MSP430ISelDAGToDAG.cpp revision e50ed30282bb5b4a9ed952580523f2dda16215ac 
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 "llvm/Support/ErrorHandling.h"
32#include "llvm/Support/raw_ostream.h"
33using namespace llvm;
34
35/// MSP430DAGToDAGISel - MSP430 specific code to select MSP430 machine
36/// instructions for SelectionDAG operations.
37///
38namespace {
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///
71FunctionPass *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.
77bool 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(), EVT::i16);
82    Disp = CurDAG->getTargetConstant(0, EVT::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(), EVT::i16);
96        else
97          Base = N0;
98
99        Disp = CurDAG->getTargetConstant(CVal, EVT::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                                            EVT::i16, G->getOffset());
109      Disp = CurDAG->getTargetConstant(0, EVT::i16);
110      return true;
111    } else if (ExternalSymbolSDNode *E = dyn_cast<ExternalSymbolSDNode>(N0)) {
112      Base = CurDAG->getTargetExternalSymbol(E->getSymbol(), EVT::i16);
113      Disp = CurDAG->getTargetConstant(0, EVT::i16);
114    }
115    break;
116  };
117
118  Base = Addr;
119  Disp = CurDAG->getTargetConstant(0, EVT::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.
128void 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
144SDNode *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() == EVT::i16);
172    int FI = cast<FrameIndexSDNode>(Node)->getIndex();
173    SDValue TFI = CurDAG->getTargetFrameIndex(FI, EVT::i16);
174    if (Node->hasOneUse())
175      return CurDAG->SelectNodeTo(Node, MSP430::ADD16ri, EVT::i16,
176                                  TFI, CurDAG->getTargetConstant(0, EVT::i16));
177    return CurDAG->getTargetNode(MSP430::ADD16ri, dl, EVT::i16,
178                                 TFI, CurDAG->getTargetConstant(0, EVT::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}
197