diff options
Diffstat (limited to 'clang/include/clang/Analysis/FlowSensitive/DataflowSolver.h')
| -rw-r--r-- | clang/include/clang/Analysis/FlowSensitive/DataflowSolver.h | 343 |
1 files changed, 343 insertions, 0 deletions
diff --git a/clang/include/clang/Analysis/FlowSensitive/DataflowSolver.h b/clang/include/clang/Analysis/FlowSensitive/DataflowSolver.h new file mode 100644 index 0000000..017da63 --- /dev/null +++ b/clang/include/clang/Analysis/FlowSensitive/DataflowSolver.h @@ -0,0 +1,343 @@ +//===--- DataflowSolver.h - Skeleton Dataflow Analysis Code -----*- C++ -*-===// +// +// The LLVM Compiler Infrastructure +// +// This file is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// +// +// This file defines skeleton code for implementing dataflow analyses. +// +//===----------------------------------------------------------------------===// + +#ifndef LLVM_CLANG_ANALYSES_DATAFLOW_SOLVER +#define LLVM_CLANG_ANALYSES_DATAFLOW_SOLVER + +#include "clang/Analysis/CFG.h" +#include "clang/Analysis/ProgramPoint.h" +#include "clang/Analysis/FlowSensitive/DataflowValues.h" +#include "llvm/ADT/DenseMap.h" +#include "llvm/ADT/SmallVector.h" +#include "functional" // STL + +namespace clang { + +//===----------------------------------------------------------------------===// +/// DataflowWorkListTy - Data structure representing the worklist used for +/// dataflow algorithms. +//===----------------------------------------------------------------------===// + +class DataflowWorkListTy { + llvm::DenseMap<const CFGBlock*, unsigned char> BlockSet; + SmallVector<const CFGBlock *, 10> BlockQueue; +public: + /// enqueue - Add a block to the worklist. Blocks already on the + /// worklist are not added a second time. + void enqueue(const CFGBlock *B) { + unsigned char &x = BlockSet[B]; + if (x == 1) + return; + x = 1; + BlockQueue.push_back(B); + } + + /// dequeue - Remove a block from the worklist. + const CFGBlock *dequeue() { + assert(!BlockQueue.empty()); + const CFGBlock *B = BlockQueue.back(); + BlockQueue.pop_back(); + BlockSet[B] = 0; + return B; + } + + /// isEmpty - Return true if the worklist is empty. + bool isEmpty() const { return BlockQueue.empty(); } +}; + +//===----------------------------------------------------------------------===// +// BlockItrTraits - Traits classes that allow transparent iteration +// over successors/predecessors of a block depending on the direction +// of our dataflow analysis. +//===----------------------------------------------------------------------===// + +namespace dataflow { +template<typename Tag> struct ItrTraits {}; + +template <> struct ItrTraits<forward_analysis_tag> { + typedef CFGBlock::const_pred_iterator PrevBItr; + typedef CFGBlock::const_succ_iterator NextBItr; + typedef CFGBlock::const_iterator StmtItr; + + static PrevBItr PrevBegin(const CFGBlock *B) { return B->pred_begin(); } + static PrevBItr PrevEnd(const CFGBlock *B) { return B->pred_end(); } + + static NextBItr NextBegin(const CFGBlock *B) { return B->succ_begin(); } + static NextBItr NextEnd(const CFGBlock *B) { return B->succ_end(); } + + static StmtItr StmtBegin(const CFGBlock *B) { return B->begin(); } + static StmtItr StmtEnd(const CFGBlock *B) { return B->end(); } + + static BlockEdge PrevEdge(const CFGBlock *B, const CFGBlock *Prev) { + return BlockEdge(Prev, B, 0); + } + + static BlockEdge NextEdge(const CFGBlock *B, const CFGBlock *Next) { + return BlockEdge(B, Next, 0); + } +}; + +template <> struct ItrTraits<backward_analysis_tag> { + typedef CFGBlock::const_succ_iterator PrevBItr; + typedef CFGBlock::const_pred_iterator NextBItr; + typedef CFGBlock::const_reverse_iterator StmtItr; + + static PrevBItr PrevBegin(const CFGBlock *B) { return B->succ_begin(); } + static PrevBItr PrevEnd(const CFGBlock *B) { return B->succ_end(); } + + static NextBItr NextBegin(const CFGBlock *B) { return B->pred_begin(); } + static NextBItr NextEnd(const CFGBlock *B) { return B->pred_end(); } + + static StmtItr StmtBegin(const CFGBlock *B) { return B->rbegin(); } + static StmtItr StmtEnd(const CFGBlock *B) { return B->rend(); } + + static BlockEdge PrevEdge(const CFGBlock *B, const CFGBlock *Prev) { + return BlockEdge(B, Prev, 0); + } + + static BlockEdge NextEdge(const CFGBlock *B, const CFGBlock *Next) { + return BlockEdge(Next, B, 0); + } +}; +} // end namespace dataflow + +//===----------------------------------------------------------------------===// +/// DataflowSolverTy - Generic dataflow solver. +//===----------------------------------------------------------------------===// + +template <typename _DFValuesTy, // Usually a subclass of DataflowValues + typename _TransferFuncsTy, + typename _MergeOperatorTy, + typename _Equal = std::equal_to<typename _DFValuesTy::ValTy> > +class DataflowSolver { + + //===----------------------------------------------------===// + // Type declarations. + //===----------------------------------------------------===// + +public: + typedef _DFValuesTy DFValuesTy; + typedef _TransferFuncsTy TransferFuncsTy; + typedef _MergeOperatorTy MergeOperatorTy; + + typedef typename _DFValuesTy::AnalysisDirTag AnalysisDirTag; + typedef typename _DFValuesTy::ValTy ValTy; + typedef typename _DFValuesTy::EdgeDataMapTy EdgeDataMapTy; + typedef typename _DFValuesTy::BlockDataMapTy BlockDataMapTy; + + typedef dataflow::ItrTraits<AnalysisDirTag> ItrTraits; + typedef typename ItrTraits::NextBItr NextBItr; + typedef typename ItrTraits::PrevBItr PrevBItr; + typedef typename ItrTraits::StmtItr StmtItr; + + //===----------------------------------------------------===// + // External interface: constructing and running the solver. + //===----------------------------------------------------===// + +public: + DataflowSolver(DFValuesTy& d) : D(d), TF(d.getAnalysisData()) {} + ~DataflowSolver() {} + + /// runOnCFG - Computes dataflow values for all blocks in a CFG. + void runOnCFG(CFG& cfg, bool recordStmtValues = false) { + // Set initial dataflow values and boundary conditions. + D.InitializeValues(cfg); + // Solve the dataflow equations. This will populate D.EdgeDataMap + // with dataflow values. + SolveDataflowEquations(cfg, recordStmtValues); + } + + /// runOnBlock - Computes dataflow values for a given block. This + /// should usually be invoked only after previously computing + /// dataflow values using runOnCFG, as runOnBlock is intended to + /// only be used for querying the dataflow values within a block + /// with and Observer object. + void runOnBlock(const CFGBlock *B, bool recordStmtValues) { + BlockDataMapTy& M = D.getBlockDataMap(); + typename BlockDataMapTy::iterator I = M.find(B); + + if (I != M.end()) { + TF.getVal().copyValues(I->second); + ProcessBlock(B, recordStmtValues, AnalysisDirTag()); + } + } + + void runOnBlock(const CFGBlock &B, bool recordStmtValues) { + runOnBlock(&B, recordStmtValues); + } + void runOnBlock(CFG::iterator &I, bool recordStmtValues) { + runOnBlock(*I, recordStmtValues); + } + void runOnBlock(CFG::const_iterator &I, bool recordStmtValues) { + runOnBlock(*I, recordStmtValues); + } + + void runOnAllBlocks(const CFG& cfg, bool recordStmtValues = false) { + for (CFG::const_iterator I=cfg.begin(), E=cfg.end(); I!=E; ++I) + runOnBlock(I, recordStmtValues); + } + + //===----------------------------------------------------===// + // Internal solver logic. + //===----------------------------------------------------===// + +private: + + /// SolveDataflowEquations - Perform the actual worklist algorithm + /// to compute dataflow values. + void SolveDataflowEquations(CFG& cfg, bool recordStmtValues) { + EnqueueBlocksOnWorklist(cfg, AnalysisDirTag()); + + while (!WorkList.isEmpty()) { + const CFGBlock *B = WorkList.dequeue(); + ProcessMerge(cfg, B); + ProcessBlock(B, recordStmtValues, AnalysisDirTag()); + UpdateEdges(cfg, B, TF.getVal()); + } + } + + void EnqueueBlocksOnWorklist(CFG &cfg, dataflow::forward_analysis_tag) { + // Enqueue all blocks to ensure the dataflow values are computed + // for every block. Not all blocks are guaranteed to reach the exit block. + for (CFG::iterator I=cfg.begin(), E=cfg.end(); I!=E; ++I) + WorkList.enqueue(&**I); + } + + void EnqueueBlocksOnWorklist(CFG &cfg, dataflow::backward_analysis_tag) { + // Enqueue all blocks to ensure the dataflow values are computed + // for every block. Not all blocks are guaranteed to reach the exit block. + // Enqueue in reverse order since that will more likely match with + // the order they should ideally processed by the dataflow algorithm. + for (CFG::reverse_iterator I=cfg.rbegin(), E=cfg.rend(); I!=E; ++I) + WorkList.enqueue(&**I); + } + + void ProcessMerge(CFG& cfg, const CFGBlock *B) { + ValTy& V = TF.getVal(); + TF.SetTopValue(V); + + // Merge dataflow values from all predecessors of this block. + MergeOperatorTy Merge; + + EdgeDataMapTy& M = D.getEdgeDataMap(); + bool firstMerge = true; + bool noEdges = true; + for (PrevBItr I=ItrTraits::PrevBegin(B),E=ItrTraits::PrevEnd(B); I!=E; ++I){ + + CFGBlock *PrevBlk = *I; + + if (!PrevBlk) + continue; + + typename EdgeDataMapTy::iterator EI = + M.find(ItrTraits::PrevEdge(B, PrevBlk)); + + if (EI != M.end()) { + noEdges = false; + if (firstMerge) { + firstMerge = false; + V.copyValues(EI->second); + } + else + Merge(V, EI->second); + } + } + + bool isInitialized = true; + typename BlockDataMapTy::iterator BI = D.getBlockDataMap().find(B); + if(BI == D.getBlockDataMap().end()) { + isInitialized = false; + BI = D.getBlockDataMap().insert( std::make_pair(B,ValTy()) ).first; + } + // If no edges have been found, it means this is the first time the solver + // has been called on block B, we copy the initialization values (if any) + // as current value for V (which will be used as edge data) + if(noEdges && isInitialized) + Merge(V, BI->second); + + // Set the data for the block. + BI->second.copyValues(V); + } + + /// ProcessBlock - Process the transfer functions for a given block. + void ProcessBlock(const CFGBlock *B, bool recordStmtValues, + dataflow::forward_analysis_tag) { + + TF.setCurrentBlock(B); + + for (StmtItr I=ItrTraits::StmtBegin(B), E=ItrTraits::StmtEnd(B); I!=E;++I) { + CFGElement El = *I; + if (const CFGStmt *S = El.getAs<CFGStmt>()) + ProcessStmt(S->getStmt(), recordStmtValues, AnalysisDirTag()); + } + + TF.VisitTerminator(const_cast<CFGBlock*>(B)); + } + + void ProcessBlock(const CFGBlock *B, bool recordStmtValues, + dataflow::backward_analysis_tag) { + + TF.setCurrentBlock(B); + + TF.VisitTerminator(const_cast<CFGBlock*>(B)); + + for (StmtItr I=ItrTraits::StmtBegin(B), E=ItrTraits::StmtEnd(B); I!=E;++I) { + CFGElement El = *I; + if (const CFGStmt *S = El.getAs<CFGStmt>()) + ProcessStmt(S->getStmt(), recordStmtValues, AnalysisDirTag()); + } + } + + void ProcessStmt(const Stmt *S, bool record, dataflow::forward_analysis_tag) { + if (record) D.getStmtDataMap()[S] = TF.getVal(); + TF.BlockStmt_Visit(const_cast<Stmt*>(S)); + } + + void ProcessStmt(const Stmt *S, bool record, dataflow::backward_analysis_tag){ + TF.BlockStmt_Visit(const_cast<Stmt*>(S)); + if (record) D.getStmtDataMap()[S] = TF.getVal(); + } + + /// UpdateEdges - After processing the transfer functions for a + /// block, update the dataflow value associated with the block's + /// outgoing/incoming edges (depending on whether we do a + // forward/backward analysis respectively) + void UpdateEdges(CFG& cfg, const CFGBlock *B, ValTy& V) { + for (NextBItr I=ItrTraits::NextBegin(B), E=ItrTraits::NextEnd(B); I!=E; ++I) + if (CFGBlock *NextBlk = *I) + UpdateEdgeValue(ItrTraits::NextEdge(B, NextBlk),V, NextBlk); + } + + /// UpdateEdgeValue - Update the value associated with a given edge. + void UpdateEdgeValue(BlockEdge E, ValTy& V, const CFGBlock *TargetBlock) { + EdgeDataMapTy& M = D.getEdgeDataMap(); + typename EdgeDataMapTy::iterator I = M.find(E); + + if (I == M.end()) { // First computed value for this edge? + M[E].copyValues(V); + WorkList.enqueue(TargetBlock); + } + else if (!_Equal()(V,I->second)) { + I->second.copyValues(V); + WorkList.enqueue(TargetBlock); + } + } + +private: + DFValuesTy& D; + DataflowWorkListTy WorkList; + TransferFuncsTy TF; +}; + +} // end namespace clang +#endif |