[llvm] [AArch64] Use firstp for SVE2.2 cttz.elts (PR #221182)

[via llvm-commits]

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@@ -9169,8 +9153,12 @@ SDValue AArch64TargetLowering::LowerOperation(SDValue Op,
     }
 
     SDValue Pg = getPredicateForVector(DAG, DL, VT);
-    SDValue NewCttzElts =
-        DAG.getNode(AArch64ISD::CTTZ_ELTS, DL, MVT::i64, Pg, CttzOp);
+    // We preserve the poison semantics here to avoid the poison path from being
+    // affected by the checks emitted for the no-poison case.
+    unsigned Opcode = Op.getOpcode() == ISD::CTTZ_ELTS_ZERO_POISON
+                          ? AArch64ISD::CTTZ_ELTS_ZERO_POISON
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Lukacma wrote:

Is there any reason  to make these new ISD nodes target specific ? Wouldn't it be better to create general ISD nodes for CTTZ_ELTS* and use those ?

https://github.com/llvm/llvm-project/pull/221182