Invert the logic of reachesChainWithoutSideEffects(). What we want to check is that there is
NO path to the destination containing side effects, not that SOME path contains no side effects.
In practice, this only manifests with CombinerAA enabled, because otherwise the chain has little
to no branching, so "any" is effectively equivalent to "all".
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@114268 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index ad06ebd..77c40af 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -5478,9 +5478,9 @@
/// reachesChainWithoutSideEffects - Return true if this operand (which must
/// be a chain) reaches the specified operand without crossing any
-/// side-effecting instructions. In practice, this looks through token
-/// factors and non-volatile loads. In order to remain efficient, this only
-/// looks a couple of nodes in, it does not do an exhaustive search.
+/// side-effecting instructions on any chain path. In practice, this looks
+/// through token factors and non-volatile loads. In order to remain efficient,
+/// this only looks a couple of nodes in, it does not do an exhaustive search.
bool SDValue::reachesChainWithoutSideEffects(SDValue Dest,
unsigned Depth) const {
if (*this == Dest) return true;
@@ -5490,12 +5490,12 @@
if (Depth == 0) return false;
// If this is a token factor, all inputs to the TF happen in parallel. If any
- // of the operands of the TF reach dest, then we can do the xform.
+ // of the operands of the TF does not reach dest, then we cannot do the xform.
if (getOpcode() == ISD::TokenFactor) {
for (unsigned i = 0, e = getNumOperands(); i != e; ++i)
- if (getOperand(i).reachesChainWithoutSideEffects(Dest, Depth-1))
- return true;
- return false;
+ if (!getOperand(i).reachesChainWithoutSideEffects(Dest, Depth-1))
+ return false;
+ return true;
}
// Loads don't have side effects, look through them.