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//== DivZeroChecker.cpp - Division by zero checker --------------*- C++ -*--==//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This defines DivZeroChecker, a builtin check in GRExprEngine that performs
// checks for division by zeros.
//
//===----------------------------------------------------------------------===//
#include "clang/Analysis/PathSensitive/CheckerVisitor.h"
#include "GRExprEngineInternalChecks.h"
using namespace clang;
namespace {
class DivZeroChecker : public CheckerVisitor<DivZeroChecker> {
BuiltinBug *BT;
public:
DivZeroChecker() : BT(0) {}
static void *getTag();
void PreVisitBinaryOperator(CheckerContext &C, const BinaryOperator *B);
};
} // end anonymous namespace
void clang::RegisterDivZeroChecker(GRExprEngine &Eng) {
Eng.registerCheck(new DivZeroChecker());
}
void *DivZeroChecker::getTag() {
static int x;
return &x;
}
void DivZeroChecker::PreVisitBinaryOperator(CheckerContext &C,
const BinaryOperator *B) {
BinaryOperator::Opcode Op = B->getOpcode();
if (Op != BinaryOperator::Div &&
Op != BinaryOperator::Rem &&
Op != BinaryOperator::DivAssign &&
Op != BinaryOperator::RemAssign)
return;
if (!B->getRHS()->getType()->isIntegerType() ||
!B->getRHS()->getType()->isScalarType())
return;
SVal Denom = C.getState()->getSVal(B->getRHS());
const DefinedSVal *DV = dyn_cast<DefinedSVal>(&Denom);
// Divide-by-undefined handled in the generic checking for uses of
// undefined values.
if (!DV)
return;
// Check for divide by zero.
ConstraintManager &CM = C.getConstraintManager();
const GRState *stateNotZero, *stateZero;
llvm::tie(stateNotZero, stateZero) = CM.AssumeDual(C.getState(), *DV);
if (stateZero && !stateNotZero) {
if (ExplodedNode *N = C.GenerateSink(stateZero)) {
if (!BT)
BT = new BuiltinBug("Division by zero");
EnhancedBugReport *R =
new EnhancedBugReport(*BT, BT->getDescription(), N);
R->addVisitorCreator(bugreporter::registerTrackNullOrUndefValue,
bugreporter::GetDenomExpr(N));
C.EmitReport(R);
}
return;
}
// If we get here, then the denom should not be zero. We abandon the implicit
// zero denom case for now.
C.addTransition(stateNotZero);
}
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