From 222e2a7620e6520ffaf4fc4e69d79c18da31542e Mon Sep 17 00:00:00 2001 From: "Zancanaro; Carlo" Date: Mon, 24 Sep 2012 09:58:17 +1000 Subject: Add the clang library to the repo (with some of my changes, too). --- clang/lib/StaticAnalyzer/Core/CoreEngine.cpp | 688 +++++++++++++++++++++++++++ 1 file changed, 688 insertions(+) create mode 100644 clang/lib/StaticAnalyzer/Core/CoreEngine.cpp (limited to 'clang/lib/StaticAnalyzer/Core/CoreEngine.cpp') diff --git a/clang/lib/StaticAnalyzer/Core/CoreEngine.cpp b/clang/lib/StaticAnalyzer/Core/CoreEngine.cpp new file mode 100644 index 0000000..ca662c7 --- /dev/null +++ b/clang/lib/StaticAnalyzer/Core/CoreEngine.cpp @@ -0,0 +1,688 @@ +//==- CoreEngine.cpp - Path-Sensitive Dataflow Engine ------------*- 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 a generic engine for intraprocedural, path-sensitive, +// dataflow analysis via graph reachability engine. +// +//===----------------------------------------------------------------------===// + +#define DEBUG_TYPE "CoreEngine" + +#include "clang/StaticAnalyzer/Core/PathSensitive/AnalysisManager.h" +#include "clang/StaticAnalyzer/Core/PathSensitive/CoreEngine.h" +#include "clang/StaticAnalyzer/Core/PathSensitive/ExprEngine.h" +#include "clang/AST/Expr.h" +#include "clang/AST/StmtCXX.h" +#include "llvm/Support/Casting.h" +#include "llvm/ADT/DenseMap.h" +#include "llvm/ADT/Statistic.h" + +using namespace clang; +using namespace ento; + +STATISTIC(NumReachedMaxSteps, + "The # of times we reached the max number of steps."); +STATISTIC(NumPathsExplored, + "The # of paths explored by the analyzer."); + +//===----------------------------------------------------------------------===// +// Worklist classes for exploration of reachable states. +//===----------------------------------------------------------------------===// + +WorkList::Visitor::~Visitor() {} + +namespace { +class DFS : public WorkList { + SmallVector Stack; +public: + virtual bool hasWork() const { + return !Stack.empty(); + } + + virtual void enqueue(const WorkListUnit& U) { + Stack.push_back(U); + } + + virtual WorkListUnit dequeue() { + assert (!Stack.empty()); + const WorkListUnit& U = Stack.back(); + Stack.pop_back(); // This technically "invalidates" U, but we are fine. + return U; + } + + virtual bool visitItemsInWorkList(Visitor &V) { + for (SmallVectorImpl::iterator + I = Stack.begin(), E = Stack.end(); I != E; ++I) { + if (V.visit(*I)) + return true; + } + return false; + } +}; + +class BFS : public WorkList { + std::deque Queue; +public: + virtual bool hasWork() const { + return !Queue.empty(); + } + + virtual void enqueue(const WorkListUnit& U) { + Queue.push_front(U); + } + + virtual WorkListUnit dequeue() { + WorkListUnit U = Queue.front(); + Queue.pop_front(); + return U; + } + + virtual bool visitItemsInWorkList(Visitor &V) { + for (std::deque::iterator + I = Queue.begin(), E = Queue.end(); I != E; ++I) { + if (V.visit(*I)) + return true; + } + return false; + } +}; + +} // end anonymous namespace + +// Place the dstor for WorkList here because it contains virtual member +// functions, and we the code for the dstor generated in one compilation unit. +WorkList::~WorkList() {} + +WorkList *WorkList::makeDFS() { return new DFS(); } +WorkList *WorkList::makeBFS() { return new BFS(); } + +namespace { + class BFSBlockDFSContents : public WorkList { + std::deque Queue; + SmallVector Stack; + public: + virtual bool hasWork() const { + return !Queue.empty() || !Stack.empty(); + } + + virtual void enqueue(const WorkListUnit& U) { + if (isa(U.getNode()->getLocation())) + Queue.push_front(U); + else + Stack.push_back(U); + } + + virtual WorkListUnit dequeue() { + // Process all basic blocks to completion. + if (!Stack.empty()) { + const WorkListUnit& U = Stack.back(); + Stack.pop_back(); // This technically "invalidates" U, but we are fine. + return U; + } + + assert(!Queue.empty()); + // Don't use const reference. The subsequent pop_back() might make it + // unsafe. + WorkListUnit U = Queue.front(); + Queue.pop_front(); + return U; + } + virtual bool visitItemsInWorkList(Visitor &V) { + for (SmallVectorImpl::iterator + I = Stack.begin(), E = Stack.end(); I != E; ++I) { + if (V.visit(*I)) + return true; + } + for (std::deque::iterator + I = Queue.begin(), E = Queue.end(); I != E; ++I) { + if (V.visit(*I)) + return true; + } + return false; + } + + }; +} // end anonymous namespace + +WorkList* WorkList::makeBFSBlockDFSContents() { + return new BFSBlockDFSContents(); +} + +//===----------------------------------------------------------------------===// +// Core analysis engine. +//===----------------------------------------------------------------------===// + +/// ExecuteWorkList - Run the worklist algorithm for a maximum number of steps. +bool CoreEngine::ExecuteWorkList(const LocationContext *L, unsigned Steps, + ProgramStateRef InitState) { + + if (G->num_roots() == 0) { // Initialize the analysis by constructing + // the root if none exists. + + const CFGBlock *Entry = &(L->getCFG()->getEntry()); + + assert (Entry->empty() && + "Entry block must be empty."); + + assert (Entry->succ_size() == 1 && + "Entry block must have 1 successor."); + + // Mark the entry block as visited. + FunctionSummaries->markVisitedBasicBlock(Entry->getBlockID(), + L->getDecl(), + L->getCFG()->getNumBlockIDs()); + + // Get the solitary successor. + const CFGBlock *Succ = *(Entry->succ_begin()); + + // Construct an edge representing the + // starting location in the function. + BlockEdge StartLoc(Entry, Succ, L); + + // Set the current block counter to being empty. + WList->setBlockCounter(BCounterFactory.GetEmptyCounter()); + + if (!InitState) + // Generate the root. + generateNode(StartLoc, SubEng.getInitialState(L), 0); + else + generateNode(StartLoc, InitState, 0); + } + + // Check if we have a steps limit + bool UnlimitedSteps = Steps == 0; + + while (WList->hasWork()) { + if (!UnlimitedSteps) { + if (Steps == 0) { + NumReachedMaxSteps++; + break; + } + --Steps; + } + + const WorkListUnit& WU = WList->dequeue(); + + // Set the current block counter. + WList->setBlockCounter(WU.getBlockCounter()); + + // Retrieve the node. + ExplodedNode *Node = WU.getNode(); + + dispatchWorkItem(Node, Node->getLocation(), WU); + } + SubEng.processEndWorklist(hasWorkRemaining()); + return WList->hasWork(); +} + +void CoreEngine::dispatchWorkItem(ExplodedNode* Pred, ProgramPoint Loc, + const WorkListUnit& WU) { + // Dispatch on the location type. + switch (Loc.getKind()) { + case ProgramPoint::BlockEdgeKind: + HandleBlockEdge(cast(Loc), Pred); + break; + + case ProgramPoint::BlockEntranceKind: + HandleBlockEntrance(cast(Loc), Pred); + break; + + case ProgramPoint::BlockExitKind: + assert (false && "BlockExit location never occur in forward analysis."); + break; + + case ProgramPoint::CallEnterKind: { + CallEnter CEnter = cast(Loc); + if (AnalyzedCallees) + if (const CallExpr* CE = + dyn_cast_or_null(CEnter.getCallExpr())) + if (const Decl *CD = CE->getCalleeDecl()) + AnalyzedCallees->insert(CD); + SubEng.processCallEnter(CEnter, Pred); + break; + } + + case ProgramPoint::CallExitKind: + SubEng.processCallExit(Pred); + break; + + case ProgramPoint::EpsilonKind: { + assert(Pred->hasSinglePred() && + "Assume epsilon has exactly one predecessor by construction"); + ExplodedNode *PNode = Pred->getFirstPred(); + dispatchWorkItem(Pred, PNode->getLocation(), WU); + break; + } + default: + assert(isa(Loc) || + isa(Loc)); + HandlePostStmt(WU.getBlock(), WU.getIndex(), Pred); + break; + } +} + +bool CoreEngine::ExecuteWorkListWithInitialState(const LocationContext *L, + unsigned Steps, + ProgramStateRef InitState, + ExplodedNodeSet &Dst) { + bool DidNotFinish = ExecuteWorkList(L, Steps, InitState); + for (ExplodedGraph::eop_iterator I = G->eop_begin(), + E = G->eop_end(); I != E; ++I) { + Dst.Add(*I); + } + return DidNotFinish; +} + +void CoreEngine::HandleBlockEdge(const BlockEdge &L, ExplodedNode *Pred) { + + const CFGBlock *Blk = L.getDst(); + NodeBuilderContext BuilderCtx(*this, Blk, Pred); + + // Mark this block as visited. + const LocationContext *LC = Pred->getLocationContext(); + FunctionSummaries->markVisitedBasicBlock(Blk->getBlockID(), + LC->getDecl(), + LC->getCFG()->getNumBlockIDs()); + + // Check if we are entering the EXIT block. + if (Blk == &(L.getLocationContext()->getCFG()->getExit())) { + + assert (L.getLocationContext()->getCFG()->getExit().size() == 0 + && "EXIT block cannot contain Stmts."); + + // Process the final state transition. + SubEng.processEndOfFunction(BuilderCtx); + + // This path is done. Don't enqueue any more nodes. + return; + } + + // Call into the SubEngine to process entering the CFGBlock. + ExplodedNodeSet dstNodes; + BlockEntrance BE(Blk, Pred->getLocationContext()); + NodeBuilderWithSinks nodeBuilder(Pred, dstNodes, BuilderCtx, BE); + SubEng.processCFGBlockEntrance(L, nodeBuilder); + + // Auto-generate a node. + if (!nodeBuilder.hasGeneratedNodes()) { + nodeBuilder.generateNode(Pred->State, Pred); + } + + // Enqueue nodes onto the worklist. + enqueue(dstNodes); +} + +void CoreEngine::HandleBlockEntrance(const BlockEntrance &L, + ExplodedNode *Pred) { + + // Increment the block counter. + const LocationContext *LC = Pred->getLocationContext(); + unsigned BlockId = L.getBlock()->getBlockID(); + BlockCounter Counter = WList->getBlockCounter(); + Counter = BCounterFactory.IncrementCount(Counter, LC->getCurrentStackFrame(), + BlockId); + WList->setBlockCounter(Counter); + + // Process the entrance of the block. + if (CFGElement E = L.getFirstElement()) { + NodeBuilderContext Ctx(*this, L.getBlock(), Pred); + SubEng.processCFGElement(E, Pred, 0, &Ctx); + } + else + HandleBlockExit(L.getBlock(), Pred); +} + +void CoreEngine::HandleBlockExit(const CFGBlock * B, ExplodedNode *Pred) { + + if (const Stmt *Term = B->getTerminator()) { + switch (Term->getStmtClass()) { + default: + llvm_unreachable("Analysis for this terminator not implemented."); + + case Stmt::BinaryOperatorClass: // '&&' and '||' + HandleBranch(cast(Term)->getLHS(), Term, B, Pred); + return; + + case Stmt::BinaryConditionalOperatorClass: + case Stmt::ConditionalOperatorClass: + HandleBranch(cast(Term)->getCond(), + Term, B, Pred); + return; + + // FIXME: Use constant-folding in CFG construction to simplify this + // case. + + case Stmt::ChooseExprClass: + HandleBranch(cast(Term)->getCond(), Term, B, Pred); + return; + + case Stmt::CXXTryStmtClass: { + // Generate a node for each of the successors. + // Our logic for EH analysis can certainly be improved. + for (CFGBlock::const_succ_iterator it = B->succ_begin(), + et = B->succ_end(); it != et; ++it) { + if (const CFGBlock *succ = *it) { + generateNode(BlockEdge(B, succ, Pred->getLocationContext()), + Pred->State, Pred); + } + } + return; + } + + case Stmt::DoStmtClass: + HandleBranch(cast(Term)->getCond(), Term, B, Pred); + return; + + case Stmt::CXXForRangeStmtClass: + HandleBranch(cast(Term)->getCond(), Term, B, Pred); + return; + + case Stmt::ForStmtClass: + HandleBranch(cast(Term)->getCond(), Term, B, Pred); + return; + + case Stmt::ContinueStmtClass: + case Stmt::BreakStmtClass: + case Stmt::GotoStmtClass: + break; + + case Stmt::IfStmtClass: + HandleBranch(cast(Term)->getCond(), Term, B, Pred); + return; + + case Stmt::IndirectGotoStmtClass: { + // Only 1 successor: the indirect goto dispatch block. + assert (B->succ_size() == 1); + + IndirectGotoNodeBuilder + builder(Pred, B, cast(Term)->getTarget(), + *(B->succ_begin()), this); + + SubEng.processIndirectGoto(builder); + return; + } + + case Stmt::ObjCForCollectionStmtClass: { + // In the case of ObjCForCollectionStmt, it appears twice in a CFG: + // + // (1) inside a basic block, which represents the binding of the + // 'element' variable to a value. + // (2) in a terminator, which represents the branch. + // + // For (1), subengines will bind a value (i.e., 0 or 1) indicating + // whether or not collection contains any more elements. We cannot + // just test to see if the element is nil because a container can + // contain nil elements. + HandleBranch(Term, Term, B, Pred); + return; + } + + case Stmt::SwitchStmtClass: { + SwitchNodeBuilder builder(Pred, B, cast(Term)->getCond(), + this); + + SubEng.processSwitch(builder); + return; + } + + case Stmt::WhileStmtClass: + HandleBranch(cast(Term)->getCond(), Term, B, Pred); + return; + } + } + + assert (B->succ_size() == 1 && + "Blocks with no terminator should have at most 1 successor."); + + generateNode(BlockEdge(B, *(B->succ_begin()), Pred->getLocationContext()), + Pred->State, Pred); +} + +void CoreEngine::HandleBranch(const Stmt *Cond, const Stmt *Term, + const CFGBlock * B, ExplodedNode *Pred) { + assert(B->succ_size() == 2); + NodeBuilderContext Ctx(*this, B, Pred); + ExplodedNodeSet Dst; + SubEng.processBranch(Cond, Term, Ctx, Pred, Dst, + *(B->succ_begin()), *(B->succ_begin()+1)); + // Enqueue the new frontier onto the worklist. + enqueue(Dst); +} + +void CoreEngine::HandlePostStmt(const CFGBlock *B, unsigned StmtIdx, + ExplodedNode *Pred) { + assert(B); + assert(!B->empty()); + + if (StmtIdx == B->size()) + HandleBlockExit(B, Pred); + else { + NodeBuilderContext Ctx(*this, B, Pred); + SubEng.processCFGElement((*B)[StmtIdx], Pred, StmtIdx, &Ctx); + } +} + +/// generateNode - Utility method to generate nodes, hook up successors, +/// and add nodes to the worklist. +void CoreEngine::generateNode(const ProgramPoint &Loc, + ProgramStateRef State, + ExplodedNode *Pred) { + + bool IsNew; + ExplodedNode *Node = G->getNode(Loc, State, false, &IsNew); + + if (Pred) + Node->addPredecessor(Pred, *G); // Link 'Node' with its predecessor. + else { + assert (IsNew); + G->addRoot(Node); // 'Node' has no predecessor. Make it a root. + } + + // Only add 'Node' to the worklist if it was freshly generated. + if (IsNew) WList->enqueue(Node); +} + +void CoreEngine::enqueueStmtNode(ExplodedNode *N, + const CFGBlock *Block, unsigned Idx) { + assert(Block); + assert (!N->isSink()); + + // Check if this node entered a callee. + if (isa(N->getLocation())) { + // Still use the index of the CallExpr. It's needed to create the callee + // StackFrameContext. + WList->enqueue(N, Block, Idx); + return; + } + + // Do not create extra nodes. Move to the next CFG element. + if (isa(N->getLocation())) { + WList->enqueue(N, Block, Idx+1); + return; + } + + if (isa(N->getLocation())) { + WList->enqueue(N, Block, Idx); + return; + } + + const CFGStmt *CS = (*Block)[Idx].getAs(); + const Stmt *St = CS ? CS->getStmt() : 0; + PostStmt Loc(St, N->getLocationContext()); + + if (Loc == N->getLocation()) { + // Note: 'N' should be a fresh node because otherwise it shouldn't be + // a member of Deferred. + WList->enqueue(N, Block, Idx+1); + return; + } + + bool IsNew; + ExplodedNode *Succ = G->getNode(Loc, N->getState(), false, &IsNew); + Succ->addPredecessor(N, *G); + + if (IsNew) + WList->enqueue(Succ, Block, Idx+1); +} + +ExplodedNode *CoreEngine::generateCallExitNode(ExplodedNode *N) { + // Create a CallExit node and enqueue it. + const StackFrameContext *LocCtx + = cast(N->getLocationContext()); + const Stmt *CE = LocCtx->getCallSite(); + + // Use the the callee location context. + CallExit Loc(CE, LocCtx); + + bool isNew; + ExplodedNode *Node = G->getNode(Loc, N->getState(), false, &isNew); + Node->addPredecessor(N, *G); + return isNew ? Node : 0; +} + + +void CoreEngine::enqueue(ExplodedNodeSet &Set) { + for (ExplodedNodeSet::iterator I = Set.begin(), + E = Set.end(); I != E; ++I) { + WList->enqueue(*I); + } +} + +void CoreEngine::enqueue(ExplodedNodeSet &Set, + const CFGBlock *Block, unsigned Idx) { + for (ExplodedNodeSet::iterator I = Set.begin(), + E = Set.end(); I != E; ++I) { + enqueueStmtNode(*I, Block, Idx); + } +} + +void CoreEngine::enqueueEndOfFunction(ExplodedNodeSet &Set) { + for (ExplodedNodeSet::iterator I = Set.begin(), E = Set.end(); I != E; ++I) { + ExplodedNode *N = *I; + // If we are in an inlined call, generate CallExit node. + if (N->getLocationContext()->getParent()) { + N = generateCallExitNode(N); + if (N) + WList->enqueue(N); + } else { + G->addEndOfPath(N); + NumPathsExplored++; + } + } +} + + +void NodeBuilder::anchor() { } + +ExplodedNode* NodeBuilder::generateNodeImpl(const ProgramPoint &Loc, + ProgramStateRef State, + ExplodedNode *FromN, + bool MarkAsSink) { + HasGeneratedNodes = true; + bool IsNew; + ExplodedNode *N = C.Eng.G->getNode(Loc, State, MarkAsSink, &IsNew); + N->addPredecessor(FromN, *C.Eng.G); + Frontier.erase(FromN); + + if (!IsNew) + return 0; + + if (!MarkAsSink) + Frontier.Add(N); + + return N; +} + +void NodeBuilderWithSinks::anchor() { } + +StmtNodeBuilder::~StmtNodeBuilder() { + if (EnclosingBldr) + for (ExplodedNodeSet::iterator I = Frontier.begin(), + E = Frontier.end(); I != E; ++I ) + EnclosingBldr->addNodes(*I); +} + +void BranchNodeBuilder::anchor() { } + +ExplodedNode *BranchNodeBuilder::generateNode(ProgramStateRef State, + bool branch, + ExplodedNode *NodePred) { + // If the branch has been marked infeasible we should not generate a node. + if (!isFeasible(branch)) + return NULL; + + ProgramPoint Loc = BlockEdge(C.Block, branch ? DstT:DstF, + NodePred->getLocationContext()); + ExplodedNode *Succ = generateNodeImpl(Loc, State, NodePred); + return Succ; +} + +ExplodedNode* +IndirectGotoNodeBuilder::generateNode(const iterator &I, + ProgramStateRef St, + bool IsSink) { + bool IsNew; + ExplodedNode *Succ = Eng.G->getNode(BlockEdge(Src, I.getBlock(), + Pred->getLocationContext()), St, + IsSink, &IsNew); + Succ->addPredecessor(Pred, *Eng.G); + + if (!IsNew) + return 0; + + if (!IsSink) + Eng.WList->enqueue(Succ); + + return Succ; +} + + +ExplodedNode* +SwitchNodeBuilder::generateCaseStmtNode(const iterator &I, + ProgramStateRef St) { + + bool IsNew; + ExplodedNode *Succ = Eng.G->getNode(BlockEdge(Src, I.getBlock(), + Pred->getLocationContext()), St, + false, &IsNew); + Succ->addPredecessor(Pred, *Eng.G); + if (!IsNew) + return 0; + + Eng.WList->enqueue(Succ); + return Succ; +} + + +ExplodedNode* +SwitchNodeBuilder::generateDefaultCaseNode(ProgramStateRef St, + bool IsSink) { + // Get the block for the default case. + assert(Src->succ_rbegin() != Src->succ_rend()); + CFGBlock *DefaultBlock = *Src->succ_rbegin(); + + // Sanity check for default blocks that are unreachable and not caught + // by earlier stages. + if (!DefaultBlock) + return NULL; + + bool IsNew; + ExplodedNode *Succ = Eng.G->getNode(BlockEdge(Src, DefaultBlock, + Pred->getLocationContext()), St, + IsSink, &IsNew); + Succ->addPredecessor(Pred, *Eng.G); + + if (!IsNew) + return 0; + + if (!IsSink) + Eng.WList->enqueue(Succ); + + return Succ; +} -- cgit v1.2.3