[lld] r239292 - COFF: Avoid callign stable_sort.
Rui Ueyama
ruiu at google.com
Mon Jun 8 01:26:29 PDT 2015
Author: ruiu
Date: Mon Jun 8 03:26:28 2015
New Revision: 239292
URL: http://llvm.org/viewvc/llvm-project?rev=239292&view=rev
Log:
COFF: Avoid callign stable_sort.
MSVC profiler reported that this stable_sort takes 7% time
when self-linking. As a result, createSection was taking 10% time.
Now createSection takes 3%. This small change actually makes
the linker a bit but perceptibly faster.
Modified:
lld/trunk/COFF/Writer.cpp
Modified: lld/trunk/COFF/Writer.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/COFF/Writer.cpp?rev=239292&r1=239291&r2=239292&view=diff
==============================================================================
--- lld/trunk/COFF/Writer.cpp (original)
+++ lld/trunk/COFF/Writer.cpp Mon Jun 8 03:26:28 2015
@@ -120,30 +120,30 @@ void Writer::createSections() {
C->printDiscardedMessage();
continue;
}
- // '$' and all following characters in input section names are
- // discarded when determining output section. So, .text$foo
- // contributes to .text, for example. See PE/COFF spec 3.2.
- Map[C->getSectionName().split('$').first].push_back(C);
+ Map[C->getSectionName()].push_back(C);
}
// Then create an OutputSection for each section.
+ // '$' and all following characters in input section names are
+ // discarded when determining output section. So, .text$foo
+ // contributes to .text, for example. See PE/COFF spec 3.2.
+ StringRef Name = Map.begin()->first.split('$').first;
+ auto Sec = new (CAlloc.Allocate()) OutputSection(Name, 0);
+ OutputSections.push_back(Sec);
for (auto &P : Map) {
StringRef SectionName = P.first;
+ StringRef Base = SectionName.split('$').first;
+ if (Base != Sec->getName()) {
+ size_t SectIdx = OutputSections.size();
+ Sec = new (CAlloc.Allocate()) OutputSection(Base, SectIdx);
+ OutputSections.push_back(Sec);
+ }
std::vector<Chunk *> &Chunks = P.second;
- // Input sections are ordered by their names including '$' parts,
- // which gives you some control over the output layout.
- std::stable_sort(Chunks.begin(), Chunks.end(),
- [](Chunk *A, Chunk *B) {
- return A->getSectionName() < B->getSectionName();
- });
- size_t SectIdx = OutputSections.size();
- auto Sec = new (CAlloc.Allocate()) OutputSection(SectionName, SectIdx);
for (Chunk *C : Chunks) {
C->setOutputSection(Sec);
Sec->addChunk(C);
Sec->addPermissions(C->getPermissions());
}
- OutputSections.push_back(Sec);
}
}
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