Skip to content

[lld] Warn for missing needed sections by --gdb-index #166626

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
wants to merge 2 commits into
base: main
Choose a base branch
from
Open

[lld] Warn for missing needed sections by --gdb-index #166626

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
027279a
[lld] Warn when missing needed sections for --gdb-index
aury6623 Nov 5, 2025
0d1b21e
add new test for warning, update existing test to not fail with the w…
aury6623 Nov 12, 2025
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
10 changes: 10 additions & 0 deletions lld/ELF/SyntheticSections.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -3566,6 +3566,16 @@ std::unique_ptr<GdbIndexSection> GdbIndexSection::create(Ctx &ctx) {
DWARFContext dwarf(std::make_unique<LLDDwarfObj<ELFT>>(file));
auto &dobj = static_cast<const LLDDwarfObj<ELFT> &>(dwarf.getDWARFObj());

if (dobj.getGnuPubnamesSection().sec == nullptr &&
dobj.getGnuPubtypesSection().sec == nullptr) {
Warn(ctx)
<< files[i]
<< ": file contains debug info but is missing .debug_gnu_pubnames or "
".debug_gnu_pubtypes sections required by --gdb-index. Compile "
"the file using -gsplit-dwarf or -ggnu-pubnames to generate these "
"sections.";
}

// If the are multiple compile units .debug_info (very rare ld -r --unique),
// this only picks the last one. Other address ranges are lost.
chunks[i].sec = dobj.getInfoSection();
Expand Down
135 changes: 135 additions & 0 deletions lld/test/ELF/gdb-index-missing-pubnames.s
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -0,0 +1,135 @@
# REQUIRES: x86

# RUN: rm -rf %t && split-file %s %t && cd %t
# RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux input.s -o input.o
# RUN: ld.lld --gdb-index input.o -o output.exe 2>&1 | FileCheck %s --check-prefix=WARNING --implicit-check-not=warning:

# WARNING: warning: input.o: file contains debug info but is missing .debug_gnu_pubnames or .debug_gnu_pubtypes sections required by --gdb-index. Compile the file using -gsplit-dwarf or -ggnu-pubnames to generate these sections.

# The input file was generated by compiling 'void _start() {}' with
# clang -g -O2 -S and stripping out some unneeded parts.

#--- input.s

.file "test.c"
.text
.globl _start # -- Begin function _start
.p2align 4
.type _start,@function
_start: # @_start
.Lfunc_begin0:
.cfi_startproc
nop
.Lfunc_end0:
.size _start, .Lfunc_end0-_start
.cfi_endproc
# -- End function
.section .debug_abbrev,"",@progbits
.byte 1 # 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 2 # Abbreviation Code
.byte 46 # DW_TAG_subprogram
.byte 0 # DW_CHILDREN_no
.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 122 # DW_AT_call_all_calls
.byte 25 # DW_FORM_flag_present
.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 63 # DW_AT_external
.byte 25 # DW_FORM_flag_present
.byte 0 # EOM(1)
.byte 0 # EOM(2)
.byte 0 # EOM(3)
.section .debug_info,"",@progbits
.Lcu_begin0:
.long .Ldebug_info_end0-.Ldebug_info_start0 # Length of Unit
.Ldebug_info_start0:
.short 5 # DWARF version number
.byte 1 # DWARF Unit Type
.byte 8 # Address Size (in bytes)
.long .debug_abbrev # Offset Into Abbrev. Section
.byte 1 # Abbrev [1] 0xc:0x23 DW_TAG_compile_unit
.byte 0 # DW_AT_producer
.short 29 # DW_AT_language
.byte 1 # DW_AT_name
.long .Lstr_offsets_base0 # DW_AT_str_offsets_base
.long .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
.long .Laddr_table_base0 # DW_AT_addr_base
.byte 2 # Abbrev [2] 0x23:0xb 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 87
# DW_AT_call_all_calls
.byte 3 # DW_AT_name
.byte 0 # DW_AT_decl_file
.byte 1 # DW_AT_decl_line
# DW_AT_external
.byte 0 # End Of Children Mark
.Ldebug_info_end0:
.section .debug_str_offsets,"",@progbits
.long 20 # Length of String Offsets Set
.short 5
.short 0
.Lstr_offsets_base0:
.section .debug_str,"MS",@progbits,1
.Linfo_string0:
.asciz "clang version 22.0.0git (027279a7ef2bedffcd0d23f605fc0e135ad77e37)"
.Linfo_string1:
.asciz "test.c"
.Linfo_string2:
.asciz ""
.Linfo_string3:
.asciz "_start"
.section .debug_str_offsets,"",@progbits
.long .Linfo_string0
.long .Linfo_string1
.long .Linfo_string2
.long .Linfo_string3
.section .debug_addr,"",@progbits
.long .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:
.ident "clang version 22.0.0git (027279a7ef2bedffcd0d23f605fc0e135ad77e37)"
.section ".note.GNU-stack","",@progbits
.addrsig
.section .debug_line,"",@progbits
.Lline_table_start0:
2 changes: 1 addition & 1 deletion lld/test/ELF/gdb-index-multiple-cu-2.s
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -1,7 +1,7 @@
# REQUIRES: x86
# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t.o
# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %p/Inputs/gdb-index-multiple-cu-2.s -o %t1.o
# RUN: ld.lld --gdb-index %t.o %t1.o -o %t 2>&1 | count 0
# RUN: ld.lld --gdb-index %t.o %t1.o -o %t 2>&1 | sed '/missing .debug_gnu_pubnames/d' | count 0
# RUN: llvm-dwarfdump -gdb-index %t | FileCheck %s

# %t.o has 2 CUs while %t1 has 1, thus _start in %t1.o should have cuIndex 2.
Expand Down
Loading