[InstCombine] check for one-use before turning simple logic op into a select

llvm-svn: 274891

2 files changed, 3 insertions, 5 deletions

diff --git a/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp b/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
index f6ec03b9721..eadf0bf67a4 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
@@ -2394,10 +2394,10 @@ Instruction *InstCombiner::visitOr(BinaryOperator &I) {
     return CastedOr;
 
   // or(sext(A), B) / or(B, sext(A)) --> A ? -1 : B, where A is i1 or <N x i1>.
-  if (match(Op0, m_SExt(m_Value(A))) &&
+  if (match(Op0, m_OneUse(m_SExt(m_Value(A)))) &&
       A->getType()->getScalarType()->isIntegerTy(1))
     return SelectInst::Create(A, ConstantInt::getSigned(I.getType(), -1), Op1);
-  if (match(Op1, m_SExt(m_Value(A))) &&
+  if (match(Op1, m_OneUse(m_SExt(m_Value(A)))) &&
       A->getType()->getScalarType()->isIntegerTy(1))
     return SelectInst::Create(A, ConstantInt::getSigned(I.getType(), -1), Op0);
 
diff --git a/llvm/test/Transforms/InstCombine/or.ll b/llvm/test/Transforms/InstCombine/or.ll
index 6ecabeea229..53cb48809fc 100644
--- a/llvm/test/Transforms/InstCombine/or.ll
+++ b/llvm/test/Transforms/InstCombine/or.ll
@@ -445,12 +445,10 @@ define i32 @orsext_to_sel_swap(i32 %x, i1 %y) {
   ret i32 %or
 }
 
-; FIXME: Don't replace an 'or' with a select unless it allows further simplification.
-
 define i32 @orsext_to_sel_multi_use(i32 %x, i1 %y) {
 ; CHECK-LABEL: @orsext_to_sel_multi_use(
 ; CHECK-NEXT:    [[SEXT:%.*]] = sext i1 %y to i32
-; CHECK-NEXT:    [[OR:%.*]] = select i1 %y, i32 -1, i32 %x
+; CHECK-NEXT:    [[OR:%.*]] = or i32 [[SEXT]], %x
 ; CHECK-NEXT:    [[ADD:%.*]] = add i32 [[SEXT]], [[OR]]
 ; CHECK-NEXT:    ret i32 [[ADD]]
 ;