MSP430ISelDAGToDAG.cpp revision cf14ae550051002283eabfb4dcbd67fa71f46f67 
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 &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  return new MSP430DAGToDAGISel(TM);
73}
74
75// FIXME: This is pretty dummy routine and needs to be rewritten in the future.
76bool MSP430DAGToDAGISel::SelectAddr(SDValue Op, SDValue Addr,
77                                    SDValue &Base, SDValue &Disp) {
78  // We don't support frame index stuff yet.
79  if (isa<FrameIndexSDNode>(Addr))
80    return false;
81
82  // Operand is a result from ADD with constant operand which fits into i16.
83  switch (Addr.getOpcode()) {
84  case ISD::ADD:
85    if (ConstantSDNode *CN = dyn_cast<ConstantSDNode>(Addr.getOperand(1))) {
86      uint64_t CVal = CN->getZExtValue();
87      // Offset should fit into 16 bits.
88      if (((CVal << 48) >> 48) == CVal) {
89        // We don't support frame index stuff yet.
90        if (isa<FrameIndexSDNode>(Addr.getOperand(0)))
91          return false;
92
93        Base = Addr.getOperand(0);
94        Disp = CurDAG->getTargetConstant(CVal, MVT::i16);
95
96        return true;
97      }
98    }
99    break;
100  case MSP430ISD::Wrapper:
101    SDValue N0 = Addr.getOperand(0);
102    if (GlobalAddressSDNode *G = dyn_cast<GlobalAddressSDNode>(N0)) {
103      Base = CurDAG->getTargetGlobalAddress(G->getGlobal(),
104                                            MVT::i16, G->getOffset());
105      Disp = CurDAG->getTargetConstant(0, MVT::i16);
106
107      return true;
108    }
109    break;
110  };
111
112  Base = Addr;
113  Disp = CurDAG->getTargetConstant(0, MVT::i16);
114
115  return true;
116}
117
118
119
120/// InstructionSelect - This callback is invoked by
121/// SelectionDAGISel when it has created a SelectionDAG for us to codegen.
122void MSP430DAGToDAGISel::InstructionSelect() {
123  DEBUG(BB->dump());
124
125  // Select target instructions for the DAG.
126  SelectRoot(*CurDAG);
127
128  CurDAG->RemoveDeadNodes();
129}
130
131SDNode *MSP430DAGToDAGISel::Select(SDValue Op) {
132  SDNode *Node = Op.getNode();
133
134  // Dump information about the Node being selected
135  #ifndef NDEBUG
136  DOUT << std::string(Indent, ' ') << "Selecting: ";
137  DEBUG(Node->dump(CurDAG));
138  DOUT << "\n";
139  Indent += 2;
140  #endif
141
142  // If we have a custom node, we already have selected!
143  if (Node->isMachineOpcode()) {
144    #ifndef NDEBUG
145    DOUT << std::string(Indent-2, ' ') << "== ";
146    DEBUG(Node->dump(CurDAG));
147    DOUT << "\n";
148    Indent -= 2;
149    #endif
150    return NULL;
151  }
152
153  // Instruction Selection not handled by the auto-generated tablegen selection
154  // should be handled here.
155  // Something like this:
156  //   unsigned Opcode = Node->getOpcode();
157  //   switch (Opcode) {
158  //   default: break;
159  //   case ISD::Foo:
160  //    return SelectFoo(Node)
161  //  }
162
163  // Select the default instruction
164  SDNode *ResNode = SelectCode(Op);
165
166  #ifndef NDEBUG
167  DOUT << std::string(Indent-2, ' ') << "=> ";
168  if (ResNode == NULL || ResNode == Op.getNode())
169    DEBUG(Op.getNode()->dump(CurDAG));
170  else
171    DEBUG(ResNode->dump(CurDAG));
172  DOUT << "\n";
173  Indent -= 2;
174  #endif
175
176  return ResNode;
177}
178