InstCombine: Fix infinite loop when encountering switch on trivial icmp.
The test case feeds the following into InstCombine's visitSelect:
%tobool8 = icmp ne i32 0, 0
%phitmp = select i1 %tobool8, i32 3, i32 0
Then instcombine replaces the right side of the switch with 0, doesn't notice
that nothing changes and tries again indefinitely.
This fixes PR12897.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@157587 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/InstCombine/InstCombineSelect.cpp b/lib/Transforms/InstCombine/InstCombineSelect.cpp
index e727b2c..0ae00ea 100644
--- a/lib/Transforms/InstCombine/InstCombineSelect.cpp
+++ b/lib/Transforms/InstCombine/InstCombineSelect.cpp
@@ -498,7 +498,7 @@
// NOTE: if we wanted to, this is where to detect integer MIN/MAX
- if (isa<Constant>(CmpRHS)) {
+ if (CmpRHS != CmpLHS && isa<Constant>(CmpRHS)) {
if (CmpLHS == TrueVal && Pred == ICmpInst::ICMP_EQ) {
// Transform (X == C) ? X : Y -> (X == C) ? C : Y
SI.setOperand(1, CmpRHS);