Instcombine: Fix pattern where the sext did not dominate the icmp using it
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@123121 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/InstCombine/InstCombineSelect.cpp b/lib/Transforms/InstCombine/InstCombineSelect.cpp
index 71a286e..ff41ab8 100644
--- a/lib/Transforms/InstCombine/InstCombineSelect.cpp
+++ b/lib/Transforms/InstCombine/InstCombineSelect.cpp
@@ -281,8 +281,8 @@
Value *FalseVal = SI.getFalseValue();
// Check cases where the comparison is with a constant that
- // can be adjusted to fit the min/max idiom. We may edit ICI in
- // place here, so make sure the select is the only user.
+ // can be adjusted to fit the min/max idiom. We may move or edit ICI
+ // here, so make sure the select is the only user.
if (ICI->hasOneUse())
if (ConstantInt *CI = dyn_cast<ConstantInt>(CmpRHS)) {
// X < MIN ? T : F --> F
@@ -364,6 +364,11 @@
ICI->setOperand(1, CmpRHS);
SI.setOperand(1, TrueVal);
SI.setOperand(2, FalseVal);
+
+ // Move ICI instruction right before the select instruction. Otherwise
+ // the sext/zext value may be defined after the ICI instruction uses it.
+ ICI->moveBefore(&SI);
+
Changed = true;
break;
}