MSP430ISelDAGToDAG.cpp revision 602b0c8c17f458d2c80f2deb3c8e554d516ee316 
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(), 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.
128void MSP430DAGToDAGISel::InstructionSelect() {
129  DEBUG(BB->dump());
130
131  // Codegen the basic block.
132  DEBUG(errs() << "===== Instruction selection begins:\n");
133  DEBUG(Indent = 0);
134  SelectRoot(*CurDAG);
135  DEBUG(errs() << "===== Instruction selection ends:\n");
136
137  CurDAG->RemoveDeadNodes();
138}
139
140SDNode *MSP430DAGToDAGISel::Select(SDValue Op) {
141  SDNode *Node = Op.getNode();
142  DebugLoc dl = Op.getDebugLoc();
143
144  // Dump information about the Node being selected
145  DEBUG(errs().indent(Indent) << "Selecting: ");
146  DEBUG(Node->dump(CurDAG));
147  DEBUG(errs() << "\n");
148  DEBUG(Indent += 2);
149
150  // If we have a custom node, we already have selected!
151  if (Node->isMachineOpcode()) {
152    DEBUG(errs().indent(Indent-2) << "== ";
153          Node->dump(CurDAG);
154          errs() << "\n");
155    DEBUG(Indent -= 2);
156    return NULL;
157  }
158
159  // Few custom selection stuff.
160  switch (Node->getOpcode()) {
161  default: break;
162  case ISD::FrameIndex: {
163    assert(Op.getValueType() == MVT::i16);
164    int FI = cast<FrameIndexSDNode>(Node)->getIndex();
165    SDValue TFI = CurDAG->getTargetFrameIndex(FI, MVT::i16);
166    if (Node->hasOneUse())
167      return CurDAG->SelectNodeTo(Node, MSP430::ADD16ri, MVT::i16,
168                                  TFI, CurDAG->getTargetConstant(0, MVT::i16));
169    return CurDAG->getMachineNode(MSP430::ADD16ri, dl, MVT::i16,
170                                  TFI, CurDAG->getTargetConstant(0, MVT::i16));
171  }
172  }
173
174  // Select the default instruction
175  SDNode *ResNode = SelectCode(Op);
176
177  DEBUG(errs() << std::string(Indent-2, ' ') << "=> ");
178  if (ResNode == NULL || ResNode == Op.getNode())
179    DEBUG(Op.getNode()->dump(CurDAG));
180  else
181    DEBUG(ResNode->dump(CurDAG));
182  DEBUG(errs() << "\n");
183  DEBUG(Indent -= 2);
184
185  return ResNode;
186}
187