SelectionDAG.h revision 61ca74bc3a29b2af2be7e4bd612289da8aae85b5 
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 "llvm/ADT/ilist"
20
21#include <map>
22#include <list>
23#include <string> // FIXME remove eventually, turning map into const char* map.
24
25namespace llvm {
26  class TargetLowering;
27  class TargetMachine;
28  class MachineFunction;
29
30/// SelectionDAG class - This is used to represent a portion of an LLVM function
31/// in a low-level Data Dependence DAG representation suitable for instruction
32/// selection.  This DAG is constructed as the first step of instruction
33/// selection in order to allow implementation of machine specific optimizations
34/// and code simplifications.
35///
36/// The representation used by the SelectionDAG is a target-independent
37/// representation, which has some similarities to the GCC RTL representation,
38/// but is significantly more simple, powerful, and is a graph form instead of a
39/// linear form.
40///
41class SelectionDAG {
42  TargetLowering &TLI;
43  MachineFunction &MF;
44
45  // Root - The root of the entire DAG.  EntryNode - The starting token.
46  SDOperand Root, EntryNode;
47
48  // AllNodes - A linked list of nodes in the current DAG.
49  ilist<SDNode> AllNodes;
50
51  // ValueNodes - track SrcValue nodes
52  std::map<std::pair<const Value*, int>, SDNode*> ValueNodes;
53
54public:
55  SelectionDAG(TargetLowering &tli, MachineFunction &mf) : TLI(tli), MF(mf) {
56    EntryNode = Root = getNode(ISD::EntryToken, MVT::Other);
57  }
58  ~SelectionDAG();
59
60  MachineFunction &getMachineFunction() const { return MF; }
61  const TargetMachine &getTarget() const;
62  TargetLowering &getTargetLoweringInfo() const { return TLI; }
63
64  /// viewGraph - Pop up a ghostview window with the DAG rendered using 'dot'.
65  ///
66  void viewGraph();
67
68
69  typedef ilist<SDNode>::const_iterator allnodes_const_iterator;
70  allnodes_const_iterator allnodes_begin() const { return AllNodes.begin(); }
71  allnodes_const_iterator allnodes_end() const { return AllNodes.end(); }
72  typedef ilist<SDNode>::iterator allnodes_iterator;
73  allnodes_iterator allnodes_begin() { return AllNodes.begin(); }
74  allnodes_iterator allnodes_end() { return AllNodes.end(); }
75
76  /// getRoot - Return the root tag of the SelectionDAG.
77  ///
78  const SDOperand &getRoot() const { return Root; }
79
80  /// getEntryNode - Return the token chain corresponding to the entry of the
81  /// function.
82  const SDOperand &getEntryNode() const { return EntryNode; }
83
84  /// setRoot - Set the current root tag of the SelectionDAG.
85  ///
86  const SDOperand &setRoot(SDOperand N) { return Root = N; }
87
88  /// Combine - This iterates over the nodes in the SelectionDAG, folding
89  /// certain types of nodes together, or eliminating superfluous nodes.  When
90  /// the AfterLegalize argument is set to 'true', Combine takes care not to
91  /// generate any nodes that will be illegal on the target.
92  void Combine(bool AfterLegalize);
93
94  /// Legalize - This transforms the SelectionDAG into a SelectionDAG that is
95  /// compatible with the target instruction selector, as indicated by the
96  /// TargetLowering object.
97  ///
98  /// Note that this is an involved process that may invalidate pointers into
99  /// the graph.
100  void Legalize();
101
102  /// RemoveDeadNodes - This method deletes all unreachable nodes in the
103  /// SelectionDAG, including nodes (like loads) that have uses of their token
104  /// chain but no other uses and no side effect.  If a node is passed in as an
105  /// argument, it is used as the seed for node deletion.
106  void RemoveDeadNodes(SDNode *N = 0);
107
108  SDOperand getString(const std::string &Val);
109  SDOperand getConstant(uint64_t Val, MVT::ValueType VT);
110  SDOperand getTargetConstant(uint64_t Val, MVT::ValueType VT);
111  SDOperand getConstantFP(double Val, MVT::ValueType VT);
112  SDOperand getGlobalAddress(const GlobalValue *GV, MVT::ValueType VT);
113  SDOperand getTargetGlobalAddress(const GlobalValue *GV, MVT::ValueType VT,
114                                   int offset=0);
115  SDOperand getFrameIndex(int FI, MVT::ValueType VT);
116  SDOperand getTargetFrameIndex(int FI, MVT::ValueType VT);
117  SDOperand getConstantPool(Constant *C, MVT::ValueType VT);
118  SDOperand getTargetConstantPool(Constant *C, MVT::ValueType VT);
119  SDOperand getBasicBlock(MachineBasicBlock *MBB);
120  SDOperand getExternalSymbol(const char *Sym, MVT::ValueType VT);
121  SDOperand getTargetExternalSymbol(const char *Sym, MVT::ValueType VT);
122  SDOperand getValueType(MVT::ValueType);
123  SDOperand getRegister(unsigned Reg, MVT::ValueType VT);
124
125  SDOperand getCopyToReg(SDOperand Chain, unsigned Reg, SDOperand N) {
126    return getNode(ISD::CopyToReg, MVT::Other, Chain,
127                   getRegister(Reg, N.getValueType()), N);
128  }
129
130  // This version of the getCopyToReg method takes an extra operand, which
131  // indicates that there is potentially an incoming flag value (if Flag is not
132  // null) and that there should be a flag result.
133  SDOperand getCopyToReg(SDOperand Chain, unsigned Reg, SDOperand N,
134                         SDOperand Flag) {
135    std::vector<MVT::ValueType> VTs;
136    VTs.push_back(MVT::Other);
137    VTs.push_back(MVT::Flag);
138    std::vector<SDOperand> Ops;
139    Ops.push_back(Chain);
140    Ops.push_back(getRegister(Reg, N.getValueType()));
141    Ops.push_back(N);
142    if (Flag.Val) Ops.push_back(Flag);
143    return getNode(ISD::CopyToReg, VTs, Ops);
144  }
145
146  SDOperand getCopyFromReg(SDOperand Chain, unsigned Reg, MVT::ValueType VT) {
147    std::vector<MVT::ValueType> ResultTys;
148    ResultTys.push_back(VT);
149    ResultTys.push_back(MVT::Other);
150    std::vector<SDOperand> Ops;
151    Ops.push_back(Chain);
152    Ops.push_back(getRegister(Reg, VT));
153    return getNode(ISD::CopyFromReg, ResultTys, Ops);
154  }
155
156  // This version of the getCopyFromReg method takes an extra operand, which
157  // indicates that there is potentially an incoming flag value (if Flag is not
158  // null) and that there should be a flag result.
159  SDOperand getCopyFromReg(SDOperand Chain, unsigned Reg, MVT::ValueType VT,
160                           SDOperand Flag) {
161    std::vector<MVT::ValueType> ResultTys;
162    ResultTys.push_back(VT);
163    ResultTys.push_back(MVT::Other);
164    ResultTys.push_back(MVT::Flag);
165    std::vector<SDOperand> Ops;
166    Ops.push_back(Chain);
167    Ops.push_back(getRegister(Reg, VT));
168    if (Flag.Val) Ops.push_back(Flag);
169    return getNode(ISD::CopyFromReg, ResultTys, Ops);
170  }
171
172  SDOperand getImplicitDef(SDOperand Chain, unsigned Reg, MVT::ValueType VT) {
173    return getNode(ISD::ImplicitDef, MVT::Other, Chain, getRegister(Reg, VT));
174  }
175
176  /// getCall - Note that this destroys the vector of RetVals passed in.
177  ///
178  SDNode *getCall(std::vector<MVT::ValueType> &RetVals, SDOperand Chain,
179                  SDOperand Callee, bool isTailCall = false) {
180    SDNode *NN = new SDNode(isTailCall ? ISD::TAILCALL : ISD::CALL, Chain,
181                            Callee);
182    setNodeValueTypes(NN, RetVals);
183    AllNodes.push_back(NN);
184    return NN;
185  }
186
187  /// getCall - This is identical to the one above, and should be used for calls
188  /// where arguments are passed in physical registers.  This destroys the
189  /// RetVals and ArgsInRegs vectors.
190  SDNode *getCall(std::vector<MVT::ValueType> &RetVals, SDOperand Chain,
191                  SDOperand Callee, std::vector<SDOperand> &ArgsInRegs,
192                  bool isTailCall = false) {
193    ArgsInRegs.insert(ArgsInRegs.begin(), Callee);
194    ArgsInRegs.insert(ArgsInRegs.begin(), Chain);
195    SDNode *NN = new SDNode(isTailCall ? ISD::TAILCALL : ISD::CALL, ArgsInRegs);
196    setNodeValueTypes(NN, RetVals);
197    AllNodes.push_back(NN);
198    return NN;
199  }
200
201  SDOperand getCondCode(ISD::CondCode Cond);
202
203  /// getZeroExtendInReg - Return the expression required to zero extend the Op
204  /// value assuming it was the smaller SrcTy value.
205  SDOperand getZeroExtendInReg(SDOperand Op, MVT::ValueType SrcTy);
206
207  /// getNode - Gets or creates the specified node.
208  ///
209  SDOperand getNode(unsigned Opcode, MVT::ValueType VT);
210  SDOperand getNode(unsigned Opcode, MVT::ValueType VT, SDOperand N);
211  SDOperand getNode(unsigned Opcode, MVT::ValueType VT,
212                    SDOperand N1, SDOperand N2);
213  SDOperand getNode(unsigned Opcode, MVT::ValueType VT,
214                    SDOperand N1, SDOperand N2, SDOperand N3);
215  SDOperand getNode(unsigned Opcode, MVT::ValueType VT,
216                    SDOperand N1, SDOperand N2, SDOperand N3, SDOperand N4);
217  SDOperand getNode(unsigned Opcode, MVT::ValueType VT,
218                    SDOperand N1, SDOperand N2, SDOperand N3, SDOperand N4,
219                    SDOperand N5);
220  SDOperand getNode(unsigned Opcode, MVT::ValueType VT,
221                    std::vector<SDOperand> &Children);
222  SDOperand getNode(unsigned Opcode, std::vector<MVT::ValueType> &ResultTys,
223                    std::vector<SDOperand> &Ops);
224
225  /// getSetCC - Helper function to make it easier to build SetCC's if you just
226  /// have an ISD::CondCode instead of an SDOperand.
227  ///
228  SDOperand getSetCC(MVT::ValueType VT, SDOperand LHS, SDOperand RHS,
229                     ISD::CondCode Cond) {
230    return getNode(ISD::SETCC, VT, LHS, RHS, getCondCode(Cond));
231  }
232
233  /// getSelectCC - Helper function to make it easier to build SelectCC's if you
234  /// just have an ISD::CondCode instead of an SDOperand.
235  ///
236  SDOperand getSelectCC(SDOperand LHS, SDOperand RHS,
237                        SDOperand True, SDOperand False, ISD::CondCode Cond) {
238    MVT::ValueType VT = True.getValueType();
239    return getNode(ISD::SELECT_CC, VT, LHS, RHS, True, False,getCondCode(Cond));
240  }
241
242  /// getBR2Way_CC - Helper function to make it easier to build BRTWOWAY_CC
243  /// nodes.
244  ///
245  SDOperand getBR2Way_CC(SDOperand Chain, SDOperand CCNode, SDOperand LHS,
246                         SDOperand RHS, SDOperand True, SDOperand False) {
247    std::vector<SDOperand> Ops;
248    Ops.push_back(Chain);
249    Ops.push_back(CCNode);
250    Ops.push_back(LHS);
251    Ops.push_back(RHS);
252    Ops.push_back(True);
253    Ops.push_back(False);
254    return getNode(ISD::BRTWOWAY_CC, MVT::Other, Ops);
255  }
256
257  /// getLoad - Loads are not normal binary operators: their result type is not
258  /// determined by their operands, and they produce a value AND a token chain.
259  ///
260  SDOperand getLoad(MVT::ValueType VT, SDOperand Chain, SDOperand Ptr,
261                    SDOperand SV);
262  SDOperand getVecLoad(unsigned Count, MVT::ValueType VT, SDOperand Chain,
263                       SDOperand Ptr, SDOperand SV);
264  SDOperand getExtLoad(unsigned Opcode, MVT::ValueType VT, SDOperand Chain,
265                       SDOperand Ptr, SDOperand SV, MVT::ValueType EVT);
266
267  // getSrcValue - construct a node to track a Value* through the backend
268  SDOperand getSrcValue(const Value* I, int offset = 0);
269
270
271  /// SelectNodeTo - These are used for target selectors to *mutate* the
272  /// specified node to have the specified return type, Target opcode, and
273  /// operands.  Note that target opcodes are stored as
274  /// ISD::BUILTIN_OP_END+TargetOpcode in the node opcode field.
275  void SelectNodeTo(SDNode *N, unsigned TargetOpc, MVT::ValueType VT);
276  void SelectNodeTo(SDNode *N, unsigned TargetOpc, MVT::ValueType VT,
277                    SDOperand Op1);
278  void SelectNodeTo(SDNode *N, unsigned TargetOpc, MVT::ValueType VT,
279                    SDOperand Op1, SDOperand Op2);
280  void SelectNodeTo(SDNode *N, unsigned TargetOpc, MVT::ValueType VT,
281                    SDOperand Op1, SDOperand Op2, SDOperand Op3);
282  void SelectNodeTo(SDNode *N, unsigned TargetOpc, MVT::ValueType VT,
283                    SDOperand Op1, SDOperand Op2, SDOperand Op3, SDOperand Op4);
284  void SelectNodeTo(SDNode *N, unsigned TargetOpc, MVT::ValueType VT,
285                    SDOperand Op1, SDOperand Op2, SDOperand Op3, SDOperand Op4,
286                    SDOperand Op5);
287  void SelectNodeTo(SDNode *N, unsigned TargetOpc, MVT::ValueType VT,
288                    SDOperand Op1, SDOperand Op2, SDOperand Op3, SDOperand Op4,
289                    SDOperand Op5, SDOperand Op6);
290  void SelectNodeTo(SDNode *N, unsigned TargetOpc, MVT::ValueType VT1,
291                    MVT::ValueType VT2, SDOperand Op1, SDOperand Op2);
292  void SelectNodeTo(SDNode *N, unsigned TargetOpc, MVT::ValueType VT1,
293                    MVT::ValueType VT2, SDOperand Op1, SDOperand Op2,
294                    SDOperand Op3);
295  void SelectNodeTo(SDNode *N, unsigned TargetOpc, MVT::ValueType VT1,
296                    MVT::ValueType VT2, SDOperand Op1, SDOperand Op2,
297                    SDOperand Op3, SDOperand Op4);
298  void SelectNodeTo(SDNode *N, unsigned TargetOpc, MVT::ValueType VT1,
299                    MVT::ValueType VT2, SDOperand Op1, SDOperand Op2,
300                    SDOperand Op3, SDOperand Op4, SDOperand Op5);
301
302  SDOperand getTargetNode(unsigned Opcode, MVT::ValueType VT) {
303    return getNode(ISD::BUILTIN_OP_END+Opcode, VT);
304  }
305  SDOperand getTargetNode(unsigned Opcode, MVT::ValueType VT,
306                          SDOperand Op1) {
307    return getNode(ISD::BUILTIN_OP_END+Opcode, VT, Op1);
308  }
309  SDOperand getTargetNode(unsigned Opcode, MVT::ValueType VT,
310                          SDOperand Op1, SDOperand Op2) {
311    return getNode(ISD::BUILTIN_OP_END+Opcode, VT, Op1, Op2);
312  }
313  SDOperand getTargetNode(unsigned Opcode, MVT::ValueType VT1,
314                          MVT::ValueType VT2, SDOperand Op1, SDOperand Op2) {
315    std::vector<MVT::ValueType> ResultTys;
316    ResultTys.push_back(VT1);
317    ResultTys.push_back(VT2);
318    std::vector<SDOperand> Ops;
319    Ops.push_back(Op1);
320    Ops.push_back(Op2);
321    return getNode(ISD::BUILTIN_OP_END+Opcode, ResultTys, Ops);
322  }
323  SDOperand getTargetNode(unsigned Opcode, MVT::ValueType VT,
324                          SDOperand Op1, SDOperand Op2, SDOperand Op3) {
325    return getNode(ISD::BUILTIN_OP_END+Opcode, VT, Op1, Op2, Op3);
326  }
327  SDOperand getTargetNode(unsigned Opcode, MVT::ValueType VT,
328                          SDOperand Op1, SDOperand Op2, SDOperand Op3,
329                          SDOperand Op4) {
330    return getNode(ISD::BUILTIN_OP_END+Opcode, VT, Op1, Op2, Op3, Op4);
331  }
332  SDOperand getTargetNode(unsigned Opcode, MVT::ValueType VT,
333                          SDOperand Op1, SDOperand Op2, SDOperand Op3,
334                          SDOperand Op4, SDOperand Op5) {
335    return getNode(ISD::BUILTIN_OP_END+Opcode, VT, Op1, Op2, Op3, Op4, Op5);
336  }
337  SDOperand getTargetNode(unsigned Opcode, MVT::ValueType VT,
338                          std::vector<SDOperand> &Ops) {
339    return getNode(ISD::BUILTIN_OP_END+Opcode, VT, Ops);
340  }
341  SDOperand getTargetNode(unsigned Opcode, MVT::ValueType VT1,
342                          MVT::ValueType VT2, std::vector<SDOperand> &Ops) {
343    std::vector<MVT::ValueType> ResultTys;
344    ResultTys.push_back(VT1);
345    ResultTys.push_back(VT2);
346    return getNode(ISD::BUILTIN_OP_END+Opcode, ResultTys, Ops);
347  }
348
349  /// ReplaceAllUsesWith - Modify anything using 'From' to use 'To' instead.
350  /// This can cause recursive merging of nodes in the DAG.  Use the first
351  /// version if 'From' is known to have a single result, use the second
352  /// if you have two nodes with identical results, use the third otherwise.
353  ///
354  /// These methods all take an optional vector, which (if not null) is
355  /// populated with any nodes that are deleted from the SelectionDAG, due to
356  /// new equivalences that are discovered.
357  ///
358  void ReplaceAllUsesWith(SDOperand From, SDOperand Op,
359                          std::vector<SDNode*> *Deleted = 0);
360  void ReplaceAllUsesWith(SDNode *From, SDNode *To,
361                          std::vector<SDNode*> *Deleted = 0);
362  void ReplaceAllUsesWith(SDNode *From, const std::vector<SDOperand> &To,
363                          std::vector<SDNode*> *Deleted = 0);
364
365
366  /// DeleteNode - Remove the specified node from the system.  This node must
367  /// have no referrers.
368  void DeleteNode(SDNode *N);
369
370  void dump() const;
371
372private:
373  void RemoveNodeFromCSEMaps(SDNode *N);
374  SDNode *AddNonLeafNodeToCSEMaps(SDNode *N);
375  void DestroyDeadNode(SDNode *N);
376  void DeleteNodeNotInCSEMaps(SDNode *N);
377  void setNodeValueTypes(SDNode *N, std::vector<MVT::ValueType> &RetVals);
378  void setNodeValueTypes(SDNode *N, MVT::ValueType VT1, MVT::ValueType VT2);
379
380
381  /// SimplifySetCC - Try to simplify a setcc built with the specified operands
382  /// and cc.  If unable to simplify it, return a null SDOperand.
383  SDOperand SimplifySetCC(MVT::ValueType VT, SDOperand N1,
384                          SDOperand N2, ISD::CondCode Cond);
385
386  // List of non-single value types.
387  std::list<std::vector<MVT::ValueType> > VTList;
388
389  // Maps to auto-CSE operations.
390  std::map<std::pair<unsigned, MVT::ValueType>, SDNode *> NullaryOps;
391  std::map<std::pair<unsigned, std::pair<SDOperand, MVT::ValueType> >,
392           SDNode *> UnaryOps;
393  std::map<std::pair<unsigned, std::pair<SDOperand, SDOperand> >,
394           SDNode *> BinaryOps;
395
396  std::map<std::pair<unsigned, MVT::ValueType>, RegisterSDNode*> RegNodes;
397  std::vector<CondCodeSDNode*> CondCodeNodes;
398
399  std::map<std::pair<SDOperand, std::pair<SDOperand, MVT::ValueType> >,
400           SDNode *> Loads;
401
402  std::map<const GlobalValue*, SDNode*> GlobalValues;
403  std::map<const GlobalValue*, SDNode*> TargetGlobalValues;
404  std::map<std::pair<uint64_t, MVT::ValueType>, SDNode*> Constants;
405  std::map<std::pair<uint64_t, MVT::ValueType>, SDNode*> TargetConstants;
406  std::map<std::pair<uint64_t, MVT::ValueType>, SDNode*> ConstantFPs;
407  std::map<int, SDNode*> FrameIndices, TargetFrameIndices;
408  std::map<Constant *, SDNode*> ConstantPoolIndices;
409  std::map<Constant *, SDNode*> TargetConstantPoolIndices;
410  std::map<MachineBasicBlock *, SDNode*> BBNodes;
411  std::vector<SDNode*> ValueTypeNodes;
412  std::map<std::string, SDNode*> ExternalSymbols;
413  std::map<std::string, SDNode*> TargetExternalSymbols;
414  std::map<std::string, StringSDNode*> StringNodes;
415  std::map<std::pair<unsigned,
416                     std::pair<MVT::ValueType, std::vector<SDOperand> > >,
417           SDNode*> OneResultNodes;
418  std::map<std::pair<unsigned,
419                     std::pair<std::vector<MVT::ValueType>,
420                               std::vector<SDOperand> > >,
421           SDNode*> ArbitraryNodes;
422};
423
424template <> struct GraphTraits<SelectionDAG*> : public GraphTraits<SDNode*> {
425  typedef SelectionDAG::allnodes_iterator nodes_iterator;
426  static nodes_iterator nodes_begin(SelectionDAG *G) {
427    return G->allnodes_begin();
428  }
429  static nodes_iterator nodes_end(SelectionDAG *G) {
430    return G->allnodes_end();
431  }
432};
433
434}  // end namespace llvm
435
436#endif
437