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//==- GRCoreEngine.h - 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.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_CLANG_ANALYSIS_GRENGINE
#define LLVM_CLANG_ANALYSIS_GRENGINE
#include "clang/AST/Expr.h"
#include "clang/Checker/PathSensitive/ExplodedGraph.h"
#include "clang/Checker/PathSensitive/GRWorkList.h"
#include "clang/Checker/PathSensitive/GRBlockCounter.h"
#include "clang/Checker/PathSensitive/GRAuditor.h"
#include "clang/Checker/PathSensitive/GRSubEngine.h"
#include "llvm/ADT/OwningPtr.h"
namespace clang {
//===----------------------------------------------------------------------===//
/// GRCoreEngine - Implements the core logic of the graph-reachability
/// analysis. It traverses the CFG and generates the ExplodedGraph.
/// Program "states" are treated as opaque void pointers.
/// The template class GRCoreEngine (which subclasses GRCoreEngine)
/// provides the matching component to the engine that knows the actual types
/// for states. Note that this engine only dispatches to transfer functions
/// at the statement and block-level. The analyses themselves must implement
/// any transfer function logic and the sub-expression level (if any).
class GRCoreEngine {
friend class GRStmtNodeBuilder;
friend class GRBranchNodeBuilder;
friend class GRIndirectGotoNodeBuilder;
friend class GRSwitchNodeBuilder;
friend class GREndPathNodeBuilder;
friend class GRCallEnterNodeBuilder;
friend class GRCallExitNodeBuilder;
GRSubEngine& SubEngine;
/// G - The simulation graph. Each node is a (location,state) pair.
llvm::OwningPtr<ExplodedGraph> G;
/// WList - A set of queued nodes that need to be processed by the
/// worklist algorithm. It is up to the implementation of WList to decide
/// the order that nodes are processed.
GRWorkList* WList;
/// BCounterFactory - A factory object for created GRBlockCounter objects.
/// These are used to record for key nodes in the ExplodedGraph the
/// number of times different CFGBlocks have been visited along a path.
GRBlockCounter::Factory BCounterFactory;
void GenerateNode(const ProgramPoint& Loc, const GRState* State,
ExplodedNode* Pred);
void HandleBlockEdge(const BlockEdge& E, ExplodedNode* Pred);
void HandleBlockEntrance(const BlockEntrance& E, ExplodedNode* Pred);
void HandleBlockExit(CFGBlock* B, ExplodedNode* Pred);
void HandlePostStmt(const PostStmt& S, CFGBlock* B,
unsigned StmtIdx, ExplodedNode *Pred);
void HandleBranch(Stmt* Cond, Stmt* Term, CFGBlock* B,
ExplodedNode* Pred);
void HandleCallEnter(const CallEnter &L, const CFGBlock *Block,
unsigned Index, ExplodedNode *Pred);
void HandleCallExit(const CallExit &L, ExplodedNode *Pred);
/// Get the initial state from the subengine.
const GRState* getInitialState(const LocationContext *InitLoc) {
return SubEngine.getInitialState(InitLoc);
}
void ProcessEndPath(GREndPathNodeBuilder& Builder);
void ProcessStmt(CFGElement E, GRStmtNodeBuilder& Builder);
bool ProcessBlockEntrance(CFGBlock* Blk, const ExplodedNode *Pred,
GRBlockCounter BC);
void ProcessBranch(Stmt* Condition, Stmt* Terminator,
GRBranchNodeBuilder& Builder);
void ProcessIndirectGoto(GRIndirectGotoNodeBuilder& Builder);
void ProcessSwitch(GRSwitchNodeBuilder& Builder);
void ProcessCallEnter(GRCallEnterNodeBuilder &Builder);
void ProcessCallExit(GRCallExitNodeBuilder &Builder);
private:
GRCoreEngine(const GRCoreEngine&); // Do not implement.
GRCoreEngine& operator=(const GRCoreEngine&);
public:
/// Construct a GRCoreEngine object to analyze the provided CFG using
/// a DFS exploration of the exploded graph.
GRCoreEngine(ASTContext& ctx, GRSubEngine& subengine)
: SubEngine(subengine), G(new ExplodedGraph(ctx)),
WList(GRWorkList::MakeBFS()),
BCounterFactory(G->getAllocator()) {}
/// Construct a GRCoreEngine object to analyze the provided CFG and to
/// use the provided worklist object to execute the worklist algorithm.
/// The GRCoreEngine object assumes ownership of 'wlist'.
GRCoreEngine(ASTContext& ctx, GRWorkList* wlist, GRSubEngine& subengine)
: SubEngine(subengine), G(new ExplodedGraph(ctx)), WList(wlist),
BCounterFactory(G->getAllocator()) {}
~GRCoreEngine() {
delete WList;
}
/// getGraph - Returns the exploded graph.
ExplodedGraph& getGraph() { return *G.get(); }
/// takeGraph - Returns the exploded graph. Ownership of the graph is
/// transfered to the caller.
ExplodedGraph* takeGraph() { return G.take(); }
/// ExecuteWorkList - Run the worklist algorithm for a maximum number of
/// steps. Returns true if there is still simulation state on the worklist.
bool ExecuteWorkList(const LocationContext *L, unsigned Steps);
};
class GRStmtNodeBuilder {
GRCoreEngine& Eng;
CFGBlock& B;
const unsigned Idx;
ExplodedNode* Pred;
GRStateManager& Mgr;
GRAuditor* Auditor;
public:
bool PurgingDeadSymbols;
bool BuildSinks;
bool HasGeneratedNode;
ProgramPoint::Kind PointKind;
const void *Tag;
const GRState* CleanedState;
typedef llvm::SmallPtrSet<ExplodedNode*,5> DeferredTy;
DeferredTy Deferred;
void GenerateAutoTransition(ExplodedNode* N);
public:
GRStmtNodeBuilder(CFGBlock* b, unsigned idx, ExplodedNode* N,
GRCoreEngine* e, GRStateManager &mgr);
~GRStmtNodeBuilder();
ExplodedNode* getBasePredecessor() const { return Pred; }
// FIXME: This should not be exposed.
GRWorkList *getWorkList() { return Eng.WList; }
void SetCleanedState(const GRState* St) {
CleanedState = St;
}
GRBlockCounter getBlockCounter() const { return Eng.WList->getBlockCounter();}
unsigned getCurrentBlockCount() const {
return getBlockCounter().getNumVisited(
Pred->getLocationContext()->getCurrentStackFrame(),
B.getBlockID());
}
ExplodedNode* generateNode(PostStmt PP,const GRState* St,ExplodedNode* Pred) {
HasGeneratedNode = true;
return generateNodeInternal(PP, St, Pred);
}
ExplodedNode* generateNode(const Stmt *S, const GRState *St,
ExplodedNode *Pred, ProgramPoint::Kind K) {
HasGeneratedNode = true;
if (PurgingDeadSymbols)
K = ProgramPoint::PostPurgeDeadSymbolsKind;
return generateNodeInternal(S, St, Pred, K, Tag);
}
ExplodedNode* generateNode(const Stmt *S, const GRState *St,
ExplodedNode *Pred) {
return generateNode(S, St, Pred, PointKind);
}
ExplodedNode *generateNode(const ProgramPoint &PP, const GRState* State,
ExplodedNode* Pred) {
HasGeneratedNode = true;
return generateNodeInternal(PP, State, Pred);
}
ExplodedNode*
generateNodeInternal(const ProgramPoint &PP, const GRState* State,
ExplodedNode* Pred);
ExplodedNode*
generateNodeInternal(const Stmt* S, const GRState* State, ExplodedNode* Pred,
ProgramPoint::Kind K = ProgramPoint::PostStmtKind,
const void *tag = 0);
/// getStmt - Return the current block-level expression associated with
/// this builder.
Stmt* getStmt() const { return B[Idx]; }
/// getBlock - Return the CFGBlock associated with the block-level expression
/// of this builder.
CFGBlock* getBlock() const { return &B; }
unsigned getIndex() const { return Idx; }
void setAuditor(GRAuditor* A) { Auditor = A; }
const GRState* GetState(ExplodedNode* Pred) const {
if (Pred == getBasePredecessor())
return CleanedState;
else
return Pred->getState();
}
ExplodedNode* MakeNode(ExplodedNodeSet& Dst, Stmt* S, ExplodedNode* Pred,
const GRState* St) {
return MakeNode(Dst, S, Pred, St, PointKind);
}
ExplodedNode* MakeNode(ExplodedNodeSet& Dst, Stmt* S, ExplodedNode* Pred,
const GRState* St, ProgramPoint::Kind K) {
const GRState* PredState = GetState(Pred);
// If the state hasn't changed, don't generate a new node.
if (!BuildSinks && St == PredState && Auditor == 0) {
Dst.Add(Pred);
return NULL;
}
ExplodedNode* N = generateNode(S, St, Pred, K);
if (N) {
if (BuildSinks)
N->markAsSink();
else {
if (Auditor && Auditor->Audit(N, Mgr))
N->markAsSink();
Dst.Add(N);
}
}
return N;
}
ExplodedNode* MakeSinkNode(ExplodedNodeSet& Dst, Stmt* S,
ExplodedNode* Pred, const GRState* St) {
bool Tmp = BuildSinks;
BuildSinks = true;
ExplodedNode* N = MakeNode(Dst, S, Pred, St);
BuildSinks = Tmp;
return N;
}
};
class GRBranchNodeBuilder {
GRCoreEngine& Eng;
CFGBlock* Src;
CFGBlock* DstT;
CFGBlock* DstF;
ExplodedNode* Pred;
typedef llvm::SmallVector<ExplodedNode*,3> DeferredTy;
DeferredTy Deferred;
bool GeneratedTrue;
bool GeneratedFalse;
bool InFeasibleTrue;
bool InFeasibleFalse;
public:
GRBranchNodeBuilder(CFGBlock* src, CFGBlock* dstT, CFGBlock* dstF,
ExplodedNode* pred, GRCoreEngine* e)
: Eng(*e), Src(src), DstT(dstT), DstF(dstF), Pred(pred),
GeneratedTrue(false), GeneratedFalse(false),
InFeasibleTrue(!DstT), InFeasibleFalse(!DstF) {}
~GRBranchNodeBuilder();
ExplodedNode* getPredecessor() const { return Pred; }
const ExplodedGraph& getGraph() const { return *Eng.G; }
GRBlockCounter getBlockCounter() const { return Eng.WList->getBlockCounter();}
ExplodedNode* generateNode(const GRState* State, bool branch);
CFGBlock* getTargetBlock(bool branch) const {
return branch ? DstT : DstF;
}
void markInfeasible(bool branch) {
if (branch)
InFeasibleTrue = GeneratedTrue = true;
else
InFeasibleFalse = GeneratedFalse = true;
}
bool isFeasible(bool branch) {
return branch ? !InFeasibleTrue : !InFeasibleFalse;
}
const GRState* getState() const {
return getPredecessor()->getState();
}
};
class GRIndirectGotoNodeBuilder {
GRCoreEngine& Eng;
CFGBlock* Src;
CFGBlock& DispatchBlock;
Expr* E;
ExplodedNode* Pred;
public:
GRIndirectGotoNodeBuilder(ExplodedNode* pred, CFGBlock* src, Expr* e,
CFGBlock* dispatch, GRCoreEngine* eng)
: Eng(*eng), Src(src), DispatchBlock(*dispatch), E(e), Pred(pred) {}
class iterator {
CFGBlock::succ_iterator I;
friend class GRIndirectGotoNodeBuilder;
iterator(CFGBlock::succ_iterator i) : I(i) {}
public:
iterator& operator++() { ++I; return *this; }
bool operator!=(const iterator& X) const { return I != X.I; }
LabelStmt* getLabel() const {
return llvm::cast<LabelStmt>((*I)->getLabel());
}
CFGBlock* getBlock() const {
return *I;
}
};
iterator begin() { return iterator(DispatchBlock.succ_begin()); }
iterator end() { return iterator(DispatchBlock.succ_end()); }
ExplodedNode* generateNode(const iterator& I, const GRState* State,
bool isSink = false);
Expr* getTarget() const { return E; }
const GRState* getState() const { return Pred->State; }
};
class GRSwitchNodeBuilder {
GRCoreEngine& Eng;
CFGBlock* Src;
Expr* Condition;
ExplodedNode* Pred;
public:
GRSwitchNodeBuilder(ExplodedNode* pred, CFGBlock* src,
Expr* condition, GRCoreEngine* eng)
: Eng(*eng), Src(src), Condition(condition), Pred(pred) {}
class iterator {
CFGBlock::succ_reverse_iterator I;
friend class GRSwitchNodeBuilder;
iterator(CFGBlock::succ_reverse_iterator i) : I(i) {}
public:
iterator& operator++() { ++I; return *this; }
bool operator!=(const iterator& X) const { return I != X.I; }
CaseStmt* getCase() const {
return llvm::cast<CaseStmt>((*I)->getLabel());
}
CFGBlock* getBlock() const {
return *I;
}
};
iterator begin() { return iterator(Src->succ_rbegin()+1); }
iterator end() { return iterator(Src->succ_rend()); }
ExplodedNode* generateCaseStmtNode(const iterator& I, const GRState* State);
ExplodedNode* generateDefaultCaseNode(const GRState* State,
bool isSink = false);
Expr* getCondition() const { return Condition; }
const GRState* getState() const { return Pred->State; }
};
class GREndPathNodeBuilder {
GRCoreEngine &Eng;
CFGBlock& B;
ExplodedNode* Pred;
public:
bool HasGeneratedNode;
public:
GREndPathNodeBuilder(CFGBlock* b, ExplodedNode* N, GRCoreEngine* e)
: Eng(*e), B(*b), Pred(N), HasGeneratedNode(false) {}
~GREndPathNodeBuilder();
GRWorkList &getWorkList() { return *Eng.WList; }
ExplodedNode* getPredecessor() const { return Pred; }
GRBlockCounter getBlockCounter() const {
return Eng.WList->getBlockCounter();
}
unsigned getCurrentBlockCount() const {
return getBlockCounter().getNumVisited(
Pred->getLocationContext()->getCurrentStackFrame(),
B.getBlockID());
}
ExplodedNode* generateNode(const GRState* State, const void *tag = 0,
ExplodedNode *P = 0);
void GenerateCallExitNode(const GRState *state);
CFGBlock* getBlock() const { return &B; }
const GRState* getState() const {
return getPredecessor()->getState();
}
};
class GRCallEnterNodeBuilder {
GRCoreEngine &Eng;
const ExplodedNode *Pred;
// The call site.
const Stmt *CE;
// The definition of callee.
const FunctionDecl *FD;
// The parent block of the CallExpr.
const CFGBlock *Block;
// The CFGBlock index of the CallExpr.
unsigned Index;
public:
GRCallEnterNodeBuilder(GRCoreEngine &eng, const ExplodedNode *pred,
const Stmt *s, const FunctionDecl *fd,
const CFGBlock *blk, unsigned idx)
: Eng(eng), Pred(pred), CE(s), FD(fd), Block(blk), Index(idx) {}
const GRState *getState() const { return Pred->getState(); }
const LocationContext *getLocationContext() const {
return Pred->getLocationContext();
}
const Stmt *getCallExpr() const { return CE; }
const FunctionDecl *getCallee() const { return FD; }
const CFGBlock *getBlock() const { return Block; }
unsigned getIndex() const { return Index; }
void GenerateNode(const GRState *state, const LocationContext *LocCtx);
};
class GRCallExitNodeBuilder {
GRCoreEngine &Eng;
const ExplodedNode *Pred;
public:
GRCallExitNodeBuilder(GRCoreEngine &eng, const ExplodedNode *pred)
: Eng(eng), Pred(pred) {}
const ExplodedNode *getPredecessor() const { return Pred; }
const GRState *getState() const { return Pred->getState(); }
void GenerateNode(const GRState *state);
};
} // end clang namespace
#endif
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