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   switch (Addr.getOpcode()) {
  83   case ISD::ADD:
  84     if (ConstantSDNode *CN = dyn_cast<ConstantSDNode>(Addr.getOperand(1))) {
  85       uint64_t CVal = CN->getZExtValue();
  86       // Offset should fit into 16 bits.
  87       if (((CVal << 48) >> 48) == CVal) {
  88         // We don't support frame index stuff yet.
  89         if (isa<FrameIndexSDNode>(Addr.getOperand(0)))
  90           return false;
  91
  92         Base = Addr.getOperand(0);
  93         Disp = CurDAG->getTargetConstant(CVal, MVT::i16);
  94
  95         return true;
  96       }
  97     }
  98     break;
  99   case MSP430ISD::Wrapper:
 100     SDValue N0 = Addr.getOperand(0);
 101     if (GlobalAddressSDNode *G = dyn_cast<GlobalAddressSDNode>(N0)) {
 102       // We can match addresses of globals without any offsets
 103       if (!G->getOffset()) {
 104         Base = CurDAG->getTargetGlobalAddress(G->getGlobal(),
 105                                               MVT::i16, 0);
 106         Disp = CurDAG->getTargetConstant(0, MVT::i16);
 107
 108         return true;
 109       }
 110     }
 111     break;
 112   };
 113
 114   Base = Addr;
 115   Disp = CurDAG->getTargetConstant(0, MVT::i16);
 116
 117   return true;
 118 }
 119
 120
 121
 122 /// InstructionSelect - This callback is invoked by
 123 /// SelectionDAGISel when it has created a SelectionDAG for us to codegen.
 124 void MSP430DAGToDAGISel::InstructionSelect() {
 125   DEBUG(BB->dump());
 126
 127   // Select target instructions for the DAG.
 128   SelectRoot(*CurDAG);
 129
 130   CurDAG->RemoveDeadNodes();
 131 }
 132
 133 SDNode *MSP430DAGToDAGISel::Select(SDValue Op) {
 134   SDNode *Node = Op.getNode();
 135
 136   // Dump information about the Node being selected
 137   #ifndef NDEBUG
 138   DOUT << std::string(Indent, ' ') << "Selecting: ";
 139   DEBUG(Node->dump(CurDAG));
 140   DOUT << "\n";
 141   Indent += 2;
 142   #endif
 143
 144   // If we have a custom node, we already have selected!
 145   if (Node->isMachineOpcode()) {
 146     #ifndef NDEBUG
 147     DOUT << std::string(Indent-2, ' ') << "== ";
 148     DEBUG(Node->dump(CurDAG));
 149     DOUT << "\n";
 150     Indent -= 2;
 151     #endif
 152     return NULL;
 153   }
 154
 155   // Instruction Selection not handled by the auto-generated tablegen selection
 156   // should be handled here.
 157   // Something like this:
 158   //   unsigned Opcode = Node->getOpcode();
 159   //   switch (Opcode) {
 160   //   default: break;
 161   //   case ISD::Foo:
 162   //    return SelectFoo(Node)
 163   //  }
 164
 165   // Select the default instruction
 166   SDNode *ResNode = SelectCode(Op);
 167
 168   #ifndef NDEBUG
 169   DOUT << std::string(Indent-2, ' ') << "=> ";
 170   if (ResNode == NULL || ResNode == Op.getNode())
 171     DEBUG(Op.getNode()->dump(CurDAG));
 172   else
 173     DEBUG(ResNode->dump(CurDAG));
 174   DOUT << "\n";
 175   Indent -= 2;
 176   #endif
 177
 178   return ResNode;
 179 }