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[PDB] Bypass generic deserialization code for publics sorting

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The number of public symbols is very large, and each deserialization
does a few heap allocations. The public symbols are serialized by the
linker, so we can assume they have the expected layout and use it
directly.

Saves O(#publics) temporary heap allocations and shrinks some data
structures.
This commit is contained in:
Reid Kleckner 2020-05-02 18:06:41 -07:00
parent e5b50f6318
commit 01043ef84e
2 changed files with 34 additions and 16 deletions
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7
include/llvm/DebugInfo/CodeView/SymbolRecord.h
View File

@ -350,6 +350,13 @@ public:
uint32_t RecordOffset = 0;
};
struct PublicSym32Header {
ulittle32_t Flags;
ulittle32_t Offset;
ulittle16_t Segment;
// char Name[];
};
// S_PUB32
class PublicSym32 : public SymbolRecord {
public:

43
lib/DebugInfo/PDB/Native/GSIStreamBuilder.cpp
View File

@ -229,15 +229,30 @@ Error GSIStreamBuilder::finalizeMsfLayout() {
return Error::success();
}
static bool comparePubSymByAddrAndName(
const std::pair<const CVSymbol *, const PublicSym32 *> &LS,
const std::pair<const CVSymbol *, const PublicSym32 *> &RS) {
if (LS.second->Segment != RS.second->Segment)
return LS.second->Segment < RS.second->Segment;
if (LS.second->Offset != RS.second->Offset)
return LS.second->Offset < RS.second->Offset;
static StringRef extractPubSym(const CVSymbol *Sym, uint16_t &Seg,
uint32_t &Offset) {
ArrayRef<uint8_t> Buf = Sym->content();
assert(Buf.size() > sizeof(PublicSym32Header));
const auto *Hdr = reinterpret_cast<const PublicSym32Header *>(Buf.data());
Buf = Buf.drop_front(sizeof(PublicSym32Header));
Seg = Hdr->Segment;
Offset = Hdr->Offset;
// Don't worry about finding the null terminator, since the strings will be
// compared later.
return StringRef(reinterpret_cast<const char *>(Buf.data()), Buf.size());
}
return LS.second->Name < RS.second->Name;
static bool comparePubSymByAddrAndName(const CVSymbol *LS, const CVSymbol *RS) {
uint16_t LSeg, RSeg;
uint32_t LOff, ROff;
StringRef LName, RName;
LName = extractPubSym(LS, LSeg, LOff);
RName = extractPubSym(RS, RSeg, ROff);
if (LSeg != RSeg)
return LSeg < RSeg;
if (LOff != ROff)
return LOff < ROff;
return LName < RName;
}
/// Compute the address map. The address map is an array of symbol offsets
@ -246,19 +261,15 @@ static std::vector<ulittle32_t> computeAddrMap(ArrayRef<CVSymbol> Records) {
// Make a vector of pointers to the symbols so we can sort it by address.
// Also gather the symbol offsets while we're at it.
std::vector<PublicSym32> DeserializedPublics;
std::vector<std::pair<const CVSymbol *, const PublicSym32 *>> PublicsByAddr;
std::vector<const CVSymbol *> PublicsByAddr;
std::vector<uint32_t> SymOffsets;
DeserializedPublics.reserve(Records.size());
PublicsByAddr.reserve(Records.size());
SymOffsets.reserve(Records.size());
uint32_t SymOffset = 0;
for (const CVSymbol &Sym : Records) {
assert(Sym.kind() == SymbolKind::S_PUB32);
DeserializedPublics.push_back(
cantFail(SymbolDeserializer::deserializeAs<PublicSym32>(Sym)));
PublicsByAddr.emplace_back(&Sym, &DeserializedPublics.back());
PublicsByAddr.push_back(&Sym);
SymOffsets.push_back(SymOffset);
SymOffset += Sym.length();
}
@ -267,8 +278,8 @@ static std::vector<ulittle32_t> computeAddrMap(ArrayRef<CVSymbol> Records) {
// Fill in the symbol offsets in the appropriate order.
std::vector<ulittle32_t> AddrMap;
AddrMap.reserve(Records.size());
for (auto &Sym : PublicsByAddr) {
ptrdiff_t Idx = std::distance(Records.data(), Sym.first);
for (const CVSymbol *Sym : PublicsByAddr) {
ptrdiff_t Idx = std::distance(Records.data(), Sym);
assert(Idx >= 0 && size_t(Idx) < Records.size());
AddrMap.push_back(ulittle32_t(SymOffsets[Idx]));
}