Fix a ValueTracking rule: RHS means operand 1, not 0. Add a simple
ashr instcombine to help expose this code. And apply the fix to
SelectionDAG's copy of this code too.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@65364 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Analysis/ValueTracking.cpp b/lib/Analysis/ValueTracking.cpp
index 7ac138b..20fa69e 100644
--- a/lib/Analysis/ValueTracking.cpp
+++ b/lib/Analysis/ValueTracking.cpp
@@ -625,7 +625,7 @@
if (Tmp == 1) return 1; // Early out.
// Special case decrementing a value (ADD X, -1):
- if (ConstantInt *CRHS = dyn_cast<ConstantInt>(U->getOperand(0)))
+ if (ConstantInt *CRHS = dyn_cast<ConstantInt>(U->getOperand(1)))
if (CRHS->isAllOnesValue()) {
APInt KnownZero(TyBits, 0), KnownOne(TyBits, 0);
APInt Mask = APInt::getAllOnesValue(TyBits);