[clang] [llvm] [mlir] [AArch64][SME] Improve codegen for aarch64.sme.cnts* when not in streaming mode (PR #154761)

[Kerry McLaughlin via llvm-commits]

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@@ -6266,25 +6266,15 @@ SDValue AArch64TargetLowering::LowerINTRINSIC_WO_CHAIN(SDValue Op,
   case Intrinsic::aarch64_sve_clz:
     return DAG.getNode(AArch64ISD::CTLZ_MERGE_PASSTHRU, DL, Op.getValueType(),
                        Op.getOperand(2), Op.getOperand(3), Op.getOperand(1));
-  case Intrinsic::aarch64_sme_cntsb:
-    return DAG.getNode(AArch64ISD::RDSVL, DL, Op.getValueType(),
-                       DAG.getConstant(1, DL, MVT::i32));
-  case Intrinsic::aarch64_sme_cntsh: {
-    SDValue One = DAG.getConstant(1, DL, MVT::i32);
-    SDValue Bytes = DAG.getNode(AArch64ISD::RDSVL, DL, Op.getValueType(), One);
-    return DAG.getNode(ISD::SRL, DL, Op.getValueType(), Bytes, One);
-  }
-  case Intrinsic::aarch64_sme_cntsw: {
-    SDValue Bytes = DAG.getNode(AArch64ISD::RDSVL, DL, Op.getValueType(),
-                                DAG.getConstant(1, DL, MVT::i32));
-    return DAG.getNode(ISD::SRL, DL, Op.getValueType(), Bytes,
-                       DAG.getConstant(2, DL, MVT::i32));
-  }
   case Intrinsic::aarch64_sme_cntsd: {
+    auto Flags = SDNodeFlags();
+    Flags.setNoUnsignedWrap(true);
+    Flags.setNoSignedWrap(true);
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kmclaughlin-arm wrote:

I only added the wrap flags here because I'm also adding them when creating the `cntsd` intrinisic and `mul`, but they aren't necessary. Adding `exact` is enough to ensure there are no extra `and` instructions.

https://github.com/llvm/llvm-project/pull/154761