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83f4c3af02
Partially reverts 0a2be46cfd as it turned
out to cause redundant module rebuilds in multi-process incremental builds.
When a module was getting out of date, all compilation processes started at the
same time were marking it as `ToBuild`. So each process was building the same
module instead of checking if it was built by someone else and using that
result. In addition to the work duplication, contention on the same .pcm file
wasn't making builds faster.
Note that for a single-process build this change would cause redundant module
reads and validations. But reading a module is faster than building it and
multi-process builds are more common than single-process. So I'm willing to
make such a trade-off.
rdar://problem/54395127
Reviewed By: dexonsmith
Differential Revision: https://reviews.llvm.org/D72860
68 lines
2.1 KiB
C++
68 lines
2.1 KiB
C++
//===- InMemoryModuleCache.cpp - Cache for loaded memory buffers ----------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#include "clang/Serialization/InMemoryModuleCache.h"
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#include "llvm/Support/MemoryBuffer.h"
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using namespace clang;
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llvm::MemoryBuffer &
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InMemoryModuleCache::addPCM(llvm::StringRef Filename,
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std::unique_ptr<llvm::MemoryBuffer> Buffer) {
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auto Insertion = PCMs.insert(std::make_pair(Filename, std::move(Buffer)));
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assert(Insertion.second && "Already has a PCM");
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return *Insertion.first->second.Buffer;
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}
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llvm::MemoryBuffer &
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InMemoryModuleCache::addFinalPCM(llvm::StringRef Filename,
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std::unique_ptr<llvm::MemoryBuffer> Buffer) {
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auto &PCM = PCMs[Filename];
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assert(!PCM.IsFinal && "Trying to override finalized PCM?");
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assert(!PCM.Buffer && "Already has a non-final PCM");
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PCM.Buffer = std::move(Buffer);
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PCM.IsFinal = true;
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return *PCM.Buffer;
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}
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llvm::MemoryBuffer *
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InMemoryModuleCache::lookupPCM(llvm::StringRef Filename) const {
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auto I = PCMs.find(Filename);
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if (I == PCMs.end())
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return nullptr;
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return I->second.Buffer.get();
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}
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bool InMemoryModuleCache::isPCMFinal(llvm::StringRef Filename) const {
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auto I = PCMs.find(Filename);
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if (I == PCMs.end())
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return false;
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return I->second.IsFinal;
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}
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bool InMemoryModuleCache::tryToRemovePCM(llvm::StringRef Filename) {
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auto I = PCMs.find(Filename);
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assert(I != PCMs.end() && "PCM to remove is unknown...");
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auto &PCM = I->second;
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if (PCM.IsFinal)
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return true;
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PCMs.erase(I);
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return false;
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}
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void InMemoryModuleCache::finalizePCM(llvm::StringRef Filename) {
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auto I = PCMs.find(Filename);
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assert(I != PCMs.end() && "PCM to finalize is unknown...");
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auto &PCM = I->second;
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assert(PCM.Buffer && "Trying to finalize a dropped PCM...");
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PCM.IsFinal = true;
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}
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