SelectionDAG.h revision 0bd4893a0726889b942405262e53d06cf3fe3be8 
1//===-- llvm/CodeGen/SelectionDAG.h - InstSelection DAG ---------*- C++ -*-===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// 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  /// LegalizeTypes - This transforms the SelectionDAG into a SelectionDAG that
124  /// only uses types natively supported by the target.
125  ///
126  /// Note that this is an involved process that may invalidate pointers into
127  /// the graph.
128  void LegalizeTypes();
129
130  /// Legalize - This transforms the SelectionDAG into a SelectionDAG that is
131  /// compatible with the target instruction selector, as indicated by the
132  /// TargetLowering object.
133  ///
134  /// Note that this is an involved process that may invalidate pointers into
135  /// the graph.
136  void Legalize();
137
138  /// RemoveDeadNodes - This method deletes all unreachable nodes in the
139  /// SelectionDAG.
140  void RemoveDeadNodes();
141
142  /// RemoveDeadNode - Remove the specified node from the system. If any of its
143  /// operands then becomes dead, remove them as well. The vector Deleted is
144  /// populated with nodes that are deleted.
145  void RemoveDeadNode(SDNode *N, std::vector<SDNode*> &Deleted);
146
147  /// DeleteNode - Remove the specified node from the system.  This node must
148  /// have no referrers.
149  void DeleteNode(SDNode *N);
150
151  /// getVTList - Return an SDVTList that represents the list of values
152  /// specified.
153  SDVTList getVTList(MVT::ValueType VT);
154  SDVTList getVTList(MVT::ValueType VT1, MVT::ValueType VT2);
155  SDVTList getVTList(MVT::ValueType VT1, MVT::ValueType VT2,MVT::ValueType VT3);
156  SDVTList getVTList(const MVT::ValueType *VTs, unsigned NumVTs);
157
158  /// getNodeValueTypes - These are obsolete, use getVTList instead.
159  const MVT::ValueType *getNodeValueTypes(MVT::ValueType VT) {
160    return getVTList(VT).VTs;
161  }
162  const MVT::ValueType *getNodeValueTypes(MVT::ValueType VT1,
163                                          MVT::ValueType VT2) {
164    return getVTList(VT1, VT2).VTs;
165  }
166  const MVT::ValueType *getNodeValueTypes(MVT::ValueType VT1,MVT::ValueType VT2,
167                                          MVT::ValueType VT3) {
168    return getVTList(VT1, VT2, VT3).VTs;
169  }
170  const MVT::ValueType *getNodeValueTypes(std::vector<MVT::ValueType> &VTList) {
171    return getVTList(&VTList[0], VTList.size()).VTs;
172  }
173
174
175  //===--------------------------------------------------------------------===//
176  // Node creation methods.
177  //
178  SDOperand getString(const std::string &Val);
179  SDOperand getConstant(uint64_t Val, MVT::ValueType VT, bool isTarget = false);
180  SDOperand getIntPtrConstant(uint64_t Val, bool isTarget = false);
181  SDOperand getTargetConstant(uint64_t Val, MVT::ValueType VT) {
182    return getConstant(Val, VT, true);
183  }
184  SDOperand getConstantFP(double Val, MVT::ValueType VT, bool isTarget = false);
185  SDOperand getConstantFP(const APFloat& Val, MVT::ValueType VT,
186                          bool isTarget = false);
187  SDOperand getTargetConstantFP(double Val, MVT::ValueType VT) {
188    return getConstantFP(Val, VT, true);
189  }
190  SDOperand getTargetConstantFP(const APFloat& Val, MVT::ValueType VT) {
191    return getConstantFP(Val, VT, true);
192  }
193  SDOperand getGlobalAddress(const GlobalValue *GV, MVT::ValueType VT,
194                             int offset = 0, bool isTargetGA = false);
195  SDOperand getTargetGlobalAddress(const GlobalValue *GV, MVT::ValueType VT,
196                                   int offset = 0) {
197    return getGlobalAddress(GV, VT, offset, true);
198  }
199  SDOperand getFrameIndex(int FI, MVT::ValueType VT, bool isTarget = false);
200  SDOperand getTargetFrameIndex(int FI, MVT::ValueType VT) {
201    return getFrameIndex(FI, VT, true);
202  }
203  SDOperand getJumpTable(int JTI, MVT::ValueType VT, bool isTarget = false);
204  SDOperand getTargetJumpTable(int JTI, MVT::ValueType VT) {
205    return getJumpTable(JTI, VT, true);
206  }
207  SDOperand getConstantPool(Constant *C, MVT::ValueType VT,
208                            unsigned Align = 0, int Offs = 0, bool isT=false);
209  SDOperand getTargetConstantPool(Constant *C, MVT::ValueType VT,
210                                  unsigned Align = 0, int Offset = 0) {
211    return getConstantPool(C, VT, Align, Offset, true);
212  }
213  SDOperand getConstantPool(MachineConstantPoolValue *C, MVT::ValueType VT,
214                            unsigned Align = 0, int Offs = 0, bool isT=false);
215  SDOperand getTargetConstantPool(MachineConstantPoolValue *C,
216                                  MVT::ValueType VT, unsigned Align = 0,
217                                  int Offset = 0) {
218    return getConstantPool(C, VT, Align, Offset, true);
219  }
220  SDOperand getBasicBlock(MachineBasicBlock *MBB);
221  SDOperand getExternalSymbol(const char *Sym, MVT::ValueType VT);
222  SDOperand getTargetExternalSymbol(const char *Sym, MVT::ValueType VT);
223  SDOperand getValueType(MVT::ValueType);
224  SDOperand getRegister(unsigned Reg, MVT::ValueType VT);
225
226  SDOperand getCopyToReg(SDOperand Chain, unsigned Reg, SDOperand N) {
227    return getNode(ISD::CopyToReg, MVT::Other, Chain,
228                   getRegister(Reg, N.getValueType()), N);
229  }
230
231  // This version of the getCopyToReg method takes an extra operand, which
232  // indicates that there is potentially an incoming flag value (if Flag is not
233  // null) and that there should be a flag result.
234  SDOperand getCopyToReg(SDOperand Chain, unsigned Reg, SDOperand N,
235                         SDOperand Flag) {
236    const MVT::ValueType *VTs = getNodeValueTypes(MVT::Other, MVT::Flag);
237    SDOperand Ops[] = { Chain, getRegister(Reg, N.getValueType()), N, Flag };
238    return getNode(ISD::CopyToReg, VTs, 2, Ops, Flag.Val ? 4 : 3);
239  }
240
241  // Similar to last getCopyToReg() except parameter Reg is a SDOperand
242  SDOperand getCopyToReg(SDOperand Chain, SDOperand Reg, SDOperand N,
243                         SDOperand Flag) {
244    const MVT::ValueType *VTs = getNodeValueTypes(MVT::Other, MVT::Flag);
245    SDOperand Ops[] = { Chain, Reg, N, Flag };
246    return getNode(ISD::CopyToReg, VTs, 2, Ops, Flag.Val ? 4 : 3);
247  }
248
249  SDOperand getCopyFromReg(SDOperand Chain, unsigned Reg, MVT::ValueType VT) {
250    const MVT::ValueType *VTs = getNodeValueTypes(VT, MVT::Other);
251    SDOperand Ops[] = { Chain, getRegister(Reg, VT) };
252    return getNode(ISD::CopyFromReg, VTs, 2, Ops, 2);
253  }
254
255  // This version of the getCopyFromReg method takes an extra operand, which
256  // indicates that there is potentially an incoming flag value (if Flag is not
257  // null) and that there should be a flag result.
258  SDOperand getCopyFromReg(SDOperand Chain, unsigned Reg, MVT::ValueType VT,
259                           SDOperand Flag) {
260    const MVT::ValueType *VTs = getNodeValueTypes(VT, MVT::Other, MVT::Flag);
261    SDOperand Ops[] = { Chain, getRegister(Reg, VT), Flag };
262    return getNode(ISD::CopyFromReg, VTs, 3, Ops, Flag.Val ? 3 : 2);
263  }
264
265  SDOperand getCondCode(ISD::CondCode Cond);
266
267  /// getZeroExtendInReg - Return the expression required to zero extend the Op
268  /// value assuming it was the smaller SrcTy value.
269  SDOperand getZeroExtendInReg(SDOperand Op, MVT::ValueType SrcTy);
270
271  /// getCALLSEQ_START - Return a new CALLSEQ_START node, which always must have
272  /// a flag result (to ensure it's not CSE'd).
273  SDOperand getCALLSEQ_START(SDOperand Chain, SDOperand Op) {
274    const MVT::ValueType *VTs = getNodeValueTypes(MVT::Other, MVT::Flag);
275    SDOperand Ops[] = { Chain,  Op };
276    return getNode(ISD::CALLSEQ_START, VTs, 2, Ops, 2);
277  }
278
279  /// getCALLSEQ_END - Return a new CALLSEQ_END node, which always must have a
280  /// flag result (to ensure it's not CSE'd).
281  SDOperand getCALLSEQ_END(SDOperand Chain, SDOperand Op1, SDOperand Op2,
282                           SDOperand InFlag) {
283    SDVTList NodeTys = getVTList(MVT::Other, MVT::Flag);
284    SmallVector<SDOperand, 4> Ops;
285    Ops.push_back(Chain);
286    Ops.push_back(Op1);
287    Ops.push_back(Op2);
288    Ops.push_back(InFlag);
289    return getNode(ISD::CALLSEQ_END, NodeTys, &Ops[0],
290                   Ops.size() - (InFlag.Val == 0 ? 1 : 0));
291  }
292
293  /// getNode - Gets or creates the specified node.
294  ///
295  SDOperand getNode(unsigned Opcode, MVT::ValueType VT);
296  SDOperand getNode(unsigned Opcode, MVT::ValueType VT, SDOperand N);
297  SDOperand getNode(unsigned Opcode, MVT::ValueType VT,
298                    SDOperand N1, SDOperand N2);
299  SDOperand getNode(unsigned Opcode, MVT::ValueType VT,
300                    SDOperand N1, SDOperand N2, SDOperand N3);
301  SDOperand getNode(unsigned Opcode, MVT::ValueType VT,
302                    SDOperand N1, SDOperand N2, SDOperand N3, SDOperand N4);
303  SDOperand getNode(unsigned Opcode, MVT::ValueType VT,
304                    SDOperand N1, SDOperand N2, SDOperand N3, SDOperand N4,
305                    SDOperand N5);
306  SDOperand getNode(unsigned Opcode, MVT::ValueType VT,
307                    const SDOperand *Ops, unsigned NumOps);
308  SDOperand getNode(unsigned Opcode, std::vector<MVT::ValueType> &ResultTys,
309                    const SDOperand *Ops, unsigned NumOps);
310  SDOperand getNode(unsigned Opcode, const MVT::ValueType *VTs, unsigned NumVTs,
311                    const SDOperand *Ops, unsigned NumOps);
312  SDOperand getNode(unsigned Opcode, SDVTList VTs);
313  SDOperand getNode(unsigned Opcode, SDVTList VTs, SDOperand N);
314  SDOperand getNode(unsigned Opcode, SDVTList VTs,
315                    SDOperand N1, SDOperand N2);
316  SDOperand getNode(unsigned Opcode, SDVTList VTs,
317                    SDOperand N1, SDOperand N2, SDOperand N3);
318  SDOperand getNode(unsigned Opcode, SDVTList VTs,
319                    SDOperand N1, SDOperand N2, SDOperand N3, SDOperand N4);
320  SDOperand getNode(unsigned Opcode, SDVTList VTs,
321                    SDOperand N1, SDOperand N2, SDOperand N3, SDOperand N4,
322                    SDOperand N5);
323  SDOperand getNode(unsigned Opcode, SDVTList VTs,
324                    const SDOperand *Ops, unsigned NumOps);
325
326  SDOperand getMemcpy(SDOperand Chain, SDOperand Dest, SDOperand Src,
327                      SDOperand Size, SDOperand Align,
328                      SDOperand AlwaysInline);
329
330  SDOperand getMemmove(SDOperand Chain, SDOperand Dest, SDOperand Src,
331                      SDOperand Size, SDOperand Align,
332                      SDOperand AlwaysInline);
333
334  SDOperand getMemset(SDOperand Chain, SDOperand Dest, SDOperand Src,
335                      SDOperand Size, SDOperand Align,
336                      SDOperand AlwaysInline);
337
338  /// getSetCC - Helper function to make it easier to build SetCC's if you just
339  /// have an ISD::CondCode instead of an SDOperand.
340  ///
341  SDOperand getSetCC(MVT::ValueType VT, SDOperand LHS, SDOperand RHS,
342                     ISD::CondCode Cond) {
343    return getNode(ISD::SETCC, VT, LHS, RHS, getCondCode(Cond));
344  }
345
346  /// getSelectCC - Helper function to make it easier to build SelectCC's if you
347  /// just have an ISD::CondCode instead of an SDOperand.
348  ///
349  SDOperand getSelectCC(SDOperand LHS, SDOperand RHS,
350                        SDOperand True, SDOperand False, ISD::CondCode Cond) {
351    return getNode(ISD::SELECT_CC, True.getValueType(), LHS, RHS, True, False,
352                   getCondCode(Cond));
353  }
354
355  /// getVAArg - VAArg produces a result and token chain, and takes a pointer
356  /// and a source value as input.
357  SDOperand getVAArg(MVT::ValueType VT, SDOperand Chain, SDOperand Ptr,
358                     SDOperand SV);
359
360  /// getLoad - Loads are not normal binary operators: their result type is not
361  /// determined by their operands, and they produce a value AND a token chain.
362  ///
363  SDOperand getLoad(MVT::ValueType VT, SDOperand Chain, SDOperand Ptr,
364                    const Value *SV, int SVOffset, bool isVolatile=false,
365                    unsigned Alignment=0);
366  SDOperand getExtLoad(ISD::LoadExtType ExtType, MVT::ValueType VT,
367                       SDOperand Chain, SDOperand Ptr, const Value *SV,
368                       int SVOffset, MVT::ValueType EVT, bool isVolatile=false,
369                       unsigned Alignment=0);
370  SDOperand getIndexedLoad(SDOperand OrigLoad, SDOperand Base,
371                           SDOperand Offset, ISD::MemIndexedMode AM);
372
373  /// getStore - Helper function to build ISD::STORE nodes.
374  ///
375  SDOperand getStore(SDOperand Chain, SDOperand Val, SDOperand Ptr,
376                     const Value *SV, int SVOffset, bool isVolatile=false,
377                     unsigned Alignment=0);
378  SDOperand getTruncStore(SDOperand Chain, SDOperand Val, SDOperand Ptr,
379                          const Value *SV, int SVOffset, MVT::ValueType TVT,
380                          bool isVolatile=false, unsigned Alignment=0);
381  SDOperand getIndexedStore(SDOperand OrigStoe, SDOperand Base,
382                           SDOperand Offset, ISD::MemIndexedMode AM);
383
384  // getSrcValue - construct a node to track a Value* through the backend
385  SDOperand getSrcValue(const Value* I, int offset = 0);
386
387  /// UpdateNodeOperands - *Mutate* the specified node in-place to have the
388  /// specified operands.  If the resultant node already exists in the DAG,
389  /// this does not modify the specified node, instead it returns the node that
390  /// already exists.  If the resultant node does not exist in the DAG, the
391  /// input node is returned.  As a degenerate case, if you specify the same
392  /// input operands as the node already has, the input node is returned.
393  SDOperand UpdateNodeOperands(SDOperand N, SDOperand Op);
394  SDOperand UpdateNodeOperands(SDOperand N, SDOperand Op1, SDOperand Op2);
395  SDOperand UpdateNodeOperands(SDOperand N, SDOperand Op1, SDOperand Op2,
396                               SDOperand Op3);
397  SDOperand UpdateNodeOperands(SDOperand N, SDOperand Op1, SDOperand Op2,
398                               SDOperand Op3, SDOperand Op4);
399  SDOperand UpdateNodeOperands(SDOperand N, SDOperand Op1, SDOperand Op2,
400                               SDOperand Op3, SDOperand Op4, SDOperand Op5);
401  SDOperand UpdateNodeOperands(SDOperand N, SDOperand *Ops, unsigned NumOps);
402
403  /// SelectNodeTo - These are used for target selectors to *mutate* the
404  /// specified node to have the specified return type, Target opcode, and
405  /// operands.  Note that target opcodes are stored as
406  /// ISD::BUILTIN_OP_END+TargetOpcode in the node opcode field.  The 0th value
407  /// of the resultant node is returned.
408  SDNode *SelectNodeTo(SDNode *N, unsigned TargetOpc, MVT::ValueType VT);
409  SDNode *SelectNodeTo(SDNode *N, unsigned TargetOpc, MVT::ValueType VT,
410                       SDOperand Op1);
411  SDNode *SelectNodeTo(SDNode *N, unsigned TargetOpc, MVT::ValueType VT,
412                       SDOperand Op1, SDOperand Op2);
413  SDNode *SelectNodeTo(SDNode *N, unsigned TargetOpc, MVT::ValueType VT,
414                       SDOperand Op1, SDOperand Op2, SDOperand Op3);
415  SDNode *SelectNodeTo(SDNode *N, unsigned TargetOpc, MVT::ValueType VT,
416                        const SDOperand *Ops, unsigned NumOps);
417  SDNode *SelectNodeTo(SDNode *N, unsigned TargetOpc, MVT::ValueType VT1,
418                       MVT::ValueType VT2, SDOperand Op1, SDOperand Op2);
419  SDNode *SelectNodeTo(SDNode *N, unsigned TargetOpc, MVT::ValueType VT1,
420                       MVT::ValueType VT2, SDOperand Op1, SDOperand Op2,
421                       SDOperand Op3);
422
423
424  /// getTargetNode - These are used for target selectors to create a new node
425  /// with specified return type(s), target opcode, and operands.
426  ///
427  /// Note that getTargetNode returns the resultant node.  If there is already a
428  /// node of the specified opcode and operands, it returns that node instead of
429  /// the current one.
430  SDNode *getTargetNode(unsigned Opcode, MVT::ValueType VT);
431  SDNode *getTargetNode(unsigned Opcode, MVT::ValueType VT,
432                        SDOperand Op1);
433  SDNode *getTargetNode(unsigned Opcode, MVT::ValueType VT,
434                        SDOperand Op1, SDOperand Op2);
435  SDNode *getTargetNode(unsigned Opcode, MVT::ValueType VT,
436                        SDOperand Op1, SDOperand Op2, SDOperand Op3);
437  SDNode *getTargetNode(unsigned Opcode, MVT::ValueType VT,
438                        const SDOperand *Ops, unsigned NumOps);
439  SDNode *getTargetNode(unsigned Opcode, MVT::ValueType VT1,
440                        MVT::ValueType VT2);
441  SDNode *getTargetNode(unsigned Opcode, MVT::ValueType VT1,
442                        MVT::ValueType VT2, SDOperand Op1);
443  SDNode *getTargetNode(unsigned Opcode, MVT::ValueType VT1,
444                        MVT::ValueType VT2, SDOperand Op1, SDOperand Op2);
445  SDNode *getTargetNode(unsigned Opcode, MVT::ValueType VT1,
446                        MVT::ValueType VT2, SDOperand Op1, SDOperand Op2,
447                        SDOperand Op3);
448  SDNode *getTargetNode(unsigned Opcode, MVT::ValueType VT1,
449                        MVT::ValueType VT2,
450                        const SDOperand *Ops, unsigned NumOps);
451  SDNode *getTargetNode(unsigned Opcode, MVT::ValueType VT1,
452                        MVT::ValueType VT2, MVT::ValueType VT3,
453                        SDOperand Op1, SDOperand Op2);
454  SDNode *getTargetNode(unsigned Opcode, MVT::ValueType VT1,
455                        MVT::ValueType VT2, MVT::ValueType VT3,
456                        SDOperand Op1, SDOperand Op2, SDOperand Op3);
457  SDNode *getTargetNode(unsigned Opcode, MVT::ValueType VT1,
458                        MVT::ValueType VT2, MVT::ValueType VT3,
459                        const SDOperand *Ops, unsigned NumOps);
460  SDNode *getTargetNode(unsigned Opcode, MVT::ValueType VT1,
461                        MVT::ValueType VT2, MVT::ValueType VT3,
462                        MVT::ValueType VT4,
463                        const SDOperand *Ops, unsigned NumOps);
464  SDNode *getTargetNode(unsigned Opcode, std::vector<MVT::ValueType> &ResultTys,
465                        const SDOperand *Ops, unsigned NumOps);
466
467  /// ReplaceAllUsesWith - Modify anything using 'From' to use 'To' instead.
468  /// This can cause recursive merging of nodes in the DAG.  Use the first
469  /// version if 'From' is known to have a single result, use the second
470  /// if you have two nodes with identical results, use the third otherwise.
471  ///
472  /// These methods all take an optional vector, which (if not null) is
473  /// populated with any nodes that are deleted from the SelectionDAG, due to
474  /// new equivalences that are discovered.
475  ///
476  void ReplaceAllUsesWith(SDOperand From, SDOperand Op,
477                          std::vector<SDNode*> *Deleted = 0);
478  void ReplaceAllUsesWith(SDNode *From, SDNode *To,
479                          std::vector<SDNode*> *Deleted = 0);
480  void ReplaceAllUsesWith(SDNode *From, const SDOperand *To,
481                          std::vector<SDNode*> *Deleted = 0);
482
483  /// ReplaceAllUsesOfValueWith - Replace any uses of From with To, leaving
484  /// uses of other values produced by From.Val alone.  The Deleted vector is
485  /// handled the same was as for ReplaceAllUsesWith, but it is required for
486  /// this method.
487  void ReplaceAllUsesOfValueWith(SDOperand From, SDOperand To,
488                                 std::vector<SDNode*> *Deleted = 0);
489
490  /// AssignNodeIds - Assign a unique node id for each node in the DAG based on
491  /// their allnodes order. It returns the maximum id.
492  unsigned AssignNodeIds();
493
494  /// AssignTopologicalOrder - Assign a unique node id for each node in the DAG
495  /// based on their topological order. It returns the maximum id and a vector
496  /// of the SDNodes* in assigned order by reference.
497  unsigned AssignTopologicalOrder(std::vector<SDNode*> &TopOrder);
498
499  /// isCommutativeBinOp - Returns true if the opcode is a commutative binary
500  /// operation.
501  static bool isCommutativeBinOp(unsigned Opcode) {
502    switch (Opcode) {
503    case ISD::ADD:
504    case ISD::MUL:
505    case ISD::MULHU:
506    case ISD::MULHS:
507    case ISD::SMUL_LOHI:
508    case ISD::UMUL_LOHI:
509    case ISD::FADD:
510    case ISD::FMUL:
511    case ISD::AND:
512    case ISD::OR:
513    case ISD::XOR:
514    case ISD::ADDC:
515    case ISD::ADDE: return true;
516    default: return false;
517    }
518  }
519
520  void dump() const;
521
522  /// CreateStackTemporary - Create a stack temporary, suitable for holding the
523  /// specified value type.
524  SDOperand CreateStackTemporary(MVT::ValueType VT);
525
526  /// FoldSetCC - Constant fold a setcc to true or false.
527  SDOperand FoldSetCC(MVT::ValueType VT, SDOperand N1,
528                      SDOperand N2, ISD::CondCode Cond);
529
530  /// MaskedValueIsZero - Return true if 'Op & Mask' is known to be zero.  We
531  /// use this predicate to simplify operations downstream.  Op and Mask are
532  /// known to be the same type.
533  bool MaskedValueIsZero(SDOperand Op, uint64_t Mask, unsigned Depth = 0)
534    const;
535
536  /// ComputeMaskedBits - Determine which of the bits specified in Mask are
537  /// known to be either zero or one and return them in the KnownZero/KnownOne
538  /// bitsets.  This code only analyzes bits in Mask, in order to short-circuit
539  /// processing.  Targets can implement the computeMaskedBitsForTargetNode
540  /// method in the TargetLowering class to allow target nodes to be understood.
541  void ComputeMaskedBits(SDOperand Op, uint64_t Mask, uint64_t &KnownZero,
542                         uint64_t &KnownOne, unsigned Depth = 0) const;
543
544  /// ComputeNumSignBits - Return the number of times the sign bit of the
545  /// register is replicated into the other bits.  We know that at least 1 bit
546  /// is always equal to the sign bit (itself), but other cases can give us
547  /// information.  For example, immediately after an "SRA X, 2", we know that
548  /// the top 3 bits are all equal to each other, so we return 3.  Targets can
549  /// implement the ComputeNumSignBitsForTarget method in the TargetLowering
550  /// class to allow target nodes to be understood.
551  unsigned ComputeNumSignBits(SDOperand Op, unsigned Depth = 0) const;
552
553private:
554  void RemoveNodeFromCSEMaps(SDNode *N);
555  SDNode *AddNonLeafNodeToCSEMaps(SDNode *N);
556  SDNode *FindModifiedNodeSlot(SDNode *N, SDOperand Op, void *&InsertPos);
557  SDNode *FindModifiedNodeSlot(SDNode *N, SDOperand Op1, SDOperand Op2,
558                               void *&InsertPos);
559  SDNode *FindModifiedNodeSlot(SDNode *N, const SDOperand *Ops, unsigned NumOps,
560                               void *&InsertPos);
561
562  void DeleteNodeNotInCSEMaps(SDNode *N);
563
564  // List of non-single value types.
565  std::list<std::vector<MVT::ValueType> > VTList;
566
567  // Maps to auto-CSE operations.
568  std::vector<CondCodeSDNode*> CondCodeNodes;
569
570  std::vector<SDNode*> ValueTypeNodes;
571  std::map<MVT::ValueType, SDNode*> ExtendedValueTypeNodes;
572  std::map<std::string, SDNode*> ExternalSymbols;
573  std::map<std::string, SDNode*> TargetExternalSymbols;
574  std::map<std::string, StringSDNode*> StringNodes;
575};
576
577template <> struct GraphTraits<SelectionDAG*> : public GraphTraits<SDNode*> {
578  typedef SelectionDAG::allnodes_iterator nodes_iterator;
579  static nodes_iterator nodes_begin(SelectionDAG *G) {
580    return G->allnodes_begin();
581  }
582  static nodes_iterator nodes_end(SelectionDAG *G) {
583    return G->allnodes_end();
584  }
585};
586
587}  // end namespace llvm
588
589#endif
590