From 8b3f6235826cb989852b44e30a26dc5a20e59128 Mon Sep 17 00:00:00 2001 From: Alexander Kornienko Date: Wed, 29 Aug 2012 00:20:03 +0000 Subject: Keep history of macro definitions and #undefs Summary: Summary: Keep history of macro definitions and #undefs with corresponding source locations, so that we can later find out all macros active in a specified source location. We don't save the history in PCH (no need currently). Memory overhead is about sizeof(void*)*3*+ I've run a test on a file composed of 109 .h files from boost 1.49 on x86-64 linux. Stats before this patch: *** Preprocessor Stats: 73222 directives found: 19171 #define. 4345 #undef. #include/#include_next/#import: 5233 source files entered. 27 max include stack depth 19210 #if/#ifndef/#ifdef. 2384 #else/#elif. 6891 #endif. 408 #pragma. 14466 #if/#ifndef#ifdef regions skipped 80023/451669/1270 obj/fn/builtin macros expanded, 85724 on the fast path. 127145 token paste (##) operations performed, 11008 on the fast path. Preprocessor Memory: 5874615B total BumpPtr: 4399104 Macro Expanded Tokens: 417768 Predefines Buffer: 8135 Macros: 1048576 #pragma push_macro Info: 0 Poison Reasons: 1024 Comment Handlers: 8 Stats with this patch: ... Preprocessor Memory: 7541687B total BumpPtr: 6066176 Macro Expanded Tokens: 417768 Predefines Buffer: 8135 Macros: 1048576 #pragma push_macro Info: 0 Poison Reasons: 1024 Comment Handlers: 8 In my test increase in memory usage is about 1.7Mb, which is ~28% of initial preprocessor's memory usage and about 0.8% of clang's total VMM allocation. As for CPU overhead, it should only be noticeable when iterating over all macros, and should mostly consist of couple extra dereferences and one comparison per macro + skipping of #undef'd macros. It's less trivial to measure, though, as the preprocessor consumes a very small fraction of compilation time. Reviewers: doug.gregor, klimek, rsmith, djasper Reviewed By: doug.gregor CC: cfe-commits, chandlerc Differential Revision: http://llvm-reviews.chandlerc.com/D28 llvm-svn: 162810 --- clang/lib/Serialization/ASTWriter.cpp | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) (limited to 'clang/lib/Serialization/ASTWriter.cpp') diff --git a/clang/lib/Serialization/ASTWriter.cpp b/clang/lib/Serialization/ASTWriter.cpp index a64e0d35795..4a3987cbdc7 100644 --- a/clang/lib/Serialization/ASTWriter.cpp +++ b/clang/lib/Serialization/ASTWriter.cpp @@ -1677,10 +1677,12 @@ void ASTWriter::WritePreprocessor(const Preprocessor &PP, bool IsModule) { for (Preprocessor::macro_iterator I = PP.macro_begin(Chain == 0), E = PP.macro_end(Chain == 0); I != E; ++I) { - const IdentifierInfo *Name = I->first; - if (!IsModule || I->second->isPublic()) { - MacroDefinitionsSeen.insert(Name); - MacrosToEmit.push_back(std::make_pair(I->first, I->second)); + // FIXME: We'll need to store macro history in PCH. + if (I->first->hasMacroDefinition()) { + if (!IsModule || I->second->isPublic()) { + MacroDefinitionsSeen.insert(I->first); + MacrosToEmit.push_back(std::make_pair(I->first, I->second)); + } } } -- cgit v1.2.3