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[ELF][PPC32] Don't report "relocation refers to a discarded section" for .got2 

Similar to D63182 [ELF][PPC64] Don't report "relocation refers to a discarded section" for .toc

Reviewed By: Bdragon28

Differential Revision: https://reviews.llvm.org/D75419
This commit is contained in:
Fangrui Song 2020-02-29 18:40:58 -08:00
parent bfdb834bc3
commit 315f8a55f5
3 changed files with 30 additions and 4 deletions
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5
lld/ELF/InputSection.cpp
View File

@ -438,11 +438,12 @@ void InputSection::copyRelocations(uint8_t *buf, ArrayRef<RelTy> rels) {
// hopefully creates a frame that is ignored at runtime. Also, don't warn // hopefully creates a frame that is ignored at runtime. Also, don't warn
// on .gcc_except_table and debug sections. // on .gcc_except_table and debug sections.
// //
// See the comment in maybeReportUndefined for PPC64 .toc . // See the comment in maybeReportUndefined for PPC32 .got2 and PPC64 .toc
auto *d = dyn_cast<Defined>(&sym); auto *d = dyn_cast<Defined>(&sym);
if (!d) { if (!d) {
if (!isDebugSection(*sec) && sec->name != ".eh_frame" && if (!isDebugSection(*sec) && sec->name != ".eh_frame" &&
sec->name != ".gcc_except_table" && sec->name != ".toc") { sec->name != ".gcc_except_table" && sec->name != ".got2" &&
sec->name != ".toc") {
uint32_t secIdx = cast<Undefined>(sym).discardedSecIdx; uint32_t secIdx = cast<Undefined>(sym).discardedSecIdx;
Elf_Shdr_Impl<ELFT> sec = Elf_Shdr_Impl<ELFT> sec =
CHECK(file->getObj().sections(), file)[secIdx]; CHECK(file->getObj().sections(), file)[secIdx];

8
lld/ELF/Relocations.cpp
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@ -946,8 +946,12 @@ static bool maybeReportUndefined(Symbol &sym, InputSectionBase &sec,
// .toc and the .rela.toc are incorrectly not placed in the comdat. The ELF // .toc and the .rela.toc are incorrectly not placed in the comdat. The ELF
// spec says references from outside the group to a STB_LOCAL symbol are not // spec says references from outside the group to a STB_LOCAL symbol are not
// allowed. Work around the bug. // allowed. Work around the bug.
if (config->emachine == EM_PPC64 && //
cast<Undefined>(sym).discardedSecIdx != 0 && sec.name == ".toc") // PPC32 .got2 is similar but cannot be fixed. Multiple .got2 is infeasible
// because .LC0-.LTOC is not representable if the two labels are in different
// .got2
if (cast<Undefined>(sym).discardedSecIdx != 0 &&
(sec.name == ".got2" || sec.name == ".toc"))
return false; return false;
bool isWarning = bool isWarning =

21
lld/test/ELF/comdat-discarded-ppc32.s Normal file
View File

@ -0,0 +1,21 @@
# REQUIRES: ppc
# RUN: llvm-mc -filetype=obj -triple=powerpc %s -o %t.o
# RUN: ld.lld %t.o %t.o -o /dev/null
# RUN: ld.lld -r --fatal-warnings %t.o %t.o -o /dev/null
## Similar to PPC64, clang/gcc PPC32 may emit a .rela.got2 which references a local symbol
## defined in a discarded .rodata section. Unfortunately, .got2 cannot be placed in a comdat
## because for lwz 3, .LC0-.LTOC(30), we cannot define .LC0 in a different .got2 section.
## Don't error "relocation refers to a discarded section".
.section .text.foo,"axG",@progbits,foo,comdat
.globl foo
foo:
lwz 3, .LC0-.LTOC(30)
.L0:
.section .got2,"aw",@progbits
.set .LTOC, .got2+32768
.LC0:
.long .L0