[binutils-gdb] PE-COFF: Fix link failure of C++ code with debug info after partial linking
Eric Botcazou via Binutils-cvs <[email protected]>
| Newsgroups | gmane.comp.gnu.binutils.cvs |
|---|---|
| Message-ID | <[email protected]> |
https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=84acfa08c7a40f01b4ae254cc4658e5865edf3c6 commit 84acfa08c7a40f01b4ae254cc4658e5865edf3c6 Author: Eric Botcazou <[email protected]> Date: Mon Mar 30 19:10:26 2026 +0200 PE-COFF: Fix link failure of C++ code with debug info after partial linking If you apply the following recipe to the attached C/C++ files with a PE-COFF toolchain, you get the specified output: 1. g++ -c clib.cpp cpplib.cpp test.c -g 2. g++ -o pl.o clib.o cpplib.o -nostdlib -Wl,-r 3. objcopy pl.o objcopy.exe: pl.o: warning: COMDAT symbol '.debug_frame$_ZNSt12_Vector_baseIiSaIiEE12_Vector_implD1Ev' does not match section name '.debug_frame' 4. g++ -o test test.o pl.o ld.exe: pl.o: warning: COMDAT symbol '.debug_frame$_ZNSt12_Vector_baseIiSaIiEE12_Vector_implD1Ev' does not match section name '.debug_frame' pl.o:clib.cpp:(.pdata$_ZNSt12_Vector_baseIiSaIiEE13_M_deallocateEPiy+0x0): relocation truncated to fit: IMAGE_REL_AMD64_ADDR32NB against `.text$_ZNSt12_Vector_baseIiSaIiEE13_M_deallocateEPiy' pl.o:clib.cpp:(.pdata$_ZNSt12_Vector_baseIiSaIiEE13_M_deallocateEPiy+0x4): relocation truncated to fit: IMAGE_REL_AMD64_ADDR32NB against `.text$_ZNSt12_Vector_baseIiSaIiEE13_M_deallocateEPiy' pl.o:clib.cpp:(.pdata$_ZNSt12_Vector_baseIiSaIiEE19_M_get_Tp_allocatorEv+0x0): relocation truncated to fit: IMAGE_REL_AMD64_ADDR32NB against `.text$_ZNSt12_Vector_baseIiSaIiEE19_M_get_Tp_allocatorEv' pl.o:clib.cpp:(.pdata$_ZNSt12_Vector_baseIiSaIiEE19_M_get_Tp_allocatorEv+0x4): relocation truncated to fit: IMAGE_REL_AMD64_ADDR32NB against `.text$_ZNSt12_Vector_baseIiSaIiEE19_M_get_Tp_allocatorEv' pl.o:clib.cpp:(.pdata$_ZNSt15__new_allocatorIiE10deallocateEPiy+0x0): relocation truncated to fit: IMAGE_REL_AMD64_ADDR32NB against `.text$_ZNSt15__new_allocatorIiE10deallocateEPiy' pl.o:clib.cpp:(.pdata$_ZNSt15__new_allocatorIiE10deallocateEPiy+0x4): relocation truncated to fit: IMAGE_REL_AMD64_ADDR32NB against `.text$_ZNSt15__new_allocatorIiE10deallocateEPiy' collect2.exe: error: ld returned 1 exit status The problem pertains to section symbols generated for COMDAT sections: they are marked as local symbols as per Microsoft's PE-COFF specification, but partial linking discards the duplicate COMDAT sections without being able to either merge them, or remove them when they are used in a relocation. So they end up as undefined local symbols after the partial link, which in turn may cause the final link to fail (in practice you need e.g. a call to objcopy in between, because it moves them to the end of the symbol list). This change instructs the linker to "relocate" them instead, that is to say to attach them to the one COMDAT section that is output among the multiple COMDAT sections that are duplicate. It also prevents partial linking from prematurely globing the .[z]debug_frame* sections together, as already done for the .eh_frame* sections. bfd/ * cofflink.c (_bfd_coff_link_input_bfd): For a relocatable output, relocate section symbols for input sections that are not going to be emitted because they are duplicate of another one in the link. ld/ * scripttempl/pe.sc (.debug_frame): Do not glob all .debug_frame* sections together when not relocating. (.zdebug_frame): Likewise for .zdebug_frame* sections. * scripttempl/pep.sc (.debug_frame): Likewise. (.zdebug_frame): Likewise. Diff: --- bfd/cofflink.c | 22 ++++++++++++++++++---- ld/scripttempl/pe.sc | 4 ++-- ld/scripttempl/pep.sc | 4 ++-- 3 files changed, 22 insertions(+), 8 deletions(-) diff --git a/bfd/cofflink.c b/bfd/cofflink.c index 3504b2d4a0c..e5c8a987d69 100644 --- a/bfd/cofflink.c +++ b/bfd/cofflink.c @@ -1857,12 +1857,26 @@ _bfd_coff_link_input_bfd (struct coff_final_link_info *flaginfo, bfd *input_bfd) /* Compute new symbol location. */ if (isym.n_scnum > 0) { - isym.n_scnum = (*secpp)->output_section->target_index; - isym.n_value += (*secpp)->output_offset; + const asection *s = *secpp; + + /* Relocate section symbols for sections that are not going to + be emitted because they are duplicate of another one. */ + if (bfd_link_relocatable (flaginfo->info) + && isym.n_sclass == C_STAT + && isym.n_type == T_NULL + && isym.n_numaux > 0 + && (s->output_section == bfd_abs_section_ptr + || bfd_section_removed_from_list + (output_bfd, s->output_section)) + && s->kept_section) + s = s->kept_section; + + isym.n_scnum = s->output_section->target_index; + isym.n_value += s->output_offset; if (! obj_pe (input_bfd)) - isym.n_value -= (*secpp)->vma; + isym.n_value -= s->vma; if (! obj_pe (flaginfo->output_bfd)) - isym.n_value += (*secpp)->output_section->vma; + isym.n_value += s->output_section->vma; } break; diff --git a/ld/scripttempl/pe.sc b/ld/scripttempl/pe.sc index f8d7c8ef6e7..a669f279eda 100644 --- a/ld/scripttempl/pe.sc +++ b/ld/scripttempl/pe.sc @@ -364,11 +364,11 @@ SECTIONS .debug_frame ${RELOCATING+BLOCK(__section_alignment__)} ${RELOCATING+(NOLOAD)} : { - *(.debug_frame*) + *(.debug_frame${RELOCATING+*}) } .zdebug_frame ${RELOCATING+BLOCK(__section_alignment__)} ${RELOCATING+(NOLOAD)} : { - *(.zdebug_frame*) + *(.zdebug_frame${RELOCATING+*}) } .debug_str ${RELOCATING+BLOCK(__section_alignment__)} ${RELOCATING+(NOLOAD)} : diff --git a/ld/scripttempl/pep.sc b/ld/scripttempl/pep.sc index a5b4679544c..45e785492c5 100644 --- a/ld/scripttempl/pep.sc +++ b/ld/scripttempl/pep.sc @@ -373,11 +373,11 @@ SECTIONS .debug_frame ${RELOCATING+BLOCK(__section_alignment__)} ${RELOCATING+(NOLOAD)} : { - *(.debug_frame*) + *(.debug_frame${RELOCATING+*}) } .zdebug_frame ${RELOCATING+BLOCK(__section_alignment__)} ${RELOCATING+(NOLOAD)} : { - *(.zdebug_frame*) + *(.zdebug_frame${RELOCATING+*}) } .debug_str ${RELOCATING+BLOCK(__section_alignment__)} ${RELOCATING+(NOLOAD)} :