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[object] Improve the performance of getSymbols used by ArchiveWriter 

In this diff we adjust the code of getSymbols to avoid creating LLVMContext when it's not necessary.
Without this patch when the function getSymbols was called on a MachO object with a __bitcode section
it was parsing the embedded bitcode and then ignoring the result.

Test plan: make check-all

Differential revision: https://reviews.llvm.org/D51759

llvm-svn: 341998
This commit is contained in:
Alexander Shaposhnikov 2018-09-11 22:00:47 +00:00
parent 26725bdc50
commit 72b27a6a39
1 changed files with 23 additions and 11 deletions
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34
llvm/lib/Object/ArchiveWriter.cpp
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@ -372,20 +372,32 @@ static void writeSymbolTable(raw_ostream &Out, object::Archive::Kind Kind,
static Expected<std::vector<unsigned>>
getSymbols(MemoryBufferRef Buf, raw_ostream &SymNames, bool &HasObject) {
std::vector<unsigned> Ret;
LLVMContext Context;
Expected<std::unique_ptr<object::SymbolicFile>> ObjOrErr =
object::SymbolicFile::createSymbolicFile(Buf, llvm::file_magic::unknown,
&Context);
if (!ObjOrErr) {
// FIXME: check only for "not an object file" errors.
consumeError(ObjOrErr.takeError());
return Ret;
// In the scenario when LLVMContext is populated SymbolicFile will contain a
// reference to it, thus SymbolicFile should be destroyed first.
LLVMContext Context;
std::unique_ptr<object::SymbolicFile> Obj;
if (identify_magic(Buf.getBuffer()) == file_magic::bitcode) {
auto ObjOrErr = object::SymbolicFile::createSymbolicFile(
Buf, file_magic::bitcode, &Context);
if (!ObjOrErr) {
// FIXME: check only for "not an object file" errors.
consumeError(ObjOrErr.takeError());
return Ret;
}
Obj = std::move(*ObjOrErr);
} else {
auto ObjOrErr = object::SymbolicFile::createSymbolicFile(Buf);
if (!ObjOrErr) {
// FIXME: check only for "not an object file" errors.
consumeError(ObjOrErr.takeError());
return Ret;
}
Obj = std::move(*ObjOrErr);
}
HasObject = true;
object::SymbolicFile &Obj = *ObjOrErr.get();
for (const object::BasicSymbolRef &S : Obj.symbols()) {
for (const object::BasicSymbolRef &S : Obj->symbols()) {
if (!isArchiveSymbol(S))
continue;
Ret.push_back(SymNames.tell());
@ -470,7 +482,7 @@ Error llvm::writeArchive(StringRef ArcName,
if (WriteSymtab) {
uint64_t MaxOffset = 0;
uint64_t LastOffset = MaxOffset;
for (const auto& M : Data) {
for (const auto &M : Data) {
// Record the start of the member's offset
LastOffset = MaxOffset;
// Account for the size of each part associated with the member.