SelectionDAG.h revision 02b86f52ed19213ef4911da902145155c03fb136 
1//===-- llvm/CodeGen/SelectionDAG.h - InstSelection DAG ---------*- C++ -*-===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file was developed by the LLVM research group and is distributed under
6// the University of Illinois Open Source License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// This file declares the SelectionDAG class, and transitively defines the
11// SDNode class and subclasses.
12//
13//===----------------------------------------------------------------------===//
14
15#ifndef LLVM_CODEGEN_SELECTIONDAG_H
16#define LLVM_CODEGEN_SELECTIONDAG_H
17
18#include "llvm/CodeGen/SelectionDAGNodes.h"
19#include <map>
20#include <string> // FIXME remove eventually, turning map into const char* map.
21
22namespace llvm {
23  class TargetLowering;
24  class TargetMachine;
25  class MachineFunction;
26
27/// SelectionDAG class - This is used to represent a portion of an LLVM function
28/// in a low-level Data Dependence DAG representation suitable for instruction
29/// selection.  This DAG is constructed as the first step of instruction
30/// selection in order to allow implementation of machine specific optimizations
31/// and code simplifications.
32///
33/// The representation used by the SelectionDAG is a target-independent
34/// representation, which has some similarities to the GCC RTL representation,
35/// but is significantly more simple, powerful, and is a graph form instead of a
36/// linear form.
37///
38class SelectionDAG {
39  const TargetMachine &TM;
40  MachineFunction &MF;
41
42  // Root - The root of the entire DAG.  EntryNode - The starting token.
43  SDOperand Root, EntryNode;
44
45  // AllNodes - All of the nodes in the DAG
46  std::vector<SDNode*> AllNodes;
47public:
48  SelectionDAG(const TargetMachine &tm, MachineFunction &mf) : TM(tm), MF(mf) {
49    EntryNode = Root = getNode(ISD::EntryToken, MVT::Other);
50  }
51  ~SelectionDAG();
52
53  MachineFunction &getMachineFunction() const { return MF; }
54  const TargetMachine &getTarget() { return TM; }
55
56  /// viewGraph - Pop up a ghostview window with the DAG rendered using 'dot'.
57  ///
58  void viewGraph();
59
60
61  typedef std::vector<SDNode*>::const_iterator allnodes_iterator;
62  allnodes_iterator allnodes_begin() const { return AllNodes.begin(); }
63  allnodes_iterator allnodes_end() const { return AllNodes.end(); }
64
65  /// getRoot - Return the root tag of the SelectionDAG.
66  ///
67  const SDOperand &getRoot() const { return Root; }
68
69  /// getEntryNode - Return the token chain corresponding to the entry of the
70  /// function.
71  const SDOperand &getEntryNode() const { return EntryNode; }
72
73  /// setRoot - Set the current root tag of the SelectionDAG.
74  ///
75  const SDOperand &setRoot(SDOperand N) { return Root = N; }
76
77  /// Legalize - This transforms the SelectionDAG into a SelectionDAG that is
78  /// compatible with the target instruction selector, as indicated by the
79  /// TargetLowering object.
80  ///
81  /// Note that this is an involved process that may invalidate pointers into
82  /// the graph.
83  void Legalize(TargetLowering &TLI);
84
85  /// RemoveDeadNodes - This method deletes all unreachable nodes in the
86  /// SelectionDAG, including nodes (like loads) that have uses of their token
87  /// chain but no other uses and no side effect.  If a node is passed in as an
88  /// argument, it is used as the seed for node deletion.
89  void RemoveDeadNodes(SDNode *N = 0);
90
91  SDOperand getConstant(uint64_t Val, MVT::ValueType VT);
92  SDOperand getConstantFP(double Val, MVT::ValueType VT);
93  SDOperand getGlobalAddress(const GlobalValue *GV, MVT::ValueType VT);
94  SDOperand getFrameIndex(int FI, MVT::ValueType VT);
95  SDOperand getConstantPool(unsigned CPIdx, MVT::ValueType VT);
96  SDOperand getBasicBlock(MachineBasicBlock *MBB);
97  SDOperand getExternalSymbol(const char *Sym, MVT::ValueType VT);
98
99  SDOperand getCopyToReg(SDOperand Chain, SDOperand N, unsigned Reg) {
100    // Note: these are auto-CSE'd because the caller doesn't make requests that
101    // could cause duplicates to occur.
102    SDNode *NN = new RegSDNode(ISD::CopyToReg, Chain, N, Reg);
103    NN->setValueTypes(MVT::Other);
104    AllNodes.push_back(NN);
105    return SDOperand(NN, 0);
106  }
107
108  SDOperand getCopyFromReg(unsigned Reg, MVT::ValueType VT, SDOperand Chain) {
109    // Note: These nodes are auto-CSE'd by the caller of this method.
110    SDNode *NN = new RegSDNode(ISD::CopyFromReg, Chain, Reg);
111    NN->setValueTypes(VT, MVT::Other);
112    AllNodes.push_back(NN);
113    return SDOperand(NN, 0);
114  }
115
116  SDOperand getImplicitDef(SDOperand Chain, unsigned Reg) {
117    // Note: These nodes are auto-CSE'd by the caller of this method.
118    SDNode *NN = new RegSDNode(ISD::ImplicitDef, Chain, Reg);
119    NN->setValueTypes(MVT::Other);
120    AllNodes.push_back(NN);
121    return SDOperand(NN, 0);
122  }
123
124  /// getCall - Note that this destroys the vector of RetVals passed in.
125  ///
126  SDNode *getCall(std::vector<MVT::ValueType> &RetVals, SDOperand Chain,
127                  SDOperand Callee) {
128    SDNode *NN = new SDNode(ISD::CALL, Chain, Callee);
129    NN->setValueTypes(RetVals);
130    AllNodes.push_back(NN);
131    return NN;
132  }
133
134  /// getCall - This is identical to the one above, and should be used for calls
135  /// where arguments are passed in physical registers.  This destroys the
136  /// RetVals and ArgsInRegs vectors.
137  SDNode *getCall(std::vector<MVT::ValueType> &RetVals, SDOperand Chain,
138                  SDOperand Callee, std::vector<SDOperand> &ArgsInRegs) {
139    ArgsInRegs.insert(ArgsInRegs.begin(), Callee);
140    ArgsInRegs.insert(ArgsInRegs.begin(), Chain);
141    SDNode *NN = new SDNode(ISD::CALL, ArgsInRegs);
142    NN->setValueTypes(RetVals);
143    AllNodes.push_back(NN);
144    return NN;
145  }
146
147
148  SDOperand getSetCC(ISD::CondCode, MVT::ValueType VT,
149                     SDOperand LHS, SDOperand RHS);
150
151  /// getNode - Gets or creates the specified node.
152  ///
153  SDOperand getNode(unsigned Opcode, MVT::ValueType VT);
154  SDOperand getNode(unsigned Opcode, MVT::ValueType VT, SDOperand N);
155  SDOperand getNode(unsigned Opcode, MVT::ValueType VT,
156                    SDOperand N1, SDOperand N2);
157  SDOperand getNode(unsigned Opcode, MVT::ValueType VT,
158                    SDOperand N1, SDOperand N2, SDOperand N3);
159  SDOperand getNode(unsigned Opcode, MVT::ValueType VT,
160                    std::vector<SDOperand> &Children);
161
162  // getNode - These versions take an extra value type for extending and
163  // truncating loads, stores, rounds, extends etc.
164  SDOperand getNode(unsigned Opcode, MVT::ValueType VT, SDOperand N1,
165                    SDOperand N2, MVT::ValueType EVT);
166  SDOperand getNode(unsigned Opcode, MVT::ValueType VT,
167                    SDOperand N, MVT::ValueType EVT);
168  SDOperand getNode(unsigned Opcode, MVT::ValueType VT, SDOperand N1,
169                    SDOperand N2, SDOperand N3, MVT::ValueType EVT);
170
171  /// getLoad - Loads are not normal binary operators: their result type is not
172  /// determined by their operands, and they produce a value AND a token chain.
173  ///
174  SDOperand getLoad(MVT::ValueType VT, SDOperand Chain, SDOperand Ptr);
175
176  void replaceAllUsesWith(SDOperand Old, SDOperand New) {
177    assert(Old != New && "RAUW self!");
178    assert(0 && "Unimplemented!");
179  }
180
181  void dump() const;
182
183private:
184  void DeleteNodeIfDead(SDNode *N, void *NodeSet);
185
186  // Maps to auto-CSE operations.
187  std::map<std::pair<unsigned, std::pair<SDOperand, MVT::ValueType> >,
188           SDNode *> UnaryOps;
189  std::map<std::pair<unsigned, std::pair<SDOperand, SDOperand> >,
190           SDNode *> BinaryOps;
191
192  std::map<std::pair<std::pair<SDOperand, SDOperand>,
193                     std::pair<ISD::CondCode, MVT::ValueType> >,
194           SetCCSDNode*> SetCCs;
195
196  std::map<std::pair<SDOperand, std::pair<SDOperand, MVT::ValueType> >,
197           SDNode *> Loads;
198
199  std::map<const GlobalValue*, SDNode*> GlobalValues;
200  std::map<std::pair<uint64_t, MVT::ValueType>, SDNode*> Constants;
201  std::map<std::pair<double, MVT::ValueType>, SDNode*> ConstantFPs;
202  std::map<int, SDNode*> FrameIndices;
203  std::map<unsigned, SDNode*> ConstantPoolIndices;
204  std::map<MachineBasicBlock *, SDNode*> BBNodes;
205  std::map<std::string, SDNode*> ExternalSymbols;
206  struct EVTStruct {
207    unsigned Opcode;
208    MVT::ValueType VT, EVT;
209    std::vector<SDOperand> Ops;
210    bool operator<(const EVTStruct &RHS) const {
211      if (Opcode < RHS.Opcode) return true;
212      if (Opcode > RHS.Opcode) return false;
213      if (VT < RHS.VT) return true;
214      if (VT > RHS.VT) return false;
215      if (EVT < RHS.EVT) return true;
216      if (EVT > RHS.EVT) return false;
217      return Ops < RHS.Ops;
218    }
219  };
220  std::map<EVTStruct, SDNode*> MVTSDNodes;
221};
222
223template <> struct GraphTraits<SelectionDAG*> : public GraphTraits<SDNode*> {
224  typedef SelectionDAG::allnodes_iterator nodes_iterator;
225  static nodes_iterator nodes_begin(SelectionDAG *G) {
226    return G->allnodes_begin();
227  }
228  static nodes_iterator nodes_end(SelectionDAG *G) {
229    return G->allnodes_end();
230  }
231};
232
233}
234
235#endif
236