SelectionDAG.h revision 66a48bbc3565b40ea0e6f2d58cf5e3a8e64802ef 
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>
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                             int offset = 0);
114  SDOperand getTargetGlobalAddress(const GlobalValue *GV, MVT::ValueType VT,
115                                   int offset = 0);
116  SDOperand getFrameIndex(int FI, MVT::ValueType VT);
117  SDOperand getTargetFrameIndex(int FI, MVT::ValueType VT);
118  SDOperand getConstantPool(Constant *C, MVT::ValueType VT);
119  SDOperand getTargetConstantPool(Constant *C, MVT::ValueType VT);
120  SDOperand getBasicBlock(MachineBasicBlock *MBB);
121  SDOperand getExternalSymbol(const char *Sym, MVT::ValueType VT);
122  SDOperand getTargetExternalSymbol(const char *Sym, MVT::ValueType VT);
123  SDOperand getValueType(MVT::ValueType);
124  SDOperand getRegister(unsigned Reg, MVT::ValueType VT);
125
126  SDOperand getCopyToReg(SDOperand Chain, unsigned Reg, SDOperand N) {
127    return getNode(ISD::CopyToReg, MVT::Other, Chain,
128                   getRegister(Reg, N.getValueType()), N);
129  }
130
131  // This version of the getCopyToReg method takes an extra operand, which
132  // indicates that there is potentially an incoming flag value (if Flag is not
133  // null) and that there should be a flag result.
134  SDOperand getCopyToReg(SDOperand Chain, unsigned Reg, SDOperand N,
135                         SDOperand Flag) {
136    std::vector<MVT::ValueType> VTs;
137    VTs.push_back(MVT::Other);
138    VTs.push_back(MVT::Flag);
139    std::vector<SDOperand> Ops;
140    Ops.push_back(Chain);
141    Ops.push_back(getRegister(Reg, N.getValueType()));
142    Ops.push_back(N);
143    if (Flag.Val) Ops.push_back(Flag);
144    return getNode(ISD::CopyToReg, VTs, Ops);
145  }
146
147  // Similar to last getCopyToReg() except parameter Reg is a SDOperand
148  SDOperand getCopyToReg(SDOperand Chain, SDOperand Reg, SDOperand N,
149                         SDOperand Flag) {
150    std::vector<MVT::ValueType> VTs;
151    VTs.push_back(MVT::Other);
152    VTs.push_back(MVT::Flag);
153    std::vector<SDOperand> Ops;
154    Ops.push_back(Chain);
155    Ops.push_back(Reg);
156    Ops.push_back(N);
157    if (Flag.Val) Ops.push_back(Flag);
158    return getNode(ISD::CopyToReg, VTs, Ops);
159  }
160
161  SDOperand getCopyFromReg(SDOperand Chain, unsigned Reg, MVT::ValueType VT) {
162    std::vector<MVT::ValueType> ResultTys;
163    ResultTys.push_back(VT);
164    ResultTys.push_back(MVT::Other);
165    std::vector<SDOperand> Ops;
166    Ops.push_back(Chain);
167    Ops.push_back(getRegister(Reg, VT));
168    return getNode(ISD::CopyFromReg, ResultTys, Ops);
169  }
170
171  // This version of the getCopyFromReg method takes an extra operand, which
172  // indicates that there is potentially an incoming flag value (if Flag is not
173  // null) and that there should be a flag result.
174  SDOperand getCopyFromReg(SDOperand Chain, unsigned Reg, MVT::ValueType VT,
175                           SDOperand Flag) {
176    std::vector<MVT::ValueType> ResultTys;
177    ResultTys.push_back(VT);
178    ResultTys.push_back(MVT::Other);
179    ResultTys.push_back(MVT::Flag);
180    std::vector<SDOperand> Ops;
181    Ops.push_back(Chain);
182    Ops.push_back(getRegister(Reg, VT));
183    if (Flag.Val) Ops.push_back(Flag);
184    return getNode(ISD::CopyFromReg, ResultTys, Ops);
185  }
186
187  SDOperand getImplicitDef(SDOperand Chain, unsigned Reg, MVT::ValueType VT) {
188    return getNode(ISD::ImplicitDef, MVT::Other, Chain, getRegister(Reg, VT));
189  }
190
191  /// getCall - Note that this destroys the vector of RetVals passed in.
192  ///
193  SDNode *getCall(std::vector<MVT::ValueType> &RetVals, SDOperand Chain,
194                  SDOperand Callee, bool isTailCall = false) {
195    SDNode *NN = new SDNode(isTailCall ? ISD::TAILCALL : ISD::CALL, Chain,
196                            Callee);
197    setNodeValueTypes(NN, RetVals);
198    AllNodes.push_back(NN);
199    return NN;
200  }
201
202  /// getCall - This is identical to the one above, and should be used for calls
203  /// where arguments are passed in physical registers.  This destroys the
204  /// RetVals and ArgsInRegs vectors.
205  SDNode *getCall(std::vector<MVT::ValueType> &RetVals, SDOperand Chain,
206                  SDOperand Callee, std::vector<SDOperand> &ArgsInRegs,
207                  bool isTailCall = false) {
208    ArgsInRegs.insert(ArgsInRegs.begin(), Callee);
209    ArgsInRegs.insert(ArgsInRegs.begin(), Chain);
210    SDNode *NN = new SDNode(isTailCall ? ISD::TAILCALL : ISD::CALL, ArgsInRegs);
211    setNodeValueTypes(NN, RetVals);
212    AllNodes.push_back(NN);
213    return NN;
214  }
215
216  SDOperand getCondCode(ISD::CondCode Cond);
217
218  /// getZeroExtendInReg - Return the expression required to zero extend the Op
219  /// value assuming it was the smaller SrcTy value.
220  SDOperand getZeroExtendInReg(SDOperand Op, MVT::ValueType SrcTy);
221
222  /// getNode - Gets or creates the specified node.
223  ///
224  SDOperand getNode(unsigned Opcode, MVT::ValueType VT);
225  SDOperand getNode(unsigned Opcode, MVT::ValueType VT, SDOperand N);
226  SDOperand getNode(unsigned Opcode, MVT::ValueType VT,
227                    SDOperand N1, SDOperand N2);
228  SDOperand getNode(unsigned Opcode, MVT::ValueType VT,
229                    SDOperand N1, SDOperand N2, SDOperand N3);
230  SDOperand getNode(unsigned Opcode, MVT::ValueType VT,
231                    SDOperand N1, SDOperand N2, SDOperand N3, SDOperand N4);
232  SDOperand getNode(unsigned Opcode, MVT::ValueType VT,
233                    SDOperand N1, SDOperand N2, SDOperand N3, SDOperand N4,
234                    SDOperand N5);
235  SDOperand getNode(unsigned Opcode, MVT::ValueType VT,
236                    std::vector<SDOperand> &Children);
237  SDOperand getNode(unsigned Opcode, std::vector<MVT::ValueType> &ResultTys,
238                    std::vector<SDOperand> &Ops);
239
240  /// getSetCC - Helper function to make it easier to build SetCC's if you just
241  /// have an ISD::CondCode instead of an SDOperand.
242  ///
243  SDOperand getSetCC(MVT::ValueType VT, SDOperand LHS, SDOperand RHS,
244                     ISD::CondCode Cond) {
245    return getNode(ISD::SETCC, VT, LHS, RHS, getCondCode(Cond));
246  }
247
248  /// getSelectCC - Helper function to make it easier to build SelectCC's if you
249  /// just have an ISD::CondCode instead of an SDOperand.
250  ///
251  SDOperand getSelectCC(SDOperand LHS, SDOperand RHS,
252                        SDOperand True, SDOperand False, ISD::CondCode Cond) {
253    MVT::ValueType VT = True.getValueType();
254    return getNode(ISD::SELECT_CC, VT, LHS, RHS, True, False,getCondCode(Cond));
255  }
256
257  /// getBR2Way_CC - Helper function to make it easier to build BRTWOWAY_CC
258  /// nodes.
259  ///
260  SDOperand getBR2Way_CC(SDOperand Chain, SDOperand CCNode, SDOperand LHS,
261                         SDOperand RHS, SDOperand True, SDOperand False) {
262    std::vector<SDOperand> Ops;
263    Ops.push_back(Chain);
264    Ops.push_back(CCNode);
265    Ops.push_back(LHS);
266    Ops.push_back(RHS);
267    Ops.push_back(True);
268    Ops.push_back(False);
269    return getNode(ISD::BRTWOWAY_CC, MVT::Other, Ops);
270  }
271
272  /// getLoad - Loads are not normal binary operators: their result type is not
273  /// determined by their operands, and they produce a value AND a token chain.
274  ///
275  SDOperand getLoad(MVT::ValueType VT, SDOperand Chain, SDOperand Ptr,
276                    SDOperand SV);
277  SDOperand getVecLoad(unsigned Count, MVT::ValueType VT, SDOperand Chain,
278                       SDOperand Ptr, SDOperand SV);
279  SDOperand getExtLoad(unsigned Opcode, MVT::ValueType VT, SDOperand Chain,
280                       SDOperand Ptr, SDOperand SV, MVT::ValueType EVT);
281
282  // getSrcValue - construct a node to track a Value* through the backend
283  SDOperand getSrcValue(const Value* I, int offset = 0);
284
285
286  /// SelectNodeTo - These are used for target selectors to *mutate* the
287  /// specified node to have the specified return type, Target opcode, and
288  /// operands.  Note that target opcodes are stored as
289  /// ISD::BUILTIN_OP_END+TargetOpcode in the node opcode field.  The 0th value
290  /// of the resultant node is returned.
291  SDOperand SelectNodeTo(SDNode *N, unsigned TargetOpc, MVT::ValueType VT);
292  SDOperand SelectNodeTo(SDNode *N, unsigned TargetOpc, MVT::ValueType VT,
293                         SDOperand Op1);
294  SDOperand SelectNodeTo(SDNode *N, unsigned TargetOpc, MVT::ValueType VT,
295                         SDOperand Op1, SDOperand Op2);
296  SDOperand SelectNodeTo(SDNode *N, unsigned TargetOpc, MVT::ValueType VT,
297                         SDOperand Op1, SDOperand Op2, SDOperand Op3);
298  SDOperand SelectNodeTo(SDNode *N, unsigned TargetOpc, MVT::ValueType VT,
299                         SDOperand Op1, SDOperand Op2, SDOperand Op3,
300                         SDOperand Op4);
301  SDOperand SelectNodeTo(SDNode *N, unsigned TargetOpc, MVT::ValueType VT,
302                         SDOperand Op1, SDOperand Op2, SDOperand Op3,
303                         SDOperand Op4, SDOperand Op5);
304  SDOperand SelectNodeTo(SDNode *N, unsigned TargetOpc, MVT::ValueType VT,
305                         SDOperand Op1, SDOperand Op2, SDOperand Op3,
306                         SDOperand Op4, SDOperand Op5, SDOperand Op6);
307  SDOperand SelectNodeTo(SDNode *N, unsigned TargetOpc, MVT::ValueType VT1,
308                         MVT::ValueType VT2, SDOperand Op1, SDOperand Op2);
309  SDOperand SelectNodeTo(SDNode *N, unsigned TargetOpc, MVT::ValueType VT1,
310                         MVT::ValueType VT2, SDOperand Op1, SDOperand Op2,
311                         SDOperand Op3);
312  SDOperand SelectNodeTo(SDNode *N, unsigned TargetOpc, MVT::ValueType VT1,
313                         MVT::ValueType VT2, SDOperand Op1, SDOperand Op2,
314                         SDOperand Op3, SDOperand Op4);
315  SDOperand SelectNodeTo(SDNode *N, unsigned TargetOpc, MVT::ValueType VT1,
316                         MVT::ValueType VT2, SDOperand Op1, SDOperand Op2,
317                         SDOperand Op3, SDOperand Op4, SDOperand Op5);
318
319  SDOperand getTargetNode(unsigned Opcode, MVT::ValueType VT) {
320    return getNode(ISD::BUILTIN_OP_END+Opcode, VT);
321  }
322  SDOperand getTargetNode(unsigned Opcode, MVT::ValueType VT,
323                          SDOperand Op1) {
324    return getNode(ISD::BUILTIN_OP_END+Opcode, VT, Op1);
325  }
326  SDOperand getTargetNode(unsigned Opcode, MVT::ValueType VT,
327                          SDOperand Op1, SDOperand Op2) {
328    return getNode(ISD::BUILTIN_OP_END+Opcode, VT, Op1, Op2);
329  }
330  SDOperand getTargetNode(unsigned Opcode, MVT::ValueType VT1,
331                          MVT::ValueType VT2, SDOperand Op1, SDOperand Op2) {
332    std::vector<MVT::ValueType> ResultTys;
333    ResultTys.push_back(VT1);
334    ResultTys.push_back(VT2);
335    std::vector<SDOperand> Ops;
336    Ops.push_back(Op1);
337    Ops.push_back(Op2);
338    return getNode(ISD::BUILTIN_OP_END+Opcode, ResultTys, Ops);
339  }
340  SDOperand getTargetNode(unsigned Opcode, MVT::ValueType VT,
341                          SDOperand Op1, SDOperand Op2, SDOperand Op3) {
342    return getNode(ISD::BUILTIN_OP_END+Opcode, VT, Op1, Op2, Op3);
343  }
344  SDOperand getTargetNode(unsigned Opcode, MVT::ValueType VT,
345                          SDOperand Op1, SDOperand Op2, SDOperand Op3,
346                          SDOperand Op4) {
347    return getNode(ISD::BUILTIN_OP_END+Opcode, VT, Op1, Op2, Op3, Op4);
348  }
349  SDOperand getTargetNode(unsigned Opcode, MVT::ValueType VT,
350                          SDOperand Op1, SDOperand Op2, SDOperand Op3,
351                          SDOperand Op4, SDOperand Op5) {
352    return getNode(ISD::BUILTIN_OP_END+Opcode, VT, Op1, Op2, Op3, Op4, Op5);
353  }
354  SDOperand getTargetNode(unsigned Opcode, MVT::ValueType VT,
355                          std::vector<SDOperand> &Ops) {
356    return getNode(ISD::BUILTIN_OP_END+Opcode, VT, Ops);
357  }
358  SDOperand getTargetNode(unsigned Opcode, MVT::ValueType VT1,
359                          MVT::ValueType VT2, std::vector<SDOperand> &Ops) {
360    std::vector<MVT::ValueType> ResultTys;
361    ResultTys.push_back(VT1);
362    ResultTys.push_back(VT2);
363    return getNode(ISD::BUILTIN_OP_END+Opcode, ResultTys, Ops);
364  }
365
366  /// ReplaceAllUsesWith - Modify anything using 'From' to use 'To' instead.
367  /// This can cause recursive merging of nodes in the DAG.  Use the first
368  /// version if 'From' is known to have a single result, use the second
369  /// if you have two nodes with identical results, use the third otherwise.
370  ///
371  /// These methods all take an optional vector, which (if not null) is
372  /// populated with any nodes that are deleted from the SelectionDAG, due to
373  /// new equivalences that are discovered.
374  ///
375  void ReplaceAllUsesWith(SDOperand From, SDOperand Op,
376                          std::vector<SDNode*> *Deleted = 0);
377  void ReplaceAllUsesWith(SDNode *From, SDNode *To,
378                          std::vector<SDNode*> *Deleted = 0);
379  void ReplaceAllUsesWith(SDNode *From, const std::vector<SDOperand> &To,
380                          std::vector<SDNode*> *Deleted = 0);
381
382
383  /// DeleteNode - Remove the specified node from the system.  This node must
384  /// have no referrers.
385  void DeleteNode(SDNode *N);
386
387  void dump() const;
388
389private:
390  void RemoveNodeFromCSEMaps(SDNode *N);
391  SDNode *AddNonLeafNodeToCSEMaps(SDNode *N);
392  void DestroyDeadNode(SDNode *N);
393  void DeleteNodeNotInCSEMaps(SDNode *N);
394  void setNodeValueTypes(SDNode *N, std::vector<MVT::ValueType> &RetVals);
395  void setNodeValueTypes(SDNode *N, MVT::ValueType VT1, MVT::ValueType VT2);
396
397
398  /// SimplifySetCC - Try to simplify a setcc built with the specified operands
399  /// and cc.  If unable to simplify it, return a null SDOperand.
400  SDOperand SimplifySetCC(MVT::ValueType VT, SDOperand N1,
401                          SDOperand N2, ISD::CondCode Cond);
402
403  // List of non-single value types.
404  std::list<std::vector<MVT::ValueType> > VTList;
405
406  // Maps to auto-CSE operations.
407  std::map<std::pair<unsigned, MVT::ValueType>, SDNode *> NullaryOps;
408  std::map<std::pair<unsigned, std::pair<SDOperand, MVT::ValueType> >,
409           SDNode *> UnaryOps;
410  std::map<std::pair<unsigned, std::pair<SDOperand, SDOperand> >,
411           SDNode *> BinaryOps;
412
413  std::map<std::pair<unsigned, MVT::ValueType>, RegisterSDNode*> RegNodes;
414  std::vector<CondCodeSDNode*> CondCodeNodes;
415
416  std::map<std::pair<SDOperand, std::pair<SDOperand, MVT::ValueType> >,
417           SDNode *> Loads;
418
419  std::map<std::pair<const GlobalValue*, int>, SDNode*> GlobalValues;
420  std::map<std::pair<const GlobalValue*, int>, SDNode*> TargetGlobalValues;
421  std::map<std::pair<uint64_t, MVT::ValueType>, SDNode*> Constants;
422  std::map<std::pair<uint64_t, MVT::ValueType>, SDNode*> TargetConstants;
423  std::map<std::pair<uint64_t, MVT::ValueType>, SDNode*> ConstantFPs;
424  std::map<int, SDNode*> FrameIndices, TargetFrameIndices;
425  std::map<Constant *, SDNode*> ConstantPoolIndices;
426  std::map<Constant *, SDNode*> TargetConstantPoolIndices;
427  std::map<MachineBasicBlock *, SDNode*> BBNodes;
428  std::vector<SDNode*> ValueTypeNodes;
429  std::map<std::string, SDNode*> ExternalSymbols;
430  std::map<std::string, SDNode*> TargetExternalSymbols;
431  std::map<std::string, StringSDNode*> StringNodes;
432  std::map<std::pair<unsigned,
433                     std::pair<MVT::ValueType, std::vector<SDOperand> > >,
434           SDNode*> OneResultNodes;
435  std::map<std::pair<unsigned,
436                     std::pair<std::vector<MVT::ValueType>,
437                               std::vector<SDOperand> > >,
438           SDNode*> ArbitraryNodes;
439};
440
441template <> struct GraphTraits<SelectionDAG*> : public GraphTraits<SDNode*> {
442  typedef SelectionDAG::allnodes_iterator nodes_iterator;
443  static nodes_iterator nodes_begin(SelectionDAG *G) {
444    return G->allnodes_begin();
445  }
446  static nodes_iterator nodes_end(SelectionDAG *G) {
447    return G->allnodes_end();
448  }
449};
450
451}  // end namespace llvm
452
453#endif
454