[lld] [LLD] Tombstone LocalTU entry in .debug_names (PR #70701)
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Mon Oct 30 11:38:42 PDT 2023
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-lld
Author: Alexander Yermolovich (ayermolo)
<details>
<summary>Changes</summary>
By default LLD uses 0x0... as a tombstone value. For Type Units this is a valid
address. Changed so that MAX value is used for tombstone.
This was introduced as a change to DWARF6 spec:
https://dwarfstd.org/issues/231013.1.html
---
Patch is 86.59 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/70701.diff
8 Files Affected:
- (modified) lld/ELF/InputFiles.cpp (+3-2)
- (modified) lld/ELF/InputSection.cpp (+18-3)
- (added) lld/test/ELF/Inputs/dwarf5-64-debug-names-type-comdat-helper.s (+397)
- (added) lld/test/ELF/Inputs/dwarf5-64-debug-names-type-comdat-main.s (+384)
- (added) lld/test/ELF/Inputs/dwarf5-debug-names-type-comdat-helper.s (+410)
- (added) lld/test/ELF/Inputs/dwarf5-debug-names-type-comdat-main.s (+397)
- (added) lld/test/ELF/x86-64-dwarf5-64-debug-names-type-comdat.test (+20)
- (added) lld/test/ELF/x86-64-dwarf5-debug-names-type-comdat.test (+10)
``````````diff
diff --git a/lld/ELF/InputFiles.cpp b/lld/ELF/InputFiles.cpp
index a0d4be8ff9885b0..9237cd451f2e568 100644
--- a/lld/ELF/InputFiles.cpp
+++ b/lld/ELF/InputFiles.cpp
@@ -1158,10 +1158,11 @@ void ObjFile<ELFT>::initSectionsAndLocalSyms(bool ignoreComdats) {
StringRef name(stringTable.data() + eSym.st_name);
symbols[i] = reinterpret_cast<Symbol *>(locals + i);
- if (eSym.st_shndx == SHN_UNDEF || sec == &InputSection::discarded)
+ if (eSym.st_shndx == SHN_UNDEF || sec == &InputSection::discarded) {
+ StringRef name = CHECK(eSym.getName(stringTable), this);
new (symbols[i]) Undefined(this, name, STB_LOCAL, eSym.st_other, type,
/*discardedSecIdx=*/secIdx);
- else
+ } else
new (symbols[i]) Defined(this, name, STB_LOCAL, eSym.st_other, type,
eSym.st_value, eSym.st_size, sec);
symbols[i]->partition = 1;
diff --git a/lld/ELF/InputSection.cpp b/lld/ELF/InputSection.cpp
index 02394cbae95d557..d839e7274763f85 100644
--- a/lld/ELF/InputSection.cpp
+++ b/lld/ELF/InputSection.cpp
@@ -20,8 +20,6 @@
#include "llvm/Support/Compression.h"
#include "llvm/Support/Endian.h"
#include "llvm/Support/xxhash.h"
-#include <algorithm>
-#include <mutex>
#include <vector>
using namespace llvm;
@@ -888,6 +886,7 @@ void InputSection::relocateNonAlloc(uint8_t *buf, ArrayRef<RelTy> rels) {
const bool isDebug = isDebugSection(*this);
const bool isDebugLocOrRanges =
isDebug && (name == ".debug_loc" || name == ".debug_ranges");
+ const bool isDebugNames = isDebug && name == ".debug_names";
const bool isDebugLine = isDebug && name == ".debug_line";
std::optional<uint64_t> tombstone;
for (const auto &patAndValue : llvm::reverse(config->deadRelocInNonAlloc))
@@ -918,7 +917,8 @@ void InputSection::relocateNonAlloc(uint8_t *buf, ArrayRef<RelTy> rels) {
continue;
if (tombstone ||
- (isDebug && (type == target.symbolicRel || expr == R_DTPREL))) {
+ ((isDebug && (type == target.symbolicRel || expr == R_DTPREL))) ||
+ isDebugNames) {
// Resolve relocations in .debug_* referencing (discarded symbols or ICF
// folded section symbols) to a tombstone value. Resolving to addend is
// unsatisfactory because the result address range may collide with a
@@ -948,6 +948,21 @@ void InputSection::relocateNonAlloc(uint8_t *buf, ArrayRef<RelTy> rels) {
// TODO To reduce disruption, we use 0 instead of -1 as the tombstone
// value. Enable -1 in a future release.
auto *ds = dyn_cast<Defined>(&sym);
+ if (isDebugNames && dyn_cast<Undefined>(&sym)) {
+ uint64_t maxVal = 0;
+ switch (type) {
+ case R_X86_64_64:
+ maxVal = llvm::maxUIntN(64);
+ break;
+ case R_X86_64_32:
+ maxVal = llvm::maxUIntN(32);
+ break;
+ default:
+ llvm_unreachable("Unsupported relocation type in .debug_names.");
+ }
+ target.relocateNoSym(bufLoc, type, SignExtend64<bits>(maxVal));
+ continue;
+ }
if (!sym.getOutputSection() || (ds && ds->folded && !isDebugLine)) {
// If -z dead-reloc-in-nonalloc= is specified, respect it.
const uint64_t value = tombstone ? SignExtend64<bits>(*tombstone)
diff --git a/lld/test/ELF/Inputs/dwarf5-64-debug-names-type-comdat-helper.s b/lld/test/ELF/Inputs/dwarf5-64-debug-names-type-comdat-helper.s
new file mode 100644
index 000000000000000..1c046bc1520dc96
--- /dev/null
+++ b/lld/test/ELF/Inputs/dwarf5-64-debug-names-type-comdat-helper.s
@@ -0,0 +1,397 @@
+ .text
+ .file "helper.cpp"
+ .globl _Z3foov # -- Begin function _Z3foov
+ .p2align 4, 0x90
+ .type _Z3foov, at function
+_Z3foov: # @_Z3foov
+.Lfunc_begin0:
+ .file 0 "/home/ayermolo/local/tasks/T138552329/typeDedupSmall" "helper.cpp" md5 0x305ec66c221c583021f8375b300e2591
+ .loc 0 2 0 # helper.cpp:2:0
+ .cfi_startproc
+# %bb.0: # %entry
+ pushq %rbp
+ .cfi_def_cfa_offset 16
+ .cfi_offset %rbp, -16
+ movq %rsp, %rbp
+ .cfi_def_cfa_register %rbp
+.Ltmp0:
+ .loc 0 4 3 prologue_end # helper.cpp:4:3
+ xorl %eax, %eax
+ .loc 0 4 3 epilogue_begin is_stmt 0 # helper.cpp:4:3
+ popq %rbp
+ .cfi_def_cfa %rsp, 8
+ retq
+.Ltmp1:
+.Lfunc_end0:
+ .size _Z3foov, .Lfunc_end0-_Z3foov
+ .cfi_endproc
+ # -- End function
+ .file 1 "." "header.h" md5 0x53699580704254cb1dd2a83230f8a7ea
+ .section .debug_info,"G", at progbits,1175092228111723119,comdat
+.Ltu_begin0:
+ .long 4294967295 # DWARF64 Mark
+ .quad .Ldebug_info_end0-.Ldebug_info_start0 # Length of Unit
+.Ldebug_info_start0:
+ .short 5 # DWARF version number
+ .byte 2 # DWARF Unit Type
+ .byte 8 # Address Size (in bytes)
+ .quad .debug_abbrev # Offset Into Abbrev. Section
+ .quad 1175092228111723119 # Type Signature
+ .quad 59 # Type DIE Offset
+ .byte 1 # Abbrev [1] 0x28:0x2d DW_TAG_type_unit
+ .short 33 # DW_AT_language
+ .quad .Lline_table_start0 # DW_AT_stmt_list
+ .quad .Lstr_offsets_base0 # DW_AT_str_offsets_base
+ .byte 2 # Abbrev [2] 0x3b:0x10 DW_TAG_structure_type
+ .byte 5 # DW_AT_calling_convention
+ .byte 9 # DW_AT_name
+ .byte 8 # DW_AT_byte_size
+ .byte 1 # DW_AT_decl_file
+ .byte 1 # DW_AT_decl_line
+ .byte 3 # Abbrev [3] 0x41:0x9 DW_TAG_member
+ .byte 7 # DW_AT_name
+ .long 75 # DW_AT_type
+ .byte 1 # DW_AT_decl_file
+ .byte 2 # DW_AT_decl_line
+ .byte 0 # DW_AT_data_member_location
+ .byte 0 # End Of Children Mark
+ .byte 4 # Abbrev [4] 0x4b:0x5 DW_TAG_pointer_type
+ .long 80 # DW_AT_type
+ .byte 5 # Abbrev [5] 0x50:0x4 DW_TAG_base_type
+ .byte 8 # DW_AT_name
+ .byte 6 # DW_AT_encoding
+ .byte 1 # DW_AT_byte_size
+ .byte 0 # End Of Children Mark
+.Ldebug_info_end0:
+ .section .debug_abbrev,"", at progbits
+ .byte 1 # Abbreviation Code
+ .byte 65 # DW_TAG_type_unit
+ .byte 1 # DW_CHILDREN_yes
+ .byte 19 # DW_AT_language
+ .byte 5 # DW_FORM_data2
+ .byte 16 # DW_AT_stmt_list
+ .byte 23 # DW_FORM_sec_offset
+ .byte 114 # DW_AT_str_offsets_base
+ .byte 23 # DW_FORM_sec_offset
+ .byte 0 # EOM(1)
+ .byte 0 # EOM(2)
+ .byte 2 # Abbreviation Code
+ .byte 19 # DW_TAG_structure_type
+ .byte 1 # DW_CHILDREN_yes
+ .byte 54 # DW_AT_calling_convention
+ .byte 11 # DW_FORM_data1
+ .byte 3 # DW_AT_name
+ .byte 37 # DW_FORM_strx1
+ .byte 11 # DW_AT_byte_size
+ .byte 11 # DW_FORM_data1
+ .byte 58 # DW_AT_decl_file
+ .byte 11 # DW_FORM_data1
+ .byte 59 # DW_AT_decl_line
+ .byte 11 # DW_FORM_data1
+ .byte 0 # EOM(1)
+ .byte 0 # EOM(2)
+ .byte 3 # Abbreviation Code
+ .byte 13 # DW_TAG_member
+ .byte 0 # DW_CHILDREN_no
+ .byte 3 # DW_AT_name
+ .byte 37 # DW_FORM_strx1
+ .byte 73 # DW_AT_type
+ .byte 19 # DW_FORM_ref4
+ .byte 58 # DW_AT_decl_file
+ .byte 11 # DW_FORM_data1
+ .byte 59 # DW_AT_decl_line
+ .byte 11 # DW_FORM_data1
+ .byte 56 # DW_AT_data_member_location
+ .byte 11 # DW_FORM_data1
+ .byte 0 # EOM(1)
+ .byte 0 # EOM(2)
+ .byte 4 # Abbreviation Code
+ .byte 15 # DW_TAG_pointer_type
+ .byte 0 # DW_CHILDREN_no
+ .byte 73 # DW_AT_type
+ .byte 19 # DW_FORM_ref4
+ .byte 0 # EOM(1)
+ .byte 0 # EOM(2)
+ .byte 5 # Abbreviation Code
+ .byte 36 # DW_TAG_base_type
+ .byte 0 # DW_CHILDREN_no
+ .byte 3 # DW_AT_name
+ .byte 37 # DW_FORM_strx1
+ .byte 62 # DW_AT_encoding
+ .byte 11 # DW_FORM_data1
+ .byte 11 # DW_AT_byte_size
+ .byte 11 # DW_FORM_data1
+ .byte 0 # EOM(1)
+ .byte 0 # EOM(2)
+ .byte 6 # Abbreviation Code
+ .byte 17 # DW_TAG_compile_unit
+ .byte 1 # DW_CHILDREN_yes
+ .byte 37 # DW_AT_producer
+ .byte 37 # DW_FORM_strx1
+ .byte 19 # DW_AT_language
+ .byte 5 # DW_FORM_data2
+ .byte 3 # DW_AT_name
+ .byte 37 # DW_FORM_strx1
+ .byte 114 # DW_AT_str_offsets_base
+ .byte 23 # DW_FORM_sec_offset
+ .byte 16 # DW_AT_stmt_list
+ .byte 23 # DW_FORM_sec_offset
+ .byte 27 # DW_AT_comp_dir
+ .byte 37 # DW_FORM_strx1
+ .byte 17 # DW_AT_low_pc
+ .byte 27 # DW_FORM_addrx
+ .byte 18 # DW_AT_high_pc
+ .byte 6 # DW_FORM_data4
+ .byte 115 # DW_AT_addr_base
+ .byte 23 # DW_FORM_sec_offset
+ .byte 0 # EOM(1)
+ .byte 0 # EOM(2)
+ .byte 7 # Abbreviation Code
+ .byte 46 # DW_TAG_subprogram
+ .byte 1 # DW_CHILDREN_yes
+ .byte 17 # DW_AT_low_pc
+ .byte 27 # DW_FORM_addrx
+ .byte 18 # DW_AT_high_pc
+ .byte 6 # DW_FORM_data4
+ .byte 64 # DW_AT_frame_base
+ .byte 24 # DW_FORM_exprloc
+ .byte 110 # DW_AT_linkage_name
+ .byte 37 # DW_FORM_strx1
+ .byte 3 # DW_AT_name
+ .byte 37 # DW_FORM_strx1
+ .byte 58 # DW_AT_decl_file
+ .byte 11 # DW_FORM_data1
+ .byte 59 # DW_AT_decl_line
+ .byte 11 # DW_FORM_data1
+ .byte 73 # DW_AT_type
+ .byte 19 # DW_FORM_ref4
+ .byte 63 # DW_AT_external
+ .byte 25 # DW_FORM_flag_present
+ .byte 0 # EOM(1)
+ .byte 0 # EOM(2)
+ .byte 8 # Abbreviation Code
+ .byte 52 # DW_TAG_variable
+ .byte 0 # DW_CHILDREN_no
+ .byte 2 # DW_AT_location
+ .byte 24 # DW_FORM_exprloc
+ .byte 3 # DW_AT_name
+ .byte 37 # DW_FORM_strx1
+ .byte 58 # DW_AT_decl_file
+ .byte 11 # DW_FORM_data1
+ .byte 59 # DW_AT_decl_line
+ .byte 11 # DW_FORM_data1
+ .byte 73 # DW_AT_type
+ .byte 19 # DW_FORM_ref4
+ .byte 0 # EOM(1)
+ .byte 0 # EOM(2)
+ .byte 9 # Abbreviation Code
+ .byte 19 # DW_TAG_structure_type
+ .byte 0 # DW_CHILDREN_no
+ .byte 60 # DW_AT_declaration
+ .byte 25 # DW_FORM_flag_present
+ .byte 105 # DW_AT_signature
+ .byte 32 # DW_FORM_ref_sig8
+ .byte 0 # EOM(1)
+ .byte 0 # EOM(2)
+ .byte 0 # EOM(3)
+ .section .debug_info,"", at progbits
+.Lcu_begin0:
+ .long 4294967295 # DWARF64 Mark
+ .quad .Ldebug_info_end1-.Ldebug_info_start1 # Length of Unit
+.Ldebug_info_start1:
+ .short 5 # DWARF version number
+ .byte 1 # DWARF Unit Type
+ .byte 8 # Address Size (in bytes)
+ .quad .debug_abbrev # Offset Into Abbrev. Section
+ .byte 6 # Abbrev [6] 0x18:0x4d DW_TAG_compile_unit
+ .byte 0 # DW_AT_producer
+ .short 33 # DW_AT_language
+ .byte 1 # DW_AT_name
+ .quad .Lstr_offsets_base0 # DW_AT_str_offsets_base
+ .quad .Lline_table_start0 # DW_AT_stmt_list
+ .byte 2 # DW_AT_comp_dir
+ .byte 0 # DW_AT_low_pc
+ .long .Lfunc_end0-.Lfunc_begin0 # DW_AT_high_pc
+ .quad .Laddr_table_base0 # DW_AT_addr_base
+ .byte 7 # Abbrev [7] 0x3b:0x1c DW_TAG_subprogram
+ .byte 0 # DW_AT_low_pc
+ .long .Lfunc_end0-.Lfunc_begin0 # DW_AT_high_pc
+ .byte 1 # DW_AT_frame_base
+ .byte 86
+ .byte 3 # DW_AT_linkage_name
+ .byte 4 # DW_AT_name
+ .byte 0 # DW_AT_decl_file
+ .byte 2 # DW_AT_decl_line
+ .long 87 # DW_AT_type
+ # DW_AT_external
+ .byte 8 # Abbrev [8] 0x4b:0xb DW_TAG_variable
+ .byte 2 # DW_AT_location
+ .byte 145
+ .byte 120
+ .byte 6 # DW_AT_name
+ .byte 0 # DW_AT_decl_file
+ .byte 3 # DW_AT_decl_line
+ .long 91 # DW_AT_type
+ .byte 0 # End Of Children Mark
+ .byte 5 # Abbrev [5] 0x57:0x4 DW_TAG_base_type
+ .byte 5 # DW_AT_name
+ .byte 5 # DW_AT_encoding
+ .byte 4 # DW_AT_byte_size
+ .byte 9 # Abbrev [9] 0x5b:0x9 DW_TAG_structure_type
+ # DW_AT_declaration
+ .quad 1175092228111723119 # DW_AT_signature
+ .byte 0 # End Of Children Mark
+.Ldebug_info_end1:
+ .section .debug_str_offsets,"", at progbits
+ .long 4294967295 # DWARF64 Mark
+ .quad 84 # Length of String Offsets Set
+ .short 5
+ .short 0
+.Lstr_offsets_base0:
+ .section .debug_str,"MS", at progbits,1
+.Linfo_string0:
+ .asciz "clang version 18.0.0 (git at github.com:ayermolo/llvm-project.git 2a059ae838c2e444f47dc1dcdfefb6fc876a53c1)" # string offset=0
+.Linfo_string1:
+ .asciz "helper.cpp" # string offset=105
+.Linfo_string2:
+ .asciz "/home/ayermolo/local/tasks/T138552329/typeDedupSmall" # string offset=116
+.Linfo_string3:
+ .asciz "foo" # string offset=169
+.Linfo_string4:
+ .asciz "_Z3foov" # string offset=173
+.Linfo_string5:
+ .asciz "int" # string offset=181
+.Linfo_string6:
+ .asciz "f" # string offset=185
+.Linfo_string7:
+ .asciz "Foo2a" # string offset=187
+.Linfo_string8:
+ .asciz "c1" # string offset=193
+.Linfo_string9:
+ .asciz "char" # string offset=196
+ .section .debug_str_offsets,"", at progbits
+ .quad .Linfo_string0
+ .quad .Linfo_string1
+ .quad .Linfo_string2
+ .quad .Linfo_string4
+ .quad .Linfo_string3
+ .quad .Linfo_string5
+ .quad .Linfo_string6
+ .quad .Linfo_string8
+ .quad .Linfo_string9
+ .quad .Linfo_string7
+ .section .debug_addr,"", at progbits
+ .long 4294967295 # DWARF64 Mark
+ .quad .Ldebug_addr_end0-.Ldebug_addr_start0 # Length of contribution
+.Ldebug_addr_start0:
+ .short 5 # DWARF version number
+ .byte 8 # Address size
+ .byte 0 # Segment selector size
+.Laddr_table_base0:
+ .quad .Lfunc_begin0
+.Ldebug_addr_end0:
+ .section .debug_names,"", at progbits
+ .long 4294967295 # DWARF64 Mark
+ .quad .Lnames_end0-.Lnames_start0 # Header: unit length
+.Lnames_start0:
+ .short 5 # Header: version
+ .short 0 # Header: padding
+ .long 1 # Header: compilation unit count
+ .long 1 # Header: local type unit count
+ .long 0 # Header: foreign type unit count
+ .long 5 # Header: bucket count
+ .long 5 # Header: name count
+ .long .Lnames_abbrev_end0-.Lnames_abbrev_start0 # Header: abbreviation table size
+ .long 8 # Header: augmentation string size
+ .ascii "LLVM0700" # Header: augmentation string
+ .quad .Lcu_begin0 # Compilation unit 0
+ .quad .Ltu_begin0 # Type unit 0
+ .long 0 # Bucket 0
+ .long 0 # Bucket 1
+ .long 0 # Bucket 2
+ .long 1 # Bucket 3
+ .long 2 # Bucket 4
+ .long 193495088 # Hash in Bucket 3
+ .long 193491849 # Hash in Bucket 4
+ .long 259227804 # Hash in Bucket 4
+ .long 2090147939 # Hash in Bucket 4
+ .long -1257882357 # Hash in Bucket 4
+ .quad .Linfo_string5 # String in Bucket 3: int
+ .quad .Linfo_string3 # String in Bucket 4: foo
+ .quad .Linfo_string7 # String in Bucket 4: Foo2a
+ .quad .Linfo_string9 # String in Bucket 4: char
+ .quad .Linfo_string4 # String in Bucket 4: _Z3foov
+ .quad .Lnames2-.Lnames_entries0 # Offset in Bucket 3
+ .quad .Lnames0-.Lnames_entries0 # Offset in...
[truncated]
``````````
</details>
https://github.com/llvm/llvm-project/pull/70701
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