproduce later. Given this patch is small and pretty self-explanatory, I'm okay with skipping the test and let D97184 to "test" it.
FYI @hubert.reinterpretcast in case he think we should still upstream a pre-compiled binary for testing.
Otherwise, the patch LGTM.

[echristo]

I would prefer you use a checked in binary to test. I think it's reasonable to create a test case based on the dwarf emission support once you're convinced that's correct and go from there. For updates you can specify what the testcase is as a comment in the check. This is similar to a number of other tests FWIW :)

[shchenz]

1: add test cases based on objects

[shchenz]

Thanks for your review @jasonliu @echristo. Could you please help to have another look?

[jhenderson]

@Higuoxing added more support to yaml2obj last year for DWARF emission via YAML. Maybe it would be best to wait on basic XCOFF yaml2obj support to be finished, add DWARF emission support to that, and then use yaml2obj to generate the DWARF output as required?

Also, the pre-merge checks claim your tests are failing.

Finally, how does this actually add support for llvm-dwarfdump + XCOFF? It's not particularly obvious to me, but I'm not all that familiar about what llvm-dwarfdump requires for this support.

llvm/lib/Object/XCOFFObjectFile.cpp

461–472

This list is missing DWARFv5 section names. Does XCOFF not support those sections?

llvm/test/tools/llvm-dwarfdump/XCOFF/lit.local.cfg

1–2 ↗

(On Diff #330885)

Why do you need this? As far as I can tell, the behaviour under test is target agnostic.

[Higuoxing]

In D97186#2628382, @jhenderson wrote:

@Higuoxing added more support to yaml2obj last year for DWARF emission via YAML. Maybe it would be best to wait on basic XCOFF yaml2obj support to be finished, add DWARF emission support to that, and then use yaml2obj to generate the DWARF output as required?

Also, the pre-merge checks claim your tests are failing.

Finally, how does this actually add support for llvm-dwarfdump + XCOFF? It's not particularly obvious to me, but I'm not all that familiar about what llvm-dwarfdump requires for this support.

I'm very happy to help implement DWARF support for yaml2xcoff (if needed), but I'm a little busy these days. I think I'm able to work on it in the next few months :-)

[shchenz]

Maybe it would be best to wait on basic XCOFF yaml2obj support to be finished, add DWARF emission support to that, and then use yaml2obj to generate the DWARF output as required?

I totally agree with your suggestions, committing an object directly is not so good.
Due to the limitation of XCOFF yaml2obj support for now in D95505 (for example, it only supports 32-bit) and the time when we need llvm-dwarfdump in, I firstly added this patch without test and I thought it can be verified together with patch D97184, in that patch, the object is generated from ll. After address @echristo comments, I added these tests based on XCOFF objects.

Finally, how does this actually add support for llvm-dwarfdump + XCOFF? It's not particularly obvious to me, but I'm not all that familiar about what llvm-dwarfdump requires for this support.

llvm-dwarfdump calls object::createBinary( to recognize a specific form object, we already added XCOFF support in object::createBinary()-> identify_magic(), so in this patch, we only need to override some functions called by DWARFContext class. llvm-dwarfdump calls DWARFContext to dump DWARF info.

I'm very happy to help implement DWARF support for yaml2xcoff (if needed), but I'm a little busy these days. I think I'm able to work on it in the next few months :-)

Thanks for your kindly help. If possible, could you please help to review the XCOFF yam2obj support patch D95505? Thanks @Higuoxing

llvm/lib/Object/XCOFFObjectFile.cpp

461–472

Yes, XCOFF does not support DWARF 5 sections for now.

llvm/test/tools/llvm-dwarfdump/XCOFF/lit.local.cfg

1–2 ↗

(On Diff #330885)

Do you think is it necessary to run these tests on other targets? These are very basic DWARF info tests and I think other targets should already cover these tests by general/their tests?

[jasonliu]

llvm/test/tools/llvm-dwarfdump/XCOFF/lit.local.cfg

2 ↗

(On Diff #330962)

If these tests are runnable on other target, then I'd prefer to let them run on other targets as well.
People might change some staff and cause behavior change and they wouldn't know they need to update XCOFF test case if this test case is only runnable for powerpc target.

[jasonliu]

llvm/test/tools/llvm-dwarfdump/XCOFF/empty.test

180 ↗

(On Diff #330962)

Could you add the empty.c test case as comment here and the compile command as well so that people know how to reproduce if needed?
Also, could we use a public available compiler (xlclang 16.1 / gcc) instead of a self-built compiler to compile this test case for better reproducibility later as well?

[shchenz]

1: update the testcases

[echristo]

llvm/test/tools/llvm-dwarfdump/XCOFF/empty.test

180 ↗

(On Diff #330962)

Couple of small things:

a) Can you name it something other than empty? Maybe basic or something?

b) Reasonable to loosen up the checks slightly? There's a lot of -NEXT in there that doesn't appear to be strictly necessary (unless you're autogenerating the checks - if so let me know).

[shchenz]

1: rename the binary names

[shchenz]

use correct file mode

[shchenz]

Thanks for review @echristo

a) Can you name it something other than empty? Maybe basic or something?

Done

b) Reasonable to loosen up the checks slightly? There's a lot of -NEXT in there that doesn't appear to be strictly necessary (unless you're autogenerating the checks - if so let me know).

Yeah, sort of auto-generating. But do we need to loosen up the checks? This DWARF info should be settled as the result of the tests comes from object files.

[jasonliu]

llvm/test/tools/llvm-dwarfdump/XCOFF/basic.test

8–9

The compiler version comment and the compile command is not consistent.

[echristo]

In D97186#2631868, @shchenz wrote:

Thanks for review @echristo

a) Can you name it something other than empty? Maybe basic or something?

Done

b) Reasonable to loosen up the checks slightly? There's a lot of -NEXT in there that doesn't appear to be strictly necessary (unless you're autogenerating the checks - if so let me know).

Yeah, sort of auto-generating. But do we need to loosen up the checks? This DWARF info should be settled as the result of the tests comes from object files.

Yeah, it's tough. Right now if anything changes even slightly in the output the test will fail, but isn't necessarily everything you need to be checking if that makes sense? That said, it's probably on the small order of update probability so it's fine if you'd like to leave it this way and we can update it later if it becomes an issue.

Accepting (though fix any other feedback first).

-eric

[shchenz]

In D97186#2632123, @echristo wrote:

In D97186#2631868, @shchenz wrote:

Thanks for review @echristo

a) Can you name it something other than empty? Maybe basic or something?

Done

b) Reasonable to loosen up the checks slightly? There's a lot of -NEXT in there that doesn't appear to be strictly necessary (unless you're autogenerating the checks - if so let me know).

Yeah, sort of auto-generating. But do we need to loosen up the checks? This DWARF info should be settled as the result of the tests comes from object files.

Yeah, it's tough. Right now if anything changes even slightly in the output the test will fail, but isn't necessarily everything you need to be checking if that makes sense? That said, it's probably on the small order of update probability so it's fine if you'd like to leave it this way and we can update it later if it becomes an issue.

Accepting (though fix any other feedback first).

-eric

Yeah. Agree, at least there is no need for the requirement of the DIE attributes' order and the fixed offset in the .dwinfo sections. This will be too tough if we regenerate the object file for every new commit. But for this case, since we directly test the object files, so I think it should be ok. Yeah, we may still have some changes in llvm-dwarfdump tool which makes the output different, but that should be not often.

Thanks for your review

llvm/test/tools/llvm-dwarfdump/XCOFF/basic.test

8–9

Will update it in the commit. Thanks

[shchenz]

1: correct xlc version

llvm/include/llvm/Object/Binary.h

public:
   }
 
   bool isMinidump() const { return TypeID == ID_Minidump; }
 
   bool isTapiFile() const { return TypeID == ID_TapiFile; }
 
   bool isLittleEndian() const {
     return !(TypeID == ID_ELF32B || TypeID == ID_ELF64B ||
-             TypeID == ID_MachO32B || TypeID == ID_MachO64B);
+             TypeID == ID_MachO32B || TypeID == ID_MachO64B ||
+             TypeID == ID_XCOFF32 || TypeID == ID_XCOFF64);
   }
 
   bool isWinRes() const { return TypeID == ID_WinRes; }
 
   Triple::ObjectFormatType getTripleObjectFormat() const {
     if (isCOFF())
       return Triple::COFF;
     if (isMachO())

llvm/include/llvm/Object/XCOFFObjectFile.h

public:
 
   section_iterator section_begin() const override;
   section_iterator section_end() const override;
   uint8_t getBytesInAddress() const override;
   StringRef getFileFormatName() const override;
   Triple::ArchType getArch() const override;
   SubtargetFeatures getFeatures() const override;
   Expected<uint64_t> getStartAddress() const override;
+  StringRef mapDebugSectionName(StringRef Name) const override;
   bool isRelocatableObject() const override;
 
   // Below here is the non-inherited interface.
   bool is64Bit() const;
 
   const XCOFFSymbolEntry *getPointerToSymbolTable() const {
     assert(!is64Bit() && "Symbol table handling not supported yet.");
     return SymbolTblPtr;

llvm/lib/Object/XCOFFObjectFile.cpp

 //===--- XCOFFObjectFile.cpp - XCOFF object file implementation -----------===//
 //
 // 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
 //
 //===----------------------------------------------------------------------===//
 //
 // This file defines the XCOFFObjectFile class.
 //
 //===----------------------------------------------------------------------===//
 
 #include "llvm/Object/XCOFFObjectFile.h"
+#include "llvm/ADT/StringSwitch.h"
 #include "llvm/MC/SubtargetFeature.h"
 #include "llvm/Support/DataExtractor.h"
 #include <cstddef>
 #include <cstring>
 
 namespace llvm {
 
 using namespace XCOFF;

 
 uint64_t XCOFFObjectFile::getSectionAlignment(DataRefImpl Sec) const {
   uint64_t Result = 0;
   llvm_unreachable("Not yet implemented!");
   return Result;
 }
 
 bool XCOFFObjectFile::isSectionCompressed(DataRefImpl Sec) const {
-  bool Result = false;
-  llvm_unreachable("Not yet implemented!");
-  return Result;
+  return false;
 }
 
 bool XCOFFObjectFile::isSectionText(DataRefImpl Sec) const {
   return getSectionFlags(Sec) & XCOFF::STYP_TEXT;
 }
 
 bool XCOFFObjectFile::isSectionData(DataRefImpl Sec) const {
   uint32_t Flags = getSectionFlags(Sec);

 }
 
 Expected<uint64_t> XCOFFObjectFile::getStartAddress() const {
   // TODO FIXME Should get from auxiliary_header->o_entry when support for the
   // auxiliary_header is added.
   return 0;
 }
 
+StringRef XCOFFObjectFile::mapDebugSectionName(StringRef Name) const {
+  return StringSwitch<StringRef>(Name)
+      .Case("dwinfo", "debug_info")
+      .Case("dwline", "debug_line")
+      .Case("dwpbnms", "debug_pubnames")
+      .Case("dwpbtyp", "debug_pubtypes")
+      .Case("dwarnge", "debug_aranges")
+      .Case("dwabrev", "debug_abbrev")
+      .Case("dwstr", "debug_str")
+      .Case("dwrnges", "debug_ranges")
+      .Case("dwloc", "debug_loc")
+      .Case("dwframe", "debug_frame")
+      .Case("dwmac", "debug_macinfo")
+      .Default(Name);
+}
+
 size_t XCOFFObjectFile::getFileHeaderSize() const {
   return is64Bit() ? sizeof(XCOFFFileHeader64) : sizeof(XCOFFFileHeader32);
 }
 
 size_t XCOFFObjectFile::getSectionHeaderSize() const {
   return is64Bit() ? sizeof(XCOFFSectionHeader64) :
                      sizeof(XCOFFSectionHeader32);
 }

llvm/test/tools/llvm-dwarfdump/XCOFF/basic.test

+# RUN: llvm-dwarfdump --all %p/Inputs/basic32.o | FileCheck %s --check-prefix=DWARF32 
+# RUN: llvm-dwarfdump --all %p/Inputs/basic64.o | FileCheck %s --check-prefix=DWARF64
+
+## basic32.o Compiled with IBM XL C/C++ for AIX, V16.1.1.0
+## Compiler command: xlc basic.c -c -qdbgfmt=dwarf -g -q32 -o basic32.o
+##
+## basic64.o Compiled with IBM XL C/C++ for AIX, V16.1.1.0
+## Compiler command: xlc basic.c -c -qdbgfmt=dwarf -g -q64 -o basic64.o
+##
+## basic.c:
+## int main(void)
+## {
+##   return 0;
+## }
+
+# DWARF32:      .debug_abbrev contents:
+# DWARF32-NEXT:  Abbrev table for offset: 0x00000000
+# DWARF32-NEXT:  [1] DW_TAG_compile_unit DW_CHILDREN_yes
+# DWARF32-NEXT:          DW_AT_name      DW_FORM_string
+# DWARF32-NEXT:          DW_AT_stmt_list DW_FORM_data4
+# DWARF32-NEXT:          DW_AT_low_pc    DW_FORM_addr
+# DWARF32-NEXT:          DW_AT_high_pc   DW_FORM_addr
+# DWARF32-NEXT:          DW_AT_language  DW_FORM_data1
+# DWARF32-NEXT:          DW_AT_comp_dir  DW_FORM_string
+# DWARF32-NEXT:          DW_AT_producer  DW_FORM_string
+# DWARF32:       [2] DW_TAG_base_type    DW_CHILDREN_no
+# DWARF32-NEXT:          DW_AT_name      DW_FORM_string
+# DWARF32-NEXT:          DW_AT_byte_size DW_FORM_data1
+# DWARF32-NEXT:          DW_AT_encoding  DW_FORM_data1
+# DWARF32:       [3] DW_TAG_const_type   DW_CHILDREN_no
+# DWARF32-NEXT:          DW_AT_type      DW_FORM_ref4
+# DWARF32:       [4] DW_TAG_array_type   DW_CHILDREN_yes
+# DWARF32-NEXT:          DW_AT_sibling   DW_FORM_ref4
+# DWARF32-NEXT:          DW_AT_type      DW_FORM_ref4
+# DWARF32:       [5] DW_TAG_subrange_type        DW_CHILDREN_no
+# DWARF32-NEXT:          DW_AT_lower_bound       DW_FORM_data1
+# DWARF32-NEXT:          DW_AT_upper_bound       DW_FORM_data1
+# DWARF32:       [6] DW_TAG_subprogram   DW_CHILDREN_yes
+# DWARF32-NEXT:          DW_AT_name      DW_FORM_string
+# DWARF32-NEXT:          DW_AT_low_pc    DW_FORM_addr
+# DWARF32-NEXT:          DW_AT_high_pc   DW_FORM_addr
+# DWARF32-NEXT:          DW_AT_prototyped        DW_FORM_flag
+# DWARF32-NEXT:          DW_AT_calling_convention        DW_FORM_data1
+# DWARF32-NEXT:          DW_AT_decl_file DW_FORM_data1
+# DWARF32-NEXT:          DW_AT_decl_line DW_FORM_data1
+# DWARF32-NEXT:          DW_AT_external  DW_FORM_flag
+# DWARF32-NEXT:          DW_AT_frame_base        DW_FORM_block1
+# DWARF32-NEXT:          DW_AT_type      DW_FORM_ref4
+# DWARF32:       [7] DW_TAG_variable     DW_CHILDREN_no
+# DWARF32-NEXT:          DW_AT_location  DW_FORM_block1
+# DWARF32-NEXT:          DW_AT_name      DW_FORM_string
+# DWARF32-NEXT:          DW_AT_decl_file DW_FORM_data1
+# DWARF32-NEXT:          DW_AT_decl_line DW_FORM_data1
+# DWARF32-NEXT:          DW_AT_type      DW_FORM_ref4
+# DWARF32:       .debug_info contents:
+# DWARF32-NEXT:  0x00000000: Compile Unit: length = 0x00000094, format = DWARF32, version = 0x0003, abbr_offset = 0x0000, addr_size = 0x04 (next unit at 0x00000098)
+# DWARF32:       0x0000000b: DW_TAG_compile_unit
+# DWARF32:                DW_AT_name        ("basic.c")
+# DWARF32-NEXT:                DW_AT_stmt_list   (0x00000000)
+# DWARF32-NEXT:                DW_AT_low_pc      (0x00000000)
+# DWARF32-NEXT:                DW_AT_high_pc     (0x00000080)
+# DWARF32-NEXT:                DW_AT_language    (DW_LANG_C89)
+# DWARF32-NEXT:                DW_AT_comp_dir    ("/")
+# DWARF32-NEXT:                DW_AT_producer    ("IBM XL C for AIX, Version 16.1.1.0")
+# DWARF32:       0x00000046:   DW_TAG_base_type
+# DWARF32-NEXT:                  DW_AT_name      ("char")
+# DWARF32-NEXT:                  DW_AT_byte_size (0x01)
+# DWARF32-NEXT:                  DW_AT_encoding  (DW_ATE_unsigned_char)
+# DWARF32:       0x0000004e:   DW_TAG_base_type
+# DWARF32-NEXT:                  DW_AT_name      ("int")
+# DWARF32-NEXT:                  DW_AT_byte_size (0x04)
+# DWARF32-NEXT:                  DW_AT_encoding  (DW_ATE_signed)
+# DWARF32:       0x00000055:   DW_TAG_const_type
+# DWARF32-NEXT:                  DW_AT_type      (0x00000046 "char")
+# DWARF32:       0x0000005a:   DW_TAG_array_type
+# DWARF32-NEXT:                  DW_AT_sibling   (0x00000067)
+# DWARF32-NEXT:                  DW_AT_type      (0x00000055 "const char")
+# DWARF32:       0x00000063:     DW_TAG_subrange_type
+# DWARF32-NEXT:                    DW_AT_lower_bound     (0x00)
+# DWARF32-NEXT:                    DW_AT_upper_bound     (0x04)
+# DWARF32:       0x00000066:     NULL
+# DWARF32:       0x00000067:   DW_TAG_subprogram
+# DWARF32-NEXT:                  DW_AT_name      ("main")
+# DWARF32-NEXT:                  DW_AT_low_pc    (0x00000000)
+# DWARF32-NEXT:                  DW_AT_high_pc   (0x00000024)
+# DWARF32-NEXT:                  DW_AT_prototyped        (0x01)
+# DWARF32-NEXT:                  DW_AT_calling_convention        (DW_CC_program)
+# DWARF32-NEXT:                  DW_AT_decl_file ("/basic.c")
+# DWARF32-NEXT:                  DW_AT_decl_line (1)
+# DWARF32-NEXT:                  DW_AT_external  (0x01)
+# DWARF32-NEXT:                  DW_AT_frame_base        (DW_OP_reg1 R1)
+# DWARF32-NEXT:                  DW_AT_type      (0x0000004e "int")
+# DWARF32:       0x00000080:     DW_TAG_variable
+# DWARF32-NEXT:                    DW_AT_location        (DW_OP_addr 0x0)
+# DWARF32-NEXT:                    DW_AT_name    ("__func__")
+# DWARF32-NEXT:                    DW_AT_decl_file       ("/basic.c")
+# DWARF32-NEXT:                    DW_AT_decl_line       (0)
+# DWARF32-NEXT:                    DW_AT_type    (0x0000005a "const char[5]")
+# DWARF32:       0x00000096:     NULL
+# DWARF32:       0x00000097:   NULL
+# DWARF32:       .debug_line contents:
+# DWARF32-NEXT:  debug_line[0x00000000]
+# DWARF32-NEXT:  Line table prologue:
+# DWARF32-NEXT:      total_length: 0x00000042
+# DWARF32-NEXT:            format: DWARF32
+# DWARF32-NEXT:           version: 3
+# DWARF32-NEXT:   prologue_length: 0x0000001e
+# DWARF32-NEXT:   min_inst_length: 1
+# DWARF32-NEXT:   default_is_stmt: 1
+# DWARF32-NEXT:         line_base: -100
+# DWARF32-NEXT:        line_range: 220
+# DWARF32-NEXT:       opcode_base: 13
+# DWARF32-NEXT:  standard_opcode_lengths[DW_LNS_copy] = 0
+# DWARF32-NEXT:  standard_opcode_lengths[DW_LNS_advance_pc] = 1
+# DWARF32-NEXT:  standard_opcode_lengths[DW_LNS_advance_line] = 1
+# DWARF32-NEXT:  standard_opcode_lengths[DW_LNS_set_file] = 1
+# DWARF32-NEXT:  standard_opcode_lengths[DW_LNS_set_column] = 1
+# DWARF32-NEXT:  standard_opcode_lengths[DW_LNS_negate_stmt] = 0
+# DWARF32-NEXT:  standard_opcode_lengths[DW_LNS_set_basic_block] = 0
+# DWARF32-NEXT:  standard_opcode_lengths[DW_LNS_const_add_pc] = 0
+# DWARF32-NEXT:  standard_opcode_lengths[DW_LNS_fixed_advance_pc] = 1
+# DWARF32-NEXT:  standard_opcode_lengths[DW_LNS_set_prologue_end] = 0
+# DWARF32-NEXT:  standard_opcode_lengths[DW_LNS_set_epilogue_begin] = 0
+# DWARF32-NEXT:  standard_opcode_lengths[DW_LNS_set_isa] = 1
+# DWARF32-NEXT:  file_names[  1]:
+# DWARF32-NEXT:             name: "basic.c"
+# DWARF32-NEXT:        dir_index: 0
+# DWARF32-NEXT:         mod_time: 0x00000000
+# DWARF32-NEXT:           length: 0x00000000
+# DWARF32:       Address            Line   Column File   ISA Discriminator Flags
+# DWARF32-NEXT:  ------------------ ------ ------ ------ --- ------------- -------------
+# DWARF32-NEXT:  0x0000000000000000      1      0      1   0             0  is_stmt
+# DWARF32-NEXT:  0x0000000000000004      3      0      1   0             0  is_stmt
+# DWARF32-NEXT:  0x0000000000000008      4      0      1   0             0  is_stmt
+# DWARF32-NEXT:  0x0000000000000080      4      0      1   0             0  is_stmt end_sequence
+# DWARF32:      .debug_pubnames contents:
+# DWARF32-NEXT:  length = 0x00000017, format = DWARF32, version = 0x0002, unit_offset = 0x00000000, unit_size = 0x00000098
+# DWARF32-NEXT:  Offset     Name
+# DWARF32-NEXT:  0x00000067 "main"
+# DWARF32:       .debug_pubtypes contents:
+# DWARF32-NEXT:  length = 0x0000001f, format = DWARF32, version = 0x0002, unit_offset = 0x00000000, unit_size = 0x00000098
+# DWARF32-NEXT:  Offset     Name
+# DWARF32-NEXT:  0x0000004e "int"
+# DWARF32-NEXT:  0x00000046 "char"
+
+# DWARF64:       .debug_abbrev contents:
+# DWARF64-NEXT:  Abbrev table for offset: 0x00000000
+# DWARF64-NEXT:  [1] DW_TAG_compile_unit DW_CHILDREN_yes
+# DWARF64-NEXT:          DW_AT_name      DW_FORM_string
+# DWARF64-NEXT:          DW_AT_stmt_list DW_FORM_data8
+# DWARF64-NEXT:          DW_AT_low_pc    DW_FORM_addr
+# DWARF64-NEXT:          DW_AT_high_pc   DW_FORM_addr
+# DWARF64-NEXT:          DW_AT_language  DW_FORM_data1
+# DWARF64-NEXT:          DW_AT_comp_dir  DW_FORM_string
+# DWARF64-NEXT:          DW_AT_producer  DW_FORM_string
+# DWARF64:       [2] DW_TAG_base_type    DW_CHILDREN_no
+# DWARF64-NEXT:          DW_AT_name      DW_FORM_string
+# DWARF64-NEXT:          DW_AT_byte_size DW_FORM_data1
+# DWARF64-NEXT:          DW_AT_encoding  DW_FORM_data1
+# DWARF64:       [3] DW_TAG_const_type   DW_CHILDREN_no
+# DWARF64-NEXT:          DW_AT_type      DW_FORM_ref8
+# DWARF64:       [4] DW_TAG_array_type   DW_CHILDREN_yes
+# DWARF64-NEXT:          DW_AT_sibling   DW_FORM_ref8
+# DWARF64-NEXT:          DW_AT_type      DW_FORM_ref8
+# DWARF64:       [5] DW_TAG_subrange_type        DW_CHILDREN_no
+# DWARF64-NEXT:          DW_AT_lower_bound       DW_FORM_data1
+# DWARF64-NEXT:          DW_AT_upper_bound       DW_FORM_data1
+# DWARF64:       [6] DW_TAG_subprogram   DW_CHILDREN_yes
+# DWARF64-NEXT:          DW_AT_name      DW_FORM_string
+# DWARF64-NEXT:          DW_AT_low_pc    DW_FORM_addr
+# DWARF64-NEXT:          DW_AT_high_pc   DW_FORM_addr
+# DWARF64-NEXT:          DW_AT_prototyped        DW_FORM_flag
+# DWARF64-NEXT:          DW_AT_calling_convention        DW_FORM_data1
+# DWARF64-NEXT:          DW_AT_decl_file DW_FORM_data1
+# DWARF64-NEXT:          DW_AT_decl_line DW_FORM_data1
+# DWARF64-NEXT:          DW_AT_external  DW_FORM_flag
+# DWARF64-NEXT:          DW_AT_frame_base        DW_FORM_block1
+# DWARF64-NEXT:          DW_AT_type      DW_FORM_ref8
+# DWARF64:       [7] DW_TAG_variable     DW_CHILDREN_no
+# DWARF64-NEXT:          DW_AT_location  DW_FORM_block1
+# DWARF64-NEXT:          DW_AT_name      DW_FORM_string
+# DWARF64-NEXT:          DW_AT_decl_file DW_FORM_data1
+# DWARF64-NEXT:          DW_AT_decl_line DW_FORM_data1
+# DWARF64-NEXT:          DW_AT_type      DW_FORM_ref8
+# DWARF64:       .debug_info contents:
+# DWARF64-NEXT:  0x00000000: Compile Unit: length = 0x00000000000000c4, format = DWARF64, version = 0x0003, abbr_offset = 0x0000, addr_size = 0x08 (next unit at 0x000000d0)
+# DWARF64:       0x00000017: DW_TAG_compile_unit
+# DWARF64-NEXT:                DW_AT_name        ("basic.c")
+# DWARF64-NEXT:                DW_AT_stmt_list   (0x0000000000000000)
+# DWARF64-NEXT:                DW_AT_low_pc      (0x0000000000000000)
+# DWARF64-NEXT:                DW_AT_high_pc     (0x0000000000000080)
+# DWARF64-NEXT:                DW_AT_language    (DW_LANG_C89)
+# DWARF64-NEXT:                DW_AT_comp_dir    ("/")
+# DWARF64-NEXT:                DW_AT_producer    ("IBM XL C for AIX, Version 16.1.1.0")
+# DWARF64:       0x0000005e:   DW_TAG_base_type
+# DWARF64-NEXT:                  DW_AT_name      ("char")
+# DWARF64-NEXT:                  DW_AT_byte_size (0x01)
+# DWARF64-NEXT:                  DW_AT_encoding  (DW_ATE_unsigned_char)
+# DWARF64:       0x00000066:   DW_TAG_base_type
+# DWARF64-NEXT:                  DW_AT_name      ("int")
+# DWARF64-NEXT:                  DW_AT_byte_size (0x04)
+# DWARF64-NEXT:                  DW_AT_encoding  (DW_ATE_signed)
+# DWARF64:       0x0000006d:   DW_TAG_const_type
+# DWARF64-NEXT:                  DW_AT_type      (0x0000005e "char")
+# DWARF64:       0x00000076:   DW_TAG_array_type
+# DWARF64-NEXT:                  DW_AT_sibling   (0x0000008b)
+# DWARF64-NEXT:                  DW_AT_type      (0x0000006d "const char")
+# DWARF64:       0x00000087:     DW_TAG_subrange_type
+# DWARF64-NEXT:                    DW_AT_lower_bound     (0x00)
+# DWARF64-NEXT:                    DW_AT_upper_bound     (0x04)
+# DWARF64:       0x0000008a:     NULL
+# DWARF64:       0x0000008b:   DW_TAG_subprogram
+# DWARF64-NEXT:                  DW_AT_name      ("main")
+# DWARF64-NEXT:                  DW_AT_low_pc    (0x0000000000000000)
+# DWARF64-NEXT:                  DW_AT_high_pc   (0x0000000000000024)
+# DWARF64-NEXT:                  DW_AT_prototyped        (0x01)
+# DWARF64-NEXT:                  DW_AT_calling_convention        (DW_CC_program)
+# DWARF64-NEXT:                  DW_AT_decl_file ("/basic.c")
+# DWARF64-NEXT:                  DW_AT_decl_line (1)
+# DWARF64-NEXT:                  DW_AT_external  (0x01)
+# DWARF64-NEXT:                  DW_AT_frame_base        (DW_OP_reg1 X1)
+# DWARF64-NEXT:                  DW_AT_type      (0x00000066 "int")
+# DWARF64:       0x000000b0:     DW_TAG_variable
+# DWARF64-NEXT:                    DW_AT_location        (DW_OP_addr 0x0)
+# DWARF64-NEXT:                    DW_AT_name    ("__func__")
+# DWARF64-NEXT:                    DW_AT_decl_file       ("/basic.c")
+# DWARF64-NEXT:                    DW_AT_decl_line       (0)
+# DWARF64-NEXT:                    DW_AT_type    (0x00000076 "const char[5]")
+# DWARF64:       0x000000ce:     NULL
+# DWARF64:       0x000000cf:   NULL
+# DWARF64:       .debug_line contents:
+# DWARF64-NEXT:  debug_line[0x00000000]
+# DWARF64-NEXT:  Line table prologue:
+# DWARF64-NEXT:      total_length: 0x000000000000004a
+# DWARF64-NEXT:            format: DWARF64
+# DWARF64-NEXT:           version: 3
+# DWARF64-NEXT:   prologue_length: 0x000000000000001e
+# DWARF64-NEXT:   min_inst_length: 1
+# DWARF64-NEXT:   default_is_stmt: 1
+# DWARF64-NEXT:         line_base: -100
+# DWARF64-NEXT:        line_range: 220
+# DWARF64-NEXT:       opcode_base: 13
+# DWARF64-NEXT:  standard_opcode_lengths[DW_LNS_copy] = 0
+# DWARF64-NEXT:  standard_opcode_lengths[DW_LNS_advance_pc] = 1
+# DWARF64-NEXT:  standard_opcode_lengths[DW_LNS_advance_line] = 1
+# DWARF64-NEXT:  standard_opcode_lengths[DW_LNS_set_file] = 1
+# DWARF64-NEXT:  standard_opcode_lengths[DW_LNS_set_column] = 1
+# DWARF64-NEXT:  standard_opcode_lengths[DW_LNS_negate_stmt] = 0
+# DWARF64-NEXT:  standard_opcode_lengths[DW_LNS_set_basic_block] = 0
+# DWARF64-NEXT:  standard_opcode_lengths[DW_LNS_const_add_pc] = 0
+# DWARF64-NEXT:  standard_opcode_lengths[DW_LNS_fixed_advance_pc] = 1
+# DWARF64-NEXT:  standard_opcode_lengths[DW_LNS_set_prologue_end] = 0
+# DWARF64-NEXT:  standard_opcode_lengths[DW_LNS_set_epilogue_begin] = 0
+# DWARF64-NEXT:  standard_opcode_lengths[DW_LNS_set_isa] = 1
+# DWARF64-NEXT:  file_names[  1]:
+# DWARF64-NEXT:             name: "basic.c"
+# DWARF64-NEXT:        dir_index: 0
+# DWARF64-NEXT:         mod_time: 0x00000000
+# DWARF64-NEXT:           length: 0x00000000
+# DWARF64:       Address            Line   Column File   ISA Discriminator Flags
+# DWARF64-NEXT:  ------------------ ------ ------ ------ --- ------------- -------------
+# DWARF64-NEXT:  0x0000000000000000      1      0      1   0             0  is_stmt
+# DWARF64-NEXT:  0x0000000000000004      3      0      1   0             0  is_stmt
+# DWARF64-NEXT:  0x0000000000000008      4      0      1   0             0  is_stmt
+# DWARF64-NEXT:  0x0000000000000080      4      0      1   0             0  is_stmt end_sequence
+# DWARF64:       .debug_pubnames contents:
+# DWARF64-NEXT:  length = 0x0000000000000027, format = DWARF64, version = 0x0002, unit_offset = 0x0000000000000000, unit_size = 0x00000000000000d0
+# DWARF64-NEXT:  Offset     Name
+# DWARF64-NEXT:  0x000000000000008b "main"
+# DWARF64:       .debug_pubtypes contents:
+# DWARF64-NEXT:  length = 0x0000000000000033, format = DWARF64, version = 0x0002, unit_offset = 0x0000000000000000, unit_size = 0x00000000000000d0
+# DWARF64-NEXT:  Offset     Name
+# DWARF64-NEXT:  0x0000000000000066 "int"
+# DWARF64-NEXT:  0x000000000000005e "char"