Fix an overly general check in SimplifyIndvar to handle useless phi cycles.
The right way to check for a binary operation is
cast<BinaryOperator>. The original check: cast<Instruction> &&
numOperands() == 2 would match phi "instructions", leading to an
infinite loop in extreme corner case: a useless phi with operands
[self, constant] that prior optimization passes failed to remove,
being used in the loop by another useless phi, in turn being used by an
lshr or udiv.
Fixes PR11350: runaway iteration assertion.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@144935 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Utils/SimplifyIndVar.cpp b/lib/Transforms/Utils/SimplifyIndVar.cpp
index 76289c0..6732a78 100644
--- a/lib/Transforms/Utils/SimplifyIndVar.cpp
+++ b/lib/Transforms/Utils/SimplifyIndVar.cpp
@@ -107,8 +107,8 @@
// Attempt to fold a binary operator with constant operand.
// e.g. ((I + 1) >> 2) => I >> 2
- if (IVOperand->getNumOperands() != 2 ||
- !isa<ConstantInt>(IVOperand->getOperand(1)))
+ if (!isa<BinaryOperator>(IVOperand)
+ || !isa<ConstantInt>(IVOperand->getOperand(1)))
return 0;
IVSrc = IVOperand->getOperand(0);