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[PDB] Use the global BumpPtrAllocator
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Profiling shows that time is spent destroying the allocator member of
PDBLinker, and that is unneeded.
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@rnk
rnk committed May 4, 2020
1 parent 5d10613 commit 2868ee5
Showing 1 changed file with 21 additions and 27 deletions.
48 changes: 21 additions & 27 deletions lld/COFF/PDB.cpp
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Expand Up @@ -87,7 +87,7 @@ class PDBLinker {

public:
PDBLinker(SymbolTable *symtab)
: alloc(), symtab(symtab), builder(alloc), tMerger(alloc) {
: symtab(symtab), builder(bAlloc), tMerger(bAlloc) {
// This isn't strictly necessary, but link.exe usually puts an empty string
// as the first "valid" string in the string table, so we do the same in
// order to maintain as much byte-for-byte compatibility as possible.
Expand Down Expand Up @@ -166,8 +166,6 @@ class PDBLinker {
void printStats();

private:
BumpPtrAllocator alloc;

SymbolTable *symtab;

pdb::PDBFileBuilder builder;
Expand Down Expand Up @@ -898,7 +896,7 @@ void PDBLinker::mergeSymbolRecords(ObjFile *file, const CVIndexMap &indexMap,
MutableArrayRef<uint8_t> alignedSymbolMem;
if (needsRealignment) {
void *alignedData =
alloc.Allocate(totalRealignedSize, alignOf(CodeViewContainer::Pdb));
bAlloc.Allocate(totalRealignedSize, alignOf(CodeViewContainer::Pdb));
alignedSymbolMem = makeMutableArrayRef(
reinterpret_cast<uint8_t *>(alignedData), totalRealignedSize);
}
Expand Down Expand Up @@ -980,9 +978,8 @@ void PDBLinker::mergeSymbolRecords(ObjFile *file, const CVIndexMap &indexMap,
}

// Allocate memory for a .debug$S / .debug$F section and relocate it.
static ArrayRef<uint8_t> relocateDebugChunk(BumpPtrAllocator &alloc,
SectionChunk &debugChunk) {
uint8_t *buffer = alloc.Allocate<uint8_t>(debugChunk.getSize());
static ArrayRef<uint8_t> relocateDebugChunk(SectionChunk &debugChunk) {
uint8_t *buffer = bAlloc.Allocate<uint8_t>(debugChunk.getSize());
assert(debugChunk.getOutputSectionIdx() == 0 &&
"debug sections should not be in output sections");
debugChunk.writeTo(buffer);
Expand Down Expand Up @@ -1030,7 +1027,7 @@ void DebugSHandler::handleDebugS(lld::coff::SectionChunk &debugS) {
DebugSubsectionArray subsections;

ArrayRef<uint8_t> relocatedDebugContents = SectionChunk::consumeDebugMagic(
relocateDebugChunk(linker.alloc, debugS), debugS.getSectionName());
relocateDebugChunk(debugS), debugS.getSectionName());

BinaryStreamReader reader(relocatedDebugContents, support::little);
exitOnErr(reader.readArray(subsections, relocatedDebugContents.size()));
Expand Down Expand Up @@ -1241,7 +1238,7 @@ void PDBLinker::addObjFile(ObjFile *file, CVIndexMap *externIndexMap) {

if (debugChunk->getSectionName() == ".debug$F") {
ArrayRef<uint8_t> relocatedDebugContents =
relocateDebugChunk(alloc, *debugChunk);
relocateDebugChunk(*debugChunk);

FixedStreamArray<object::FpoData> fpoRecords;
BinaryStreamReader reader(relocatedDebugContents, support::little);
Expand Down Expand Up @@ -1522,8 +1519,7 @@ static void fillLinkerVerRecord(Compile3Sym &cs) {
}

static void addCommonLinkerModuleSymbols(StringRef path,
pdb::DbiModuleDescriptorBuilder &mod,
BumpPtrAllocator &allocator) {
pdb::DbiModuleDescriptorBuilder &mod) {
ObjNameSym ons(SymbolRecordKind::ObjNameSym);
EnvBlockSym ebs(SymbolRecordKind::EnvBlockSym);
Compile3Sym cs(SymbolRecordKind::Compile3Sym);
Expand All @@ -1550,17 +1546,16 @@ static void addCommonLinkerModuleSymbols(StringRef path,
ebs.Fields.push_back("cmd");
ebs.Fields.push_back(argStr);
mod.addSymbol(codeview::SymbolSerializer::writeOneSymbol(
ons, allocator, CodeViewContainer::Pdb));
ons, bAlloc, CodeViewContainer::Pdb));
mod.addSymbol(codeview::SymbolSerializer::writeOneSymbol(
cs, allocator, CodeViewContainer::Pdb));
cs, bAlloc, CodeViewContainer::Pdb));
mod.addSymbol(codeview::SymbolSerializer::writeOneSymbol(
ebs, allocator, CodeViewContainer::Pdb));
ebs, bAlloc, CodeViewContainer::Pdb));
}

static void addLinkerModuleCoffGroup(PartialSection *sec,
pdb::DbiModuleDescriptorBuilder &mod,
OutputSection &os,
BumpPtrAllocator &allocator) {
OutputSection &os) {
// If there's a section, there's at least one chunk
assert(!sec->chunks.empty());
const Chunk *firstChunk = *sec->chunks.begin();
Expand All @@ -1581,12 +1576,11 @@ static void addLinkerModuleCoffGroup(PartialSection *sec,
cgs.Characteristics |= llvm::COFF::IMAGE_SCN_MEM_WRITE;

mod.addSymbol(codeview::SymbolSerializer::writeOneSymbol(
cgs, allocator, CodeViewContainer::Pdb));
cgs, bAlloc, CodeViewContainer::Pdb));
}

static void addLinkerModuleSectionSymbol(pdb::DbiModuleDescriptorBuilder &mod,
OutputSection &os,
BumpPtrAllocator &allocator) {
OutputSection &os) {
SectionSym sym(SymbolRecordKind::SectionSym);
sym.Alignment = 12; // 2^12 = 4KB
sym.Characteristics = os.header.Characteristics;
Expand All @@ -1595,7 +1589,7 @@ static void addLinkerModuleSectionSymbol(pdb::DbiModuleDescriptorBuilder &mod,
sym.Rva = os.getRVA();
sym.SectionNumber = os.sectionIndex;
mod.addSymbol(codeview::SymbolSerializer::writeOneSymbol(
sym, allocator, CodeViewContainer::Pdb));
sym, bAlloc, CodeViewContainer::Pdb));

// Skip COFF groups in MinGW because it adds a significant footprint to the
// PDB, due to each function being in its own section
Expand All @@ -1604,7 +1598,7 @@ static void addLinkerModuleSectionSymbol(pdb::DbiModuleDescriptorBuilder &mod,

// Output COFF groups for individual chunks of this section.
for (PartialSection *sec : os.contribSections) {
addLinkerModuleCoffGroup(sec, mod, os, allocator);
addLinkerModuleCoffGroup(sec, mod, os);
}
}

Expand Down Expand Up @@ -1671,18 +1665,18 @@ void PDBLinker::addImportFilesToPDB(ArrayRef<OutputSection *> outputSections) {
ts.Offset = thunkChunk->getRVA() - thunkOS->getRVA();

mod->addSymbol(codeview::SymbolSerializer::writeOneSymbol(
ons, alloc, CodeViewContainer::Pdb));
ons, bAlloc, CodeViewContainer::Pdb));
mod->addSymbol(codeview::SymbolSerializer::writeOneSymbol(
cs, alloc, CodeViewContainer::Pdb));
cs, bAlloc, CodeViewContainer::Pdb));

SmallVector<SymbolScope, 4> scopes;
CVSymbol newSym = codeview::SymbolSerializer::writeOneSymbol(
ts, alloc, CodeViewContainer::Pdb);
ts, bAlloc, CodeViewContainer::Pdb);
scopeStackOpen(scopes, mod->getNextSymbolOffset(), newSym);

mod->addSymbol(newSym);

newSym = codeview::SymbolSerializer::writeOneSymbol(es, alloc,
newSym = codeview::SymbolSerializer::writeOneSymbol(es, bAlloc,
CodeViewContainer::Pdb);
scopeStackClose(scopes, mod->getNextSymbolOffset(), file);

Expand Down Expand Up @@ -1758,11 +1752,11 @@ void PDBLinker::addSections(ArrayRef<OutputSection *> outputSections,
uint32_t pdbFilePathNI = dbiBuilder.addECName(nativePath);
auto &linkerModule = exitOnErr(dbiBuilder.addModuleInfo("* Linker *"));
linkerModule.setPdbFilePathNI(pdbFilePathNI);
addCommonLinkerModuleSymbols(nativePath, linkerModule, alloc);
addCommonLinkerModuleSymbols(nativePath, linkerModule);

// Add section contributions. They must be ordered by ascending RVA.
for (OutputSection *os : outputSections) {
addLinkerModuleSectionSymbol(linkerModule, *os, alloc);
addLinkerModuleSectionSymbol(linkerModule, *os);
for (Chunk *c : os->chunks) {
pdb::SectionContrib sc =
createSectionContrib(c, linkerModule.getModuleIndex());
Expand Down

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