Revert "[ARM] Stop gluing ALU nodes to branches / selects (#116970)"

This reverts commit a348f22.

Author: mstorsjo

llvm/lib/Target/ARM/ARMISelDAGToDAG.cpp

@@ -111,6 +111,13 @@ class ARMDAGToDAGISel : public SelectionDAGISel {
   bool SelectAddrModeImm12(SDValue N, SDValue &Base, SDValue &OffImm);
   bool SelectLdStSOReg(SDValue N, SDValue &Base, SDValue &Offset, SDValue &Opc);
 
+  bool SelectCMOVPred(SDValue N, SDValue &Pred, SDValue &Reg) {
+    const ConstantSDNode *CN = cast<ConstantSDNode>(N);
+    Pred = CurDAG->getTargetConstant(CN->getZExtValue(), SDLoc(N), MVT::i32);
+    Reg = CurDAG->getRegister(ARM::CPSR, MVT::i32);
+    return true;
+  }
+
   bool SelectAddrMode2OffsetReg(SDNode *Op, SDValue N,
                              SDValue &Offset, SDValue &Opc);
   bool SelectAddrMode2OffsetImm(SDNode *Op, SDValue N,
@@ -4116,15 +4123,17 @@ void ARMDAGToDAGISel::Select(SDNode *N) {
     SDValue Chain = N->getOperand(0);
     SDValue N1 = N->getOperand(1);
     SDValue N2 = N->getOperand(2);
-    SDValue Flags = N->getOperand(3);
+    SDValue N3 = N->getOperand(3);
+    SDValue InGlue = N->getOperand(4);
     assert(N1.getOpcode() == ISD::BasicBlock);
     assert(N2.getOpcode() == ISD::Constant);
+    assert(N3.getOpcode() == ISD::Register);
 
     unsigned CC = (unsigned)N2->getAsZExtVal();
 
-    if (Flags.getOpcode() == ARMISD::CMPZ) {
-      if (Flags.getOperand(0).getOpcode() == ISD::INTRINSIC_W_CHAIN) {
-        SDValue Int = Flags.getOperand(0);
+    if (InGlue.getOpcode() == ARMISD::CMPZ) {
+      if (InGlue.getOperand(0).getOpcode() == ISD::INTRINSIC_W_CHAIN) {
+        SDValue Int = InGlue.getOperand(0);
         uint64_t ID = Int->getConstantOperandVal(1);
 
         // Handle low-overhead loops.
@@ -4146,15 +4155,15 @@ void ARMDAGToDAGISel::Select(SDNode *N) {
 
           ReplaceUses(N, LoopEnd);
           CurDAG->RemoveDeadNode(N);
-          CurDAG->RemoveDeadNode(Flags.getNode());
+          CurDAG->RemoveDeadNode(InGlue.getNode());
           CurDAG->RemoveDeadNode(Int.getNode());
           return;
         }
       }
 
       bool SwitchEQNEToPLMI;
-      SelectCMPZ(Flags.getNode(), SwitchEQNEToPLMI);
-      Flags = N->getOperand(3);
+      SelectCMPZ(InGlue.getNode(), SwitchEQNEToPLMI);
+      InGlue = N->getOperand(4);
 
       if (SwitchEQNEToPLMI) {
         switch ((ARMCC::CondCodes)CC) {
@@ -4170,18 +4179,25 @@ void ARMDAGToDAGISel::Select(SDNode *N) {
     }
 
     SDValue Tmp2 = CurDAG->getTargetConstant(CC, dl, MVT::i32);
-    Chain = CurDAG->getCopyToReg(Chain, dl, ARM::CPSR, Flags, SDValue());
-    SDValue Ops[] = {N1, Tmp2, CurDAG->getRegister(ARM::CPSR, MVT::i32), Chain,
-                     Chain.getValue(1)};
-    CurDAG->SelectNodeTo(N, Opc, MVT::Other, Ops);
+    SDValue Ops[] = { N1, Tmp2, N3, Chain, InGlue };
+    SDNode *ResNode = CurDAG->getMachineNode(Opc, dl, MVT::Other,
+                                             MVT::Glue, Ops);
+    Chain = SDValue(ResNode, 0);
+    if (N->getNumValues() == 2) {
+      InGlue = SDValue(ResNode, 1);
+      ReplaceUses(SDValue(N, 1), InGlue);
+    }
+    ReplaceUses(SDValue(N, 0),
+                SDValue(Chain.getNode(), Chain.getResNo()));
+    CurDAG->RemoveDeadNode(N);
     return;
   }
 
   case ARMISD::CMPZ: {
     // select (CMPZ X, #-C) -> (CMPZ (ADDS X, #C), #0)
     //   This allows us to avoid materializing the expensive negative constant.
-    //   The CMPZ #0 is useless and will be peepholed away but we need to keep
-    //   it for its flags output.
+    //   The CMPZ #0 is useless and will be peepholed away but we need to keep it
+    //   for its glue output.
     SDValue X = N->getOperand(0);
     auto *C = dyn_cast<ConstantSDNode>(N->getOperand(1).getNode());
     if (C && C->getSExtValue() < 0 && Subtarget->isThumb()) {
@@ -4208,19 +4224,19 @@ void ARMDAGToDAGISel::Select(SDNode *N) {
       }
       if (Add) {
         SDValue Ops2[] = {SDValue(Add, 0), CurDAG->getConstant(0, dl, MVT::i32)};
-        CurDAG->MorphNodeTo(N, ARMISD::CMPZ, N->getVTList(), Ops2);
+        CurDAG->MorphNodeTo(N, ARMISD::CMPZ, CurDAG->getVTList(MVT::Glue), Ops2);
       }
     }
     // Other cases are autogenerated.
     break;
   }
 
   case ARMISD::CMOV: {
-    SDValue Flags = N->getOperand(3);
+    SDValue InGlue = N->getOperand(4);
 
-    if (Flags.getOpcode() == ARMISD::CMPZ) {
+    if (InGlue.getOpcode() == ARMISD::CMPZ) {
       bool SwitchEQNEToPLMI;
-      SelectCMPZ(Flags.getNode(), SwitchEQNEToPLMI);
+      SelectCMPZ(InGlue.getNode(), SwitchEQNEToPLMI);
 
       if (SwitchEQNEToPLMI) {
         SDValue ARMcc = N->getOperand(2);
@@ -4237,9 +4253,10 @@ void ARMDAGToDAGISel::Select(SDNode *N) {
         }
         SDValue NewARMcc = CurDAG->getConstant((unsigned)CC, dl, MVT::i32);
         SDValue Ops[] = {N->getOperand(0), N->getOperand(1), NewARMcc,
-                         N->getOperand(3)};
+                         N->getOperand(3), N->getOperand(4)};
         CurDAG->MorphNodeTo(N, ARMISD::CMOV, N->getVTList(), Ops);
       }
+
     }
     // Other cases are autogenerated.
     break;