SelectionDAG.h revision 1efba0ecb4d0b3807c48e6e0f74e3ce5c9fad809 
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/CodeGen/SelectionDAGCSEMap.h"
20#include "llvm/ADT/ilist"
21
22#include <list>
23#include <vector>
24#include <map>
25#include <set>
26#include <string>
27
28namespace llvm {
29  class TargetLowering;
30  class TargetMachine;
31  class MachineDebugInfo;
32  class MachineFunction;
33
34/// SelectionDAG class - This is used to represent a portion of an LLVM function
35/// in a low-level Data Dependence DAG representation suitable for instruction
36/// selection.  This DAG is constructed as the first step of instruction
37/// selection in order to allow implementation of machine specific optimizations
38/// and code simplifications.
39///
40/// The representation used by the SelectionDAG is a target-independent
41/// representation, which has some similarities to the GCC RTL representation,
42/// but is significantly more simple, powerful, and is a graph form instead of a
43/// linear form.
44///
45class SelectionDAG {
46  TargetLowering &TLI;
47  MachineFunction &MF;
48  MachineDebugInfo *DI;
49
50  /// Root - The root of the entire DAG.  EntryNode - The starting token.
51  SDOperand Root, EntryNode;
52
53  /// AllNodes - A linked list of nodes in the current DAG.
54  ilist<SDNode> AllNodes;
55
56  /// CSEMap - This structure is used to memoize nodes, automatically performing
57  /// CSE with existing nodes with a duplicate is requested.
58  SelectionDAGCSEMap CSEMap;
59
60public:
61  SelectionDAG(TargetLowering &tli, MachineFunction &mf, MachineDebugInfo *di)
62  : TLI(tli), MF(mf), DI(di) {
63    EntryNode = Root = getNode(ISD::EntryToken, MVT::Other);
64  }
65  ~SelectionDAG();
66
67  MachineFunction &getMachineFunction() const { return MF; }
68  const TargetMachine &getTarget() const;
69  TargetLowering &getTargetLoweringInfo() const { return TLI; }
70  MachineDebugInfo *getMachineDebugInfo() const { return DI; }
71
72  /// viewGraph - Pop up a ghostview window with the DAG rendered using 'dot'.
73  ///
74  void viewGraph();
75
76
77  typedef ilist<SDNode>::const_iterator allnodes_const_iterator;
78  allnodes_const_iterator allnodes_begin() const { return AllNodes.begin(); }
79  allnodes_const_iterator allnodes_end() const { return AllNodes.end(); }
80  typedef ilist<SDNode>::iterator allnodes_iterator;
81  allnodes_iterator allnodes_begin() { return AllNodes.begin(); }
82  allnodes_iterator allnodes_end() { return AllNodes.end(); }
83
84  /// getRoot - Return the root tag of the SelectionDAG.
85  ///
86  const SDOperand &getRoot() const { return Root; }
87
88  /// getEntryNode - Return the token chain corresponding to the entry of the
89  /// function.
90  const SDOperand &getEntryNode() const { return EntryNode; }
91
92  /// setRoot - Set the current root tag of the SelectionDAG.
93  ///
94  const SDOperand &setRoot(SDOperand N) { return Root = N; }
95
96  /// Combine - This iterates over the nodes in the SelectionDAG, folding
97  /// certain types of nodes together, or eliminating superfluous nodes.  When
98  /// the AfterLegalize argument is set to 'true', Combine takes care not to
99  /// generate any nodes that will be illegal on the target.
100  void Combine(bool AfterLegalize);
101
102  /// Legalize - This transforms the SelectionDAG into a SelectionDAG that is
103  /// compatible with the target instruction selector, as indicated by the
104  /// TargetLowering object.
105  ///
106  /// Note that this is an involved process that may invalidate pointers into
107  /// the graph.
108  void Legalize();
109
110  /// RemoveDeadNodes - This method deletes all unreachable nodes in the
111  /// SelectionDAG.
112  void RemoveDeadNodes();
113
114  /// getVTList - Return an SDVTList that represents the list of values
115  /// specified.
116  SDVTList getVTList(MVT::ValueType VT);
117  SDVTList getVTList(MVT::ValueType VT1, MVT::ValueType VT2);
118  SDVTList getVTList(MVT::ValueType VT1, MVT::ValueType VT2,MVT::ValueType VT3);
119  SDVTList getVTList(const MVT::ValueType *VTs, unsigned NumVTs);
120
121  /// getNodeValueTypes - These are obsolete, use getVTList instead.
122  const MVT::ValueType *getNodeValueTypes(MVT::ValueType VT) {
123    return getVTList(VT).VTs;
124  }
125  const MVT::ValueType *getNodeValueTypes(MVT::ValueType VT1,
126                                          MVT::ValueType VT2) {
127    return getVTList(VT1, VT2).VTs;
128  }
129  const MVT::ValueType *getNodeValueTypes(MVT::ValueType VT1,MVT::ValueType VT2,
130                                          MVT::ValueType VT3) {
131    return getVTList(VT1, VT2, VT3).VTs;
132  }
133  const MVT::ValueType *getNodeValueTypes(std::vector<MVT::ValueType> &VTList) {
134    return getVTList(&VTList[0], VTList.size()).VTs;
135  }
136
137
138  //===----------------------------------------------------------------------===//
139  // Node creation methods.
140  //
141  SDOperand getString(const std::string &Val);
142  SDOperand getConstant(uint64_t Val, MVT::ValueType VT, bool isTarget = false);
143  SDOperand getTargetConstant(uint64_t Val, MVT::ValueType VT) {
144    return getConstant(Val, VT, true);
145  }
146  SDOperand getConstantFP(double Val, MVT::ValueType VT, bool isTarget = false);
147  SDOperand getTargetConstantFP(double Val, MVT::ValueType VT) {
148    return getConstantFP(Val, VT, true);
149  }
150  SDOperand getGlobalAddress(const GlobalValue *GV, MVT::ValueType VT,
151                             int offset = 0, bool isTargetGA = false);
152  SDOperand getTargetGlobalAddress(const GlobalValue *GV, MVT::ValueType VT,
153                                   int offset = 0) {
154    return getGlobalAddress(GV, VT, offset, true);
155  }
156  SDOperand getFrameIndex(int FI, MVT::ValueType VT, bool isTarget = false);
157  SDOperand getTargetFrameIndex(int FI, MVT::ValueType VT) {
158    return getFrameIndex(FI, VT, true);
159  }
160  SDOperand getJumpTable(int JTI, MVT::ValueType VT, bool isTarget = false);
161  SDOperand getTargetJumpTable(int JTI, MVT::ValueType VT) {
162    return getJumpTable(JTI, VT, true);
163  }
164  SDOperand getConstantPool(Constant *C, MVT::ValueType VT,
165                            unsigned Align = 0, int Offs = 0, bool isT=false);
166  SDOperand getTargetConstantPool(Constant *C, MVT::ValueType VT,
167                                  unsigned Align = 0, int Offset = 0) {
168    return getConstantPool(C, VT, Align, Offset, true);
169  }
170  SDOperand getBasicBlock(MachineBasicBlock *MBB);
171  SDOperand getExternalSymbol(const char *Sym, MVT::ValueType VT);
172  SDOperand getTargetExternalSymbol(const char *Sym, MVT::ValueType VT);
173  SDOperand getValueType(MVT::ValueType);
174  SDOperand getRegister(unsigned Reg, MVT::ValueType VT);
175
176  SDOperand getCopyToReg(SDOperand Chain, unsigned Reg, SDOperand N) {
177    return getNode(ISD::CopyToReg, MVT::Other, Chain,
178                   getRegister(Reg, N.getValueType()), N);
179  }
180
181  // This version of the getCopyToReg method takes an extra operand, which
182  // indicates that there is potentially an incoming flag value (if Flag is not
183  // null) and that there should be a flag result.
184  SDOperand getCopyToReg(SDOperand Chain, unsigned Reg, SDOperand N,
185                         SDOperand Flag) {
186    const MVT::ValueType *VTs = getNodeValueTypes(MVT::Other, MVT::Flag);
187    SDOperand Ops[] = { Chain, getRegister(Reg, N.getValueType()), N, Flag };
188    return getNode(ISD::CopyToReg, VTs, 2, Ops, Flag.Val ? 4 : 3);
189  }
190
191  // Similar to last getCopyToReg() except parameter Reg is a SDOperand
192  SDOperand getCopyToReg(SDOperand Chain, SDOperand Reg, SDOperand N,
193                         SDOperand Flag) {
194    const MVT::ValueType *VTs = getNodeValueTypes(MVT::Other, MVT::Flag);
195    SDOperand Ops[] = { Chain, Reg, N, Flag };
196    return getNode(ISD::CopyToReg, VTs, 2, Ops, Flag.Val ? 4 : 3);
197  }
198
199  SDOperand getCopyFromReg(SDOperand Chain, unsigned Reg, MVT::ValueType VT) {
200    const MVT::ValueType *VTs = getNodeValueTypes(VT, MVT::Other);
201    SDOperand Ops[] = { Chain, getRegister(Reg, VT) };
202    return getNode(ISD::CopyFromReg, VTs, 2, Ops, 2);
203  }
204
205  // This version of the getCopyFromReg method takes an extra operand, which
206  // indicates that there is potentially an incoming flag value (if Flag is not
207  // null) and that there should be a flag result.
208  SDOperand getCopyFromReg(SDOperand Chain, unsigned Reg, MVT::ValueType VT,
209                           SDOperand Flag) {
210    const MVT::ValueType *VTs = getNodeValueTypes(VT, MVT::Other, MVT::Flag);
211    SDOperand Ops[] = { Chain, getRegister(Reg, VT), Flag };
212    return getNode(ISD::CopyFromReg, VTs, 3, Ops, Flag.Val ? 3 : 2);
213  }
214
215  SDOperand getCondCode(ISD::CondCode Cond);
216
217  /// getZeroExtendInReg - Return the expression required to zero extend the Op
218  /// value assuming it was the smaller SrcTy value.
219  SDOperand getZeroExtendInReg(SDOperand Op, MVT::ValueType SrcTy);
220
221  /// getCALLSEQ_START - Return a new CALLSEQ_START node, which always must have
222  /// a flag result (to ensure it's not CSE'd).
223  SDOperand getCALLSEQ_START(SDOperand Chain, SDOperand Op) {
224    const MVT::ValueType *VTs = getNodeValueTypes(MVT::Other, MVT::Flag);
225    SDOperand Ops[] = { Chain,  Op };
226    return getNode(ISD::CALLSEQ_START, VTs, 2, Ops, 2);
227  }
228
229  /// getNode - Gets or creates the specified node.
230  ///
231  SDOperand getNode(unsigned Opcode, MVT::ValueType VT);
232  SDOperand getNode(unsigned Opcode, MVT::ValueType VT, SDOperand N);
233  SDOperand getNode(unsigned Opcode, MVT::ValueType VT,
234                    SDOperand N1, SDOperand N2);
235  SDOperand getNode(unsigned Opcode, MVT::ValueType VT,
236                    SDOperand N1, SDOperand N2, SDOperand N3);
237  SDOperand getNode(unsigned Opcode, MVT::ValueType VT,
238                    SDOperand N1, SDOperand N2, SDOperand N3, SDOperand N4);
239  SDOperand getNode(unsigned Opcode, MVT::ValueType VT,
240                    SDOperand N1, SDOperand N2, SDOperand N3, SDOperand N4,
241                    SDOperand N5);
242  SDOperand getNode(unsigned Opcode, MVT::ValueType VT,
243                    const SDOperand *Ops, unsigned NumOps);
244  SDOperand getNode(unsigned Opcode, std::vector<MVT::ValueType> &ResultTys,
245                    const SDOperand *Ops, unsigned NumOps);
246  SDOperand getNode(unsigned Opcode, const MVT::ValueType *VTs, unsigned NumVTs,
247                    const SDOperand *Ops, unsigned NumOps);
248  SDOperand getNode(unsigned Opcode, SDVTList VTs,
249                    const SDOperand *Ops, unsigned NumOps);
250
251  /// getSetCC - Helper function to make it easier to build SetCC's if you just
252  /// have an ISD::CondCode instead of an SDOperand.
253  ///
254  SDOperand getSetCC(MVT::ValueType VT, SDOperand LHS, SDOperand RHS,
255                     ISD::CondCode Cond) {
256    return getNode(ISD::SETCC, VT, LHS, RHS, getCondCode(Cond));
257  }
258
259  /// getSelectCC - Helper function to make it easier to build SelectCC's if you
260  /// just have an ISD::CondCode instead of an SDOperand.
261  ///
262  SDOperand getSelectCC(SDOperand LHS, SDOperand RHS,
263                        SDOperand True, SDOperand False, ISD::CondCode Cond) {
264    return getNode(ISD::SELECT_CC, True.getValueType(), LHS, RHS, True, False,
265                   getCondCode(Cond));
266  }
267
268  /// getVAArg - VAArg produces a result and token chain, and takes a pointer
269  /// and a source value as input.
270  SDOperand getVAArg(MVT::ValueType VT, SDOperand Chain, SDOperand Ptr,
271                     SDOperand SV);
272
273  /// getLoad - Loads are not normal binary operators: their result type is not
274  /// determined by their operands, and they produce a value AND a token chain.
275  ///
276  SDOperand getLoad(MVT::ValueType VT, SDOperand Chain, SDOperand Ptr,
277                    SDOperand SV);
278  SDOperand getVecLoad(unsigned Count, MVT::ValueType VT, SDOperand Chain,
279                       SDOperand Ptr, SDOperand SV);
280  SDOperand getExtLoad(unsigned Opcode, MVT::ValueType VT, SDOperand Chain,
281                       SDOperand Ptr, SDOperand SV, MVT::ValueType EVT);
282
283  // getSrcValue - construct a node to track a Value* through the backend
284  SDOperand getSrcValue(const Value* I, int offset = 0);
285
286  /// UpdateNodeOperands - *Mutate* the specified node in-place to have the
287  /// specified operands.  If the resultant node already exists in the DAG,
288  /// this does not modify the specified node, instead it returns the node that
289  /// already exists.  If the resultant node does not exist in the DAG, the
290  /// input node is returned.  As a degenerate case, if you specify the same
291  /// input operands as the node already has, the input node is returned.
292  SDOperand UpdateNodeOperands(SDOperand N, SDOperand Op);
293  SDOperand UpdateNodeOperands(SDOperand N, SDOperand Op1, SDOperand Op2);
294  SDOperand UpdateNodeOperands(SDOperand N, SDOperand Op1, SDOperand Op2,
295                               SDOperand Op3);
296  SDOperand UpdateNodeOperands(SDOperand N, SDOperand Op1, SDOperand Op2,
297                               SDOperand Op3, SDOperand Op4);
298  SDOperand UpdateNodeOperands(SDOperand N, SDOperand Op1, SDOperand Op2,
299                               SDOperand Op3, SDOperand Op4, SDOperand Op5);
300  SDOperand UpdateNodeOperands(SDOperand N, SDOperand *Ops, unsigned NumOps);
301
302  /// SelectNodeTo - These are used for target selectors to *mutate* the
303  /// specified node to have the specified return type, Target opcode, and
304  /// operands.  Note that target opcodes are stored as
305  /// ISD::BUILTIN_OP_END+TargetOpcode in the node opcode field.  The 0th value
306  /// of the resultant node is returned.
307  SDNode *SelectNodeTo(SDNode *N, unsigned TargetOpc, MVT::ValueType VT);
308  SDNode *SelectNodeTo(SDNode *N, unsigned TargetOpc, MVT::ValueType VT,
309                       SDOperand Op1);
310  SDNode *SelectNodeTo(SDNode *N, unsigned TargetOpc, MVT::ValueType VT,
311                       SDOperand Op1, SDOperand Op2);
312  SDNode *SelectNodeTo(SDNode *N, unsigned TargetOpc, MVT::ValueType VT,
313                       SDOperand Op1, SDOperand Op2, SDOperand Op3);
314  SDNode *SelectNodeTo(SDNode *N, unsigned TargetOpc, MVT::ValueType VT,
315                        const SDOperand *Ops, unsigned NumOps);
316  SDNode *SelectNodeTo(SDNode *N, unsigned TargetOpc, MVT::ValueType VT1,
317                       MVT::ValueType VT2, SDOperand Op1, SDOperand Op2);
318  SDNode *SelectNodeTo(SDNode *N, unsigned TargetOpc, MVT::ValueType VT1,
319                       MVT::ValueType VT2, SDOperand Op1, SDOperand Op2,
320                       SDOperand Op3);
321
322
323  /// getTargetNode - These are used for target selectors to create a new node
324  /// with specified return type(s), target opcode, and operands.
325  ///
326  /// Note that getTargetNode returns the resultant node.  If there is already a
327  /// node of the specified opcode and operands, it returns that node instead of
328  /// the current one.
329  SDNode *getTargetNode(unsigned Opcode, MVT::ValueType VT);
330  SDNode *getTargetNode(unsigned Opcode, MVT::ValueType VT,
331                        SDOperand Op1);
332  SDNode *getTargetNode(unsigned Opcode, MVT::ValueType VT,
333                        SDOperand Op1, SDOperand Op2);
334  SDNode *getTargetNode(unsigned Opcode, MVT::ValueType VT,
335                        SDOperand Op1, SDOperand Op2, SDOperand Op3);
336  SDNode *getTargetNode(unsigned Opcode, MVT::ValueType VT,
337                        const SDOperand *Ops, unsigned NumOps);
338  SDNode *getTargetNode(unsigned Opcode, MVT::ValueType VT1,
339                        MVT::ValueType VT2, SDOperand Op1);
340  SDNode *getTargetNode(unsigned Opcode, MVT::ValueType VT1,
341                        MVT::ValueType VT2, SDOperand Op1, SDOperand Op2);
342  SDNode *getTargetNode(unsigned Opcode, MVT::ValueType VT1,
343                        MVT::ValueType VT2, SDOperand Op1, SDOperand Op2,
344                        SDOperand Op3);
345  SDNode *getTargetNode(unsigned Opcode, MVT::ValueType VT1,
346                        MVT::ValueType VT2,
347                        const SDOperand *Ops, unsigned NumOps);
348  SDNode *getTargetNode(unsigned Opcode, MVT::ValueType VT1,
349                        MVT::ValueType VT2, MVT::ValueType VT3,
350                        SDOperand Op1, SDOperand Op2);
351  SDNode *getTargetNode(unsigned Opcode, MVT::ValueType VT1,
352                        MVT::ValueType VT2, MVT::ValueType VT3,
353                        const SDOperand *Ops, unsigned NumOps);
354
355  /// ReplaceAllUsesWith - Modify anything using 'From' to use 'To' instead.
356  /// This can cause recursive merging of nodes in the DAG.  Use the first
357  /// version if 'From' is known to have a single result, use the second
358  /// if you have two nodes with identical results, use the third otherwise.
359  ///
360  /// These methods all take an optional vector, which (if not null) is
361  /// populated with any nodes that are deleted from the SelectionDAG, due to
362  /// new equivalences that are discovered.
363  ///
364  void ReplaceAllUsesWith(SDOperand From, SDOperand Op,
365                          std::vector<SDNode*> *Deleted = 0);
366  void ReplaceAllUsesWith(SDNode *From, SDNode *To,
367                          std::vector<SDNode*> *Deleted = 0);
368  void ReplaceAllUsesWith(SDNode *From, const SDOperand *To,
369                          std::vector<SDNode*> *Deleted = 0);
370
371  /// ReplaceAllUsesOfValueWith - Replace any uses of From with To, leaving
372  /// uses of other values produced by From.Val alone.  The Deleted vector is
373  /// handled the same was as for ReplaceAllUsesWith, but it is required for
374  /// this method.
375  void ReplaceAllUsesOfValueWith(SDOperand From, SDOperand To,
376                                 std::vector<SDNode*> &Deleted);
377
378  /// DeleteNode - Remove the specified node from the system.  This node must
379  /// have no referrers.
380  void DeleteNode(SDNode *N);
381
382  /// AssignNodeIds - Assign a unique node id for each node in the DAG based on
383  /// their allnodes order. It returns the maximum id.
384  unsigned AssignNodeIds();
385
386  /// AssignTopologicalOrder - Assign a unique node id for each node in the DAG
387  /// based on their topological order. It returns the maximum id and a vector
388  /// of the SDNodes* in assigned order by reference.
389  unsigned AssignTopologicalOrder(std::vector<SDNode*> &TopOrder);
390
391  /// isCommutativeBinOp - Returns true if the opcode is a commutative binary
392  /// operation.
393  static bool isCommutativeBinOp(unsigned Opcode) {
394    switch (Opcode) {
395    case ISD::ADD:
396    case ISD::MUL:
397    case ISD::MULHU:
398    case ISD::MULHS:
399    case ISD::FADD:
400    case ISD::FMUL:
401    case ISD::AND:
402    case ISD::OR:
403    case ISD::XOR:
404    case ISD::ADDC:
405    case ISD::ADDE: return true;
406    default: return false;
407    }
408  }
409
410  void dump() const;
411
412private:
413  void RemoveNodeFromCSEMaps(SDNode *N);
414  SDNode *AddNonLeafNodeToCSEMaps(SDNode *N);
415  SDNode *FindModifiedNodeSlot(SDNode *N, SDOperand Op, void *&InsertPos);
416  SDNode *FindModifiedNodeSlot(SDNode *N, SDOperand Op1, SDOperand Op2,
417                               void *&InsertPos);
418  SDNode *FindModifiedNodeSlot(SDNode *N, const SDOperand *Ops, unsigned NumOps,
419                               void *&InsertPos);
420
421  void DeleteNodeNotInCSEMaps(SDNode *N);
422
423  /// SimplifySetCC - Try to simplify a setcc built with the specified operands
424  /// and cc.  If unable to simplify it, return a null SDOperand.
425  SDOperand SimplifySetCC(MVT::ValueType VT, SDOperand N1,
426                          SDOperand N2, ISD::CondCode Cond);
427
428  // List of non-single value types.
429  std::list<std::vector<MVT::ValueType> > VTList;
430
431  // Maps to auto-CSE operations.
432  std::vector<CondCodeSDNode*> CondCodeNodes;
433
434  std::vector<SDNode*> ValueTypeNodes;
435  std::map<std::string, SDNode*> ExternalSymbols;
436  std::map<std::string, SDNode*> TargetExternalSymbols;
437  std::map<std::string, StringSDNode*> StringNodes;
438};
439
440template <> struct GraphTraits<SelectionDAG*> : public GraphTraits<SDNode*> {
441  typedef SelectionDAG::allnodes_iterator nodes_iterator;
442  static nodes_iterator nodes_begin(SelectionDAG *G) {
443    return G->allnodes_begin();
444  }
445  static nodes_iterator nodes_end(SelectionDAG *G) {
446    return G->allnodes_end();
447  }
448};
449
450}  // end namespace llvm
451
452#endif
453