[llvm] [AArch64] Extend usage of `XAR` instruction for fixed-length operations (PR #139460)

[David Green via llvm-commits]

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@@ -4606,7 +4606,36 @@ bool AArch64DAGToDAGISel::trySelectXAR(SDNode *N) {
     return false;
   }
 
-  if (!Subtarget->hasSHA3())
+  // We have Neon SHA3 XAR operation for v2i64 but for types
+  // v4i32, v8i16, v16i8 we can use SVE operations when SVE2-SHA3
+  // is available.
+  EVT SVT;
+  switch (VT.getSimpleVT().SimpleTy) {
+  case MVT::v4i32:
+    SVT = MVT::nxv4i32;
+    break;
+  case MVT::v8i16:
+    SVT = MVT::nxv8i16;
+    break;
+  case MVT::v16i8:
+    SVT = MVT::nxv16i8;
+    break;
+  case MVT::v1i64:
+  case MVT::v2i32:
+  case MVT::v4i16:
+  case MVT::v8i8:
----------------
davemgreen wrote:

I think we need to treat v2i32/v4i16/v8i8 like a nxv4i32/nxv8i16/nxv16i8, not like a v2i64. Otherwise the rotate would not be correct I believe.

https://github.com/llvm/llvm-project/pull/139460