[PATCH] D105624: [SelectionDAG] Simplify PromoteIntRes_INSERT_SUBVECTOR to only handle result

[Craig Topper via Phabricator via llvm-commits]

craig.topper added inline comments.


================
Comment at: llvm/lib/CodeGen/SelectionDAG/LegalizeIntegerTypes.cpp:4745
   EVT SubVecVT = SubVec.getValueType();
+  EVT NSubVT = SubVecVT.changeVectorElementType(NOutVT.getVectorElementType());
 
----------------
I'm not sure we should use changeVectorElementType here. If SubVecVT is an MVT, changeVectorElementType will only work if NSubVT can also be represented as an MVT. I don't think that's guaranteed so `EVT::getVectorVT(NOutV.getVectorElementType(), SubVecVT.getVectorElementCount())` would be better.


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Comment at: llvm/lib/CodeGen/SelectionDAG/LegalizeIntegerTypes.cpp:4747
 
-  // To insert SubVec into Vec, store the wider vector to memory, overwrite the
-  // appropriate bits with the narrower vector, and reload.
-  Align SmallestAlign = DAG.getReducedAlign(SubVecVT, /*UseABI=*/false);
-
-  SDValue StackPtr =
-      DAG.CreateStackTemporary(VecVT.getStoreSize(), SmallestAlign);
-  auto StackPtrVT = StackPtr->getValueType(0);
-  auto &MF = DAG.getMachineFunction();
-  auto FrameIndex = cast<FrameIndexSDNode>(StackPtr.getNode())->getIndex();
-  auto PtrInfo = MachinePointerInfo::getFixedStack(MF, FrameIndex);
-
-  SDValue Store = DAG.getStore(DAG.getEntryNode(), dl, Vec, StackPtr, PtrInfo,
-                               SmallestAlign);
-
-  SDValue ScaledIdx = Idx;
-  if (SubVecVT.isScalableVector() && IdxN != 0) {
-    APInt IdxAPInt = cast<ConstantSDNode>(Idx)->getAPIntValue();
-    ScaledIdx = DAG.getVScale(dl, StackPtrVT,
-                              IdxAPInt.sextOrSelf(StackPtrVT.getSizeInBits()));
-  }
+  Vec = DAG.getNode(ISD::ANY_EXTEND, dl, NOutVT, Vec);
+  SubVec = DAG.getNode(ISD::ANY_EXTEND, dl, NSubVT, SubVec);
----------------
This can be `Vec = GetPromotedInteger(Vec)` to get the already legalized value for that operand.


Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D105624/new/

https://reviews.llvm.org/D105624