[AArch64] Refactor opcode selection for LowerMUL (NFC)

Move the logic for selecting `NewOpc` out of `LowerMUL`

Reviewed By: fhahn

Differential Revision: https://reviews.llvm.org/D134875

diff --git a/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp b/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
index 5d0866e..c391974 100644 (file)
--- a/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
+++ b/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
@@ -4377,6 +4377,39 @@ SDValue AArch64TargetLowering::LowerSET_ROUNDING(SDValue Op,
   return DAG.getNode(ISD::INTRINSIC_VOID, DL, MVT::Other, Ops2);
 }
 
+static unsigned selectUmullSmull(SDNode *&N0, SDNode *&N1, SelectionDAG &DAG,
+                                 bool &IsMLA) {
+  bool IsN0SExt = isSignExtended(N0, DAG);
+  bool IsN1SExt = isSignExtended(N1, DAG);
+  if (IsN0SExt && IsN1SExt)
+    return AArch64ISD::SMULL;
+
+  bool IsN0ZExt = isZeroExtended(N0, DAG);
+  bool IsN1ZExt = isZeroExtended(N1, DAG);
+
+  if (IsN0ZExt && IsN1ZExt)
+    return AArch64ISD::UMULL;
+
+  if (!IsN1SExt && !IsN1ZExt)
+    return 0;
+  // Look for (s/zext A + s/zext B) * (s/zext C). We want to turn these
+  // into (s/zext A * s/zext C) + (s/zext B * s/zext C)
+  if (IsN1SExt && isAddSubSExt(N0, DAG)) {
+    IsMLA = true;
+    return AArch64ISD::SMULL;
+  }
+  if (IsN1ZExt && isAddSubZExt(N0, DAG)) {
+    IsMLA = true;
+    return AArch64ISD::UMULL;
+  }
+  if (IsN0ZExt && isAddSubZExt(N1, DAG)) {
+    std::swap(N0, N1);
+    IsMLA = true;
+    return AArch64ISD::UMULL;
+  }
+  return 0;
+}
+
 SDValue AArch64TargetLowering::LowerMUL(SDValue Op, SelectionDAG &DAG) const {
   EVT VT = Op.getValueType();
 
@@ -4392,41 +4425,16 @@ SDValue AArch64TargetLowering::LowerMUL(SDValue Op, SelectionDAG &DAG) const {
          "unexpected type for custom-lowering ISD::MUL");
   SDNode *N0 = Op.getOperand(0).getNode();
   SDNode *N1 = Op.getOperand(1).getNode();
-  unsigned NewOpc = 0;
   bool isMLA = false;
-  bool isN0SExt = isSignExtended(N0, DAG);
-  bool isN1SExt = isSignExtended(N1, DAG);
-  if (isN0SExt && isN1SExt)
-    NewOpc = AArch64ISD::SMULL;
-  else {
-    bool isN0ZExt = isZeroExtended(N0, DAG);
-    bool isN1ZExt = isZeroExtended(N1, DAG);
-    if (isN0ZExt && isN1ZExt)
-      NewOpc = AArch64ISD::UMULL;
-    else if (isN1SExt || isN1ZExt) {
-      // Look for (s/zext A + s/zext B) * (s/zext C). We want to turn these
-      // into (s/zext A * s/zext C) + (s/zext B * s/zext C)
-      if (isN1SExt && isAddSubSExt(N0, DAG)) {
-        NewOpc = AArch64ISD::SMULL;
-        isMLA = true;
-      } else if (isN1ZExt && isAddSubZExt(N0, DAG)) {
-        NewOpc =  AArch64ISD::UMULL;
-        isMLA = true;
-      } else if (isN0ZExt && isAddSubZExt(N1, DAG)) {
-        std::swap(N0, N1);
-        NewOpc =  AArch64ISD::UMULL;
-        isMLA = true;
-      }
-    }
+  unsigned NewOpc = selectUmullSmull(N0, N1, DAG, isMLA);
 
-    if (!NewOpc) {
-      if (VT == MVT::v2i64)
-        // Fall through to expand this.  It is not legal.
-        return SDValue();
-      else
-        // Other vector multiplications are legal.
-        return Op;
-    }
+  if (!NewOpc) {
+    if (VT == MVT::v2i64)
+      // Fall through to expand this.  It is not legal.
+      return SDValue();
+    else
+      // Other vector multiplications are legal.
+      return Op;
   }
 
   // Legalize to a S/UMULL instruction