maxjhandsome
/
llvm-project
forked from OSchip/llvm-project
1
0
Fork 0
Code Issues Pull Requests Packages Releases Wiki Activity

Hash symbol names only once per global SymbolBody. 

The DenseMap doesn't store hash results. This means that when it is
resized it has to recompute them.

This patch is a small hack that wraps the StringRef in a struct that
remembers the hash value. That way we can be sure it is only hashed
once.

llvm-svn: 266357
This commit is contained in:
Rafael Espindola 2016-04-14 19:17:16 +00:00
parent 000c5af3e6
commit c9157d35d9
2 changed files with 34 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
lld/ELF/MarkLive.cpp
View File

@ -113,7 +113,7 @@ template <class ELFT> void elf::markLive(SymbolTable<ELFT> *Symtab) {
// Preserve externally-visible symbols if the symbols defined by this
// file can interrupt other ELF file's symbols at runtime.
if (Config->Shared || Config->ExportDynamic) {
for (const std::pair<StringRef, Symbol *> &P : Symtab->getSymbols()) {
for (const std::pair<SymName, Symbol *> &P : Symtab->getSymbols()) {
SymbolBody *B = P.second->Body;
if (B->getVisibility() == STV_DEFAULT)
MarkSymbol(B);

35
lld/ELF/SymbolTable.h
View File

@ -20,6 +20,37 @@ class Lazy;
template <class ELFT> class OutputSectionBase;
struct Symbol;
struct SymName {
SymName(StringRef Name) : Name(Name) {
Hash = llvm::DenseMapInfo<StringRef>::getHashValue(Name);
}
SymName(StringRef Name, unsigned Hash) : Name(Name), Hash(Hash) {}
StringRef Name;
unsigned Hash;
};
}
}
namespace llvm {
template <> struct DenseMapInfo<lld::elf::SymName> {
static lld::elf::SymName getEmptyKey() {
StringRef N = DenseMapInfo<StringRef>::getEmptyKey();
return {N, 0};
}
static lld::elf::SymName getTombstoneKey() {
StringRef N = DenseMapInfo<StringRef>::getTombstoneKey();
return {N, 0};
}
static unsigned getHashValue(lld::elf::SymName Name) { return Name.Hash; }
static bool isEqual(lld::elf::SymName A, lld::elf::SymName B) {
return A.Name == B.Name;
}
};
}
namespace lld {
namespace elf {
// SymbolTable is a bucket of all known symbols, including defined,
// undefined, or lazy symbols (the last one is symbols in archive
// files whose archive members are not yet loaded).
@ -38,7 +69,7 @@ public:
void addFile(std::unique_ptr<InputFile> File);
void addCombinedLtoObject();
const llvm::MapVector<StringRef, Symbol *> &getSymbols() const {
const llvm::MapVector<SymName, Symbol *> &getSymbols() const {
return Symtab;
}
@ -79,7 +110,7 @@ private:
// a bit inefficient.
// FIXME: Experiment with passing in a custom hashing or sorting the symbols
// once symbol resolution is finished.
llvm::MapVector<StringRef, Symbol *> Symtab;
llvm::MapVector<SymName, Symbol *> Symtab;
llvm::BumpPtrAllocator Alloc;
// Comdat groups define "link once" sections. If two comdat groups have the