[lld] r232460 - [ELF] Use parallel_for_each for writing.
Shankar Easwaran
shankare at codeaurora.org
Mon Mar 16 20:29:32 PDT 2015
Author: shankare
Date: Mon Mar 16 22:29:32 2015
New Revision: 232460
URL: http://llvm.org/viewvc/llvm-project?rev=232460&view=rev
Log:
[ELF] Use parallel_for_each for writing.
This changes improves performance of lld, when self-hosting lld, when compared
with the bfd linker. BFD linker on average takes 8 seconds in elapsed time.
lld takes 3 seconds elapased time average. Without this change, lld takes ~5
seconds average. The runtime comparisons were done on a release build and
measured by running linking thrice.
lld self-host without the change
----------------------------------
real 0m3.196s
user 0m4.580s
sys 0m0.832s
lld self-host with lld
-----------------------
user 0m3.024s
user 0m3.252s
sys 0m0.796s
time taken to build lld with bfd
--------------------------------
real 0m8.419s
user 0m7.748s
sys 0m0.632s
Modified:
lld/trunk/lib/ReaderWriter/ELF/OutputELFWriter.h
lld/trunk/lib/ReaderWriter/ELF/SectionChunks.h
Modified: lld/trunk/lib/ReaderWriter/ELF/OutputELFWriter.h
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/lib/ReaderWriter/ELF/OutputELFWriter.h?rev=232460&r1=232459&r2=232460&view=diff
==============================================================================
--- lld/trunk/lib/ReaderWriter/ELF/OutputELFWriter.h (original)
+++ lld/trunk/lib/ReaderWriter/ELF/OutputELFWriter.h Mon Mar 16 22:29:32 2015
@@ -586,8 +586,10 @@ std::error_code OutputELFWriter<ELFT>::w
_elfHeader->write(this, _layout, *buffer);
_programHeader->write(this, _layout, *buffer);
- for (auto section : _layout.sections())
- section->write(this, _layout, *buffer);
+ auto sections = _layout.sections();
+ parallel_for_each(
+ sections.begin(), sections.end(),
+ [&](Chunk<ELFT> *section) { section->write(this, _layout, *buffer); });
writeTask.end();
ScopedTask commitTask(getDefaultDomain(), "ELF Writer commit to disk");
Modified: lld/trunk/lib/ReaderWriter/ELF/SectionChunks.h
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/lib/ReaderWriter/ELF/SectionChunks.h?rev=232460&r1=232459&r2=232460&view=diff
==============================================================================
--- lld/trunk/lib/ReaderWriter/ELF/SectionChunks.h (original)
+++ lld/trunk/lib/ReaderWriter/ELF/SectionChunks.h Mon Mar 16 22:29:32 2015
@@ -234,17 +234,17 @@ public:
/// routine gets called after the linker fixes up the virtual address
/// of the section
virtual void assignVirtualAddress(uint64_t addr) override {
- for (auto &ai : _atoms) {
+ parallel_for_each(_atoms.begin(), _atoms.end(), [&](AtomLayout *ai) {
ai->_virtualAddr = addr + ai->_fileOffset;
- }
+ });
}
/// \brief Set the file offset of each Atom in the section. This routine
/// gets called after the linker fixes up the section offset
void assignFileOffsets(uint64_t offset) override {
- for (auto &ai : _atoms) {
+ parallel_for_each(_atoms.begin(), _atoms.end(), [&](AtomLayout *ai) {
ai->_fileOffset = offset + ai->_fileOffset;
- }
+ });
}
/// \brief Find the Atom address given a name, this is needed to properly
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