From 8318f61bb87b15e21572e7650ad7c0a6b7e327b8 Mon Sep 17 00:00:00 2001 From: Ilya Biryukov Date: Fri, 24 Nov 2017 13:12:38 +0000 Subject: [PATCH] Avoid copying the data of in-memory preambles Summary: Preambles are large and we should avoid copying them. Reviewers: bkramer, klimek Reviewed By: bkramer Subscribers: cfe-commits Differential Revision: https://reviews.llvm.org/D40302 llvm-svn: 318945 --- clang/include/clang/Frontend/PrecompiledPreamble.h | 4 ++++ clang/lib/Frontend/PrecompiledPreamble.cpp | 4 +--- 2 files changed, 5 insertions(+), 3 deletions(-) diff --git a/clang/include/clang/Frontend/PrecompiledPreamble.h b/clang/include/clang/Frontend/PrecompiledPreamble.h index 28e25bc..13edea0 100644 --- a/clang/include/clang/Frontend/PrecompiledPreamble.h +++ b/clang/include/clang/Frontend/PrecompiledPreamble.h @@ -98,6 +98,10 @@ public: /// Changes options inside \p CI to use PCH from this preamble. Also remaps /// main file to \p MainFileBuffer and updates \p VFS to ensure the preamble /// is accessible. + /// For in-memory preambles, PrecompiledPreamble instance continues to own + /// the MemoryBuffer with the Preamble after this method returns. The caller + /// is reponsible for making sure the PrecompiledPreamble instance outlives + /// the compiler run and the AST that will be using the PCH. void AddImplicitPreamble(CompilerInvocation &CI, IntrusiveRefCntPtr &VFS, llvm::MemoryBuffer *MainFileBuffer) const; diff --git a/clang/lib/Frontend/PrecompiledPreamble.cpp b/clang/lib/Frontend/PrecompiledPreamble.cpp index 130b904..c6ee4d0 100644 --- a/clang/lib/Frontend/PrecompiledPreamble.cpp +++ b/clang/lib/Frontend/PrecompiledPreamble.cpp @@ -699,9 +699,7 @@ void PrecompiledPreamble::setupPreambleStorage( StringRef PCHPath = getInMemoryPreamblePath(); PreprocessorOpts.ImplicitPCHInclude = PCHPath; - // FIMXE(ibiryukov): Preambles can be large. We should allow shared access - // to the preamble data instead of copying it here. - auto Buf = llvm::MemoryBuffer::getMemBufferCopy(Storage.asMemory().Data); + auto Buf = llvm::MemoryBuffer::getMemBuffer(Storage.asMemory().Data); VFS = createVFSOverlayForPreamblePCH(PCHPath, std::move(Buf), VFS); } } -- 2.7.4