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[COFF] Simplify relocation to discarded section diagnostic code, NFC 

Move it out of the loop that applies relocations for readability.

llvm-svn: 346777
This commit is contained in:
Reid Kleckner 2018-11-13 18:30:31 +00:00
parent b23f430ec9
commit 551acf03dc
1 changed files with 35 additions and 28 deletions
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63
lld/COFF/Chunks.cpp
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@ -316,6 +316,32 @@ void SectionChunk::applyRelARM64(uint8_t *Off, uint16_t Type, OutputSection *OS,
}
}
static void maybeReportRelocationToDiscarded(const SectionChunk *FromChunk,
Defined *Sym,
const coff_relocation &Rel) {
// Don't report these errors when the relocation comes from a debug info
// section or in mingw mode. MinGW mode object files (built by GCC) can
// have leftover sections with relocations against discarded comdat
// sections. Such sections are left as is, with relocations untouched.
if (FromChunk->isCodeView() || FromChunk->isDWARF() || Config->MinGW)
return;
// Get the name of the symbol. If it's null, it was discarded early, so we
// have to go back to the object file.
ObjFile *File = FromChunk->File;
StringRef Name;
if (Sym) {
Name = Sym->getName();
} else {
COFFSymbolRef COFFSym =
check(File->getCOFFObj()->getSymbol(Rel.SymbolTableIndex));
File->getCOFFObj()->getSymbolName(COFFSym, Name);
}
error("relocation against symbol in discarded section: " + Name +
getSymbolLocations(File, Rel.SymbolTableIndex));
}
void SectionChunk::writeTo(uint8_t *Buf) const {
if (!hasData())
return;
@ -343,42 +369,23 @@ void SectionChunk::writeTo(uint8_t *Buf) const {
// Use the potentially remapped Symbol instead of the one that the
// relocation points to.
auto *Sym = dyn_cast_or_null<Defined>(RelocTargets[I]);
if (!Sym) {
if (isCodeView() || isDWARF())
continue;
// Symbols in early discarded sections are represented using null pointers,
// so we need to retrieve the name from the object file.
COFFSymbolRef Sym =
check(File->getCOFFObj()->getSymbol(Rel.SymbolTableIndex));
StringRef Name;
File->getCOFFObj()->getSymbolName(Sym, Name);
// MinGW mode object files (built by GCC) can have leftover sections
// with relocations against discarded comdat sections. Such sections
// are left as is, with relocations untouched.
if (!Config->MinGW)
error("relocation against symbol in discarded section: " + Name +
getSymbolLocations(File, Rel.SymbolTableIndex));
continue;
}
// Get the output section of the symbol for this relocation. The output
// section is needed to compute SECREL and SECTION relocations used in debug
// info.
Chunk *C = Sym->getChunk();
Chunk *C = Sym ? Sym->getChunk() : nullptr;
OutputSection *OS = C ? C->getOutputSection() : nullptr;
// Only absolute and __ImageBase symbols lack an output section. For any
// other symbol, this indicates that the chunk was discarded. Normally
// relocations against discarded sections are an error. However, debug info
// sections are not GC roots and can end up with these kinds of relocations.
// Skip these relocations.
if (!OS && !isa<DefinedAbsolute>(Sym) && !isa<DefinedSynthetic>(Sym)) {
if (isCodeView() || isDWARF())
continue;
error("relocation against symbol in discarded section: " +
Sym->getName() + getSymbolLocations(File, Rel.SymbolTableIndex));
// Skip the relocation if it refers to a discarded section, and diagnose it
// as an error if appropriate. If a symbol was discarded early, it may be
// null. If it was discarded late, the output section will be null, unless
// it was an absolute or synthetic symbol.
if (!Sym ||
(!OS && !isa<DefinedAbsolute>(Sym) && !isa<DefinedSynthetic>(Sym))) {
maybeReportRelocationToDiscarded(this, Sym, Rel);
continue;
}
uint64_t S = Sym->getRVA();
// Compute the RVA of the relocation for relative relocations.