SelectionDAG.h revision 26005b1b672aebd437edc561d381c5dd19a03ddb 
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 getTargetConstant(uint64_t Val, MVT::ValueType VT);
98  SDOperand getConstantFP(double Val, MVT::ValueType VT);
99  SDOperand getGlobalAddress(const GlobalValue *GV, MVT::ValueType VT);
100  SDOperand getTargetGlobalAddress(const GlobalValue *GV, MVT::ValueType VT);
101  SDOperand getFrameIndex(int FI, MVT::ValueType VT);
102  SDOperand getTargetFrameIndex(int FI, MVT::ValueType VT);
103  SDOperand getConstantPool(Constant *C, MVT::ValueType VT);
104  SDOperand getTargetConstantPool(Constant *C, MVT::ValueType VT);
105  SDOperand getBasicBlock(MachineBasicBlock *MBB);
106  SDOperand getExternalSymbol(const char *Sym, MVT::ValueType VT);
107  SDOperand getValueType(MVT::ValueType);
108  SDOperand getRegister(unsigned Reg, MVT::ValueType VT);
109
110  SDOperand getCopyToReg(SDOperand Chain, unsigned Reg, SDOperand N) {
111    return getNode(ISD::CopyToReg, MVT::Other, Chain,
112                   getRegister(Reg, N.getValueType()), N);
113  }
114
115  SDOperand getCopyFromReg(SDOperand Chain, unsigned Reg, MVT::ValueType VT) {
116    std::vector<MVT::ValueType> ResultTys;
117    ResultTys.push_back(VT);
118    ResultTys.push_back(MVT::Other);
119    std::vector<SDOperand> Ops;
120    Ops.push_back(Chain);
121    Ops.push_back(getRegister(Reg, VT));
122    return getNode(ISD::CopyFromReg, ResultTys, Ops);
123  }
124
125  SDOperand getImplicitDef(SDOperand Chain, unsigned Reg, MVT::ValueType VT) {
126    return getNode(ISD::ImplicitDef, MVT::Other, Chain, getRegister(Reg, VT));
127  }
128
129  /// getCall - Note that this destroys the vector of RetVals passed in.
130  ///
131  SDNode *getCall(std::vector<MVT::ValueType> &RetVals, SDOperand Chain,
132                  SDOperand Callee, bool isTailCall = false) {
133    SDNode *NN = new SDNode(isTailCall ? ISD::TAILCALL : ISD::CALL, Chain,
134                            Callee);
135    NN->setValueTypes(RetVals);
136    AllNodes.push_back(NN);
137    return NN;
138  }
139
140  /// getCall - This is identical to the one above, and should be used for calls
141  /// where arguments are passed in physical registers.  This destroys the
142  /// RetVals and ArgsInRegs vectors.
143  SDNode *getCall(std::vector<MVT::ValueType> &RetVals, SDOperand Chain,
144                  SDOperand Callee, std::vector<SDOperand> &ArgsInRegs,
145                  bool isTailCall = false) {
146    ArgsInRegs.insert(ArgsInRegs.begin(), Callee);
147    ArgsInRegs.insert(ArgsInRegs.begin(), Chain);
148    SDNode *NN = new SDNode(isTailCall ? ISD::TAILCALL : ISD::CALL, ArgsInRegs);
149    NN->setValueTypes(RetVals);
150    AllNodes.push_back(NN);
151    return NN;
152  }
153
154  SDOperand getCondCode(ISD::CondCode Cond);
155
156  /// getZeroExtendInReg - Return the expression required to zero extend the Op
157  /// value assuming it was the smaller SrcTy value.
158  SDOperand getZeroExtendInReg(SDOperand Op, MVT::ValueType SrcTy);
159
160  /// getNode - Gets or creates the specified node.
161  ///
162  SDOperand getNode(unsigned Opcode, MVT::ValueType VT);
163  SDOperand getNode(unsigned Opcode, MVT::ValueType VT, SDOperand N);
164  SDOperand getNode(unsigned Opcode, MVT::ValueType VT,
165                    SDOperand N1, SDOperand N2);
166  SDOperand getNode(unsigned Opcode, MVT::ValueType VT,
167                    SDOperand N1, SDOperand N2, SDOperand N3);
168  SDOperand getNode(unsigned Opcode, MVT::ValueType VT,
169                    SDOperand N1, SDOperand N2, SDOperand N3, SDOperand N4);
170  SDOperand getNode(unsigned Opcode, MVT::ValueType VT,
171                    SDOperand N1, SDOperand N2, SDOperand N3, SDOperand N4,
172                    SDOperand N5);
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  /// getSetCC - Helper function to make it easier to build SetCC's if you just
179  /// have an ISD::CondCode instead of an SDOperand.
180  ///
181  SDOperand getSetCC(MVT::ValueType VT, SDOperand LHS, SDOperand RHS,
182                     ISD::CondCode Cond) {
183    return getNode(ISD::SETCC, VT, LHS, RHS, getCondCode(Cond));
184  }
185
186  /// getSelectCC - Helper function to make it easier to build SelectCC's if you
187  /// just have an ISD::CondCode instead of an SDOperand.
188  ///
189  SDOperand getSelectCC(SDOperand LHS, SDOperand RHS,
190                        SDOperand True, SDOperand False, ISD::CondCode Cond) {
191    MVT::ValueType VT = True.getValueType();
192    return getNode(ISD::SELECT_CC, VT, LHS, RHS, True, False,getCondCode(Cond));
193  }
194
195  /// getBR2Way_CC - Helper function to make it easier to build BRTWOWAY_CC
196  /// nodes.
197  ///
198  SDOperand getBR2Way_CC(SDOperand Chain, SDOperand CCNode, SDOperand LHS,
199                         SDOperand RHS, SDOperand True, SDOperand False) {
200    std::vector<SDOperand> Ops;
201    Ops.push_back(Chain);
202    Ops.push_back(CCNode);
203    Ops.push_back(LHS);
204    Ops.push_back(RHS);
205    Ops.push_back(True);
206    Ops.push_back(False);
207    return getNode(ISD::BRTWOWAY_CC, MVT::Other, Ops);
208  }
209
210  /// getLoad - Loads are not normal binary operators: their result type is not
211  /// determined by their operands, and they produce a value AND a token chain.
212  ///
213  SDOperand getLoad(MVT::ValueType VT, SDOperand Chain, SDOperand Ptr,
214                    SDOperand SV);
215  SDOperand getExtLoad(unsigned Opcode, MVT::ValueType VT, SDOperand Chain,
216                       SDOperand Ptr, SDOperand SV, MVT::ValueType EVT);
217
218  // getSrcValue - construct a node to track a Value* through the backend
219  SDOperand getSrcValue(const Value* I, int offset = 0);
220
221
222  /// SelectNodeTo - These are used for target selectors to *mutate* the
223  /// specified node to have the specified return type, Target opcode, and
224  /// operands.  Note that target opcodes are stored as
225  /// ISD::BUILTIN_OP_END+TargetOpcode in the node opcode field.
226  void SelectNodeTo(SDNode *N, unsigned TargetOpc, MVT::ValueType VT);
227  void SelectNodeTo(SDNode *N, unsigned TargetOpc, MVT::ValueType VT,
228                    SDOperand Op1);
229  void SelectNodeTo(SDNode *N, unsigned TargetOpc, MVT::ValueType VT,
230                    SDOperand Op1, SDOperand Op2);
231  void SelectNodeTo(SDNode *N, unsigned TargetOpc, MVT::ValueType VT,
232                    SDOperand Op1, SDOperand Op2, SDOperand Op3);
233  void SelectNodeTo(SDNode *N, unsigned TargetOpc, MVT::ValueType VT,
234                    SDOperand Op1, SDOperand Op2, SDOperand Op3, SDOperand Op4);
235  void SelectNodeTo(SDNode *N, unsigned TargetOpc, MVT::ValueType VT,
236                    SDOperand Op1, SDOperand Op2, SDOperand Op3, SDOperand Op4,
237                    SDOperand Op5);
238  void SelectNodeTo(SDNode *N, unsigned TargetOpc, MVT::ValueType VT1,
239                    MVT::ValueType VT2, SDOperand Op1, SDOperand Op2);
240  void SelectNodeTo(SDNode *N, unsigned TargetOpc, MVT::ValueType VT1,
241                    MVT::ValueType VT2, SDOperand Op1, SDOperand Op2,
242                    SDOperand Op3);
243
244  SDOperand getTargetNode(unsigned Opcode, MVT::ValueType VT,
245                          SDOperand Op1) {
246    return getNode(ISD::BUILTIN_OP_END+Opcode, VT, Op1);
247  }
248  SDOperand getTargetNode(unsigned Opcode, MVT::ValueType VT,
249                          SDOperand Op1, SDOperand Op2) {
250    return getNode(ISD::BUILTIN_OP_END+Opcode, VT, Op1, Op2);
251  }
252  SDOperand getTargetNode(unsigned Opcode, MVT::ValueType VT1,
253                          MVT::ValueType VT2, SDOperand Op1, SDOperand Op2) {
254    std::vector<MVT::ValueType> ResultTys;
255    ResultTys.push_back(VT1);
256    ResultTys.push_back(VT2);
257    std::vector<SDOperand> Ops;
258    Ops.push_back(Op1);
259    Ops.push_back(Op2);
260    return getNode(ISD::BUILTIN_OP_END+Opcode, ResultTys, Ops);
261  }
262  SDOperand getTargetNode(unsigned Opcode, MVT::ValueType VT,
263                          SDOperand Op1, SDOperand Op2, SDOperand Op3) {
264    return getNode(ISD::BUILTIN_OP_END+Opcode, VT, Op1, Op2, Op3);
265  }
266  SDOperand getTargetNode(unsigned Opcode, MVT::ValueType VT,
267                          SDOperand Op1, SDOperand Op2, SDOperand Op3,
268                          SDOperand Op4) {
269    return getNode(ISD::BUILTIN_OP_END+Opcode, VT, Op1, Op2, Op3, Op4);
270  }
271  SDOperand getTargetNode(unsigned Opcode, MVT::ValueType VT,
272                          SDOperand Op1, SDOperand Op2, SDOperand Op3,
273                          SDOperand Op4, SDOperand Op5) {
274    return getNode(ISD::BUILTIN_OP_END+Opcode, VT, Op1, Op2, Op3, Op4, Op5);
275  }
276  SDOperand getTargetNode(unsigned Opcode, MVT::ValueType VT,
277                          std::vector<SDOperand> &Ops) {
278    return getNode(ISD::BUILTIN_OP_END+Opcode, VT, Ops);
279  }
280
281  /// ReplaceAllUsesWith - Modify anything using 'From' to use 'To' instead.
282  /// This can cause recursive merging of nodes in the DAG.  Use the first
283  /// version if 'From' is known to have a single result, use the second
284  /// if you have two nodes with identical results, use the third otherwise.
285  ///
286  void ReplaceAllUsesWith(SDOperand From, SDOperand Op);
287  void ReplaceAllUsesWith(SDNode *From, SDNode *To);
288  void ReplaceAllUsesWith(SDNode *From, const std::vector<SDOperand> &To);
289
290  void dump() const;
291
292private:
293  void RemoveNodeFromCSEMaps(SDNode *N);
294  SDNode *AddNonLeafNodeToCSEMaps(SDNode *N);
295  void DeleteNodeIfDead(SDNode *N, void *NodeSet);
296
297  /// SimplifySetCC - Try to simplify a setcc built with the specified operands
298  /// and cc.  If unable to simplify it, return a null SDOperand.
299  SDOperand SimplifySetCC(MVT::ValueType VT, SDOperand N1,
300                          SDOperand N2, ISD::CondCode Cond);
301
302  /// SimplifySelectCC - Try to simplify a select_cc built with the specified
303  /// operands and cc.  This can be used to simplify both the select_cc node,
304  /// and a select node whose first operand is a setcc.
305  SDOperand SimplifySelectCC(SDOperand N1, SDOperand N2, SDOperand N3,
306                             SDOperand N4, ISD::CondCode CC);
307
308  // Maps to auto-CSE operations.
309  std::map<std::pair<unsigned, std::pair<SDOperand, MVT::ValueType> >,
310           SDNode *> UnaryOps;
311  std::map<std::pair<unsigned, std::pair<SDOperand, SDOperand> >,
312           SDNode *> BinaryOps;
313
314  std::vector<RegisterSDNode*> RegNodes;
315  std::vector<CondCodeSDNode*> CondCodeNodes;
316
317  std::map<std::pair<SDOperand, std::pair<SDOperand, MVT::ValueType> >,
318           SDNode *> Loads;
319
320  std::map<const GlobalValue*, SDNode*> GlobalValues;
321  std::map<const GlobalValue*, SDNode*> TargetGlobalValues;
322  std::map<std::pair<uint64_t, MVT::ValueType>, SDNode*> Constants;
323  std::map<std::pair<uint64_t, MVT::ValueType>, SDNode*> TargetConstants;
324  std::map<std::pair<uint64_t, MVT::ValueType>, SDNode*> ConstantFPs;
325  std::map<int, SDNode*> FrameIndices, TargetFrameIndices;
326  std::map<Constant *, SDNode*> ConstantPoolIndices;
327  std::map<Constant *, SDNode*> TargetConstantPoolIndices;
328  std::map<MachineBasicBlock *, SDNode*> BBNodes;
329  std::vector<SDNode*> ValueTypeNodes;
330  std::map<std::string, SDNode*> ExternalSymbols;
331  std::map<std::pair<unsigned,
332                     std::pair<MVT::ValueType, std::vector<SDOperand> > >,
333           SDNode*> OneResultNodes;
334  std::map<std::pair<unsigned,
335                     std::pair<std::vector<MVT::ValueType>,
336                               std::vector<SDOperand> > >,
337           SDNode*> ArbitraryNodes;
338};
339
340template <> struct GraphTraits<SelectionDAG*> : public GraphTraits<SDNode*> {
341  typedef SelectionDAG::allnodes_iterator nodes_iterator;
342  static nodes_iterator nodes_begin(SelectionDAG *G) {
343    return G->allnodes_begin();
344  }
345  static nodes_iterator nodes_end(SelectionDAG *G) {
346    return G->allnodes_end();
347  }
348};
349
350}
351
352#endif
353