Re-commit r98683 ("remove redundant writeback flag from ARM address mode 6")
with changes to add a separate optional register update argument.  Change all
the NEON instructions with address register writeback to use it.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@99095 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/ARM/ARMISelDAGToDAG.cpp b/lib/Target/ARM/ARMISelDAGToDAG.cpp
index 0ddf5a0..71207c8 100644
--- a/lib/Target/ARM/ARMISelDAGToDAG.cpp
+++ b/lib/Target/ARM/ARMISelDAGToDAG.cpp
@@ -80,8 +80,7 @@
                        SDValue &Mode);
   bool SelectAddrMode5(SDNode *Op, SDValue N, SDValue &Base,
                        SDValue &Offset);
-  bool SelectAddrMode6(SDNode *Op, SDValue N, SDValue &Addr, SDValue &Update,
-                       SDValue &Opc, SDValue &Align);
+  bool SelectAddrMode6(SDNode *Op, SDValue N, SDValue &Addr, SDValue &Align);
 
   bool SelectAddrModePC(SDNode *Op, SDValue N, SDValue &Offset,
                         SDValue &Label);
@@ -502,12 +501,8 @@
 }
 
 bool ARMDAGToDAGISel::SelectAddrMode6(SDNode *Op, SDValue N,
-                                      SDValue &Addr, SDValue &Update,
-                                      SDValue &Opc, SDValue &Align) {
+                                      SDValue &Addr, SDValue &Align) {
   Addr = N;
-  // Default to no writeback.
-  Update = CurDAG->getRegister(0, MVT::i32);
-  Opc = CurDAG->getTargetConstant(ARM_AM::getAM6Opc(false), MVT::i32);
   // Default to no alignment.
   Align = CurDAG->getTargetConstant(0, MVT::i32);
   return true;
@@ -1030,8 +1025,8 @@
   assert(NumVecs >=2 && NumVecs <= 4 && "VLD NumVecs out-of-range");
   DebugLoc dl = N->getDebugLoc();
 
-  SDValue MemAddr, MemUpdate, MemOpc, Align;
-  if (!SelectAddrMode6(N, N->getOperand(2), MemAddr, MemUpdate, MemOpc, Align))
+  SDValue MemAddr, Align;
+  if (!SelectAddrMode6(N, N->getOperand(2), MemAddr, Align))
     return NULL;
 
   SDValue Chain = N->getOperand(0);
@@ -1055,14 +1050,13 @@
   }
 
   SDValue Pred = CurDAG->getTargetConstant(14, MVT::i32);
-  SDValue PredReg = CurDAG->getRegister(0, MVT::i32);
+  SDValue Reg0 = CurDAG->getRegister(0, MVT::i32);
   if (is64BitVector) {
     unsigned Opc = DOpcodes[OpcodeIndex];
-    const SDValue Ops[] = { MemAddr, MemUpdate, MemOpc, Align,
-                            Pred, PredReg, Chain };
+    const SDValue Ops[] = { MemAddr, Align, Pred, Reg0, Chain };
     std::vector<EVT> ResTys(NumVecs, VT);
     ResTys.push_back(MVT::Other);
-    return CurDAG->getMachineNode(Opc, dl, ResTys, Ops, 7);
+    return CurDAG->getMachineNode(Opc, dl, ResTys, Ops, 5);
   }
 
   EVT RegVT = GetNEONSubregVT(VT);
@@ -1070,11 +1064,10 @@
     // Quad registers are directly supported for VLD2,
     // loading 2 pairs of D regs.
     unsigned Opc = QOpcodes0[OpcodeIndex];
-    const SDValue Ops[] = { MemAddr, MemUpdate, MemOpc, Align,
-                            Pred, PredReg, Chain };
+    const SDValue Ops[] = { MemAddr, Align, Pred, Reg0, Chain };
     std::vector<EVT> ResTys(4, VT);
     ResTys.push_back(MVT::Other);
-    SDNode *VLd = CurDAG->getMachineNode(Opc, dl, ResTys, Ops, 7);
+    SDNode *VLd = CurDAG->getMachineNode(Opc, dl, ResTys, Ops, 5);
     Chain = SDValue(VLd, 4);
 
     // Combine the even and odd subregs to produce the result.
@@ -1086,25 +1079,21 @@
     // Otherwise, quad registers are loaded with two separate instructions,
     // where one loads the even registers and the other loads the odd registers.
 
-    // Enable writeback to the address register.
-    MemOpc = CurDAG->getTargetConstant(ARM_AM::getAM6Opc(true), MVT::i32);
-
     std::vector<EVT> ResTys(NumVecs, RegVT);
     ResTys.push_back(MemAddr.getValueType());
     ResTys.push_back(MVT::Other);
 
     // Load the even subregs.
     unsigned Opc = QOpcodes0[OpcodeIndex];
-    const SDValue OpsA[] = { MemAddr, MemUpdate, MemOpc, Align,
-                             Pred, PredReg, Chain };
-    SDNode *VLdA = CurDAG->getMachineNode(Opc, dl, ResTys, OpsA, 7);
+    const SDValue OpsA[] = { MemAddr, Align, Reg0, Pred, Reg0, Chain };
+    SDNode *VLdA = CurDAG->getMachineNode(Opc, dl, ResTys, OpsA, 6);
     Chain = SDValue(VLdA, NumVecs+1);
 
     // Load the odd subregs.
     Opc = QOpcodes1[OpcodeIndex];
-    const SDValue OpsB[] = { SDValue(VLdA, NumVecs), MemUpdate, MemOpc,
-                             Align, Pred, PredReg, Chain };
-    SDNode *VLdB = CurDAG->getMachineNode(Opc, dl, ResTys, OpsB, 7);
+    const SDValue OpsB[] = { SDValue(VLdA, NumVecs),
+                             Align, Reg0, Pred, Reg0, Chain };
+    SDNode *VLdB = CurDAG->getMachineNode(Opc, dl, ResTys, OpsB, 6);
     Chain = SDValue(VLdB, NumVecs+1);
 
     // Combine the even and odd subregs to produce the result.
@@ -1123,8 +1112,8 @@
   assert(NumVecs >=2 && NumVecs <= 4 && "VST NumVecs out-of-range");
   DebugLoc dl = N->getDebugLoc();
 
-  SDValue MemAddr, MemUpdate, MemOpc, Align;
-  if (!SelectAddrMode6(N, N->getOperand(2), MemAddr, MemUpdate, MemOpc, Align))
+  SDValue MemAddr, Align;
+  if (!SelectAddrMode6(N, N->getOperand(2), MemAddr, Align))
     return NULL;
 
   SDValue Chain = N->getOperand(0);
@@ -1148,12 +1137,10 @@
   }
 
   SDValue Pred = CurDAG->getTargetConstant(14, MVT::i32);
-  SDValue PredReg = CurDAG->getRegister(0, MVT::i32);
+  SDValue Reg0 = CurDAG->getRegister(0, MVT::i32);
 
-  SmallVector<SDValue, 8> Ops;
+  SmallVector<SDValue, 10> Ops;
   Ops.push_back(MemAddr);
-  Ops.push_back(MemUpdate);
-  Ops.push_back(MemOpc);
   Ops.push_back(Align);
 
   if (is64BitVector) {
@@ -1161,9 +1148,9 @@
     for (unsigned Vec = 0; Vec < NumVecs; ++Vec)
       Ops.push_back(N->getOperand(Vec+3));
     Ops.push_back(Pred);
-    Ops.push_back(PredReg);
+    Ops.push_back(Reg0); // predicate register
     Ops.push_back(Chain);
-    return CurDAG->getMachineNode(Opc, dl, MVT::Other, Ops.data(), NumVecs+7);
+    return CurDAG->getMachineNode(Opc, dl, MVT::Other, Ops.data(), NumVecs+5);
   }
 
   EVT RegVT = GetNEONSubregVT(VT);
@@ -1178,40 +1165,37 @@
                                                    N->getOperand(Vec+3)));
     }
     Ops.push_back(Pred);
-    Ops.push_back(PredReg);
+    Ops.push_back(Reg0); // predicate register
     Ops.push_back(Chain);
-    return CurDAG->getMachineNode(Opc, dl, MVT::Other, Ops.data(), 11);
+    return CurDAG->getMachineNode(Opc, dl, MVT::Other, Ops.data(), 9);
   }
 
   // Otherwise, quad registers are stored with two separate instructions,
   // where one stores the even registers and the other stores the odd registers.
 
-  // Enable writeback to the address register.
-  MemOpc = CurDAG->getTargetConstant(ARM_AM::getAM6Opc(true), MVT::i32);
+  Ops.push_back(Reg0); // post-access address offset
 
   // Store the even subregs.
   for (unsigned Vec = 0; Vec < NumVecs; ++Vec)
     Ops.push_back(CurDAG->getTargetExtractSubreg(ARM::DSUBREG_0, dl, RegVT,
                                                  N->getOperand(Vec+3)));
   Ops.push_back(Pred);
-  Ops.push_back(PredReg);
+  Ops.push_back(Reg0); // predicate register
   Ops.push_back(Chain);
   unsigned Opc = QOpcodes0[OpcodeIndex];
   SDNode *VStA = CurDAG->getMachineNode(Opc, dl, MemAddr.getValueType(),
-                                        MVT::Other, Ops.data(), NumVecs+7);
+                                        MVT::Other, Ops.data(), NumVecs+6);
   Chain = SDValue(VStA, 1);
 
   // Store the odd subregs.
   Ops[0] = SDValue(VStA, 0); // MemAddr
   for (unsigned Vec = 0; Vec < NumVecs; ++Vec)
-    Ops[Vec+4] = CurDAG->getTargetExtractSubreg(ARM::DSUBREG_1, dl, RegVT,
+    Ops[Vec+3] = CurDAG->getTargetExtractSubreg(ARM::DSUBREG_1, dl, RegVT,
                                                 N->getOperand(Vec+3));
-  Ops[NumVecs+4] = Pred;
-  Ops[NumVecs+5] = PredReg;
-  Ops[NumVecs+6] = Chain;
+  Ops[NumVecs+5] = Chain;
   Opc = QOpcodes1[OpcodeIndex];
   SDNode *VStB = CurDAG->getMachineNode(Opc, dl, MemAddr.getValueType(),
-                                        MVT::Other, Ops.data(), NumVecs+7);
+                                        MVT::Other, Ops.data(), NumVecs+6);
   Chain = SDValue(VStB, 1);
   ReplaceUses(SDValue(N, 0), Chain);
   return NULL;
@@ -1224,8 +1208,8 @@
   assert(NumVecs >=2 && NumVecs <= 4 && "VLDSTLane NumVecs out-of-range");
   DebugLoc dl = N->getDebugLoc();
 
-  SDValue MemAddr, MemUpdate, MemOpc, Align;
-  if (!SelectAddrMode6(N, N->getOperand(2), MemAddr, MemUpdate, MemOpc, Align))
+  SDValue MemAddr, Align;
+  if (!SelectAddrMode6(N, N->getOperand(2), MemAddr, Align))
     return NULL;
 
   SDValue Chain = N->getOperand(0);
@@ -1259,12 +1243,10 @@
   }
 
   SDValue Pred = CurDAG->getTargetConstant(14, MVT::i32);
-  SDValue PredReg = CurDAG->getRegister(0, MVT::i32);
+  SDValue Reg0 = CurDAG->getRegister(0, MVT::i32);
 
-  SmallVector<SDValue, 9> Ops;
+  SmallVector<SDValue, 10> Ops;
   Ops.push_back(MemAddr);
-  Ops.push_back(MemUpdate);
-  Ops.push_back(MemOpc);
   Ops.push_back(Align);
 
   unsigned Opc = 0;
@@ -1287,16 +1269,16 @@
   }
   Ops.push_back(getI32Imm(Lane));
   Ops.push_back(Pred);
-  Ops.push_back(PredReg);
+  Ops.push_back(Reg0);
   Ops.push_back(Chain);
 
   if (!IsLoad)
-    return CurDAG->getMachineNode(Opc, dl, MVT::Other, Ops.data(), NumVecs+8);
+    return CurDAG->getMachineNode(Opc, dl, MVT::Other, Ops.data(), NumVecs+6);
 
   std::vector<EVT> ResTys(NumVecs, RegVT);
   ResTys.push_back(MVT::Other);
   SDNode *VLdLn =
-    CurDAG->getMachineNode(Opc, dl, ResTys, Ops.data(), NumVecs+8);
+    CurDAG->getMachineNode(Opc, dl, ResTys, Ops.data(), NumVecs+6);
   // For a 64-bit vector load to D registers, nothing more needs to be done.
   if (is64BitVector)
     return VLdLn;