[lld] [lld][ELF] Implement merged .debug_names section. (PR #86508)

[Fangrui Song via llvm-commits]

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@@ -0,0 +1,294 @@
+# REQUIRES: x86
+# RUN: llvm-mc -filetype=obj -triple=x86_64 %s -o %t1.o
+# RUN: llvm-mc -filetype=obj -triple=x86_64 %p/Inputs/debug-names-2.s -o %t2.o
+# RUN: ld.lld --debug-names %t1.o %t2.o -o %t
+
+# RUN: llvm-objdump -d %t | FileCheck %s --check-prefix=DISASM
+# RUN: llvm-dwarfdump -debug-names %t | FileCheck %s --check-prefix=DWARF
+# RUN: llvm-readelf -SW %t | FileCheck %s --check-prefix=READELF
+	
+# DISASM:       Disassembly of section .text:
+# DISASM-EMPTY:
+# DISASM:       <_Z2f12t1>:
+# DISASM-CHECK:   201180: 55       pushq %rbp
+# DISASM-CHECK:   201181: 48 89 e5 movq  %rsp, %rbp
+# DISASM-CHECK:   201184: 5d       popq  %rbp
+# DISASM-CHECK:   201185: c3       retq
+# DISASM-CHECK:   201186: cc       int3
+# DISASM-CHECK:   201187: cc       int3
+# DISASM-CHECK:   201188: cc       int3
+# DISASM-CHECK:   201189: cc       int3
+# DISASM-CHECK:   20118a: cc       int3
+# DISASM-CHECK:   20118b: cc       int3
+# DISASM-CHECK:   20118c: cc       int3
+# DISASM-CHECK:   20118d: cc       int3
+# DISASM-CHECK:   20118e: cc       int3
+# DISASM-CHECK:   20118f: cc       int3
+# DISASM:       <main>:
+# DISASM-CHECK:   201190: 55       pushq %rbp
+# DISASM-CHECK:   201191: 48 89 e5 movq  %rsp, %rbp
+# DISASM-CHECK:   201194: 31 c0    xorl  %eax, %eax
+# DISASM-CHECK:   201196: 5d       popq  %rbp
+# DISASM-CHECK:   201197: c3       retq
+
+# DWARF:      .debug_names contents:
+# DWARF:      Name Index @ 0x0 {
+# DWARF-NEXT:   Header {
+# DWARF-NEXT:     Length: 0xCC
+# DWARF-NEXT:     Format: DWARF32
+# DWARF-NEXT:     Version: 5
+# DWARF-NEXT:     CU count: 2
+# DWARF-NEXT:     Local TU count: 0
+# DWARF-NEXT:     Foreign TU count: 0
+# DWARF-NEXT:     Bucket count: 5
+# DWARF-NEXT:     Name count: 5
+# DWARF-NEXT:     Abbreviations table size: 0x1F
+# DWARF-NEXT:     Augmentation: 'LLVM0700'
+# DWARF:        Compilation Unit offsets [
+# DWARF-NEXT:     CU[0]: 0x00000000
+# DWARF-NEXT:     CU[1]: 0x00000041
+# DWARF:          Abbreviations [
+# DWARF-NEXT:     Abbreviation 0x1 {
+# DWARF:            Tag: DW_TAG_structure_type
+# DWARF-NEXT:       DW_IDX_die_offset: DW_FORM_ref4
+# DWARF-NEXT:       DW_IDX_parent: DW_FORM_flag_present
+# DWARF-NEXT:       DW_IDX_compile_unit: DW_FORM_data1
+# DWARF:          Abbreviation 0x2 {
+# DWARF-NEXT:       Tag: DW_TAG_subprogram
+# DWARF-NEXT:       DW_IDX_die_offset: DW_FORM_ref4
+# DWARF-NEXT:       DW_IDX_parent: DW_FORM_flag_present
+# DWARF-NEXT:       DW_IDX_compile_unit: DW_FORM_data1
+# DWARF:          Abbreviation 0x3 {
+# DWARF-NEXT:       Tag: DW_TAG_base_type
+# DWARF-NEXT:       DW_IDX_die_offset: DW_FORM_ref4
+# DWARF-NEXT:       DW_IDX_parent: DW_FORM_flag_present
+# DWARF-NEXT:       DW_IDX_compile_unit: DW_FORM_data1
+# DWARF:        Bucket 0 [
+# DWARF:        Bucket 1 [
+# DWARF:            String: 0x00000089 "f1"
+# DWARF-NEXT:       Entry @ 0xa3 {
+# DWARF-NEXT:         Abbrev: 0x2
+# DWARF-NEXT:         Tag: DW_TAG_subprogram
+# DWARF-NEXT:         DW_IDX_die_offset: 0x00000023
+# DWARF-NEXT:         DW_IDX_parent: <parent not indexed>
+# DWARF-NEXT:         DW_IDX_compile_unit: 0x00
+# DWARF:            String: 0x00000095 "t1"
+# DWARF-NEXT:       Entry @ 0xaa {
+# DWARF-NEXT:         Abbrev: 0x1
+# DWARF-NEXT:         Tag: DW_TAG_structure_type
+# DWARF-NEXT:         DW_IDX_die_offset: 0x0000003a
+# DWARF-NEXT:         DW_IDX_parent: <parent not indexed>
+# DWARF-NEXT:         DW_IDX_compile_unit: 0x00
+# DWARF-NEXT:       }
+# DWARF-NEXT:       Entry @ 0xb0 {
+# DWARF-NEXT:         Abbrev: 0x1
+# DWARF-NEXT:         Tag: DW_TAG_structure_type
+# DWARF-NEXT:         DW_IDX_die_offset: 0x00000042
+# DWARF-NEXT:         DW_IDX_parent: <parent not indexed>
+# DWARF-NEXT:         DW_IDX_compile_unit: 0x01
+# DWARF:            String: 0x00000130 "int"
+# DWARF-NEXT:       Entry @ 0xb7 {
+# DWARF-NEXT:         Abbrev: 0x3
+# DWARF-NEXT:         Tag: DW_TAG_base_type
+# DWARF-NEXT:         DW_IDX_die_offset: 0x0000003e
+# DWARF-NEXT:         DW_IDX_parent: <parent not indexed>
+# DWARF-NEXT:         DW_IDX_compile_unit: 0x01
+# DWARF:        Bucket 2 [
+# DWARF:        Bucket 3 [
+# DWARF:            String: 0x0000008c "_Z2f12t1"
+# DWARF-NEXT:       Entry @ 0xbe {
+# DWARF-NEXT:         Abbrev: 0x2
+# DWARF-NEXT:         Tag: DW_TAG_subprogram
+# DWARF-NEXT:         DW_IDX_die_offset: 0x00000023
+# DWARF-NEXT:         DW_IDX_parent: <parent not indexed>
+# DWARF-NEXT:         DW_IDX_compile_unit: 0x00
+# DWARF:        Bucket 4 [
+# DWARF:            String: 0x0000012b "main"
+# DWARF-NEXT:       Entry @ 0xc5 {
+# DWARF-NEXT:         Abbrev: 0x2
+# DWARF-NEXT:         Tag: DW_TAG_subprogram
+# DWARF-NEXT:         DW_IDX_die_offset: 0x00000023
+# DWARF-NEXT:         DW_IDX_parent: <parent not indexed>
+# DWARF-NEXT:         DW_IDX_compile_unit: 0x01
+
+# READELF: .debug_names PROGBITS 0000000000000000 0003eb 0000d0
----------------
MaskRay wrote:

`s/0003eb/[[#%x,]]/` so that the test is less sensitive to section offset changes.
The size, while sensitive, is useful as a change detector.

I's just one line and displays the section size. It's better to move it before `# DWARF`

https://github.com/llvm/llvm-project/pull/86508