================
@@ -4939,6 +4939,86 @@ void LoongArchTargetLowering::ReplaceNodeResults(
}
}
+// Helper to attempt to return a cheaper, bit-inverted version of \p V.
+static SDValue isNOT(SDValue V, SelectionDAG &DAG) {
+ // TODO: don't always ignore oneuse constraints.
+ V = peekThroughBitcasts(V);
+ EVT VT = V.getValueType();
+
+ // Match not(xor X, -1) -> X.
+ if (V.getOpcode() == ISD::XOR &&
+ (ISD::isBuildVectorAllOnes(V.getOperand(1).getNode()) ||
+ isAllOnesConstant(V.getOperand(1))))
+ return V.getOperand(0);
+
+ // Match not(extract_subvector(not(X)) -> extract_subvector(X).
+ if (V.getOpcode() == ISD::EXTRACT_SUBVECTOR &&
+ (isNullConstant(V.getOperand(1)) || V.getOperand(0).hasOneUse())) {
----------------
heiher wrote:
Could you add a test to cover this case?
https://github.com/llvm/llvm-project/pull/161037
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