refactor divrem8 lowering; NFCI

The code duplication contributed to PR25754:
https://llvm.org/bugs/show_bug.cgi?id=25754

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@256957 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Target/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp
index d31aab0fa141f0772603daa30c86c4d87ea0b30c..9b379aec4031e3d9658a7712ef00c1880302a411 100644 (file)
--- a/lib/Target/X86/X86ISelLowering.cpp
+++ b/lib/Target/X86/X86ISelLowering.cpp
@@ -27233,6 +27233,32 @@ static SDValue promoteSextBeforeAddNSW(SDNode *Sext, SelectionDAG &DAG,
   return DAG.getNode(ISD::ADD, SDLoc(Add), VT, NewSext, NewConstant, &Flags);
 }
 
+/// (i8,i32 {s/z}ext ({s/u}divrem (i8 x, i8 y)) ->
+/// (i8,i32 ({s/u}divrem_sext_hreg (i8 x, i8 y)
+/// This exposes the {s/z}ext to the sdivrem lowering, so that it directly
+/// extends from AH (which we otherwise need to do contortions to access).
+static SDValue getDivRem8(SDNode *N, SelectionDAG &DAG) {
+  SDValue N0 = N->getOperand(0);
+  auto OpcodeN = N->getOpcode();
+  auto OpcodeN0 = N0.getOpcode();
+  if (!((OpcodeN == ISD::SIGN_EXTEND && OpcodeN0 == ISD::SDIVREM) ||
+        (OpcodeN == ISD::ZERO_EXTEND && OpcodeN0 == ISD::UDIVREM)))
+    return SDValue();
+
+  EVT VT = N->getValueType(0);
+  EVT InVT = N0.getValueType();
+  if (N0.getResNo() != 1 || InVT != MVT::i8 || VT != MVT::i32)
+    return SDValue();
+
+  SDVTList NodeTys = DAG.getVTList(MVT::i8, VT);
+  auto DivRemOpcode = OpcodeN0 == ISD::SDIVREM ? X86ISD::SDIVREM8_SEXT_HREG
+                                               : X86ISD::UDIVREM8_ZEXT_HREG;
+  SDValue R = DAG.getNode(DivRemOpcode, SDLoc(N), NodeTys, N0.getOperand(0),
+                          N0.getOperand(1));
+  DAG.ReplaceAllUsesOfValueWith(N0.getValue(0), R.getValue(0));
+  return R.getValue(1);
+}
+
 static SDValue PerformSExtCombine(SDNode *N, SelectionDAG &DAG,
                                   TargetLowering::DAGCombinerInfo &DCI,
                                   const X86Subtarget *Subtarget) {
@@ -27243,18 +27269,8 @@ static SDValue PerformSExtCombine(SDNode *N, SelectionDAG &DAG,
   EVT InSVT = InVT.getScalarType();
   SDLoc DL(N);
 
-  // (i8,i32 sext (sdivrem (i8 x, i8 y)) ->
-  // (i8,i32 (sdivrem_sext_hreg (i8 x, i8 y)
-  // This exposes the sext to the sdivrem lowering, so that it directly extends
-  // from AH (which we otherwise need to do contortions to access).
-  if (N0.getOpcode() == ISD::SDIVREM && N0.getResNo() == 1 &&
-      InVT == MVT::i8 && VT == MVT::i32) {
-    SDVTList NodeTys = DAG.getVTList(MVT::i8, VT);
-    SDValue R = DAG.getNode(X86ISD::SDIVREM8_SEXT_HREG, DL, NodeTys,
-                            N0.getOperand(0), N0.getOperand(1));
-    DAG.ReplaceAllUsesOfValueWith(N0.getValue(0), R.getValue(0));
-    return R.getValue(1);
-  }
+  if (SDValue DivRem8 = getDivRem8(N, DAG))
+    return DivRem8;
 
   if (!DCI.isBeforeLegalizeOps()) {
     if (InVT == MVT::i1) {
@@ -27413,19 +27429,8 @@ static SDValue PerformZExtCombine(SDNode *N, SelectionDAG &DAG,
     if (SDValue R = WidenMaskArithmetic(N, DAG, DCI, Subtarget))
       return R;
 
-  // (i8,i32 zext (udivrem (i8 x, i8 y)) ->
-  // (i8,i32 (udivrem_zext_hreg (i8 x, i8 y)
-  // This exposes the zext to the udivrem lowering, so that it directly extends
-  // from AH (which we otherwise need to do contortions to access).
-  if (N0.getOpcode() == ISD::UDIVREM &&
-      N0.getResNo() == 1 && N0.getValueType() == MVT::i8 &&
-      VT == MVT::i32) {
-    SDVTList NodeTys = DAG.getVTList(MVT::i8, VT);
-    SDValue R = DAG.getNode(X86ISD::UDIVREM8_ZEXT_HREG, dl, NodeTys,
-                            N0.getOperand(0), N0.getOperand(1));
-    DAG.ReplaceAllUsesOfValueWith(N0.getValue(0), R.getValue(0));
-    return R.getValue(1);
-  }
+  if (SDValue DivRem8 = getDivRem8(N, DAG))
+    return DivRem8;
 
   return SDValue();
 }
@@ -27923,7 +27928,6 @@ SDValue X86TargetLowering::PerformDAGCombine(SDNode *N,
   case X86ISD::FANDN:       return PerformFANDNCombine(N, DAG, Subtarget);
   case X86ISD::BT:          return PerformBTCombine(N, DAG, DCI);
   case X86ISD::VZEXT_MOVL:  return PerformVZEXT_MOVLCombine(N, DAG);
-// TODO: refactor the [SU]DIVREM8_[SZ]EXT_HREG code so that it's not duplicated.
   case ISD::ANY_EXTEND:
   case ISD::ZERO_EXTEND:    return PerformZExtCombine(N, DAG, DCI, Subtarget);
   case ISD::SIGN_EXTEND:    return PerformSExtCombine(N, DAG, DCI, Subtarget);