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)
  45       : SelectionDAGISel(TM),
  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 &Disp, SDValue &Base);
  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   return new MSP430DAGToDAGISel(TM);
  73 }
  74
  75 bool MSP430DAGToDAGISel::SelectAddr(SDValue Op, SDValue Addr,
  76                                     SDValue &Disp, SDValue &Base) {
  77   // We don't support frame index stuff yet.
  78   if (isa<FrameIndexSDNode>(Addr))
  79     return false;
  80
  81   // Operand is a result from ADD with constant operand which fits into i16.
  82   if (Addr.getOpcode() == ISD::ADD) {
  83     if (ConstantSDNode *CN = dyn_cast<ConstantSDNode>(Addr.getOperand(1))) {
  84       uint64_t CVal = CN->getZExtValue();
  85       // Offset should fit into 16 bits.
  86       if (((CVal << 48) >> 48) == CVal) {
  87         // We don't support frame index stuff yet.
  88         if (isa<FrameIndexSDNode>(Addr.getOperand(0)))
  89           return false;
  90
  91         Base = Addr.getOperand(0);
  92         Disp = CurDAG->getTargetConstant(CVal, MVT::i16);
  93
  94         return true;
  95       }
  96     }
  97   }
  98
  99   Base = Addr;
 100   Disp = CurDAG->getTargetConstant(0, MVT::i16);
 101
 102   return true;
 103 }
 104
 105
 106
 107 /// InstructionSelect - This callback is invoked by
 108 /// SelectionDAGISel when it has created a SelectionDAG for us to codegen.
 109 void MSP430DAGToDAGISel::InstructionSelect() {
 110   DEBUG(BB->dump());
 111
 112   // Select target instructions for the DAG.
 113   SelectRoot(*CurDAG);
 114
 115   CurDAG->RemoveDeadNodes();
 116 }
 117
 118 SDNode *MSP430DAGToDAGISel::Select(SDValue Op) {
 119   SDNode *Node = Op.getNode();
 120
 121   // Dump information about the Node being selected
 122   #ifndef NDEBUG
 123   DOUT << std::string(Indent, ' ') << "Selecting: ";
 124   DEBUG(Node->dump(CurDAG));
 125   DOUT << "\n";
 126   Indent += 2;
 127   #endif
 128
 129   // If we have a custom node, we already have selected!
 130   if (Node->isMachineOpcode()) {
 131     #ifndef NDEBUG
 132     DOUT << std::string(Indent-2, ' ') << "== ";
 133     DEBUG(Node->dump(CurDAG));
 134     DOUT << "\n";
 135     Indent -= 2;
 136     #endif
 137     return NULL;
 138   }
 139
 140   // Instruction Selection not handled by the auto-generated tablegen selection
 141   // should be handled here.
 142   // Something like this:
 143   //   unsigned Opcode = Node->getOpcode();
 144   //   switch (Opcode) {
 145   //   default: break;
 146   //   case ISD::Foo:
 147   //    return SelectFoo(Node)
 148   //  }
 149
 150   // Select the default instruction
 151   SDNode *ResNode = SelectCode(Op);
 152
 153   #ifndef NDEBUG
 154   DOUT << std::string(Indent-2, ' ') << "=> ";
 155   if (ResNode == NULL || ResNode == Op.getNode())
 156     DEBUG(Op.getNode()->dump(CurDAG));
 157   else
 158     DEBUG(ResNode->dump(CurDAG));
 159   DOUT << "\n";
 160   Indent -= 2;
 161   #endif
 162
 163   return ResNode;
 164 }