Author: bcraig Date: Fri Jun 10 08:22:13 2016 New Revision: 272394 URL: http://llvm.org/viewvc/llvm-project?rev=272394&view=rev Log: Preallocate ExplodedNode hash table
Rehashing the ExplodedNode table is very expensive. The hashing itself is expensive, and the general activity of iterating over the hash table is highly cache unfriendly. Instead, we guess at the eventual size by using the maximum number of steps allowed. This generally avoids a rehash. It is possible that we still need to rehash if the backlog of work that is added to the worklist significantly exceeds the number of work items that we process. Even if we do need to rehash in that scenario, this change is still a win, as we still have fewer rehashes that we would have prior to this change. For small work loads, this will increase the memory used. For large work loads, it will somewhat reduce the memory used. Speed is significantly increased. A large .C file took 3m53.812s to analyze prior to this change. Now it takes 3m38.976s, for a ~6% improvement. http://reviews.llvm.org/D20933 Modified: cfe/trunk/include/clang/StaticAnalyzer/Core/PathSensitive/ExplodedGraph.h cfe/trunk/lib/StaticAnalyzer/Core/CoreEngine.cpp Modified: cfe/trunk/include/clang/StaticAnalyzer/Core/PathSensitive/ExplodedGraph.h URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/StaticAnalyzer/Core/PathSensitive/ExplodedGraph.h?rev=272394&r1=272393&r2=272394&view=diff ============================================================================== --- cfe/trunk/include/clang/StaticAnalyzer/Core/PathSensitive/ExplodedGraph.h (original) +++ cfe/trunk/include/clang/StaticAnalyzer/Core/PathSensitive/ExplodedGraph.h Fri Jun 10 08:22:13 2016 @@ -321,6 +321,8 @@ public: bool empty() const { return NumNodes == 0; } unsigned size() const { return NumNodes; } + void reserve(unsigned NodeCount) { Nodes.reserve(NodeCount); } + // Iterators. typedef ExplodedNode NodeTy; typedef llvm::FoldingSet<ExplodedNode> AllNodesTy; Modified: cfe/trunk/lib/StaticAnalyzer/Core/CoreEngine.cpp URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/StaticAnalyzer/Core/CoreEngine.cpp?rev=272394&r1=272393&r2=272394&view=diff ============================================================================== --- cfe/trunk/lib/StaticAnalyzer/Core/CoreEngine.cpp (original) +++ cfe/trunk/lib/StaticAnalyzer/Core/CoreEngine.cpp Fri Jun 10 08:22:13 2016 @@ -208,6 +208,11 @@ bool CoreEngine::ExecuteWorkList(const L // Check if we have a steps limit bool UnlimitedSteps = Steps == 0; + // Cap our pre-reservation in the event that the user specifies + // a very large number of maximum steps. + const unsigned PreReservationCap = 4000000; + if(!UnlimitedSteps) + G.reserve(std::min(Steps,PreReservationCap)); while (WList->hasWork()) { if (!UnlimitedSteps) { _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
