replica
/
hanchenye-llvm-project
2
0
Fork 0
Code Issues Pull Requests Projects Releases Wiki Activity

[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

llvm-svn: 232460
This commit is contained in:
Shankar Easwaran 2015-03-17 03:29:32 +00:00
parent e0afb1fe6c
commit baf1aaaf1f
2 changed files with 8 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
lld/lib/ReaderWriter/ELF/OutputELFWriter.h
View File

@ -586,8 +586,10 @@ std::error_code OutputELFWriter<ELFT>::writeOutput(const File &file,
_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");

8
lld/lib/ReaderWriter/ELF/SectionChunks.h
View File

@ -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