[llvm] [SelectionDAG] Use unaligned store/load to move AVX registers onto stack for `insertelement` (PR #82130)

[Matt Arsenault via llvm-commits]

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@@ -1485,22 +1484,26 @@ SDValue SelectionDAGLegalize::ExpandInsertToVectorThroughStack(SDValue Op) {
         TLI.getVectorSubVecPointer(DAG, StackPtr, VecVT, PartVT, Idx);
 
     // Store the subvector.
-    Ch = DAG.getStore(
-        Ch, dl, Part, SubStackPtr,
-        MachinePointerInfo::getUnknownStack(DAG.getMachineFunction()));
+    Ch = DAG.getStore(Ch, dl, Part, SubStackPtr, AlignedMMO);
   } else {
     SDValue SubStackPtr =
         TLI.getVectorElementPointer(DAG, StackPtr, VecVT, Idx);
 
     // Store the scalar value.
-    Ch = DAG.getTruncStore(
-        Ch, dl, Part, SubStackPtr,
-        MachinePointerInfo::getUnknownStack(DAG.getMachineFunction()),
-        VecVT.getVectorElementType());
+    Ch = DAG.getTruncStore(Ch, dl, Part, SubStackPtr,
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arsenm wrote:

Ditto? 

https://github.com/llvm/llvm-project/pull/82130