SelectionDAG.h revision 1b95095857b78e12138c22e76c7936611c51355b 
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  SDOperand getCondCode(ISD::CondCode Cond);
156
157  /// getZeroExtendInReg - Return the expression required to zero extend the Op
158  /// value assuming it was the smaller SrcTy value.
159  SDOperand getZeroExtendInReg(SDOperand Op, MVT::ValueType SrcTy);
160
161  /// getNode - Gets or creates the specified node.
162  ///
163  SDOperand getNode(unsigned Opcode, MVT::ValueType VT);
164  SDOperand getNode(unsigned Opcode, MVT::ValueType VT, SDOperand N);
165  SDOperand getNode(unsigned Opcode, MVT::ValueType VT,
166                    SDOperand N1, SDOperand N2);
167  SDOperand getNode(unsigned Opcode, MVT::ValueType VT,
168                    SDOperand N1, SDOperand N2, SDOperand N3);
169  SDOperand getNode(unsigned Opcode, MVT::ValueType VT,
170                    SDOperand N1, SDOperand N2, SDOperand N3, SDOperand N4);
171  SDOperand getNode(unsigned Opcode, MVT::ValueType VT,
172                    SDOperand N1, SDOperand N2, SDOperand N3, SDOperand N4,
173                    SDOperand N5);
174  SDOperand getNode(unsigned Opcode, MVT::ValueType VT,
175                    std::vector<SDOperand> &Children);
176  SDOperand getNode(unsigned Opcode, std::vector<MVT::ValueType> &ResultTys,
177                    std::vector<SDOperand> &Ops);
178
179  /// getSetCC - Helper function to make it easier to build SetCC's if you just
180  /// have an ISD::CondCode instead of an SDOperand.
181  ///
182  SDOperand getSetCC(MVT::ValueType VT, SDOperand LHS, SDOperand RHS,
183                     ISD::CondCode Cond) {
184    return getNode(ISD::SETCC, VT, LHS, RHS, getCondCode(Cond));
185  }
186
187  /// getSelectCC - Helper function to make it easier to build SelectCC's if you
188  /// just have an ISD::CondCode instead of an SDOperand.
189  ///
190  SDOperand getSelectCC(SDOperand LHS, SDOperand RHS,
191                        SDOperand True, SDOperand False, ISD::CondCode Cond) {
192    MVT::ValueType VT = True.getValueType();
193    return getNode(ISD::SELECT_CC, VT, LHS, RHS, True, False,getCondCode(Cond));
194  }
195
196  /// getLoad - Loads are not normal binary operators: their result type is not
197  /// determined by their operands, and they produce a value AND a token chain.
198  ///
199  SDOperand getLoad(MVT::ValueType VT, SDOperand Chain, SDOperand Ptr,
200                    SDOperand SV);
201  SDOperand getExtLoad(unsigned Opcode, MVT::ValueType VT, SDOperand Chain,
202                       SDOperand Ptr, SDOperand SV, MVT::ValueType EVT);
203
204  // getSrcValue - construct a node to track a Value* through the backend
205  SDOperand getSrcValue(const Value* I, int offset = 0);
206
207
208  /// SelectNodeTo - These are used for target selectors to *mutate* the
209  /// specified node to have the specified return type, Target opcode, and
210  /// operands.  Note that target opcodes are stored as
211  /// ISD::BUILTIN_OP_END+TargetOpcode in the node opcode field.
212  void SelectNodeTo(SDNode *N, MVT::ValueType VT, unsigned TargetOpc,
213                    SDOperand Op1);
214  void SelectNodeTo(SDNode *N, MVT::ValueType VT, unsigned TargetOpc,
215                    SDOperand Op1, SDOperand Op2);
216  void SelectNodeTo(SDNode *N, MVT::ValueType VT, unsigned TargetOpc,
217                    SDOperand Op1, SDOperand Op2, SDOperand Op3);
218
219
220  void dump() const;
221
222private:
223  void RemoveNodeFromCSEMaps(SDNode *N);
224  void DeleteNodeIfDead(SDNode *N, void *NodeSet);
225
226  /// SimplifySetCC - Try to simplify a setcc built with the specified operands
227  /// and cc.  If unable to simplify it, return a null SDOperand.
228  SDOperand SimplifySetCC(MVT::ValueType VT, SDOperand N1,
229                          SDOperand N2, ISD::CondCode Cond);
230
231  /// SimplifySelectCC - Try to simplify a select_cc built with the specified
232  /// operands and cc.  This can be used to simplify both the select_cc node,
233  /// and a select node whose first operand is a setcc.
234  SDOperand SimplifySelectCC(SDOperand N1, SDOperand N2, SDOperand N3,
235                             SDOperand N4, ISD::CondCode CC);
236
237  // Maps to auto-CSE operations.
238  std::map<std::pair<unsigned, std::pair<SDOperand, MVT::ValueType> >,
239           SDNode *> UnaryOps;
240  std::map<std::pair<unsigned, std::pair<SDOperand, SDOperand> >,
241           SDNode *> BinaryOps;
242
243  std::vector<CondCodeSDNode*> CondCodeNodes;
244
245  std::map<std::pair<SDOperand, std::pair<SDOperand, MVT::ValueType> >,
246           SDNode *> Loads;
247
248  std::map<const GlobalValue*, SDNode*> GlobalValues;
249  std::map<std::pair<uint64_t, MVT::ValueType>, SDNode*> Constants;
250  std::map<std::pair<uint64_t, MVT::ValueType>, SDNode*> ConstantFPs;
251  std::map<int, SDNode*> FrameIndices;
252  std::map<unsigned, SDNode*> ConstantPoolIndices;
253  std::map<MachineBasicBlock *, SDNode*> BBNodes;
254  std::vector<SDNode*> ValueTypeNodes;
255  std::map<std::string, SDNode*> ExternalSymbols;
256  std::map<std::pair<unsigned,
257                     std::pair<MVT::ValueType, std::vector<SDOperand> > >,
258           SDNode*> OneResultNodes;
259  std::map<std::pair<unsigned,
260                     std::pair<std::vector<MVT::ValueType>,
261                               std::vector<SDOperand> > >,
262           SDNode*> ArbitraryNodes;
263};
264
265template <> struct GraphTraits<SelectionDAG*> : public GraphTraits<SDNode*> {
266  typedef SelectionDAG::allnodes_iterator nodes_iterator;
267  static nodes_iterator nodes_begin(SelectionDAG *G) {
268    return G->allnodes_begin();
269  }
270  static nodes_iterator nodes_end(SelectionDAG *G) {
271    return G->allnodes_end();
272  }
273};
274
275}
276
277#endif
278