Introduce a caching mechanism for macro expanded tokens.
Previously macro expanded tokens were added to Preprocessor's bump allocator and never released,
even after the TokenLexer that were lexing them was finished, thus they were wasting memory.
A very "useful" boost library was causing clang to eat 1 GB just for the expanded macro tokens.
Introduce a special cache that works like a stack; a TokenLexer can add the macro expanded tokens
in the cache, and when it finishes, the tokens are removed from the end of the cache.
Now consumed memory by expanded tokens for that library is ~ 1.5 MB.
Part of rdar://9327049.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@134105 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Lex/PPMacroExpansion.cpp b/lib/Lex/PPMacroExpansion.cpp
index 9e8533a..d7c4def 100644
--- a/lib/Lex/PPMacroExpansion.cpp
+++ b/lib/Lex/PPMacroExpansion.cpp
@@ -22,6 +22,7 @@
#include "clang/Lex/CodeCompletionHandler.h"
#include "clang/Lex/ExternalPreprocessorSource.h"
#include "llvm/ADT/StringSwitch.h"
+#include "llvm/ADT/STLExtras.h"
#include "llvm/Config/config.h"
#include "llvm/Support/raw_ostream.h"
#include <cstdio>
@@ -490,6 +491,46 @@
isVarargsElided, *this);
}
+/// \brief Keeps macro expanded tokens for TokenLexers.
+//
+/// Works like a stack; a TokenLexer adds the macro expanded tokens that is
+/// going to lex in the cache and when it finishes the tokens are removed
+/// from the end of the cache.
+Token *Preprocessor::cacheMacroExpandedTokens(TokenLexer *tokLexer,
+ llvm::ArrayRef<Token> tokens) {
+ assert(tokLexer);
+ if (tokens.empty())
+ return 0;
+
+ size_t newIndex = MacroExpandedTokens.size();
+ bool cacheNeedsToGrow = tokens.size() >
+ MacroExpandedTokens.capacity()-MacroExpandedTokens.size();
+ MacroExpandedTokens.append(tokens.begin(), tokens.end());
+
+ if (cacheNeedsToGrow) {
+ // Go through all the TokenLexers whose 'Tokens' pointer points in the
+ // buffer and update the pointers to the (potential) new buffer array.
+ for (unsigned i = 0, e = MacroExpandingLexersStack.size(); i != e; ++i) {
+ TokenLexer *prevLexer;
+ size_t tokIndex;
+ llvm::tie(prevLexer, tokIndex) = MacroExpandingLexersStack[i];
+ prevLexer->Tokens = MacroExpandedTokens.data() + tokIndex;
+ }
+ }
+
+ MacroExpandingLexersStack.push_back(std::make_pair(tokLexer, newIndex));
+ return MacroExpandedTokens.data() + newIndex;
+}
+
+void Preprocessor::removeCachedMacroExpandedTokensOfLastLexer() {
+ assert(!MacroExpandingLexersStack.empty());
+ size_t tokIndex = MacroExpandingLexersStack.back().second;
+ assert(tokIndex < MacroExpandedTokens.size());
+ // Pop the cached macro expanded tokens from the end.
+ MacroExpandedTokens.resize(tokIndex);
+ MacroExpandingLexersStack.pop_back();
+}
+
/// ComputeDATE_TIME - Compute the current time, enter it into the specified
/// scratch buffer, then return DATELoc/TIMELoc locations with the position of
/// the identifier tokens inserted.