[lld] r303787 - Simplify a variable type by using StringRef instead of CachedHashStringRef.
Rafael Espíndola via llvm-commits
llvm-commits at lists.llvm.org
Wed May 24 15:54:40 PDT 2017
Hi,
Unfortunately the results I get are the opposite. The largest slowdown
is in firefox with -O0 (2.5%). That is somewhat expected, as the
basics take a larger part of the link at -O0. I also don't see any
case where it is faster.
What testcase have you used? If you can share the reproduce.tar I can
add it to the set I normally use.
Cheers,
Rafael
On 24 May 2017 at 11:22, Rui Ueyama via llvm-commits
<llvm-commits at lists.llvm.org> wrote:
> Author: ruiu
> Date: Wed May 24 13:22:27 2017
> New Revision: 303787
>
> URL: http://llvm.org/viewvc/llvm-project?rev=303787&view=rev
> Log:
> Simplify a variable type by using StringRef instead of CachedHashStringRef.
>
> A variable `ComdatGroup` is not supposed to contain a large number of
> items. Even when linking clang, it ends up having only 300K strings.
> It doesn't make sense to use CachedHashStringRef for this hash table.
> This patch has neutral or slightly positive impact on performance while
> reducing code complexity.
>
> Modified:
> lld/trunk/ELF/InputFiles.cpp
> lld/trunk/ELF/InputFiles.h
> lld/trunk/ELF/SymbolTable.cpp
> lld/trunk/ELF/SymbolTable.h
>
> Modified: lld/trunk/ELF/InputFiles.cpp
> URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/InputFiles.cpp?rev=303787&r1=303786&r2=303787&view=diff
> ==============================================================================
> --- lld/trunk/ELF/InputFiles.cpp (original)
> +++ lld/trunk/ELF/InputFiles.cpp Wed May 24 13:22:27 2017
> @@ -192,7 +192,7 @@ ArrayRef<SymbolBody *> elf::ObjectFile<E
> }
>
> template <class ELFT>
> -void elf::ObjectFile<ELFT>::parse(DenseSet<CachedHashStringRef> &ComdatGroups) {
> +void elf::ObjectFile<ELFT>::parse(DenseSet<StringRef> &ComdatGroups) {
> // Read section and symbol tables.
> initializeSections(ComdatGroups);
> initializeSymbols();
> @@ -280,7 +280,7 @@ bool elf::ObjectFile<ELFT>::shouldMerge(
>
> template <class ELFT>
> void elf::ObjectFile<ELFT>::initializeSections(
> - DenseSet<CachedHashStringRef> &ComdatGroups) {
> + DenseSet<StringRef> &ComdatGroups) {
> ArrayRef<Elf_Shdr> ObjSections =
> check(this->getObj().sections(), toString(this));
> const ELFFile<ELFT> &Obj = this->getObj();
> @@ -305,10 +305,7 @@ void elf::ObjectFile<ELFT>::initializeSe
> switch (Sec.sh_type) {
> case SHT_GROUP:
> this->Sections[I] = &InputSection::Discarded;
> - if (ComdatGroups
> - .insert(
> - CachedHashStringRef(getShtGroupSignature(ObjSections, Sec)))
> - .second)
> + if (ComdatGroups.insert(getShtGroupSignature(ObjSections, Sec)).second)
> continue;
> for (uint32_t SecIndex : getShtGroupEntries(Sec)) {
> if (SecIndex >= Size)
> @@ -876,10 +873,10 @@ static Symbol *createBitcodeSymbol(const
> }
>
> template <class ELFT>
> -void BitcodeFile::parse(DenseSet<CachedHashStringRef> &ComdatGroups) {
> +void BitcodeFile::parse(DenseSet<StringRef> &ComdatGroups) {
> std::vector<bool> KeptComdats;
> for (StringRef S : Obj->getComdatTable())
> - KeptComdats.push_back(ComdatGroups.insert(CachedHashStringRef(S)).second);
> + KeptComdats.push_back(ComdatGroups.insert(StringRef(S)).second);
>
> for (const lto::InputFile::Symbol &ObjSym : Obj->symbols())
> Symbols.push_back(createBitcodeSymbol<ELFT>(KeptComdats, ObjSym, this));
> @@ -1048,10 +1045,10 @@ template void ArchiveFile::parse<ELF32BE
> template void ArchiveFile::parse<ELF64LE>();
> template void ArchiveFile::parse<ELF64BE>();
>
> -template void BitcodeFile::parse<ELF32LE>(DenseSet<CachedHashStringRef> &);
> -template void BitcodeFile::parse<ELF32BE>(DenseSet<CachedHashStringRef> &);
> -template void BitcodeFile::parse<ELF64LE>(DenseSet<CachedHashStringRef> &);
> -template void BitcodeFile::parse<ELF64BE>(DenseSet<CachedHashStringRef> &);
> +template void BitcodeFile::parse<ELF32LE>(DenseSet<StringRef> &);
> +template void BitcodeFile::parse<ELF32BE>(DenseSet<StringRef> &);
> +template void BitcodeFile::parse<ELF64LE>(DenseSet<StringRef> &);
> +template void BitcodeFile::parse<ELF64BE>(DenseSet<StringRef> &);
>
> template void LazyObjectFile::parse<ELF32LE>();
> template void LazyObjectFile::parse<ELF32BE>();
>
> Modified: lld/trunk/ELF/InputFiles.h
> URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/InputFiles.h?rev=303787&r1=303786&r2=303787&view=diff
> ==============================================================================
> --- lld/trunk/ELF/InputFiles.h (original)
> +++ lld/trunk/ELF/InputFiles.h Wed May 24 13:22:27 2017
> @@ -17,7 +17,6 @@
>
> #include "lld/Core/LLVM.h"
> #include "lld/Core/Reproduce.h"
> -#include "llvm/ADT/CachedHashString.h"
> #include "llvm/ADT/DenseSet.h"
> #include "llvm/ADT/STLExtras.h"
> #include "llvm/IR/Comdat.h"
> @@ -157,7 +156,7 @@ public:
> ArrayRef<SymbolBody *> getLocalSymbols();
>
> ObjectFile(MemoryBufferRef M, StringRef ArchiveName);
> - void parse(llvm::DenseSet<llvm::CachedHashStringRef> &ComdatGroups);
> + void parse(llvm::DenseSet<StringRef> &ComdatGroups);
>
> InputSectionBase *getSection(const Elf_Sym &Sym) const;
>
> @@ -189,8 +188,7 @@ public:
> StringRef SourceFile;
>
> private:
> - void
> - initializeSections(llvm::DenseSet<llvm::CachedHashStringRef> &ComdatGroups);
> + void initializeSections(llvm::DenseSet<StringRef> &ComdatGroups);
> void initializeSymbols();
> void initializeDwarfLine();
> InputSectionBase *getRelocTarget(const Elf_Shdr &Sec);
> @@ -265,8 +263,7 @@ public:
> BitcodeFile(MemoryBufferRef M, StringRef ArchiveName,
> uint64_t OffsetInArchive);
> static bool classof(const InputFile *F) { return F->kind() == BitcodeKind; }
> - template <class ELFT>
> - void parse(llvm::DenseSet<llvm::CachedHashStringRef> &ComdatGroups);
> + template <class ELFT> void parse(llvm::DenseSet<StringRef> &ComdatGroups);
> ArrayRef<Symbol *> getSymbols() { return Symbols; }
> std::unique_ptr<llvm::lto::InputFile> Obj;
>
>
> Modified: lld/trunk/ELF/SymbolTable.cpp
> URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/SymbolTable.cpp?rev=303787&r1=303786&r2=303787&view=diff
> ==============================================================================
> --- lld/trunk/ELF/SymbolTable.cpp (original)
> +++ lld/trunk/ELF/SymbolTable.cpp Wed May 24 13:22:27 2017
> @@ -122,7 +122,7 @@ template <class ELFT> void SymbolTable<E
>
> for (InputFile *File : LTO->compile()) {
> ObjectFile<ELFT> *Obj = cast<ObjectFile<ELFT>>(File);
> - DenseSet<CachedHashStringRef> DummyGroups;
> + DenseSet<StringRef> DummyGroups;
> Obj->parse(DummyGroups);
> ObjectFiles.push_back(Obj);
> }
>
> Modified: lld/trunk/ELF/SymbolTable.h
> URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/SymbolTable.h?rev=303787&r1=303786&r2=303787&view=diff
> ==============================================================================
> --- lld/trunk/ELF/SymbolTable.h (original)
> +++ lld/trunk/ELF/SymbolTable.h Wed May 24 13:22:27 2017
> @@ -117,7 +117,7 @@ private:
> // Comdat groups define "link once" sections. If two comdat groups have the
> // same name, only one of them is linked, and the other is ignored. This set
> // is used to uniquify them.
> - llvm::DenseSet<llvm::CachedHashStringRef> ComdatGroups;
> + llvm::DenseSet<StringRef> ComdatGroups;
>
> std::vector<ObjectFile<ELFT> *> ObjectFiles;
> std::vector<SharedFile<ELFT> *> SharedFiles;
>
>
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> llvm-commits at lists.llvm.org
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