MSP430ISelDAGToDAG.cpp revision 0eb6af40e3f7ea5949667bd90d5eb39df125e593 
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>
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)
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///
71FunctionPass *llvm::createMSP430ISelDag(MSP430TargetMachine &TM) {
72  return new MSP430DAGToDAGISel(TM);
73}
74
75bool 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.
124void MSP430DAGToDAGISel::InstructionSelect() {
125  DEBUG(BB->dump());
126
127  // Select target instructions for the DAG.
128  SelectRoot(*CurDAG);
129
130  CurDAG->RemoveDeadNodes();
131}
132
133SDNode *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}
180