[IndVarSimplify] Handle the case where both operands are the same when widening IV

Author: dtcxzyw

llvm/lib/Transforms/Utils/SimplifyIndVar.cpp

@@ -1743,6 +1743,9 @@ bool WidenIV::widenWithVariantUse(WidenIV::NarrowIVDefUse DU) {
     // TODO: Support case for NarrowDef = NarrowUse->getOperand(1).
     if (NarrowUse->getOperand(0) != NarrowDef)
       return false;
+    // We cannot use a different extend kind for the same operand.
+    if (NarrowUse->getOperand(1) == NarrowDef)
+      return false;
     if (!SE->isKnownNegative(RHS))
       return false;
     bool ProvedSubNUW = SE->isKnownPredicateAt(ICmpInst::ICMP_UGE, LHS,

llvm/test/Transforms/IndVarSimplify/pr135182.ll

@@ -10,7 +10,7 @@ define i32 @pr135182() {
 ; CHECK:       [[FOR_BODY]]:
 ; CHECK-NEXT:    br i1 false, label %[[FOR_BODY]], label %[[FOR_END:.*]]
 ; CHECK:       [[FOR_END]]:
-; CHECK-NEXT:    ret i32 131048
+; CHECK-NEXT:    ret i32 65512
 ;
 entry:
   br label %for.body