Don't attempt to add 'nsw' when intermediate instructions had no such guarantee.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@137572 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/InstCombine/InstructionCombining.cpp b/lib/Transforms/InstCombine/InstructionCombining.cpp
index 85091af..4166636 100644
--- a/lib/Transforms/InstCombine/InstructionCombining.cpp
+++ b/lib/Transforms/InstCombine/InstructionCombining.cpp
@@ -146,7 +146,6 @@
return !Overflow;
}
-
/// SimplifyAssociativeOrCommutative - This performs a few simplifications for
/// operators which are associative or commutative:
//
@@ -197,7 +196,10 @@
I.setOperand(1, V);
// Conservatively clear the optional flags, since they may not be
// preserved by the reassociation.
- if (MaintainNoSignedWrap(I, B, C)) {
+ if (MaintainNoSignedWrap(I, B, C) &&
+ (!Op0 || (isa<BinaryOperator>(Op0) && Op0->hasNoSignedWrap()))) {
+ // Note: this is only valid because SimplifyBinOp doesn't look at
+ // the operands to Op0.
I.clearSubclassOptionalData();
I.setHasNoSignedWrap(true);
} else {
@@ -292,10 +294,11 @@
I.setOperand(1, Folded);
// Conservatively clear the optional flags, since they may not be
// preserved by the reassociation.
- if (MaintainNoSignedWrap(I, C1, C2)) {
+ if (MaintainNoSignedWrap(I, C1, C2) && Op0->hasNoSignedWrap() &&
+ Op1->hasNoSignedWrap()) {
+ New->setHasNoSignedWrap(true);
I.clearSubclassOptionalData();
I.setHasNoSignedWrap(true);
- New->setHasNoSignedWrap(true);
} else {
I.clearSubclassOptionalData();
}