/// \brief Instrument signed relational comparisons.
///
- /// Handle (x<0) and (x>=0) comparisons (essentially, sign bit tests) by
- /// propagating the highest bit of the shadow. Everything else is delegated
- /// to handleShadowOr().
+ /// Handle sign bit tests: x<0, x>=0, x<=-1, x>-1 by propagating the highest
+ /// bit of the shadow. Everything else is delegated to handleShadowOr().
void handleSignedRelationalComparison(ICmpInst &I) {
- Constant *constOp0 = dyn_cast<Constant>(I.getOperand(0));
- Constant *constOp1 = dyn_cast<Constant>(I.getOperand(1));
- Value* op = nullptr;
- CmpInst::Predicate pre = I.getPredicate();
- if (constOp0 && constOp0->isNullValue() &&
- (pre == CmpInst::ICMP_SGT || pre == CmpInst::ICMP_SLE)) {
- op = I.getOperand(1);
- } else if (constOp1 && constOp1->isNullValue() &&
- (pre == CmpInst::ICMP_SLT || pre == CmpInst::ICMP_SGE)) {
+ Constant *constOp;
+ Value *op = nullptr;
+ CmpInst::Predicate pre;
+ if ((constOp = dyn_cast<Constant>(I.getOperand(1)))) {
op = I.getOperand(0);
+ pre = I.getPredicate();
+ } else if ((constOp = dyn_cast<Constant>(I.getOperand(0)))) {
+ op = I.getOperand(1);
+ pre = I.getSwappedPredicate();
+ } else {
+ handleShadowOr(I);
+ return;
}
- if (op) {
+
+ if ((constOp->isNullValue() &&
+ (pre == CmpInst::ICMP_SLT || pre == CmpInst::ICMP_SGE)) ||
+ (constOp->isAllOnesValue() &&
+ (pre == CmpInst::ICMP_SGT || pre == CmpInst::ICMP_SLE))) {
IRBuilder<> IRB(&I);
- Value* Shadow =
- IRB.CreateICmpSLT(getShadow(op), getCleanShadow(op), "_msprop_icmpslt");
+ Value *Shadow = IRB.CreateICmpSLT(getShadow(op), getCleanShadow(op),
+ "_msprop_icmp_s");
setShadow(&I, Shadow);
setOrigin(&I, getOrigin(op));
} else {