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-rw-r--r--llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp24
-rw-r--r--llvm/test/Transforms/InstCombine/select.ll10
2 files changed, 31 insertions, 3 deletions
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp b/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
index d2fbcdd3991..4dec1542495 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
@@ -292,10 +292,28 @@ static Value *SimplifyWithOpReplaced(Value *V, Value *Op, Value *RepOp,
// If this is a binary operator, try to simplify it with the replaced op.
if (BinaryOperator *B = dyn_cast<BinaryOperator>(I)) {
+ Value *Simplified = nullptr;
if (B->getOperand(0) == Op)
- return SimplifyBinOp(B->getOpcode(), RepOp, B->getOperand(1), DL, TLI);
- if (B->getOperand(1) == Op)
- return SimplifyBinOp(B->getOpcode(), B->getOperand(0), RepOp, DL, TLI);
+ Simplified =
+ SimplifyBinOp(B->getOpcode(), RepOp, B->getOperand(1), DL, TLI);
+ if (!Simplified && B->getOperand(1) == Op)
+ Simplified =
+ SimplifyBinOp(B->getOpcode(), B->getOperand(0), RepOp, DL, TLI);
+ if (Simplified) {
+ // Consider:
+ // %cmp = icmp eq i32 %x, 2147483647
+ // %add = add nsw i32 %x, 1
+ // %sel = select i1 %cmp, i32 -2147483648, i32 %add
+ //
+ // We can't replace %sel with %add unless we strip away the flags.
+ if (isa<OverflowingBinaryOperator>(B)) {
+ B->setHasNoSignedWrap(false);
+ B->setHasNoUnsignedWrap(false);
+ }
+ if (isa<PossiblyExactOperator>(B))
+ B->setIsExact(false);
+ }
+ return Simplified;
}
// Same for CmpInsts.
diff --git a/llvm/test/Transforms/InstCombine/select.ll b/llvm/test/Transforms/InstCombine/select.ll
index e4bc96cff17..b05f2ca2c4c 100644
--- a/llvm/test/Transforms/InstCombine/select.ll
+++ b/llvm/test/Transforms/InstCombine/select.ll
@@ -1532,3 +1532,13 @@ define i32 @test_max_of_min(i32 %a) {
%s1 = select i1 %c1, i32 %s0, i32 -1
ret i32 %s1
}
+
+define i32 @PR23757(i32 %x) {
+; CHECK-LABEL: @PR23757
+; CHECK: %[[add:.*]] = add i32 %x, 1
+; CHECK-NEXT: ret i32 %[[add]]
+ %cmp = icmp eq i32 %x, 2147483647
+ %add = add nsw i32 %x, 1
+ %sel = select i1 %cmp, i32 -2147483648, i32 %add
+ ret i32 %sel
+}
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