lib/Target/MSP430/MSP430ISelDAGToDAG.cpp

   1 //===-- MSP430ISelDAGToDAG.cpp - A dag to dag inst selector for MSP430 ----===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file is distributed under the University of Illinois Open Source
   6 // License. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9 //
  10 // This file defines an instruction selector for the MSP430 target.
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  14 #include "MSP430.h"
  15 #include "MSP430ISelLowering.h"
  16 #include "MSP430TargetMachine.h"
  17 #include "llvm/DerivedTypes.h"
  18 #include "llvm/Function.h"
  19 #include "llvm/Intrinsics.h"
  20 #include "llvm/CallingConv.h"
  21 #include "llvm/Constants.h"
  22 #include "llvm/CodeGen/MachineFrameInfo.h"
  23 #include "llvm/CodeGen/MachineFunction.h"
  24 #include "llvm/CodeGen/MachineInstrBuilder.h"
  25 #include "llvm/CodeGen/MachineRegisterInfo.h"
  26 #include "llvm/CodeGen/SelectionDAG.h"
  27 #include "llvm/CodeGen/SelectionDAGISel.h"
  28 #include "llvm/Target/TargetLowering.h"
  29 #include "llvm/Support/Compiler.h"
  30 #include "llvm/Support/Debug.h"
  31 #include <queue>
  32 #include <set>
  33 using namespace llvm;
  34
  35 /// MSP430DAGToDAGISel - MSP430 specific code to select MSP430 machine
  36 /// instructions for SelectionDAG operations.
  37 ///
  38 namespace {
  39   class MSP430DAGToDAGISel : public SelectionDAGISel {
  40     MSP430TargetLowering &Lowering;
  41     const MSP430Subtarget &Subtarget;
  42
  43   public:
  44     MSP430DAGToDAGISel(MSP430TargetMachine &TM, CodeGenOpt::Level OptLevel)
  45       : SelectionDAGISel(TM, OptLevel),
  46         Lowering(*TM.getTargetLowering()),
  47         Subtarget(*TM.getSubtargetImpl()) { }
  48
  49     virtual void InstructionSelect();
  50
  51     virtual const char *getPassName() const {
  52       return "MSP430 DAG->DAG Pattern Instruction Selection";
  53     }
  54
  55     // Include the pieces autogenerated from the target description.
  56   #include "MSP430GenDAGISel.inc"
  57
  58   private:
  59     SDNode *Select(SDValue Op);
  60     bool SelectAddr(SDValue Op, SDValue Addr, SDValue &Base, SDValue &Disp);
  61
  62   #ifndef NDEBUG
  63     unsigned Indent;
  64   #endif
  65   };
  66 }  // end anonymous namespace
  67
  68 /// createMSP430ISelDag - This pass converts a legalized DAG into a
  69 /// MSP430-specific DAG, ready for instruction scheduling.
  70 ///
  71 FunctionPass *llvm::createMSP430ISelDag(MSP430TargetMachine &TM,
  72                                         CodeGenOpt::Level OptLevel) {
  73   return new MSP430DAGToDAGISel(TM, OptLevel);
  74 }
  75
  76 // FIXME: This is pretty dummy routine and needs to be rewritten in the future.
  77 bool MSP430DAGToDAGISel::SelectAddr(SDValue Op, SDValue Addr,
  78                                     SDValue &Base, SDValue &Disp) {
  79   // Try to match frame address first.
  80   if (FrameIndexSDNode *FIN = dyn_cast<FrameIndexSDNode>(Addr)) {
  81     Base = CurDAG->getTargetFrameIndex(FIN->getIndex(), MVT::i16);
  82     Disp = CurDAG->getTargetConstant(0, MVT::i16);
  83     return true;
  84   }
  85
  86   switch (Addr.getOpcode()) {
  87   case ISD::ADD:
  88    // Operand is a result from ADD with constant operand which fits into i16.
  89    if (ConstantSDNode *CN = dyn_cast<ConstantSDNode>(Addr.getOperand(1))) {
  90       uint64_t CVal = CN->getZExtValue();
  91       // Offset should fit into 16 bits.
  92       if (((CVal << 48) >> 48) == CVal) {
  93         SDValue N0 = Addr.getOperand(0);
  94         if (FrameIndexSDNode *FIN = dyn_cast<FrameIndexSDNode>(N0))
  95           Base = CurDAG->getTargetFrameIndex(FIN->getIndex(), MVT::i16);
  96         else
  97           Base = N0;
  98
  99         Disp = CurDAG->getTargetConstant(CVal, MVT::i16);
 100         return true;
 101       }
 102     }
 103     break;
 104   case MSP430ISD::Wrapper:
 105     SDValue N0 = Addr.getOperand(0);
 106     if (GlobalAddressSDNode *G = dyn_cast<GlobalAddressSDNode>(N0)) {
 107       Base = CurDAG->getTargetGlobalAddress(G->getGlobal(),
 108                                             MVT::i16, G->getOffset());
 109       Disp = CurDAG->getTargetConstant(0, MVT::i16);
 110       return true;
 111     } else if (ExternalSymbolSDNode *E = dyn_cast<ExternalSymbolSDNode>(N0)) {
 112       Base = CurDAG->getTargetExternalSymbol(E->getSymbol(), MVT::i16);
 113       Disp = CurDAG->getTargetConstant(0, MVT::i16);
 114     }
 115     break;
 116   };
 117
 118   Base = Addr;
 119   Disp = CurDAG->getTargetConstant(0, MVT::i16);
 120
 121   return true;
 122 }
 123
 124
 125
 126 /// InstructionSelect - This callback is invoked by
 127 /// SelectionDAGISel when it has created a SelectionDAG for us to codegen.
 128 void MSP430DAGToDAGISel::InstructionSelect() {
 129   DEBUG(BB->dump());
 130
 131   // Codegen the basic block.
 132 #ifndef NDEBUG
 133   DOUT << "===== Instruction selection begins:\n";
 134   Indent = 0;
 135 #endif
 136   SelectRoot(*CurDAG);
 137 #ifndef NDEBUG
 138   DOUT << "===== Instruction selection ends:\n";
 139 #endif
 140
 141   CurDAG->RemoveDeadNodes();
 142 }
 143
 144 SDNode *MSP430DAGToDAGISel::Select(SDValue Op) {
 145   SDNode *Node = Op.getNode();
 146   DebugLoc dl = Op.getDebugLoc();
 147
 148   // Dump information about the Node being selected
 149   #ifndef NDEBUG
 150   DOUT << std::string(Indent, ' ') << "Selecting: ";
 151   DEBUG(Node->dump(CurDAG));
 152   DOUT << "\n";
 153   Indent += 2;
 154   #endif
 155
 156   // If we have a custom node, we already have selected!
 157   if (Node->isMachineOpcode()) {
 158     #ifndef NDEBUG
 159     DOUT << std::string(Indent-2, ' ') << "== ";
 160     DEBUG(Node->dump(CurDAG));
 161     DOUT << "\n";
 162     Indent -= 2;
 163     #endif
 164     return NULL;
 165   }
 166
 167   // Few custom selection stuff.
 168   switch (Node->getOpcode()) {
 169   default: break;
 170   case ISD::FrameIndex: {
 171     assert(Op.getValueType() == MVT::i16);
 172     int FI = cast<FrameIndexSDNode>(Node)->getIndex();
 173     SDValue TFI = CurDAG->getTargetFrameIndex(FI, MVT::i16);
 174     if (Node->hasOneUse())
 175       return CurDAG->SelectNodeTo(Node, MSP430::ADD16ri, MVT::i16,
 176                                   TFI, CurDAG->getTargetConstant(0, MVT::i16));
 177     return CurDAG->getTargetNode(MSP430::ADD16ri, dl, MVT::i16,
 178                                  TFI, CurDAG->getTargetConstant(0, MVT::i16));
 179   }
 180   }
 181
 182   // Select the default instruction
 183   SDNode *ResNode = SelectCode(Op);
 184
 185   #ifndef NDEBUG
 186   DOUT << std::string(Indent-2, ' ') << "=> ";
 187   if (ResNode == NULL || ResNode == Op.getNode())
 188     DEBUG(Op.getNode()->dump(CurDAG));
 189   else
 190     DEBUG(ResNode->dump(CurDAG));
 191   DOUT << "\n";
 192   Indent -= 2;
 193   #endif
 194
 195   return ResNode;
 196 }