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Instcombine: Fix pattern where the sext did not dominate the icmp using it

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@123121 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Tobias Grosser
2011-01-09 16:00:11 +00:00
parent 3a723ab344
commit aa2be84356
2 changed files with 18 additions and 2 deletions
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lib/Transforms/InstCombine/InstCombineSelect.cpp
+7 -2
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@@ -281,8 +281,8 @@ Instruction *InstCombiner::visitSelectInstWithICmp(SelectInst &SI,
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 @@ Instruction *InstCombiner::visitSelectInstWithICmp(SelectInst &SI,
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;
}