forked from OSchip/llvm-project
120 lines
3.9 KiB
C++
120 lines
3.9 KiB
C++
//=== UndefBranchChecker.cpp -----------------------------------*- C++ -*--===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file defines UndefBranchChecker, which checks for undefined branch
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// condition.
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//
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//===----------------------------------------------------------------------===//
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#include "GRExprEngineInternalChecks.h"
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#include "clang/Checker/BugReporter/BugType.h"
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#include "clang/Checker/PathSensitive/Checker.h"
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using namespace clang;
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namespace {
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class UndefBranchChecker : public Checker {
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BuiltinBug *BT;
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struct FindUndefExpr {
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GRStateManager& VM;
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const GRState* St;
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FindUndefExpr(GRStateManager& V, const GRState* S) : VM(V), St(S) {}
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const Expr* FindExpr(const Expr* Ex) {
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if (!MatchesCriteria(Ex))
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return 0;
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for (Stmt::const_child_iterator I = Ex->child_begin(),
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E = Ex->child_end();I!=E;++I)
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if (const Expr* ExI = dyn_cast_or_null<Expr>(*I)) {
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const Expr* E2 = FindExpr(ExI);
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if (E2) return E2;
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}
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return Ex;
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}
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bool MatchesCriteria(const Expr* Ex) { return St->getSVal(Ex).isUndef(); }
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};
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public:
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UndefBranchChecker() : BT(0) {}
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static void *getTag();
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void VisitBranchCondition(GRBranchNodeBuilder &Builder, GRExprEngine &Eng,
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const Stmt *Condition, void *tag);
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};
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}
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void clang::RegisterUndefBranchChecker(GRExprEngine &Eng) {
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Eng.registerCheck(new UndefBranchChecker());
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}
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void *UndefBranchChecker::getTag() {
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static int x;
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return &x;
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}
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void UndefBranchChecker::VisitBranchCondition(GRBranchNodeBuilder &Builder,
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GRExprEngine &Eng,
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const Stmt *Condition, void *tag){
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const GRState *state = Builder.getState();
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SVal X = state->getSVal(Condition);
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if (X.isUndef()) {
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ExplodedNode *N = Builder.generateNode(state, true);
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if (N) {
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N->markAsSink();
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if (!BT)
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BT = new BuiltinBug("Branch condition evaluates to a garbage value");
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// What's going on here: we want to highlight the subexpression of the
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// condition that is the most likely source of the "uninitialized
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// branch condition." We do a recursive walk of the condition's
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// subexpressions and roughly look for the most nested subexpression
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// that binds to Undefined. We then highlight that expression's range.
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BlockEdge B = cast<BlockEdge>(N->getLocation());
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const Expr* Ex = cast<Expr>(B.getSrc()->getTerminatorCondition());
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assert (Ex && "Block must have a terminator.");
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// Get the predecessor node and check if is a PostStmt with the Stmt
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// being the terminator condition. We want to inspect the state
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// of that node instead because it will contain main information about
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// the subexpressions.
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assert (!N->pred_empty());
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// Note: any predecessor will do. They should have identical state,
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// since all the BlockEdge did was act as an error sink since the value
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// had to already be undefined.
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ExplodedNode *PrevN = *N->pred_begin();
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ProgramPoint P = PrevN->getLocation();
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const GRState* St = N->getState();
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if (PostStmt* PS = dyn_cast<PostStmt>(&P))
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if (PS->getStmt() == Ex)
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St = PrevN->getState();
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FindUndefExpr FindIt(Eng.getStateManager(), St);
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Ex = FindIt.FindExpr(Ex);
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// Emit the bug report.
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EnhancedBugReport *R = new EnhancedBugReport(*BT, BT->getDescription(),N);
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R->addVisitorCreator(bugreporter::registerTrackNullOrUndefValue, Ex);
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R->addRange(Ex->getSourceRange());
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Eng.getBugReporter().EmitReport(R);
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}
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Builder.markInfeasible(true);
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Builder.markInfeasible(false);
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}
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}
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