[llvm] r269682 - ThinLTO caching: reload cached file with mmap and drop heap-allocated memory buffer
Mehdi Amini via llvm-commits
llvm-commits at lists.llvm.org
Mon May 16 12:12:00 PDT 2016
Author: mehdi_amini
Date: Mon May 16 14:11:59 2016
New Revision: 269682
URL: http://llvm.org/viewvc/llvm-project?rev=269682&view=rev
Log:
ThinLTO caching: reload cached file with mmap and drop heap-allocated memory buffer
This is reducing pressure on the OS memory system, and is NFC
when not using a cache.
I measure a 10x memory consumption reduction when linking opt
with full debug info.
From: Mehdi Amini <mehdi.amini at apple.com>
Modified:
llvm/trunk/lib/LTO/ThinLTOCodeGenerator.cpp
Modified: llvm/trunk/lib/LTO/ThinLTOCodeGenerator.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/LTO/ThinLTOCodeGenerator.cpp?rev=269682&r1=269681&r2=269682&view=diff
==============================================================================
--- llvm/trunk/lib/LTO/ThinLTOCodeGenerator.cpp (original)
+++ llvm/trunk/lib/LTO/ThinLTOCodeGenerator.cpp Mon May 16 14:11:59 2016
@@ -484,9 +484,10 @@ public:
}
// Cache the Produced object file
- void write(MemoryBufferRef OutputBuffer) {
+ std::unique_ptr<MemoryBuffer>
+ write(std::unique_ptr<MemoryBuffer> OutputBuffer) {
if (EntryPath.empty())
- return;
+ return OutputBuffer;
// Write to a temporary to avoid race condition
SmallString<128> TempFilename;
@@ -499,7 +500,7 @@ public:
}
{
raw_fd_ostream OS(TempFD, /* ShouldClose */ true);
- OS << OutputBuffer.getBuffer();
+ OS << OutputBuffer->getBuffer();
}
// Rename to final destination (hopefully race condition won't matter here)
EC = sys::fs::rename(TempFilename, EntryPath);
@@ -509,8 +510,16 @@ public:
if (EC)
report_fatal_error(Twine("Failed to open ") + EntryPath +
" to save cached entry\n");
- OS << OutputBuffer.getBuffer();
+ OS << OutputBuffer->getBuffer();
}
+ auto ReloadedBufferOrErr = MemoryBuffer::getFile(EntryPath);
+ if (auto EC = ReloadedBufferOrErr.getError()) {
+ // FIXME diagnose
+ errs() << "error: can't reload cached file '" << EntryPath
+ << "': " << EC.message() << "\n";
+ return OutputBuffer;
+ }
+ return std::move(*ReloadedBufferOrErr);
}
};
@@ -943,7 +952,7 @@ void ThinLTOCodeGenerator::run() {
ExportList, GUIDPreservedSymbols, ResolvedODR, CacheOptions,
DisableCodeGen, SaveTempsDir, count);
- CacheEntry.write(*OutputBuffer);
+ OutputBuffer = CacheEntry.write(std::move(OutputBuffer));
ProducedBinaries[count] = std::move(OutputBuffer);
}, count);
count++;
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