[NFC] Restructure code without changing behavior

Author: heiher

llvm/lib/Target/LoongArch/LoongArchISelLowering.cpp

@@ -4302,65 +4302,66 @@ static SDValue performBITCASTCombine(SDNode *N, SelectionDAG &DAG,
   if (!SrcVT.isSimple() || SrcVT.getScalarType() != MVT::i1)
     return SDValue();
 
-  if (Src.getOpcode() != ISD::SETCC || !Src.hasOneUse())
-    return SDValue();
-
-  bool UseLASX;
-  EVT CmpVT = Src.getOperand(0).getValueType();
-  EVT EltVT = CmpVT.getVectorElementType();
-  if (Subtarget.hasExtLSX() && CmpVT.getSizeInBits() <= 128)
-    UseLASX = false;
-  else if (Subtarget.has32S() && Subtarget.hasExtLASX() &&
-           CmpVT.getSizeInBits() <= 256)
-    UseLASX = true;
-  else
-    return SDValue();
+  unsigned Opc = ISD::DELETED_NODE;
+  // Combine SETCC and BITCAST into [X]VMSK{LT,GE,NE} when possible
+  if (Src.getOpcode() == ISD::SETCC && Src.hasOneUse()) {
+    bool UseLASX;
+    EVT CmpVT = Src.getOperand(0).getValueType();
+    EVT EltVT = CmpVT.getVectorElementType();
+
+    if (Subtarget.hasExtLSX() && CmpVT.getSizeInBits() <= 128)
+      UseLASX = false;
+    else if (Subtarget.has32S() && Subtarget.hasExtLASX() &&
+             CmpVT.getSizeInBits() <= 256)
+      UseLASX = true;
+    else
+      return SDValue();
 
-  unsigned ISD = ISD::DELETED_NODE;
-  SDValue SrcN1 = Src.getOperand(1);
-  switch (cast<CondCodeSDNode>(Src.getOperand(2))->get()) {
-  default:
-    return SDValue();
-  case ISD::SETEQ:
-    // x == 0 => not (vmsknez.b x)
-    if (ISD::isBuildVectorAllZeros(SrcN1.getNode()) && EltVT == MVT::i8)
-      ISD = UseLASX ? LoongArchISD::XVMSKEQZ : LoongArchISD::VMSKEQZ;
-    break;
-  case ISD::SETGT:
-    // x > -1 => vmskgez.b x
-    if (ISD::isBuildVectorAllOnes(SrcN1.getNode()) && EltVT == MVT::i8)
-      ISD = UseLASX ? LoongArchISD::XVMSKGEZ : LoongArchISD::VMSKGEZ;
-    break;
-  case ISD::SETGE:
-    // x >= 0 => vmskgez.b x
-    if (ISD::isBuildVectorAllZeros(SrcN1.getNode()) && EltVT == MVT::i8)
-      ISD = UseLASX ? LoongArchISD::XVMSKGEZ : LoongArchISD::VMSKGEZ;
-    break;
-  case ISD::SETLT:
-    // x < 0 => vmskltz.{b,h,w,d} x
-    if (ISD::isBuildVectorAllZeros(SrcN1.getNode()) &&
-        (EltVT == MVT::i8 || EltVT == MVT::i16 || EltVT == MVT::i32 ||
-         EltVT == MVT::i64))
-      ISD = UseLASX ? LoongArchISD::XVMSKLTZ : LoongArchISD::VMSKLTZ;
-    break;
-  case ISD::SETLE:
-    // x <= -1 => vmskltz.{b,h,w,d} x
-    if (ISD::isBuildVectorAllOnes(SrcN1.getNode()) &&
-        (EltVT == MVT::i8 || EltVT == MVT::i16 || EltVT == MVT::i32 ||
-         EltVT == MVT::i64))
-      ISD = UseLASX ? LoongArchISD::XVMSKLTZ : LoongArchISD::VMSKLTZ;
-    break;
-  case ISD::SETNE:
-    // x != 0 => vmsknez.b x
-    if (ISD::isBuildVectorAllZeros(SrcN1.getNode()) && EltVT == MVT::i8)
-      ISD = UseLASX ? LoongArchISD::XVMSKNEZ : LoongArchISD::VMSKNEZ;
-    break;
+    SDValue SrcN1 = Src.getOperand(1);
+    switch (cast<CondCodeSDNode>(Src.getOperand(2))->get()) {
+    default:
+      break;
+    case ISD::SETEQ:
+      // x == 0 => not (vmsknez.b x)
+      if (ISD::isBuildVectorAllZeros(SrcN1.getNode()) && EltVT == MVT::i8)
+        Opc = UseLASX ? LoongArchISD::XVMSKEQZ : LoongArchISD::VMSKEQZ;
+      break;
+    case ISD::SETGT:
+      // x > -1 => vmskgez.b x
+      if (ISD::isBuildVectorAllOnes(SrcN1.getNode()) && EltVT == MVT::i8)
+        Opc = UseLASX ? LoongArchISD::XVMSKGEZ : LoongArchISD::VMSKGEZ;
+      break;
+    case ISD::SETGE:
+      // x >= 0 => vmskgez.b x
+      if (ISD::isBuildVectorAllZeros(SrcN1.getNode()) && EltVT == MVT::i8)
+        Opc = UseLASX ? LoongArchISD::XVMSKGEZ : LoongArchISD::VMSKGEZ;
+      break;
+    case ISD::SETLT:
+      // x < 0 => vmskltz.{b,h,w,d} x
+      if (ISD::isBuildVectorAllZeros(SrcN1.getNode()) &&
+          (EltVT == MVT::i8 || EltVT == MVT::i16 || EltVT == MVT::i32 ||
+           EltVT == MVT::i64))
+        Opc = UseLASX ? LoongArchISD::XVMSKLTZ : LoongArchISD::VMSKLTZ;
+      break;
+    case ISD::SETLE:
+      // x <= -1 => vmskltz.{b,h,w,d} x
+      if (ISD::isBuildVectorAllOnes(SrcN1.getNode()) &&
+          (EltVT == MVT::i8 || EltVT == MVT::i16 || EltVT == MVT::i32 ||
+           EltVT == MVT::i64))
+        Opc = UseLASX ? LoongArchISD::XVMSKLTZ : LoongArchISD::VMSKLTZ;
+      break;
+    case ISD::SETNE:
+      // x != 0 => vmsknez.b x
+      if (ISD::isBuildVectorAllZeros(SrcN1.getNode()) && EltVT == MVT::i8)
+        Opc = UseLASX ? LoongArchISD::XVMSKNEZ : LoongArchISD::VMSKNEZ;
+      break;
+    }
   }
 
-  if (ISD == ISD::DELETED_NODE)
+  if (Opc == ISD::DELETED_NODE)
     return SDValue();
 
-  SDValue V = DAG.getNode(ISD, DL, MVT::i64, Src.getOperand(0));
+  SDValue V = DAG.getNode(Opc, DL, MVT::i64, Src.getOperand(0));
   EVT T = EVT::getIntegerVT(*DAG.getContext(), SrcVT.getVectorNumElements());
   V = DAG.getZExtOrTrunc(V, DL, T);
   return DAG.getBitcast(VT, V);