[AArch64] Create a performRNDRCombine to pull code out of PerformDAGCombine. NFC

Author: davemgreen

llvm/lib/Target/AArch64/AArch64ISelLowering.cpp

@@ -26926,6 +26926,23 @@ static SDValue performSHLCombine(SDNode *N,
   return DAG.getNode(ISD::AND, DL, VT, NewShift, NewRHS);
 }
 
+static SDValue performRNDRCombine(SDNode *N, SelectionDAG &DAG) {
+  unsigned IntrinsicID = N->getConstantOperandVal(1);
+  auto Register =
+      (IntrinsicID == Intrinsic::aarch64_rndr ? AArch64SysReg::RNDR
+                                              : AArch64SysReg::RNDRRS);
+  SDLoc DL(N);
+  SDValue A = DAG.getNode(
+      AArch64ISD::MRS, DL, DAG.getVTList(MVT::i64, FlagsVT, MVT::Other),
+      N->getOperand(0), DAG.getConstant(Register, DL, MVT::i32));
+  SDValue B = DAG.getNode(
+      AArch64ISD::CSINC, DL, MVT::i32, DAG.getConstant(0, DL, MVT::i32),
+      DAG.getConstant(0, DL, MVT::i32),
+      DAG.getConstant(AArch64CC::NE, DL, MVT::i32), A.getValue(1));
+  return DAG.getMergeValues(
+      {A, DAG.getZExtOrTrunc(B, DL, MVT::i1), A.getValue(2)}, DL);
+}
+
 SDValue AArch64TargetLowering::PerformDAGCombine(SDNode *N,
                                                  DAGCombinerInfo &DCI) const {
   SelectionDAG &DAG = DCI.DAG;
@@ -27241,22 +27258,8 @@ SDValue AArch64TargetLowering::PerformDAGCombine(SDNode *N,
     case Intrinsic::aarch64_sve_st1_scatter_scalar_offset:
       return performScatterStoreCombine(N, DAG, AArch64ISD::SST1_IMM_PRED);
     case Intrinsic::aarch64_rndr:
-    case Intrinsic::aarch64_rndrrs: {
-      unsigned IntrinsicID = N->getConstantOperandVal(1);
-      auto Register =
-          (IntrinsicID == Intrinsic::aarch64_rndr ? AArch64SysReg::RNDR
-                                                  : AArch64SysReg::RNDRRS);
-      SDLoc DL(N);
-      SDValue A = DAG.getNode(
-          AArch64ISD::MRS, DL, DAG.getVTList(MVT::i64, FlagsVT, MVT::Other),
-          N->getOperand(0), DAG.getConstant(Register, DL, MVT::i32));
-      SDValue B = DAG.getNode(
-          AArch64ISD::CSINC, DL, MVT::i32, DAG.getConstant(0, DL, MVT::i32),
-          DAG.getConstant(0, DL, MVT::i32),
-          DAG.getConstant(AArch64CC::NE, DL, MVT::i32), A.getValue(1));
-      return DAG.getMergeValues(
-          {A, DAG.getZExtOrTrunc(B, DL, MVT::i1), A.getValue(2)}, DL);
-    }
+    case Intrinsic::aarch64_rndrrs:
+      return performRNDRCombine(N, DAG);
     case Intrinsic::aarch64_sme_ldr_zt:
       return DAG.getNode(AArch64ISD::RESTORE_ZT, SDLoc(N),
                          DAG.getVTList(MVT::Other), N->getOperand(0),