Fix PR1907, a nasty miscompilation because instcombine didn't
realize that ne & sgt was a signed comparison (it was only
looking at whether the left compare was signed).
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@45937 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Scalar/InstructionCombining.cpp b/lib/Transforms/Scalar/InstructionCombining.cpp
index ea53aec..9465a31 100644
--- a/lib/Transforms/Scalar/InstructionCombining.cpp
+++ b/lib/Transforms/Scalar/InstructionCombining.cpp
@@ -3495,8 +3495,14 @@
ICmpInst::isSignedPredicate(LHSCC) ==
ICmpInst::isSignedPredicate(RHSCC))) {
// Ensure that the larger constant is on the RHS.
- ICmpInst::Predicate GT = ICmpInst::isSignedPredicate(LHSCC) ?
- ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT;
+ ICmpInst::Predicate GT;
+ if (ICmpInst::isSignedPredicate(LHSCC) ||
+ (ICmpInst::isEquality(LHSCC) &&
+ ICmpInst::isSignedPredicate(RHSCC)))
+ GT = ICmpInst::ICMP_SGT;
+ else
+ GT = ICmpInst::ICMP_UGT;
+
Constant *Cmp = ConstantExpr::getICmp(GT, LHSCst, RHSCst);
ICmpInst *LHS = cast<ICmpInst>(Op0);
if (cast<ConstantInt>(Cmp)->getZExtValue()) {