diff options
Diffstat (limited to 'COFF/Chunks.cpp')
| -rw-r--r-- | COFF/Chunks.cpp | 33 |
1 files changed, 26 insertions, 7 deletions
diff --git a/COFF/Chunks.cpp b/COFF/Chunks.cpp index 359dbe69559f5..56124acaf9a12 100644 --- a/COFF/Chunks.cpp +++ b/COFF/Chunks.cpp @@ -37,8 +37,14 @@ SectionChunk::SectionChunk(ObjectFile *F, const coff_section *H) Align = Header->getAlignment(); - // Only COMDAT sections are subject of dead-stripping. - Live = !isCOMDAT(); + // Chunks may be discarded during comdat merging. + Discarded = false; + + // If linker GC is disabled, every chunk starts out alive. If linker GC is + // enabled, treat non-comdat sections as roots. Generally optimized object + // files will be built with -ffunction-sections or /Gy, so most things worth + // stripping will be in a comdat. + Live = !Config->DoGC || !isCOMDAT(); } static void add16(uint8_t *P, int16_t V) { write16le(P, read16le(P) + V); } @@ -46,6 +52,15 @@ static void add32(uint8_t *P, int32_t V) { write32le(P, read32le(P) + V); } static void add64(uint8_t *P, int64_t V) { write64le(P, read64le(P) + V); } static void or16(uint8_t *P, uint16_t V) { write16le(P, read16le(P) | V); } +static void applySecRel(const SectionChunk *Sec, uint8_t *Off, Defined *Sym) { + // Don't apply section relative relocations to absolute symbols in codeview + // debug info sections. MSVC does not treat such relocations as fatal errors, + // and they can be found in the standard library for linker-provided symbols + // like __guard_fids_table and __safe_se_handler_table. + if (!(isa<DefinedAbsolute>(Sym) && Sec->isCodeView())) + add32(Off, Sym->getSecrel()); +} + void SectionChunk::applyRelX64(uint8_t *Off, uint16_t Type, Defined *Sym, uint64_t P) const { uint64_t S = Sym->getRVA(); @@ -60,7 +75,7 @@ void SectionChunk::applyRelX64(uint8_t *Off, uint16_t Type, Defined *Sym, case IMAGE_REL_AMD64_REL32_4: add32(Off, S - P - 8); break; case IMAGE_REL_AMD64_REL32_5: add32(Off, S - P - 9); break; case IMAGE_REL_AMD64_SECTION: add16(Off, Sym->getSectionIndex()); break; - case IMAGE_REL_AMD64_SECREL: add32(Off, Sym->getSecrel()); break; + case IMAGE_REL_AMD64_SECREL: applySecRel(this, Off, Sym); break; default: fatal("unsupported relocation type 0x" + Twine::utohexstr(Type)); } @@ -75,7 +90,7 @@ void SectionChunk::applyRelX86(uint8_t *Off, uint16_t Type, Defined *Sym, case IMAGE_REL_I386_DIR32NB: add32(Off, S); break; case IMAGE_REL_I386_REL32: add32(Off, S - P - 4); break; case IMAGE_REL_I386_SECTION: add16(Off, Sym->getSectionIndex()); break; - case IMAGE_REL_I386_SECREL: add32(Off, Sym->getSecrel()); break; + case IMAGE_REL_I386_SECREL: applySecRel(this, Off, Sym); break; default: fatal("unsupported relocation type 0x" + Twine::utohexstr(Type)); } @@ -135,7 +150,7 @@ void SectionChunk::applyRelARM(uint8_t *Off, uint16_t Type, Defined *Sym, case IMAGE_REL_ARM_BRANCH20T: applyBranch20T(Off, S - P - 4); break; case IMAGE_REL_ARM_BRANCH24T: applyBranch24T(Off, S - P - 4); break; case IMAGE_REL_ARM_BLX23T: applyBranch24T(Off, S - P - 4); break; - case IMAGE_REL_ARM_SECREL: add32(Off, Sym->getSecrel()); break; + case IMAGE_REL_ARM_SECREL: applySecRel(this, Off, Sym); break; default: fatal("unsupported relocation type 0x" + Twine::utohexstr(Type)); } @@ -226,8 +241,12 @@ bool SectionChunk::isCOMDAT() const { void SectionChunk::printDiscardedMessage() const { // Removed by dead-stripping. If it's removed by ICF, ICF already // printed out the name, so don't repeat that here. - if (Sym && this == Repl) - message("Discarded " + Sym->getName()); + if (Sym && this == Repl) { + if (Discarded) + message("Discarded comdat symbol " + Sym->getName()); + else if (!Live) + message("Discarded " + Sym->getName()); + } } StringRef SectionChunk::getDebugName() { |