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[lld-macho][nfc] Factor out findSymbolAtOffset

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Our compact unwind handling code currently has some logic to locate a
symbol at a given offset in an InputSection. The EH frame code will need
to do something similar, so let's factor out the code.

Reviewed By: #lld-macho, thakis

Differential Revision: https://reviews.llvm.org/D123301
This commit is contained in:
Jez Ng 2022-04-07 09:05:33 -04:00
parent dc15bedfb9
commit da6b6b3c82
1 changed files with 17 additions and 8 deletions
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25
lld/MachO/InputFiles.cpp
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@ -385,6 +385,20 @@ static InputSection *findContainingSubsection(const Section &section,
return it->isec;
}
// Find a symbol at offset `off` within `isec`.
static Defined *findSymbolAtOffset(const ConcatInputSection *isec,
uint64_t off) {
auto it = llvm::lower_bound(isec->symbols, off, [](Defined *d, uint64_t off) {
return d->value < off;
});
// The offset should point at the exact address of a symbol (with no addend.)
if (it == isec->symbols.end() || (*it)->value != off) {
assert(isec->wasCoalesced);
return nullptr;
}
return *it;
}
template <class SectionHeader>
static bool validateRelocationInfo(InputFile *file, const SectionHeader &sec,
relocation_info rel) {
@ -1002,17 +1016,12 @@ void ObjFile::registerCompactUnwind() {
// The functionAddress relocations are typically section relocations.
// However, unwind info operates on a per-symbol basis, so we search for
// the function symbol here.
auto symIt = llvm::lower_bound(
referentIsec->symbols, add,
[](Defined *d, uint64_t add) { return d->value < add; });
// The relocation should point at the exact address of a symbol (with no
// addend).
if (symIt == referentIsec->symbols.end() || (*symIt)->value != add) {
assert(referentIsec->wasCoalesced);
Defined *d = findSymbolAtOffset(referentIsec, add);
if (!d) {
++it;
continue;
}
(*symIt)->unwindEntry = isec;
d->unwindEntry = isec;
// Since we've sliced away the functionAddress, we should remove the
// corresponding relocation too. Given that clang emits relocations in
// reverse order of address, this relocation should be at the end of the