Address issues found by Duncan during post-commit review of r177856.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@177863 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/InstCombine/InstCombineCompares.cpp b/lib/Transforms/InstCombine/InstCombineCompares.cpp
index 24af2bf..a96e754 100644
--- a/lib/Transforms/InstCombine/InstCombineCompares.cpp
+++ b/lib/Transforms/InstCombine/InstCombineCompares.cpp
@@ -139,38 +139,27 @@
}
}
-/// Returns true if the exploded icmp can be expressed as a comparison to zero
-/// and update the predicate accordingly. The signedness of the comparison is
+/// Returns true if the exploded icmp can be expressed as a signed comparison
+/// to zero and updates the predicate accordingly.
+/// The signedness of the comparison is preserved.
static bool isSignTest(ICmpInst::Predicate &pred, const ConstantInt *RHS) {
if (!ICmpInst::isSigned(pred))
return false;
if (RHS->isZero())
- return true;
+ return ICmpInst::isRelational(pred);
- if (RHS->isOne())
- switch (pred) {
- case ICmpInst::ICMP_SGE:
- pred = ICmpInst::ICMP_SGT;
- return true;
- case ICmpInst::ICMP_SLT:
+ if (RHS->isOne()) {
+ if (pred == ICmpInst::ICMP_SLT) {
pred = ICmpInst::ICMP_SLE;
return true;
- default:
- return false;
}
-
- if (RHS->isAllOnesValue())
- switch (pred) {
- case ICmpInst::ICMP_SLE:
- pred = ICmpInst::ICMP_SLT;
- return true;
- case ICmpInst::ICMP_SGT:
+ } else if (RHS->isAllOnesValue()) {
+ if (pred == ICmpInst::ICMP_SGT) {
pred = ICmpInst::ICMP_SGE;
return true;
- default:
- return false;
}
+ }
return false;
}
@@ -1322,17 +1311,15 @@
ConstantInt *Val = dyn_cast<ConstantInt>(LHSI->getOperand(1));
if (!Val) break;
- if (!ICI.isEquality()) {
- // If this is a signed comparison to 0 and the mul is sign preserving,
- // use the mul LHS operand instead.
- ICmpInst::Predicate pred = ICI.getPredicate();
- if (isSignTest(pred, RHS) && !Val->isZero() &&
- cast<BinaryOperator>(LHSI)->hasNoSignedWrap())
- return new ICmpInst(Val->isNegative() ?
- ICmpInst::getSwappedPredicate(pred) : pred,
- LHSI->getOperand(0),
- Constant::getNullValue(RHS->getType()));
- }
+ // If this is a signed comparison to 0 and the mul is sign preserving,
+ // use the mul LHS operand instead.
+ ICmpInst::Predicate pred = ICI.getPredicate();
+ if (isSignTest(pred, RHS) && !Val->isZero() &&
+ cast<BinaryOperator>(LHSI)->hasNoSignedWrap())
+ return new ICmpInst(Val->isNegative() ?
+ ICmpInst::getSwappedPredicate(pred) : pred,
+ LHSI->getOperand(0),
+ Constant::getNullValue(RHS->getType()));
break;
}
@@ -1613,7 +1600,7 @@
}
break;
case Instruction::Mul:
- if (RHSV == 0) {
+ if (RHSV == 0 && BO->hasNoSignedWrap()) {
if (ConstantInt *BOC = dyn_cast<ConstantInt>(BO->getOperand(1))) {
// The trivial case (mul X, 0) is handled by InstSimplify
// General case : (mul X, C) != 0 iff X != 0