[llvm] [SelectionDAG][RISCV] Use VP_LOAD to widen MLOAD in type legalization when possible. (PR #140595)

[Luke Lau via llvm-commits]

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@@ -6111,18 +6111,37 @@ SDValue DAGTypeLegalizer::WidenVecRes_VECTOR_COMPRESS(SDNode *N) {
 }
 
 SDValue DAGTypeLegalizer::WidenVecRes_MLOAD(MaskedLoadSDNode *N) {
-
-  EVT WidenVT = TLI.getTypeToTransformTo(*DAG.getContext(),N->getValueType(0));
+  EVT VT = N->getValueType(0);
+  EVT WidenVT = TLI.getTypeToTransformTo(*DAG.getContext(), VT);
   SDValue Mask = N->getMask();
   EVT MaskVT = Mask.getValueType();
   SDValue PassThru = GetWidenedVector(N->getPassThru());
   ISD::LoadExtType ExtType = N->getExtensionType();
   SDLoc dl(N);
 
+  EVT WideMaskVT =
+      EVT::getVectorVT(*DAG.getContext(), MaskVT.getVectorElementType(),
+                       WidenVT.getVectorElementCount());
+
+  if (ExtType == ISD::NON_EXTLOAD &&
+      TLI.isOperationLegalOrCustom(ISD::VP_LOAD, WidenVT) &&
+      TLI.isTypeLegal(WideMaskVT)) {
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lukel97 wrote:

Does this need to be limited to scalable vectors only? If the existing widening already worked for fixed vectors

https://github.com/llvm/llvm-project/pull/140595