[lld] 09602d3 - [ELF] Parallelize initializeLocalSymbols
Fangrui Song via llvm-commits
llvm-commits at lists.llvm.org
Thu Feb 24 20:06:06 PST 2022
Author: Fangrui Song
Date: 2022-02-24T20:05:59-08:00
New Revision: 09602d3b47ec83abb2c26efa5a199c13b72c7abf
URL: https://github.com/llvm/llvm-project/commit/09602d3b47ec83abb2c26efa5a199c13b72c7abf
DIFF: https://github.com/llvm/llvm-project/commit/09602d3b47ec83abb2c26efa5a199c13b72c7abf.diff
LOG: [ELF] Parallelize initializeLocalSymbols
ObjFile::parse combines symbol initialization and resolution. Many tasks
unrelated to symbol resolution can be postponed and parallelized. This patch
extracts local symbol initialization and parallelizes it.
Technically the new function initializeLocalSymbols can be merged into
ObjFile::postParse, but functions like getSrcMsg may access the
uninitialized (all nullptr) local part of InputFile::symbols.
Linking chrome: 1.02x as fast with glibc malloc, 1.04x as fast with mimalloc
Reviewed By: ikudrin
Differential Revision: https://reviews.llvm.org/D119909
Added:
Modified:
lld/ELF/Driver.cpp
lld/ELF/InputFiles.cpp
lld/ELF/InputFiles.h
lld/ELF/InputSection.cpp
Removed:
################################################################################
diff --git a/lld/ELF/Driver.cpp b/lld/ELF/Driver.cpp
index 5af69e78a3ad9..4951eb91edb67 100644
--- a/lld/ELF/Driver.cpp
+++ b/lld/ELF/Driver.cpp
@@ -2219,6 +2219,25 @@ static uint32_t getAndFeatures() {
return ret;
}
+static void initializeLocalSymbols(ELFFileBase *file) {
+ switch (config->ekind) {
+ case ELF32LEKind:
+ cast<ObjFile<ELF32LE>>(file)->initializeLocalSymbols();
+ break;
+ case ELF32BEKind:
+ cast<ObjFile<ELF32BE>>(file)->initializeLocalSymbols();
+ break;
+ case ELF64LEKind:
+ cast<ObjFile<ELF64LE>>(file)->initializeLocalSymbols();
+ break;
+ case ELF64BEKind:
+ cast<ObjFile<ELF64BE>>(file)->initializeLocalSymbols();
+ break;
+ default:
+ llvm_unreachable("");
+ }
+}
+
static void postParseObjectFile(ELFFileBase *file) {
switch (config->ekind) {
case ELF32LEKind:
@@ -2357,6 +2376,7 @@ void LinkerDriver::link(opt::InputArgList &args) {
// No more lazy bitcode can be extracted at this point. Do post parse work
// like checking duplicate symbols.
+ parallelForEach(objectFiles, initializeLocalSymbols);
parallelForEach(objectFiles, postParseObjectFile);
parallelForEach(bitcodeFiles, [](BitcodeFile *file) { file->postParse(); });
@@ -2428,6 +2448,7 @@ void LinkerDriver::link(opt::InputArgList &args) {
// compileBitcodeFiles may have produced lto.tmp object files. After this, no
// more file will be added.
auto newObjectFiles = makeArrayRef(objectFiles).slice(numObjsBeforeLTO);
+ parallelForEach(newObjectFiles, initializeLocalSymbols);
parallelForEach(newObjectFiles, postParseObjectFile);
// Handle --exclude-libs again because lto.tmp may reference additional
diff --git a/lld/ELF/InputFiles.cpp b/lld/ELF/InputFiles.cpp
index adedb1611c080..da6fc3a6e627c 100644
--- a/lld/ELF/InputFiles.cpp
+++ b/lld/ELF/InputFiles.cpp
@@ -1021,41 +1021,6 @@ void ObjFile<ELFT>::initializeSymbols(const object::ELFFile<ELFT> &obj) {
ArrayRef<Elf_Sym> eSyms = this->getELFSyms<ELFT>();
symbols.resize(eSyms.size());
- SymbolUnion *locals =
- firstGlobal == 0
- ? nullptr
- : getSpecificAllocSingleton<SymbolUnion>().Allocate(firstGlobal);
-
- for (size_t i = 0, end = firstGlobal; i != end; ++i) {
- const Elf_Sym &eSym = eSyms[i];
- uint32_t secIdx = eSym.st_shndx;
- if (LLVM_UNLIKELY(secIdx == SHN_XINDEX))
- secIdx = check(getExtendedSymbolTableIndex<ELFT>(eSym, i, shndxTable));
- else if (secIdx >= SHN_LORESERVE)
- secIdx = 0;
- if (LLVM_UNLIKELY(secIdx >= sections.size()))
- fatal(toString(this) + ": invalid section index: " + Twine(secIdx));
- if (LLVM_UNLIKELY(eSym.getBinding() != STB_LOCAL))
- error(toString(this) + ": non-local symbol (" + Twine(i) +
- ") found at index < .symtab's sh_info (" + Twine(end) + ")");
-
- InputSectionBase *sec = sections[secIdx];
- uint8_t type = eSym.getType();
- if (type == STT_FILE)
- sourceFile = CHECK(eSym.getName(stringTable), this);
- if (LLVM_UNLIKELY(stringTable.size() <= eSym.st_name))
- fatal(toString(this) + ": invalid symbol name offset");
- StringRef name(stringTable.data() + eSym.st_name);
-
- symbols[i] = reinterpret_cast<Symbol *>(locals + i);
- if (eSym.st_shndx == SHN_UNDEF || sec == &InputSection::discarded)
- new (symbols[i]) Undefined(this, name, STB_LOCAL, eSym.st_other, type,
- /*discardedSecIdx=*/secIdx);
- else
- new (symbols[i]) Defined(this, name, STB_LOCAL, eSym.st_other, type,
- eSym.st_value, eSym.st_size, sec);
- symbols[i]->isUsedInRegularObj = true;
- }
// Some entries have been filled by LazyObjFile.
for (size_t i = firstGlobal, end = eSyms.size(); i != end; ++i)
@@ -1149,6 +1114,45 @@ void ObjFile<ELFT>::initializeSymbols(const object::ELFFile<ELFT> &obj) {
}
}
+template <class ELFT> void ObjFile<ELFT>::initializeLocalSymbols() {
+ if (!firstGlobal)
+ return;
+ localSymStorage = std::make_unique<SymbolUnion[]>(firstGlobal);
+ SymbolUnion *locals = localSymStorage.get();
+
+ ArrayRef<Elf_Sym> eSyms = this->getELFSyms<ELFT>();
+ for (size_t i = 0, end = firstGlobal; i != end; ++i) {
+ const Elf_Sym &eSym = eSyms[i];
+ uint32_t secIdx = eSym.st_shndx;
+ if (LLVM_UNLIKELY(secIdx == SHN_XINDEX))
+ secIdx = check(getExtendedSymbolTableIndex<ELFT>(eSym, i, shndxTable));
+ else if (secIdx >= SHN_LORESERVE)
+ secIdx = 0;
+ if (LLVM_UNLIKELY(secIdx >= sections.size()))
+ fatal(toString(this) + ": invalid section index: " + Twine(secIdx));
+ if (LLVM_UNLIKELY(eSym.getBinding() != STB_LOCAL))
+ error(toString(this) + ": non-local symbol (" + Twine(i) +
+ ") found at index < .symtab's sh_info (" + Twine(end) + ")");
+
+ InputSectionBase *sec = sections[secIdx];
+ uint8_t type = eSym.getType();
+ if (type == STT_FILE)
+ sourceFile = CHECK(eSym.getName(stringTable), this);
+ if (LLVM_UNLIKELY(stringTable.size() <= eSym.st_name))
+ fatal(toString(this) + ": invalid symbol name offset");
+ StringRef name(stringTable.data() + eSym.st_name);
+
+ symbols[i] = reinterpret_cast<Symbol *>(locals + i);
+ if (eSym.st_shndx == SHN_UNDEF || sec == &InputSection::discarded)
+ new (symbols[i]) Undefined(this, name, STB_LOCAL, eSym.st_other, type,
+ /*discardedSecIdx=*/secIdx);
+ else
+ new (symbols[i]) Defined(this, name, STB_LOCAL, eSym.st_other, type,
+ eSym.st_value, eSym.st_size, sec);
+ symbols[i]->isUsedInRegularObj = true;
+ }
+}
+
// Called after all ObjFile::parse is called for all ObjFiles. This checks
// duplicate symbols and may do symbol property merge in the future.
template <class ELFT> void ObjFile<ELFT>::postParse() {
diff --git a/lld/ELF/InputFiles.h b/lld/ELF/InputFiles.h
index e2aba8e6250cf..68129d0d298d1 100644
--- a/lld/ELF/InputFiles.h
+++ b/lld/ELF/InputFiles.h
@@ -10,6 +10,7 @@
#define LLD_ELF_INPUT_FILES_H
#include "Config.h"
+#include "Symbols.h"
#include "lld/Common/ErrorHandler.h"
#include "lld/Common/LLVM.h"
#include "lld/Common/Reproduce.h"
@@ -273,6 +274,7 @@ template <class ELFT> class ObjFile : public ELFFileBase {
// Get cached DWARF information.
DWARFCache *getDwarf();
+ void initializeLocalSymbols();
void postParse();
private:
@@ -302,6 +304,9 @@ template <class ELFT> class ObjFile : public ELFFileBase {
// If the section does not exist (which is common), the array is empty.
ArrayRef<Elf_Word> shndxTable;
+ // Storage for local symbols.
+ std::unique_ptr<SymbolUnion[]> localSymStorage;
+
// Debugging information to retrieve source file and line for error
// reporting. Linker may find reasonable number of errors in a
// single object file, so we cache debugging information in order to
diff --git a/lld/ELF/InputSection.cpp b/lld/ELF/InputSection.cpp
index 7f6d275e327d4..b76ee7a532eaf 100644
--- a/lld/ELF/InputSection.cpp
+++ b/lld/ELF/InputSection.cpp
@@ -297,9 +297,10 @@ std::string InputSectionBase::getObjMsg(uint64_t off) {
if (!file->archiveName.empty())
archive = (" in archive " + file->archiveName).str();
- // Find a symbol that encloses a given location.
+ // Find a symbol that encloses a given location. getObjMsg may be called
+ // before ObjFile::initializeLocalSymbols where local symbols are initialized.
for (Symbol *b : file->getSymbols())
- if (auto *d = dyn_cast<Defined>(b))
+ if (auto *d = dyn_cast_or_null<Defined>(b))
if (d->section == this && d->value <= off && off < d->value + d->size)
return filename + ":(" + toString(*d) + ")" + archive;
More information about the llvm-commits
mailing list