SelectionDAG.h revision 15e4b01920d6a0ffbe35d3e5aa88a4b42970b6a7 
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  TargetLowering &TLI;
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;
47
48  // ValueNodes - track SrcValue nodes
49  std::map<std::pair<const Value*, int>, SDNode*> ValueNodes;
50
51public:
52  SelectionDAG(TargetLowering &tli, MachineFunction &mf) : TLI(tli), MF(mf) {
53    EntryNode = Root = getNode(ISD::EntryToken, MVT::Other);
54  }
55  ~SelectionDAG();
56
57  MachineFunction &getMachineFunction() const { return MF; }
58  const TargetMachine &getTarget() const;
59  TargetLowering &getTargetLoweringInfo() const { return TLI; }
60
61  /// viewGraph - Pop up a ghostview window with the DAG rendered using 'dot'.
62  ///
63  void viewGraph();
64
65
66  typedef std::vector<SDNode*>::const_iterator allnodes_iterator;
67  allnodes_iterator allnodes_begin() const { return AllNodes.begin(); }
68  allnodes_iterator allnodes_end() const { return AllNodes.end(); }
69
70  /// getRoot - Return the root tag of the SelectionDAG.
71  ///
72  const SDOperand &getRoot() const { return Root; }
73
74  /// getEntryNode - Return the token chain corresponding to the entry of the
75  /// function.
76  const SDOperand &getEntryNode() const { return EntryNode; }
77
78  /// setRoot - Set the current root tag of the SelectionDAG.
79  ///
80  const SDOperand &setRoot(SDOperand N) { return Root = N; }
81
82  /// Legalize - This transforms the SelectionDAG into a SelectionDAG that is
83  /// compatible with the target instruction selector, as indicated by the
84  /// TargetLowering object.
85  ///
86  /// Note that this is an involved process that may invalidate pointers into
87  /// the graph.
88  void Legalize();
89
90  /// RemoveDeadNodes - This method deletes all unreachable nodes in the
91  /// SelectionDAG, including nodes (like loads) that have uses of their token
92  /// chain but no other uses and no side effect.  If a node is passed in as an
93  /// argument, it is used as the seed for node deletion.
94  void RemoveDeadNodes(SDNode *N = 0);
95
96  SDOperand getConstant(uint64_t Val, MVT::ValueType VT);
97  SDOperand getConstantFP(double Val, MVT::ValueType VT);
98  SDOperand getGlobalAddress(const GlobalValue *GV, MVT::ValueType VT);
99  SDOperand getFrameIndex(int FI, MVT::ValueType VT);
100  SDOperand getConstantPool(unsigned CPIdx, MVT::ValueType VT);
101  SDOperand getBasicBlock(MachineBasicBlock *MBB);
102  SDOperand getExternalSymbol(const char *Sym, MVT::ValueType VT);
103  SDOperand getValueType(MVT::ValueType);
104
105  SDOperand getCopyToReg(SDOperand Chain, SDOperand N, unsigned Reg) {
106    // Note: these are auto-CSE'd because the caller doesn't make requests that
107    // could cause duplicates to occur.
108    SDNode *NN = new RegSDNode(ISD::CopyToReg, Chain, N, Reg);
109    NN->setValueTypes(MVT::Other);
110    AllNodes.push_back(NN);
111    return SDOperand(NN, 0);
112  }
113
114  SDOperand getCopyFromReg(unsigned Reg, MVT::ValueType VT, SDOperand Chain) {
115    // Note: These nodes are auto-CSE'd by the caller of this method.
116    SDNode *NN = new RegSDNode(ISD::CopyFromReg, Chain, Reg);
117    NN->setValueTypes(VT, MVT::Other);
118    AllNodes.push_back(NN);
119    return SDOperand(NN, 0);
120  }
121
122  SDOperand getImplicitDef(SDOperand Chain, unsigned Reg) {
123    // Note: These nodes are auto-CSE'd by the caller of this method.
124    SDNode *NN = new RegSDNode(ISD::ImplicitDef, Chain, Reg);
125    NN->setValueTypes(MVT::Other);
126    AllNodes.push_back(NN);
127    return SDOperand(NN, 0);
128  }
129
130  /// getCall - Note that this destroys the vector of RetVals passed in.
131  ///
132  SDNode *getCall(std::vector<MVT::ValueType> &RetVals, SDOperand Chain,
133                  SDOperand Callee, bool isTailCall = false) {
134    SDNode *NN = new SDNode(isTailCall ? ISD::TAILCALL : ISD::CALL, Chain,
135                            Callee);
136    NN->setValueTypes(RetVals);
137    AllNodes.push_back(NN);
138    return NN;
139  }
140
141  /// getCall - This is identical to the one above, and should be used for calls
142  /// where arguments are passed in physical registers.  This destroys the
143  /// RetVals and ArgsInRegs vectors.
144  SDNode *getCall(std::vector<MVT::ValueType> &RetVals, SDOperand Chain,
145                  SDOperand Callee, std::vector<SDOperand> &ArgsInRegs,
146                  bool isTailCall = false) {
147    ArgsInRegs.insert(ArgsInRegs.begin(), Callee);
148    ArgsInRegs.insert(ArgsInRegs.begin(), Chain);
149    SDNode *NN = new SDNode(isTailCall ? ISD::TAILCALL : ISD::CALL, ArgsInRegs);
150    NN->setValueTypes(RetVals);
151    AllNodes.push_back(NN);
152    return NN;
153  }
154
155
156  SDOperand getSetCC(ISD::CondCode, MVT::ValueType VT,
157                     SDOperand LHS, SDOperand RHS);
158
159  /// getZeroExtendInReg - Return the expression required to zero extend the Op
160  /// value assuming it was the smaller SrcTy value.
161  SDOperand getZeroExtendInReg(SDOperand Op, MVT::ValueType SrcTy);
162
163  /// getNode - Gets or creates the specified node.
164  ///
165  SDOperand getNode(unsigned Opcode, MVT::ValueType VT);
166  SDOperand getNode(unsigned Opcode, MVT::ValueType VT, SDOperand N);
167  SDOperand getNode(unsigned Opcode, MVT::ValueType VT,
168                    SDOperand N1, SDOperand N2);
169  SDOperand getNode(unsigned Opcode, MVT::ValueType VT,
170                    SDOperand N1, SDOperand N2, SDOperand N3);
171  SDOperand getNode(unsigned Opcode, MVT::ValueType VT,
172                    SDOperand N1, SDOperand N2, SDOperand N3, SDOperand N4);
173  SDOperand getNode(unsigned Opcode, MVT::ValueType VT,
174                    std::vector<SDOperand> &Children);
175  SDOperand getNode(unsigned Opcode, std::vector<MVT::ValueType> &ResultTys,
176                    std::vector<SDOperand> &Ops);
177
178  // getNode - These versions take an extra value type for extending and
179  // truncating loads, stores, rounds, extends etc.
180  SDOperand getNode(unsigned Opcode, MVT::ValueType VT, SDOperand N1,
181                    SDOperand N2, MVT::ValueType EVT);
182  SDOperand getNode(unsigned Opcode, MVT::ValueType VT,
183                    SDOperand N, MVT::ValueType EVT);
184  SDOperand getNode(unsigned Opcode, MVT::ValueType VT, SDOperand N1,
185                    SDOperand N2, SDOperand N3, MVT::ValueType EVT);
186  SDOperand getNode(unsigned Opcode, MVT::ValueType VT, SDOperand N1,
187                    SDOperand N2, SDOperand N3, SDOperand N4,
188                    MVT::ValueType EVT);
189
190
191  /// getLoad - Loads are not normal binary operators: their result type is not
192  /// determined by their operands, and they produce a value AND a token chain.
193  ///
194  SDOperand getLoad(MVT::ValueType VT, SDOperand Chain, SDOperand Ptr,
195                    SDOperand SV);
196
197  // getSrcValue - construct a node to track a Value* through the backend
198  SDOperand getSrcValue(const Value* I, int offset = 0);
199
200  void replaceAllUsesWith(SDOperand Old, SDOperand New) {
201    assert(Old != New && "RAUW self!");
202    assert(0 && "Unimplemented!");
203  }
204
205  void dump() const;
206
207private:
208  void DeleteNodeIfDead(SDNode *N, void *NodeSet);
209
210  // Maps to auto-CSE operations.
211  std::map<std::pair<unsigned, std::pair<SDOperand, MVT::ValueType> >,
212           SDNode *> UnaryOps;
213  std::map<std::pair<unsigned, std::pair<SDOperand, SDOperand> >,
214           SDNode *> BinaryOps;
215
216  std::map<std::pair<std::pair<SDOperand, SDOperand>,
217                     std::pair<ISD::CondCode, MVT::ValueType> >,
218           SetCCSDNode*> SetCCs;
219
220  std::map<std::pair<SDOperand, std::pair<SDOperand, MVT::ValueType> >,
221           SDNode *> Loads;
222
223  std::map<const GlobalValue*, SDNode*> GlobalValues;
224  std::map<std::pair<uint64_t, MVT::ValueType>, SDNode*> Constants;
225  std::map<std::pair<uint64_t, MVT::ValueType>, SDNode*> ConstantFPs;
226  std::map<int, SDNode*> FrameIndices;
227  std::map<unsigned, SDNode*> ConstantPoolIndices;
228  std::map<MachineBasicBlock *, SDNode*> BBNodes;
229  std::vector<SDNode*> ValueTypeNodes;
230  std::map<std::pair<unsigned,
231                     std::pair<MVT::ValueType, std::vector<SDOperand> > >,
232           SDNode*> OneResultNodes;
233  std::map<std::pair<unsigned,
234                     std::pair<std::vector<MVT::ValueType>,
235                               std::vector<SDOperand> > >,
236           SDNode*> ArbitraryNodes;
237
238  std::map<std::string, SDNode*> ExternalSymbols;
239  struct EVTStruct {
240    unsigned Opcode;
241    MVT::ValueType VT, EVT;
242    std::vector<SDOperand> Ops;
243    bool operator<(const EVTStruct &RHS) const {
244      if (Opcode < RHS.Opcode) return true;
245      if (Opcode > RHS.Opcode) return false;
246      if (VT < RHS.VT) return true;
247      if (VT > RHS.VT) return false;
248      if (EVT < RHS.EVT) return true;
249      if (EVT > RHS.EVT) return false;
250      return Ops < RHS.Ops;
251    }
252  };
253  std::map<EVTStruct, SDNode*> MVTSDNodes;
254};
255
256template <> struct GraphTraits<SelectionDAG*> : public GraphTraits<SDNode*> {
257  typedef SelectionDAG::allnodes_iterator nodes_iterator;
258  static nodes_iterator nodes_begin(SelectionDAG *G) {
259    return G->allnodes_begin();
260  }
261  static nodes_iterator nodes_end(SelectionDAG *G) {
262    return G->allnodes_end();
263  }
264};
265
266}
267
268#endif
269