SelectionDAG.h revision 08ce9769718354e6767d3815e4c255e7c9fc0a46 
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/ADT/FoldingSet.h"
19#include "llvm/ADT/ilist"
20#include "llvm/CodeGen/SelectionDAGNodes.h"
21
22#include <list>
23#include <vector>
24#include <map>
25#include <set>
26#include <string>
27
28namespace llvm {
29  class AliasAnalysis;
30  class TargetLowering;
31  class TargetMachine;
32  class MachineModuleInfo;
33  class MachineFunction;
34  class MachineConstantPoolValue;
35
36/// SelectionDAG class - This is used to represent a portion of an LLVM function
37/// in a low-level Data Dependence DAG representation suitable for instruction
38/// selection.  This DAG is constructed as the first step of instruction
39/// selection in order to allow implementation of machine specific optimizations
40/// and code simplifications.
41///
42/// The representation used by the SelectionDAG is a target-independent
43/// representation, which has some similarities to the GCC RTL representation,
44/// but is significantly more simple, powerful, and is a graph form instead of a
45/// linear form.
46///
47class SelectionDAG {
48  TargetLowering &TLI;
49  MachineFunction &MF;
50  MachineModuleInfo *MMI;
51
52  /// Root - The root of the entire DAG.  EntryNode - The starting token.
53  SDOperand Root, EntryNode;
54
55  /// AllNodes - A linked list of nodes in the current DAG.
56  ilist<SDNode> AllNodes;
57
58  /// CSEMap - This structure is used to memoize nodes, automatically performing
59  /// CSE with existing nodes with a duplicate is requested.
60  FoldingSet<SDNode> CSEMap;
61
62public:
63  SelectionDAG(TargetLowering &tli, MachineFunction &mf, MachineModuleInfo *mmi)
64  : TLI(tli), MF(mf), MMI(mmi) {
65    EntryNode = Root = getNode(ISD::EntryToken, MVT::Other);
66  }
67  ~SelectionDAG();
68
69  MachineFunction &getMachineFunction() const { return MF; }
70  const TargetMachine &getTarget() const;
71  TargetLowering &getTargetLoweringInfo() const { return TLI; }
72  MachineModuleInfo *getMachineModuleInfo() const { return MMI; }
73
74  /// viewGraph - Pop up a GraphViz/gv window with the DAG rendered using 'dot'.
75  ///
76  void viewGraph();
77
78#ifndef NDEBUG
79  std::map<const SDNode *, std::string> NodeGraphAttrs;
80#endif
81
82  /// clearGraphAttrs - Clear all previously defined node graph attributes.
83  /// Intended to be used from a debugging tool (eg. gdb).
84  void clearGraphAttrs();
85
86  /// setGraphAttrs - Set graph attributes for a node. (eg. "color=red".)
87  ///
88  void setGraphAttrs(const SDNode *N, const char *Attrs);
89
90  /// getGraphAttrs - Get graph attributes for a node. (eg. "color=red".)
91  /// Used from getNodeAttributes.
92  const std::string getGraphAttrs(const SDNode *N) const;
93
94  /// setGraphColor - Convenience for setting node color attribute.
95  ///
96  void setGraphColor(const SDNode *N, const char *Color);
97
98  typedef ilist<SDNode>::const_iterator allnodes_const_iterator;
99  allnodes_const_iterator allnodes_begin() const { return AllNodes.begin(); }
100  allnodes_const_iterator allnodes_end() const { return AllNodes.end(); }
101  typedef ilist<SDNode>::iterator allnodes_iterator;
102  allnodes_iterator allnodes_begin() { return AllNodes.begin(); }
103  allnodes_iterator allnodes_end() { return AllNodes.end(); }
104
105  /// getRoot - Return the root tag of the SelectionDAG.
106  ///
107  const SDOperand &getRoot() const { return Root; }
108
109  /// getEntryNode - Return the token chain corresponding to the entry of the
110  /// function.
111  const SDOperand &getEntryNode() const { return EntryNode; }
112
113  /// setRoot - Set the current root tag of the SelectionDAG.
114  ///
115  const SDOperand &setRoot(SDOperand N) { return Root = N; }
116
117  /// Combine - This iterates over the nodes in the SelectionDAG, folding
118  /// certain types of nodes together, or eliminating superfluous nodes.  When
119  /// the AfterLegalize argument is set to 'true', Combine takes care not to
120  /// generate any nodes that will be illegal on the target.
121  void Combine(bool AfterLegalize, AliasAnalysis &AA);
122
123  /// Legalize - This transforms the SelectionDAG into a SelectionDAG that is
124  /// compatible with the target instruction selector, as indicated by the
125  /// TargetLowering object.
126  ///
127  /// Note that this is an involved process that may invalidate pointers into
128  /// the graph.
129  void Legalize();
130
131  /// RemoveDeadNodes - This method deletes all unreachable nodes in the
132  /// SelectionDAG.
133  void RemoveDeadNodes();
134
135  /// RemoveDeadNode - Remove the specified node from the system. If any of its
136  /// operands then becomes dead, remove them as well. The vector Deleted is
137  /// populated with nodes that are deleted.
138  void RemoveDeadNode(SDNode *N, std::vector<SDNode*> &Deleted);
139
140  /// DeleteNode - Remove the specified node from the system.  This node must
141  /// have no referrers.
142  void DeleteNode(SDNode *N);
143
144  /// getVTList - Return an SDVTList that represents the list of values
145  /// specified.
146  SDVTList getVTList(MVT::ValueType VT);
147  SDVTList getVTList(MVT::ValueType VT1, MVT::ValueType VT2);
148  SDVTList getVTList(MVT::ValueType VT1, MVT::ValueType VT2,MVT::ValueType VT3);
149  SDVTList getVTList(const MVT::ValueType *VTs, unsigned NumVTs);
150
151  /// getNodeValueTypes - These are obsolete, use getVTList instead.
152  const MVT::ValueType *getNodeValueTypes(MVT::ValueType VT) {
153    return getVTList(VT).VTs;
154  }
155  const MVT::ValueType *getNodeValueTypes(MVT::ValueType VT1,
156                                          MVT::ValueType VT2) {
157    return getVTList(VT1, VT2).VTs;
158  }
159  const MVT::ValueType *getNodeValueTypes(MVT::ValueType VT1,MVT::ValueType VT2,
160                                          MVT::ValueType VT3) {
161    return getVTList(VT1, VT2, VT3).VTs;
162  }
163  const MVT::ValueType *getNodeValueTypes(std::vector<MVT::ValueType> &VTList) {
164    return getVTList(&VTList[0], VTList.size()).VTs;
165  }
166
167
168  //===--------------------------------------------------------------------===//
169  // Node creation methods.
170  //
171  SDOperand getString(const std::string &Val);
172  SDOperand getConstant(uint64_t Val, MVT::ValueType VT, bool isTarget = false);
173  SDOperand getTargetConstant(uint64_t Val, MVT::ValueType VT) {
174    return getConstant(Val, VT, true);
175  }
176  SDOperand getConstantFP(double Val, MVT::ValueType VT, bool isTarget = false);
177  SDOperand getConstantFP(const APFloat& Val, MVT::ValueType VT,
178                          bool isTarget = false);
179  SDOperand getTargetConstantFP(double Val, MVT::ValueType VT) {
180    return getConstantFP(Val, VT, true);
181  }
182  SDOperand getTargetConstantFP(const APFloat& Val, MVT::ValueType VT) {
183    return getConstantFP(Val, VT, true);
184  }
185  SDOperand getGlobalAddress(const GlobalValue *GV, MVT::ValueType VT,
186                             int offset = 0, bool isTargetGA = false);
187  SDOperand getTargetGlobalAddress(const GlobalValue *GV, MVT::ValueType VT,
188                                   int offset = 0) {
189    return getGlobalAddress(GV, VT, offset, true);
190  }
191  SDOperand getFrameIndex(int FI, MVT::ValueType VT, bool isTarget = false);
192  SDOperand getTargetFrameIndex(int FI, MVT::ValueType VT) {
193    return getFrameIndex(FI, VT, true);
194  }
195  SDOperand getJumpTable(int JTI, MVT::ValueType VT, bool isTarget = false);
196  SDOperand getTargetJumpTable(int JTI, MVT::ValueType VT) {
197    return getJumpTable(JTI, VT, true);
198  }
199  SDOperand getConstantPool(Constant *C, MVT::ValueType VT,
200                            unsigned Align = 0, int Offs = 0, bool isT=false);
201  SDOperand getTargetConstantPool(Constant *C, MVT::ValueType VT,
202                                  unsigned Align = 0, int Offset = 0) {
203    return getConstantPool(C, VT, Align, Offset, true);
204  }
205  SDOperand getConstantPool(MachineConstantPoolValue *C, MVT::ValueType VT,
206                            unsigned Align = 0, int Offs = 0, bool isT=false);
207  SDOperand getTargetConstantPool(MachineConstantPoolValue *C,
208                                  MVT::ValueType VT, unsigned Align = 0,
209                                  int Offset = 0) {
210    return getConstantPool(C, VT, Align, Offset, true);
211  }
212  SDOperand getBasicBlock(MachineBasicBlock *MBB);
213  SDOperand getExternalSymbol(const char *Sym, MVT::ValueType VT);
214  SDOperand getTargetExternalSymbol(const char *Sym, MVT::ValueType VT);
215  SDOperand getValueType(MVT::ValueType);
216  SDOperand getRegister(unsigned Reg, MVT::ValueType VT);
217
218  SDOperand getCopyToReg(SDOperand Chain, unsigned Reg, SDOperand N) {
219    return getNode(ISD::CopyToReg, MVT::Other, Chain,
220                   getRegister(Reg, N.getValueType()), N);
221  }
222
223  // This version of the getCopyToReg method takes an extra operand, which
224  // indicates that there is potentially an incoming flag value (if Flag is not
225  // null) and that there should be a flag result.
226  SDOperand getCopyToReg(SDOperand Chain, unsigned Reg, SDOperand N,
227                         SDOperand Flag) {
228    const MVT::ValueType *VTs = getNodeValueTypes(MVT::Other, MVT::Flag);
229    SDOperand Ops[] = { Chain, getRegister(Reg, N.getValueType()), N, Flag };
230    return getNode(ISD::CopyToReg, VTs, 2, Ops, Flag.Val ? 4 : 3);
231  }
232
233  // Similar to last getCopyToReg() except parameter Reg is a SDOperand
234  SDOperand getCopyToReg(SDOperand Chain, SDOperand Reg, SDOperand N,
235                         SDOperand Flag) {
236    const MVT::ValueType *VTs = getNodeValueTypes(MVT::Other, MVT::Flag);
237    SDOperand Ops[] = { Chain, Reg, N, Flag };
238    return getNode(ISD::CopyToReg, VTs, 2, Ops, Flag.Val ? 4 : 3);
239  }
240
241  SDOperand getCopyFromReg(SDOperand Chain, unsigned Reg, MVT::ValueType VT) {
242    const MVT::ValueType *VTs = getNodeValueTypes(VT, MVT::Other);
243    SDOperand Ops[] = { Chain, getRegister(Reg, VT) };
244    return getNode(ISD::CopyFromReg, VTs, 2, Ops, 2);
245  }
246
247  // This version of the getCopyFromReg method takes an extra operand, which
248  // indicates that there is potentially an incoming flag value (if Flag is not
249  // null) and that there should be a flag result.
250  SDOperand getCopyFromReg(SDOperand Chain, unsigned Reg, MVT::ValueType VT,
251                           SDOperand Flag) {
252    const MVT::ValueType *VTs = getNodeValueTypes(VT, MVT::Other, MVT::Flag);
253    SDOperand Ops[] = { Chain, getRegister(Reg, VT), Flag };
254    return getNode(ISD::CopyFromReg, VTs, 3, Ops, Flag.Val ? 3 : 2);
255  }
256
257  SDOperand getCondCode(ISD::CondCode Cond);
258
259  /// getZeroExtendInReg - Return the expression required to zero extend the Op
260  /// value assuming it was the smaller SrcTy value.
261  SDOperand getZeroExtendInReg(SDOperand Op, MVT::ValueType SrcTy);
262
263  /// getCALLSEQ_START - Return a new CALLSEQ_START node, which always must have
264  /// a flag result (to ensure it's not CSE'd).
265  SDOperand getCALLSEQ_START(SDOperand Chain, SDOperand Op) {
266    const MVT::ValueType *VTs = getNodeValueTypes(MVT::Other, MVT::Flag);
267    SDOperand Ops[] = { Chain,  Op };
268    return getNode(ISD::CALLSEQ_START, VTs, 2, Ops, 2);
269  }
270
271  /// getNode - Gets or creates the specified node.
272  ///
273  SDOperand getNode(unsigned Opcode, MVT::ValueType VT);
274  SDOperand getNode(unsigned Opcode, MVT::ValueType VT, SDOperand N);
275  SDOperand getNode(unsigned Opcode, MVT::ValueType VT,
276                    SDOperand N1, SDOperand N2);
277  SDOperand getNode(unsigned Opcode, MVT::ValueType VT,
278                    SDOperand N1, SDOperand N2, SDOperand N3);
279  SDOperand getNode(unsigned Opcode, MVT::ValueType VT,
280                    SDOperand N1, SDOperand N2, SDOperand N3, SDOperand N4);
281  SDOperand getNode(unsigned Opcode, MVT::ValueType VT,
282                    SDOperand N1, SDOperand N2, SDOperand N3, SDOperand N4,
283                    SDOperand N5);
284  SDOperand getNode(unsigned Opcode, MVT::ValueType VT,
285                    const SDOperand *Ops, unsigned NumOps);
286  SDOperand getNode(unsigned Opcode, std::vector<MVT::ValueType> &ResultTys,
287                    const SDOperand *Ops, unsigned NumOps);
288  SDOperand getNode(unsigned Opcode, const MVT::ValueType *VTs, unsigned NumVTs,
289                    const SDOperand *Ops, unsigned NumOps);
290  SDOperand getNode(unsigned Opcode, SDVTList VTs);
291  SDOperand getNode(unsigned Opcode, SDVTList VTs, SDOperand N);
292  SDOperand getNode(unsigned Opcode, SDVTList VTs,
293                    SDOperand N1, SDOperand N2);
294  SDOperand getNode(unsigned Opcode, SDVTList VTs,
295                    SDOperand N1, SDOperand N2, SDOperand N3);
296  SDOperand getNode(unsigned Opcode, SDVTList VTs,
297                    SDOperand N1, SDOperand N2, SDOperand N3, SDOperand N4);
298  SDOperand getNode(unsigned Opcode, SDVTList VTs,
299                    SDOperand N1, SDOperand N2, SDOperand N3, SDOperand N4,
300                    SDOperand N5);
301  SDOperand getNode(unsigned Opcode, SDVTList VTs,
302                    const SDOperand *Ops, unsigned NumOps);
303
304  /// getSetCC - Helper function to make it easier to build SetCC's if you just
305  /// have an ISD::CondCode instead of an SDOperand.
306  ///
307  SDOperand getSetCC(MVT::ValueType VT, SDOperand LHS, SDOperand RHS,
308                     ISD::CondCode Cond) {
309    return getNode(ISD::SETCC, VT, LHS, RHS, getCondCode(Cond));
310  }
311
312  /// getSelectCC - Helper function to make it easier to build SelectCC's if you
313  /// just have an ISD::CondCode instead of an SDOperand.
314  ///
315  SDOperand getSelectCC(SDOperand LHS, SDOperand RHS,
316                        SDOperand True, SDOperand False, ISD::CondCode Cond) {
317    return getNode(ISD::SELECT_CC, True.getValueType(), LHS, RHS, True, False,
318                   getCondCode(Cond));
319  }
320
321  /// getVAArg - VAArg produces a result and token chain, and takes a pointer
322  /// and a source value as input.
323  SDOperand getVAArg(MVT::ValueType VT, SDOperand Chain, SDOperand Ptr,
324                     SDOperand SV);
325
326  /// getLoad - Loads are not normal binary operators: their result type is not
327  /// determined by their operands, and they produce a value AND a token chain.
328  ///
329  SDOperand getLoad(MVT::ValueType VT, SDOperand Chain, SDOperand Ptr,
330                    const Value *SV, int SVOffset, bool isVolatile=false,
331                    unsigned Alignment=0);
332  SDOperand getExtLoad(ISD::LoadExtType ExtType, MVT::ValueType VT,
333                       SDOperand Chain, SDOperand Ptr, const Value *SV,
334                       int SVOffset, MVT::ValueType EVT, bool isVolatile=false,
335                       unsigned Alignment=0);
336  SDOperand getIndexedLoad(SDOperand OrigLoad, SDOperand Base,
337                           SDOperand Offset, ISD::MemIndexedMode AM);
338
339  /// getStore - Helper function to build ISD::STORE nodes.
340  ///
341  SDOperand getStore(SDOperand Chain, SDOperand Val, SDOperand Ptr,
342                     const Value *SV, int SVOffset, bool isVolatile=false,
343                     unsigned Alignment=0);
344  SDOperand getTruncStore(SDOperand Chain, SDOperand Val, SDOperand Ptr,
345                          const Value *SV, int SVOffset, MVT::ValueType TVT,
346                          bool isVolatile=false, unsigned Alignment=0);
347  SDOperand getIndexedStore(SDOperand OrigStoe, SDOperand Base,
348                           SDOperand Offset, ISD::MemIndexedMode AM);
349
350  // getSrcValue - construct a node to track a Value* through the backend
351  SDOperand getSrcValue(const Value* I, int offset = 0);
352
353  /// UpdateNodeOperands - *Mutate* the specified node in-place to have the
354  /// specified operands.  If the resultant node already exists in the DAG,
355  /// this does not modify the specified node, instead it returns the node that
356  /// already exists.  If the resultant node does not exist in the DAG, the
357  /// input node is returned.  As a degenerate case, if you specify the same
358  /// input operands as the node already has, the input node is returned.
359  SDOperand UpdateNodeOperands(SDOperand N, SDOperand Op);
360  SDOperand UpdateNodeOperands(SDOperand N, SDOperand Op1, SDOperand Op2);
361  SDOperand UpdateNodeOperands(SDOperand N, SDOperand Op1, SDOperand Op2,
362                               SDOperand Op3);
363  SDOperand UpdateNodeOperands(SDOperand N, SDOperand Op1, SDOperand Op2,
364                               SDOperand Op3, SDOperand Op4);
365  SDOperand UpdateNodeOperands(SDOperand N, SDOperand Op1, SDOperand Op2,
366                               SDOperand Op3, SDOperand Op4, SDOperand Op5);
367  SDOperand UpdateNodeOperands(SDOperand N, SDOperand *Ops, unsigned NumOps);
368
369  /// SelectNodeTo - These are used for target selectors to *mutate* the
370  /// specified node to have the specified return type, Target opcode, and
371  /// operands.  Note that target opcodes are stored as
372  /// ISD::BUILTIN_OP_END+TargetOpcode in the node opcode field.  The 0th value
373  /// of the resultant node is returned.
374  SDNode *SelectNodeTo(SDNode *N, unsigned TargetOpc, MVT::ValueType VT);
375  SDNode *SelectNodeTo(SDNode *N, unsigned TargetOpc, MVT::ValueType VT,
376                       SDOperand Op1);
377  SDNode *SelectNodeTo(SDNode *N, unsigned TargetOpc, MVT::ValueType VT,
378                       SDOperand Op1, SDOperand Op2);
379  SDNode *SelectNodeTo(SDNode *N, unsigned TargetOpc, MVT::ValueType VT,
380                       SDOperand Op1, SDOperand Op2, SDOperand Op3);
381  SDNode *SelectNodeTo(SDNode *N, unsigned TargetOpc, MVT::ValueType VT,
382                        const SDOperand *Ops, unsigned NumOps);
383  SDNode *SelectNodeTo(SDNode *N, unsigned TargetOpc, MVT::ValueType VT1,
384                       MVT::ValueType VT2, SDOperand Op1, SDOperand Op2);
385  SDNode *SelectNodeTo(SDNode *N, unsigned TargetOpc, MVT::ValueType VT1,
386                       MVT::ValueType VT2, SDOperand Op1, SDOperand Op2,
387                       SDOperand Op3);
388
389
390  /// getTargetNode - These are used for target selectors to create a new node
391  /// with specified return type(s), target opcode, and operands.
392  ///
393  /// Note that getTargetNode returns the resultant node.  If there is already a
394  /// node of the specified opcode and operands, it returns that node instead of
395  /// the current one.
396  SDNode *getTargetNode(unsigned Opcode, MVT::ValueType VT);
397  SDNode *getTargetNode(unsigned Opcode, MVT::ValueType VT,
398                        SDOperand Op1);
399  SDNode *getTargetNode(unsigned Opcode, MVT::ValueType VT,
400                        SDOperand Op1, SDOperand Op2);
401  SDNode *getTargetNode(unsigned Opcode, MVT::ValueType VT,
402                        SDOperand Op1, SDOperand Op2, SDOperand Op3);
403  SDNode *getTargetNode(unsigned Opcode, MVT::ValueType VT,
404                        const SDOperand *Ops, unsigned NumOps);
405  SDNode *getTargetNode(unsigned Opcode, MVT::ValueType VT1,
406                        MVT::ValueType VT2, SDOperand Op1);
407  SDNode *getTargetNode(unsigned Opcode, MVT::ValueType VT1,
408                        MVT::ValueType VT2, SDOperand Op1, SDOperand Op2);
409  SDNode *getTargetNode(unsigned Opcode, MVT::ValueType VT1,
410                        MVT::ValueType VT2, SDOperand Op1, SDOperand Op2,
411                        SDOperand Op3);
412  SDNode *getTargetNode(unsigned Opcode, MVT::ValueType VT1,
413                        MVT::ValueType VT2,
414                        const SDOperand *Ops, unsigned NumOps);
415  SDNode *getTargetNode(unsigned Opcode, MVT::ValueType VT1,
416                        MVT::ValueType VT2, MVT::ValueType VT3,
417                        SDOperand Op1, SDOperand Op2);
418  SDNode *getTargetNode(unsigned Opcode, MVT::ValueType VT1,
419                        MVT::ValueType VT2, MVT::ValueType VT3,
420                        SDOperand Op1, SDOperand Op2, SDOperand Op3);
421  SDNode *getTargetNode(unsigned Opcode, MVT::ValueType VT1,
422                        MVT::ValueType VT2, MVT::ValueType VT3,
423                        const SDOperand *Ops, unsigned NumOps);
424  SDNode *getTargetNode(unsigned Opcode, MVT::ValueType VT1,
425                        MVT::ValueType VT2, MVT::ValueType VT3,
426                        MVT::ValueType VT4,
427                        const SDOperand *Ops, unsigned NumOps);
428  SDNode *getTargetNode(unsigned Opcode, std::vector<MVT::ValueType> &ResultTys,
429                        const SDOperand *Ops, unsigned NumOps);
430
431  /// ReplaceAllUsesWith - Modify anything using 'From' to use 'To' instead.
432  /// This can cause recursive merging of nodes in the DAG.  Use the first
433  /// version if 'From' is known to have a single result, use the second
434  /// if you have two nodes with identical results, use the third otherwise.
435  ///
436  /// These methods all take an optional vector, which (if not null) is
437  /// populated with any nodes that are deleted from the SelectionDAG, due to
438  /// new equivalences that are discovered.
439  ///
440  void ReplaceAllUsesWith(SDOperand From, SDOperand Op,
441                          std::vector<SDNode*> *Deleted = 0);
442  void ReplaceAllUsesWith(SDNode *From, SDNode *To,
443                          std::vector<SDNode*> *Deleted = 0);
444  void ReplaceAllUsesWith(SDNode *From, const SDOperand *To,
445                          std::vector<SDNode*> *Deleted = 0);
446
447  /// ReplaceAllUsesOfValueWith - Replace any uses of From with To, leaving
448  /// uses of other values produced by From.Val alone.  The Deleted vector is
449  /// handled the same was as for ReplaceAllUsesWith, but it is required for
450  /// this method.
451  void ReplaceAllUsesOfValueWith(SDOperand From, SDOperand To,
452                                 std::vector<SDNode*> &Deleted);
453
454  /// AssignNodeIds - Assign a unique node id for each node in the DAG based on
455  /// their allnodes order. It returns the maximum id.
456  unsigned AssignNodeIds();
457
458  /// AssignTopologicalOrder - Assign a unique node id for each node in the DAG
459  /// based on their topological order. It returns the maximum id and a vector
460  /// of the SDNodes* in assigned order by reference.
461  unsigned AssignTopologicalOrder(std::vector<SDNode*> &TopOrder);
462
463  /// isCommutativeBinOp - Returns true if the opcode is a commutative binary
464  /// operation.
465  static bool isCommutativeBinOp(unsigned Opcode) {
466    switch (Opcode) {
467    case ISD::ADD:
468    case ISD::MUL:
469    case ISD::MULHU:
470    case ISD::MULHS:
471    case ISD::SMUL_LOHI:
472    case ISD::UMUL_LOHI:
473    case ISD::FADD:
474    case ISD::FMUL:
475    case ISD::AND:
476    case ISD::OR:
477    case ISD::XOR:
478    case ISD::ADDC:
479    case ISD::ADDE: return true;
480    default: return false;
481    }
482  }
483
484  void dump() const;
485
486  /// FoldSetCC - Constant fold a setcc to true or false.
487  SDOperand FoldSetCC(MVT::ValueType VT, SDOperand N1,
488                      SDOperand N2, ISD::CondCode Cond);
489
490  /// MaskedValueIsZero - Return true if 'Op & Mask' is known to be zero.  We
491  /// use this predicate to simplify operations downstream.  Op and Mask are
492  /// known to be the same type.
493  bool MaskedValueIsZero(SDOperand Op, uint64_t Mask, unsigned Depth = 0)
494    const;
495
496  /// ComputeMaskedBits - Determine which of the bits specified in Mask are
497  /// known to be either zero or one and return them in the KnownZero/KnownOne
498  /// bitsets.  This code only analyzes bits in Mask, in order to short-circuit
499  /// processing.  Targets can implement the computeMaskedBitsForTargetNode
500  /// method in the TargetLowering class to allow target nodes to be understood.
501  void ComputeMaskedBits(SDOperand Op, uint64_t Mask, uint64_t &KnownZero,
502                         uint64_t &KnownOne, unsigned Depth = 0) const;
503
504  /// ComputeNumSignBits - Return the number of times the sign bit of the
505  /// register is replicated into the other bits.  We know that at least 1 bit
506  /// is always equal to the sign bit (itself), but other cases can give us
507  /// information.  For example, immediately after an "SRA X, 2", we know that
508  /// the top 3 bits are all equal to each other, so we return 3.  Targets can
509  /// implement the ComputeNumSignBitsForTarget method in the TargetLowering
510  /// class to allow target nodes to be understood.
511  unsigned ComputeNumSignBits(SDOperand Op, unsigned Depth = 0) const;
512
513private:
514  void RemoveNodeFromCSEMaps(SDNode *N);
515  SDNode *AddNonLeafNodeToCSEMaps(SDNode *N);
516  SDNode *FindModifiedNodeSlot(SDNode *N, SDOperand Op, void *&InsertPos);
517  SDNode *FindModifiedNodeSlot(SDNode *N, SDOperand Op1, SDOperand Op2,
518                               void *&InsertPos);
519  SDNode *FindModifiedNodeSlot(SDNode *N, const SDOperand *Ops, unsigned NumOps,
520                               void *&InsertPos);
521
522  void DeleteNodeNotInCSEMaps(SDNode *N);
523
524  // List of non-single value types.
525  std::list<std::vector<MVT::ValueType> > VTList;
526
527  // Maps to auto-CSE operations.
528  std::vector<CondCodeSDNode*> CondCodeNodes;
529
530  std::vector<SDNode*> ValueTypeNodes;
531  std::map<std::string, SDNode*> ExternalSymbols;
532  std::map<std::string, SDNode*> TargetExternalSymbols;
533  std::map<std::string, StringSDNode*> StringNodes;
534};
535
536template <> struct GraphTraits<SelectionDAG*> : public GraphTraits<SDNode*> {
537  typedef SelectionDAG::allnodes_iterator nodes_iterator;
538  static nodes_iterator nodes_begin(SelectionDAG *G) {
539    return G->allnodes_begin();
540  }
541  static nodes_iterator nodes_end(SelectionDAG *G) {
542    return G->allnodes_end();
543  }
544};
545
546}  // end namespace llvm
547
548#endif
549