[llvm] [AArch64][SME] Allow memory operations lowering to custom SME functions. (PR #79263)

[Kerry McLaughlin via llvm-commits]

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@@ -76,12 +76,74 @@ SDValue AArch64SelectionDAGInfo::EmitMOPS(AArch64ISD::NodeType SDOpcode,
   }
 }
 
+SDValue AArch64SelectionDAGInfo::EmitSpecializedLibcall(
+    SelectionDAG &DAG, const SDLoc &DL, SDValue Chain, SDValue Dst, SDValue Src,
+    SDValue Size, RTLIB::Libcall LC) const {
+  const AArch64Subtarget &STI =
+      DAG.getMachineFunction().getSubtarget<AArch64Subtarget>();
+  const AArch64TargetLowering *TLI = STI.getTargetLowering();
+  TargetLowering::ArgListTy Args;
+  TargetLowering::ArgListEntry Entry;
+  Entry.Ty = DAG.getDataLayout().getIntPtrType(*DAG.getContext());
+  Entry.Node = Dst;
+  Args.push_back(Entry);
+
+  enum { SME_MEMCPY = 0, SME_MEMMOVE, SME_MEMSET } SMELibcall;
+  switch (LC) {
+  case RTLIB::MEMCPY:
+    SMELibcall = SME_MEMCPY;
+    Entry.Node = Src;
+    Args.push_back(Entry);
+    break;
+  case RTLIB::MEMMOVE:
+    SMELibcall = SME_MEMMOVE;
+    Entry.Node = Src;
+    Args.push_back(Entry);
+    break;
+  case RTLIB::MEMSET:
+    SMELibcall = SME_MEMSET;
+    if (Src.getValueType().bitsGT(MVT::i32))
+      Src = DAG.getNode(ISD::TRUNCATE, DL, MVT::i32, Src);
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kmclaughlin-arm wrote:

Thanks for sharing this test @dtemirbulatov.
I think in your example, Src still needs to be extended? The case I was trying to write was one where Src requires truncating, for example from i64 to i32.

https://github.com/llvm/llvm-project/pull/79263