DivZeroChecker.cpp revision 5eca482fe895ea57bc82410222e6426c09e63284
1//== DivZeroChecker.cpp - Division by zero checker --------------*- C++ -*--==// 2// 3// The LLVM Compiler Infrastructure 4// 5// This file is distributed under the University of Illinois Open Source 6// License. See LICENSE.TXT for details. 7// 8//===----------------------------------------------------------------------===// 9// 10// This defines DivZeroChecker, a builtin check in ExprEngine that performs 11// checks for division by zeros. 12// 13//===----------------------------------------------------------------------===// 14 15#include "ClangSACheckers.h" 16#include "clang/StaticAnalyzer/Core/Checker.h" 17#include "clang/StaticAnalyzer/Core/CheckerManager.h" 18#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h" 19#include "clang/StaticAnalyzer/Core/BugReporter/BugType.h" 20 21using namespace clang; 22using namespace ento; 23 24namespace { 25class DivZeroChecker : public Checker< check::PreStmt<BinaryOperator> > { 26 mutable llvm::OwningPtr<BuiltinBug> BT; 27public: 28 void checkPreStmt(const BinaryOperator *B, CheckerContext &C) const; 29}; 30} // end anonymous namespace 31 32void DivZeroChecker::checkPreStmt(const BinaryOperator *B, 33 CheckerContext &C) const { 34 BinaryOperator::Opcode Op = B->getOpcode(); 35 if (Op != BO_Div && 36 Op != BO_Rem && 37 Op != BO_DivAssign && 38 Op != BO_RemAssign) 39 return; 40 41 if (!B->getRHS()->getType()->isIntegerType() || 42 !B->getRHS()->getType()->isScalarType()) 43 return; 44 45 SVal Denom = C.getState()->getSVal(B->getRHS(), C.getLocationContext()); 46 const DefinedSVal *DV = dyn_cast<DefinedSVal>(&Denom); 47 48 // Divide-by-undefined handled in the generic checking for uses of 49 // undefined values. 50 if (!DV) 51 return; 52 53 // Check for divide by zero. 54 ConstraintManager &CM = C.getConstraintManager(); 55 const ProgramState *stateNotZero, *stateZero; 56 llvm::tie(stateNotZero, stateZero) = CM.assumeDual(C.getState(), *DV); 57 58 if (!stateNotZero) { 59 assert(stateZero); 60 if (ExplodedNode *N = C.generateSink(stateZero)) { 61 if (!BT) 62 BT.reset(new BuiltinBug("Division by zero")); 63 64 BugReport *R = 65 new BugReport(*BT, BT->getDescription(), N); 66 67 R->addVisitor(bugreporter::getTrackNullOrUndefValueVisitor(N, 68 bugreporter::GetDenomExpr(N))); 69 70 C.EmitReport(R); 71 } 72 return; 73 } 74 75 // If we get here, then the denom should not be zero. We abandon the implicit 76 // zero denom case for now. 77 C.addTransition(stateNotZero); 78} 79 80void ento::registerDivZeroChecker(CheckerManager &mgr) { 81 mgr.registerChecker<DivZeroChecker>(); 82} 83