[lld] r231454 - PECOFF: Optimize the writer using parallel_for.

[Rui Ueyama]

Author: ruiu
Date: Fri Mar  6 00:53:13 2015
New Revision: 231454

URL: http://llvm.org/viewvc/llvm-project?rev=231454&view=rev
Log:
PECOFF: Optimize the writer using parallel_for.

Previously applying 1 million relocations took about 2 seconds on my
Xeon 2.4GHz 8 core workstation. After this patch, it takes about 300
milliseconds. As a result, time to link chrome.dll becomes 23 seconds
to 21 seconds.

Modified:
    lld/trunk/lib/ReaderWriter/PECOFF/WriterPECOFF.cpp

Modified: lld/trunk/lib/ReaderWriter/PECOFF/WriterPECOFF.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/lib/ReaderWriter/PECOFF/WriterPECOFF.cpp?rev=231454&r1=231453&r2=231454&view=diff
==============================================================================
--- lld/trunk/lib/ReaderWriter/PECOFF/WriterPECOFF.cpp (original)
+++ lld/trunk/lib/ReaderWriter/PECOFF/WriterPECOFF.cpp Fri Mar  6 00:53:13 2015
@@ -602,8 +602,9 @@ void AtomChunk::applyRelocationsARM(uint
                                     std::vector<uint64_t> &SectionRVA,
                                     uint64_t ImageBase) {
   Buffer = Buffer + _fileOffset;
-  for (const auto *Layout : _atomLayouts) {
-    const DefinedAtom *Atom = cast<DefinedAtom>(Layout->_atom);
+  parallel_for_each(_atomLayouts.begin(), _atomLayouts.end(),
+                    [&](const AtomLayout *layout) {
+    const DefinedAtom *Atom = cast<DefinedAtom>(layout->_atom);
     for (const Reference *R : *Atom) {
       if (R->kindNamespace() != Reference::KindNamespace::COFF)
         continue;
@@ -614,7 +615,7 @@ void AtomChunk::applyRelocationsARM(uint
                           Target->permissions() == DefinedAtom::permRWX;
 
       const auto AtomOffset = R->offsetInAtom();
-      const auto FileOffset = Layout->_fileOffset;
+      const auto FileOffset = layout->_fileOffset;
       const auto TargetAddr = AtomRVA[R->target()] | (AssumeTHUMBCode ? 1 : 0);
       auto RelocSite16 =
           reinterpret_cast<ulittle16_t *>(Buffer + FileOffset + AtomOffset);
@@ -645,7 +646,7 @@ void AtomChunk::applyRelocationsARM(uint
         break;
       }
     }
-  }
+  });
 }
 
 void AtomChunk::applyRelocationsX86(uint8_t *buffer,
@@ -653,7 +654,8 @@ void AtomChunk::applyRelocationsX86(uint
                                     std::vector<uint64_t> &sectionRva,
                                     uint64_t imageBaseAddress) {
   buffer += _fileOffset;
-  for (const auto *layout : _atomLayouts) {
+  parallel_for_each(_atomLayouts.begin(), _atomLayouts.end(),
+                    [&](const AtomLayout *layout) {
     const DefinedAtom *atom = cast<DefinedAtom>(layout->_atom);
     for (const Reference *ref : *atom) {
       // Skip if this reference is not for COFF relocation.
@@ -702,7 +704,7 @@ void AtomChunk::applyRelocationsX86(uint
         llvm::report_fatal_error("Unsupported relocation kind");
       }
     }
-  }
+  });
 }
 
 void AtomChunk::applyRelocationsX64(uint8_t *buffer,
@@ -710,7 +712,8 @@ void AtomChunk::applyRelocationsX64(uint
                                     std::vector<uint64_t> &sectionRva,
                                     uint64_t imageBase) {
   buffer += _fileOffset;
-  for (const auto *layout : _atomLayouts) {
+  parallel_for_each(_atomLayouts.begin(), _atomLayouts.end(),
+                    [&](const AtomLayout *layout) {
     const DefinedAtom *atom = cast<DefinedAtom>(layout->_atom);
     for (const Reference *ref : *atom) {
       if (ref->kindNamespace() != Reference::KindNamespace::COFF)
@@ -762,7 +765,7 @@ void AtomChunk::applyRelocationsX64(uint
         llvm::report_fatal_error("Unsupported relocation kind");
       }
     }
-  }
+  });
 }
 
 /// Print atom VAs. Used only for debugging.