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1 //===-- llvm/CodeGen/MachineInstr.h - MachineInstr class --------*- 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 contains the declaration of the MachineInstr class, which is the
11 // basic representation for all target dependent machine instructions used by
12 // the back end.
13 //
14 //===----------------------------------------------------------------------===//
15 
16 #ifndef LLVM_CODEGEN_MACHINEINSTR_H
17 #define LLVM_CODEGEN_MACHINEINSTR_H
18 
19 #include "llvm/CodeGen/MachineOperand.h"
20 #include "llvm/MC/MCInstrDesc.h"
21 #include "llvm/Target/TargetOpcodes.h"
22 #include "llvm/ADT/ilist.h"
23 #include "llvm/ADT/ilist_node.h"
24 #include "llvm/ADT/STLExtras.h"
25 #include "llvm/ADT/StringRef.h"
26 #include "llvm/ADT/DenseMapInfo.h"
27 #include "llvm/Support/DebugLoc.h"
28 #include <vector>
29 
30 namespace llvm {
31 
32 template <typename T> class SmallVectorImpl;
33 class AliasAnalysis;
34 class TargetInstrInfo;
35 class TargetRegisterClass;
36 class TargetRegisterInfo;
37 class MachineFunction;
38 class MachineMemOperand;
39 
40 //===----------------------------------------------------------------------===//
41 /// MachineInstr - Representation of each machine instruction.
42 ///
43 class MachineInstr : public ilist_node<MachineInstr> {
44 public:
45   typedef MachineMemOperand **mmo_iterator;
46 
47   /// Flags to specify different kinds of comments to output in
48   /// assembly code.  These flags carry semantic information not
49   /// otherwise easily derivable from the IR text.
50   ///
51   enum CommentFlag {
52     ReloadReuse = 0x1
53   };
54 
55   enum MIFlag {
56     NoFlags    = 0,
57     FrameSetup = 1 << 0                 // Instruction is used as a part of
58                                         // function frame setup code.
59   };
60 private:
61   const MCInstrDesc *MCID;              // Instruction descriptor.
62 
63   uint8_t Flags;                        // Various bits of additional
64                                         // information about machine
65                                         // instruction.
66 
67   uint8_t AsmPrinterFlags;              // Various bits of information used by
68                                         // the AsmPrinter to emit helpful
69                                         // comments.  This is *not* semantic
70                                         // information.  Do not use this for
71                                         // anything other than to convey comment
72                                         // information to AsmPrinter.
73 
74   std::vector<MachineOperand> Operands; // the operands
75   mmo_iterator MemRefs;                 // information on memory references
76   mmo_iterator MemRefsEnd;
77   MachineBasicBlock *Parent;            // Pointer to the owning basic block.
78   DebugLoc debugLoc;                    // Source line information.
79 
80   MachineInstr(const MachineInstr&);   // DO NOT IMPLEMENT
81   void operator=(const MachineInstr&); // DO NOT IMPLEMENT
82 
83   // Intrusive list support
84   friend struct ilist_traits<MachineInstr>;
85   friend struct ilist_traits<MachineBasicBlock>;
86   void setParent(MachineBasicBlock *P) { Parent = P; }
87 
88   /// MachineInstr ctor - This constructor creates a copy of the given
89   /// MachineInstr in the given MachineFunction.
90   MachineInstr(MachineFunction &, const MachineInstr &);
91 
92   /// MachineInstr ctor - This constructor creates a dummy MachineInstr with
93   /// MCID NULL and no operands.
94   MachineInstr();
95 
96   // The next two constructors have DebugLoc and non-DebugLoc versions;
97   // over time, the non-DebugLoc versions should be phased out and eventually
98   // removed.
99 
100   /// MachineInstr ctor - This constructor creates a MachineInstr and adds the
101   /// implicit operands.  It reserves space for the number of operands specified
102   /// by the MCInstrDesc.  The version with a DebugLoc should be preferred.
103   explicit MachineInstr(const MCInstrDesc &MCID, bool NoImp = false);
104 
105   /// MachineInstr ctor - Work exactly the same as the ctor above, except that
106   /// the MachineInstr is created and added to the end of the specified basic
107   /// block.  The version with a DebugLoc should be preferred.
108   MachineInstr(MachineBasicBlock *MBB, const MCInstrDesc &MCID);
109 
110   /// MachineInstr ctor - This constructor create a MachineInstr and add the
111   /// implicit operands.  It reserves space for number of operands specified by
112   /// MCInstrDesc.  An explicit DebugLoc is supplied.
113   explicit MachineInstr(const MCInstrDesc &MCID, const DebugLoc dl,
114                         bool NoImp = false);
115 
116   /// MachineInstr ctor - Work exactly the same as the ctor above, except that
117   /// the MachineInstr is created and added to the end of the specified basic
118   /// block.
119   MachineInstr(MachineBasicBlock *MBB, const DebugLoc dl,
120                const MCInstrDesc &MCID);
121 
122   ~MachineInstr();
123 
124   // MachineInstrs are pool-allocated and owned by MachineFunction.
125   friend class MachineFunction;
126 
127 public:
128   const MachineBasicBlock* getParent() const { return Parent; }
129   MachineBasicBlock* getParent() { return Parent; }
130 
131   /// getAsmPrinterFlags - Return the asm printer flags bitvector.
132   ///
133   uint8_t getAsmPrinterFlags() const { return AsmPrinterFlags; }
134 
135   /// clearAsmPrinterFlags - clear the AsmPrinter bitvector
136   ///
137   void clearAsmPrinterFlags() { AsmPrinterFlags = 0; }
138 
139   /// getAsmPrinterFlag - Return whether an AsmPrinter flag is set.
140   ///
141   bool getAsmPrinterFlag(CommentFlag Flag) const {
142     return AsmPrinterFlags & Flag;
143   }
144 
145   /// setAsmPrinterFlag - Set a flag for the AsmPrinter.
146   ///
147   void setAsmPrinterFlag(CommentFlag Flag) {
148     AsmPrinterFlags |= (uint8_t)Flag;
149   }
150 
151   /// getFlags - Return the MI flags bitvector.
152   uint8_t getFlags() const {
153     return Flags;
154   }
155 
156   /// getFlag - Return whether an MI flag is set.
157   bool getFlag(MIFlag Flag) const {
158     return Flags & Flag;
159   }
160 
161   /// setFlag - Set a MI flag.
162   void setFlag(MIFlag Flag) {
163     Flags |= (uint8_t)Flag;
164   }
165 
166   void setFlags(unsigned flags) {
167     Flags = flags;
168   }
169 
170   /// clearAsmPrinterFlag - clear specific AsmPrinter flags
171   ///
172   void clearAsmPrinterFlag(CommentFlag Flag) {
173     AsmPrinterFlags &= ~Flag;
174   }
175 
176   /// getDebugLoc - Returns the debug location id of this MachineInstr.
177   ///
178   DebugLoc getDebugLoc() const { return debugLoc; }
179 
180   /// emitError - Emit an error referring to the source location of this
181   /// instruction. This should only be used for inline assembly that is somehow
182   /// impossible to compile. Other errors should have been handled much
183   /// earlier.
184   ///
185   /// If this method returns, the caller should try to recover from the error.
186   ///
187   void emitError(StringRef Msg) const;
188 
189   /// getDesc - Returns the target instruction descriptor of this
190   /// MachineInstr.
191   const MCInstrDesc &getDesc() const { return *MCID; }
192 
193   /// getOpcode - Returns the opcode of this MachineInstr.
194   ///
195   int getOpcode() const { return MCID->Opcode; }
196 
197   /// Access to explicit operands of the instruction.
198   ///
199   unsigned getNumOperands() const { return (unsigned)Operands.size(); }
200 
201   const MachineOperand& getOperand(unsigned i) const {
202     assert(i < getNumOperands() && "getOperand() out of range!");
203     return Operands[i];
204   }
205   MachineOperand& getOperand(unsigned i) {
206     assert(i < getNumOperands() && "getOperand() out of range!");
207     return Operands[i];
208   }
209 
210   /// getNumExplicitOperands - Returns the number of non-implicit operands.
211   ///
212   unsigned getNumExplicitOperands() const;
213 
214   /// iterator/begin/end - Iterate over all operands of a machine instruction.
215   typedef std::vector<MachineOperand>::iterator mop_iterator;
216   typedef std::vector<MachineOperand>::const_iterator const_mop_iterator;
217 
218   mop_iterator operands_begin() { return Operands.begin(); }
219   mop_iterator operands_end() { return Operands.end(); }
220 
221   const_mop_iterator operands_begin() const { return Operands.begin(); }
222   const_mop_iterator operands_end() const { return Operands.end(); }
223 
224   /// Access to memory operands of the instruction
225   mmo_iterator memoperands_begin() const { return MemRefs; }
226   mmo_iterator memoperands_end() const { return MemRefsEnd; }
227   bool memoperands_empty() const { return MemRefsEnd == MemRefs; }
228 
229   /// hasOneMemOperand - Return true if this instruction has exactly one
230   /// MachineMemOperand.
231   bool hasOneMemOperand() const {
232     return MemRefsEnd - MemRefs == 1;
233   }
234 
235   enum MICheckType {
236     CheckDefs,      // Check all operands for equality
237     CheckKillDead,  // Check all operands including kill / dead markers
238     IgnoreDefs,     // Ignore all definitions
239     IgnoreVRegDefs  // Ignore virtual register definitions
240   };
241 
242   /// isIdenticalTo - Return true if this instruction is identical to (same
243   /// opcode and same operands as) the specified instruction.
244   bool isIdenticalTo(const MachineInstr *Other,
245                      MICheckType Check = CheckDefs) const;
246 
247   /// removeFromParent - This method unlinks 'this' from the containing basic
248   /// block, and returns it, but does not delete it.
249   MachineInstr *removeFromParent();
250 
251   /// eraseFromParent - This method unlinks 'this' from the containing basic
252   /// block and deletes it.
253   void eraseFromParent();
254 
255   /// isLabel - Returns true if the MachineInstr represents a label.
256   ///
257   bool isLabel() const {
258     return getOpcode() == TargetOpcode::PROLOG_LABEL ||
259            getOpcode() == TargetOpcode::EH_LABEL ||
260            getOpcode() == TargetOpcode::GC_LABEL;
261   }
262 
263   bool isPrologLabel() const {
264     return getOpcode() == TargetOpcode::PROLOG_LABEL;
265   }
266   bool isEHLabel() const { return getOpcode() == TargetOpcode::EH_LABEL; }
267   bool isGCLabel() const { return getOpcode() == TargetOpcode::GC_LABEL; }
268   bool isDebugValue() const { return getOpcode() == TargetOpcode::DBG_VALUE; }
269 
270   bool isPHI() const { return getOpcode() == TargetOpcode::PHI; }
271   bool isKill() const { return getOpcode() == TargetOpcode::KILL; }
272   bool isImplicitDef() const { return getOpcode()==TargetOpcode::IMPLICIT_DEF; }
273   bool isInlineAsm() const { return getOpcode() == TargetOpcode::INLINEASM; }
274   bool isStackAligningInlineAsm() const;
275   bool isInsertSubreg() const {
276     return getOpcode() == TargetOpcode::INSERT_SUBREG;
277   }
278   bool isSubregToReg() const {
279     return getOpcode() == TargetOpcode::SUBREG_TO_REG;
280   }
281   bool isRegSequence() const {
282     return getOpcode() == TargetOpcode::REG_SEQUENCE;
283   }
284   bool isCopy() const {
285     return getOpcode() == TargetOpcode::COPY;
286   }
287   bool isFullCopy() const {
288     return isCopy() && !getOperand(0).getSubReg() && !getOperand(1).getSubReg();
289   }
290 
291   /// isCopyLike - Return true if the instruction behaves like a copy.
292   /// This does not include native copy instructions.
293   bool isCopyLike() const {
294     return isCopy() || isSubregToReg();
295   }
296 
297   /// isIdentityCopy - Return true is the instruction is an identity copy.
298   bool isIdentityCopy() const {
299     return isCopy() && getOperand(0).getReg() == getOperand(1).getReg() &&
300       getOperand(0).getSubReg() == getOperand(1).getSubReg();
301   }
302 
303   /// readsRegister - Return true if the MachineInstr reads the specified
304   /// register. If TargetRegisterInfo is passed, then it also checks if there
305   /// is a read of a super-register.
306   /// This does not count partial redefines of virtual registers as reads:
307   ///   %reg1024:6 = OP.
308   bool readsRegister(unsigned Reg, const TargetRegisterInfo *TRI = NULL) const {
309     return findRegisterUseOperandIdx(Reg, false, TRI) != -1;
310   }
311 
312   /// readsVirtualRegister - Return true if the MachineInstr reads the specified
313   /// virtual register. Take into account that a partial define is a
314   /// read-modify-write operation.
315   bool readsVirtualRegister(unsigned Reg) const {
316     return readsWritesVirtualRegister(Reg).first;
317   }
318 
319   /// readsWritesVirtualRegister - Return a pair of bools (reads, writes)
320   /// indicating if this instruction reads or writes Reg. This also considers
321   /// partial defines.
322   /// If Ops is not null, all operand indices for Reg are added.
323   std::pair<bool,bool> readsWritesVirtualRegister(unsigned Reg,
324                                       SmallVectorImpl<unsigned> *Ops = 0) const;
325 
326   /// killsRegister - Return true if the MachineInstr kills the specified
327   /// register. If TargetRegisterInfo is passed, then it also checks if there is
328   /// a kill of a super-register.
329   bool killsRegister(unsigned Reg, const TargetRegisterInfo *TRI = NULL) const {
330     return findRegisterUseOperandIdx(Reg, true, TRI) != -1;
331   }
332 
333   /// definesRegister - Return true if the MachineInstr fully defines the
334   /// specified register. If TargetRegisterInfo is passed, then it also checks
335   /// if there is a def of a super-register.
336   /// NOTE: It's ignoring subreg indices on virtual registers.
337   bool definesRegister(unsigned Reg, const TargetRegisterInfo *TRI=NULL) const {
338     return findRegisterDefOperandIdx(Reg, false, false, TRI) != -1;
339   }
340 
341   /// modifiesRegister - Return true if the MachineInstr modifies (fully define
342   /// or partially define) the specified register.
343   /// NOTE: It's ignoring subreg indices on virtual registers.
344   bool modifiesRegister(unsigned Reg, const TargetRegisterInfo *TRI) const {
345     return findRegisterDefOperandIdx(Reg, false, true, TRI) != -1;
346   }
347 
348   /// registerDefIsDead - Returns true if the register is dead in this machine
349   /// instruction. If TargetRegisterInfo is passed, then it also checks
350   /// if there is a dead def of a super-register.
351   bool registerDefIsDead(unsigned Reg,
352                          const TargetRegisterInfo *TRI = NULL) const {
353     return findRegisterDefOperandIdx(Reg, true, false, TRI) != -1;
354   }
355 
356   /// findRegisterUseOperandIdx() - Returns the operand index that is a use of
357   /// the specific register or -1 if it is not found. It further tightens
358   /// the search criteria to a use that kills the register if isKill is true.
359   int findRegisterUseOperandIdx(unsigned Reg, bool isKill = false,
360                                 const TargetRegisterInfo *TRI = NULL) const;
361 
362   /// findRegisterUseOperand - Wrapper for findRegisterUseOperandIdx, it returns
363   /// a pointer to the MachineOperand rather than an index.
364   MachineOperand *findRegisterUseOperand(unsigned Reg, bool isKill = false,
365                                          const TargetRegisterInfo *TRI = NULL) {
366     int Idx = findRegisterUseOperandIdx(Reg, isKill, TRI);
367     return (Idx == -1) ? NULL : &getOperand(Idx);
368   }
369 
370   /// findRegisterDefOperandIdx() - Returns the operand index that is a def of
371   /// the specified register or -1 if it is not found. If isDead is true, defs
372   /// that are not dead are skipped. If Overlap is true, then it also looks for
373   /// defs that merely overlap the specified register. If TargetRegisterInfo is
374   /// non-null, then it also checks if there is a def of a super-register.
375   int findRegisterDefOperandIdx(unsigned Reg,
376                                 bool isDead = false, bool Overlap = false,
377                                 const TargetRegisterInfo *TRI = NULL) const;
378 
379   /// findRegisterDefOperand - Wrapper for findRegisterDefOperandIdx, it returns
380   /// a pointer to the MachineOperand rather than an index.
381   MachineOperand *findRegisterDefOperand(unsigned Reg, bool isDead = false,
382                                          const TargetRegisterInfo *TRI = NULL) {
383     int Idx = findRegisterDefOperandIdx(Reg, isDead, false, TRI);
384     return (Idx == -1) ? NULL : &getOperand(Idx);
385   }
386 
387   /// findFirstPredOperandIdx() - Find the index of the first operand in the
388   /// operand list that is used to represent the predicate. It returns -1 if
389   /// none is found.
390   int findFirstPredOperandIdx() const;
391 
392   /// findInlineAsmFlagIdx() - Find the index of the flag word operand that
393   /// corresponds to operand OpIdx on an inline asm instruction.  Returns -1 if
394   /// getOperand(OpIdx) does not belong to an inline asm operand group.
395   ///
396   /// If GroupNo is not NULL, it will receive the number of the operand group
397   /// containing OpIdx.
398   ///
399   /// The flag operand is an immediate that can be decoded with methods like
400   /// InlineAsm::hasRegClassConstraint().
401   ///
402   int findInlineAsmFlagIdx(unsigned OpIdx, unsigned *GroupNo = 0) const;
403 
404   /// getRegClassConstraint - Compute the static register class constraint for
405   /// operand OpIdx.  For normal instructions, this is derived from the
406   /// MCInstrDesc.  For inline assembly it is derived from the flag words.
407   ///
408   /// Returns NULL if the static register classs constraint cannot be
409   /// determined.
410   ///
411   const TargetRegisterClass*
412   getRegClassConstraint(unsigned OpIdx,
413                         const TargetInstrInfo *TII,
414                         const TargetRegisterInfo *TRI) const;
415 
416   /// isRegTiedToUseOperand - Given the index of a register def operand,
417   /// check if the register def is tied to a source operand, due to either
418   /// two-address elimination or inline assembly constraints. Returns the
419   /// first tied use operand index by reference is UseOpIdx is not null.
420   bool isRegTiedToUseOperand(unsigned DefOpIdx, unsigned *UseOpIdx = 0) const;
421 
422   /// isRegTiedToDefOperand - Return true if the use operand of the specified
423   /// index is tied to an def operand. It also returns the def operand index by
424   /// reference if DefOpIdx is not null.
425   bool isRegTiedToDefOperand(unsigned UseOpIdx, unsigned *DefOpIdx = 0) const;
426 
427   /// clearKillInfo - Clears kill flags on all operands.
428   ///
429   void clearKillInfo();
430 
431   /// copyKillDeadInfo - Copies kill / dead operand properties from MI.
432   ///
433   void copyKillDeadInfo(const MachineInstr *MI);
434 
435   /// copyPredicates - Copies predicate operand(s) from MI.
436   void copyPredicates(const MachineInstr *MI);
437 
438   /// substituteRegister - Replace all occurrences of FromReg with ToReg:SubIdx,
439   /// properly composing subreg indices where necessary.
440   void substituteRegister(unsigned FromReg, unsigned ToReg, unsigned SubIdx,
441                           const TargetRegisterInfo &RegInfo);
442 
443   /// addRegisterKilled - We have determined MI kills a register. Look for the
444   /// operand that uses it and mark it as IsKill. If AddIfNotFound is true,
445   /// add a implicit operand if it's not found. Returns true if the operand
446   /// exists / is added.
447   bool addRegisterKilled(unsigned IncomingReg,
448                          const TargetRegisterInfo *RegInfo,
449                          bool AddIfNotFound = false);
450 
451   /// addRegisterDead - We have determined MI defined a register without a use.
452   /// Look for the operand that defines it and mark it as IsDead. If
453   /// AddIfNotFound is true, add a implicit operand if it's not found. Returns
454   /// true if the operand exists / is added.
455   bool addRegisterDead(unsigned IncomingReg, const TargetRegisterInfo *RegInfo,
456                        bool AddIfNotFound = false);
457 
458   /// addRegisterDefined - We have determined MI defines a register. Make sure
459   /// there is an operand defining Reg.
460   void addRegisterDefined(unsigned IncomingReg,
461                           const TargetRegisterInfo *RegInfo = 0);
462 
463   /// setPhysRegsDeadExcept - Mark every physreg used by this instruction as
464   /// dead except those in the UsedRegs list.
465   void setPhysRegsDeadExcept(const SmallVectorImpl<unsigned> &UsedRegs,
466                              const TargetRegisterInfo &TRI);
467 
468   /// isSafeToMove - Return true if it is safe to move this instruction. If
469   /// SawStore is set to true, it means that there is a store (or call) between
470   /// the instruction's location and its intended destination.
471   bool isSafeToMove(const TargetInstrInfo *TII, AliasAnalysis *AA,
472                     bool &SawStore) const;
473 
474   /// isSafeToReMat - Return true if it's safe to rematerialize the specified
475   /// instruction which defined the specified register instead of copying it.
476   bool isSafeToReMat(const TargetInstrInfo *TII, AliasAnalysis *AA,
477                      unsigned DstReg) const;
478 
479   /// hasVolatileMemoryRef - Return true if this instruction may have a
480   /// volatile memory reference, or if the information describing the
481   /// memory reference is not available. Return false if it is known to
482   /// have no volatile memory references.
483   bool hasVolatileMemoryRef() const;
484 
485   /// isInvariantLoad - Return true if this instruction is loading from a
486   /// location whose value is invariant across the function.  For example,
487   /// loading a value from the constant pool or from the argument area of
488   /// a function if it does not change.  This should only return true of *all*
489   /// loads the instruction does are invariant (if it does multiple loads).
490   bool isInvariantLoad(AliasAnalysis *AA) const;
491 
492   /// isConstantValuePHI - If the specified instruction is a PHI that always
493   /// merges together the same virtual register, return the register, otherwise
494   /// return 0.
495   unsigned isConstantValuePHI() const;
496 
497   /// hasUnmodeledSideEffects - Return true if this instruction has side
498   /// effects that are not modeled by mayLoad / mayStore, etc.
499   /// For all instructions, the property is encoded in MCInstrDesc::Flags
500   /// (see MCInstrDesc::hasUnmodeledSideEffects(). The only exception is
501   /// INLINEASM instruction, in which case the side effect property is encoded
502   /// in one of its operands (see InlineAsm::Extra_HasSideEffect).
503   ///
504   bool hasUnmodeledSideEffects() const;
505 
506   /// allDefsAreDead - Return true if all the defs of this instruction are dead.
507   ///
508   bool allDefsAreDead() const;
509 
510   /// copyImplicitOps - Copy implicit register operands from specified
511   /// instruction to this instruction.
512   void copyImplicitOps(const MachineInstr *MI);
513 
514   //
515   // Debugging support
516   //
517   void print(raw_ostream &OS, const TargetMachine *TM = 0) const;
518   void dump() const;
519 
520   //===--------------------------------------------------------------------===//
521   // Accessors used to build up machine instructions.
522 
523   /// addOperand - Add the specified operand to the instruction.  If it is an
524   /// implicit operand, it is added to the end of the operand list.  If it is
525   /// an explicit operand it is added at the end of the explicit operand list
526   /// (before the first implicit operand).
527   void addOperand(const MachineOperand &Op);
528 
529   /// setDesc - Replace the instruction descriptor (thus opcode) of
530   /// the current instruction with a new one.
531   ///
532   void setDesc(const MCInstrDesc &tid) { MCID = &tid; }
533 
534   /// setDebugLoc - Replace current source information with new such.
535   /// Avoid using this, the constructor argument is preferable.
536   ///
537   void setDebugLoc(const DebugLoc dl) { debugLoc = dl; }
538 
539   /// RemoveOperand - Erase an operand  from an instruction, leaving it with one
540   /// fewer operand than it started with.
541   ///
542   void RemoveOperand(unsigned i);
543 
544   /// addMemOperand - Add a MachineMemOperand to the machine instruction.
545   /// This function should be used only occasionally. The setMemRefs function
546   /// is the primary method for setting up a MachineInstr's MemRefs list.
547   void addMemOperand(MachineFunction &MF, MachineMemOperand *MO);
548 
549   /// setMemRefs - Assign this MachineInstr's memory reference descriptor
550   /// list. This does not transfer ownership.
551   void setMemRefs(mmo_iterator NewMemRefs, mmo_iterator NewMemRefsEnd) {
552     MemRefs = NewMemRefs;
553     MemRefsEnd = NewMemRefsEnd;
554   }
555 
556 private:
557   /// getRegInfo - If this instruction is embedded into a MachineFunction,
558   /// return the MachineRegisterInfo object for the current function, otherwise
559   /// return null.
560   MachineRegisterInfo *getRegInfo();
561 
562   /// addImplicitDefUseOperands - Add all implicit def and use operands to
563   /// this instruction.
564   void addImplicitDefUseOperands();
565 
566   /// RemoveRegOperandsFromUseLists - Unlink all of the register operands in
567   /// this instruction from their respective use lists.  This requires that the
568   /// operands already be on their use lists.
569   void RemoveRegOperandsFromUseLists();
570 
571   /// AddRegOperandsToUseLists - Add all of the register operands in
572   /// this instruction from their respective use lists.  This requires that the
573   /// operands not be on their use lists yet.
574   void AddRegOperandsToUseLists(MachineRegisterInfo &RegInfo);
575 };
576 
577 /// MachineInstrExpressionTrait - Special DenseMapInfo traits to compare
578 /// MachineInstr* by *value* of the instruction rather than by pointer value.
579 /// The hashing and equality testing functions ignore definitions so this is
580 /// useful for CSE, etc.
581 struct MachineInstrExpressionTrait : DenseMapInfo<MachineInstr*> {
582   static inline MachineInstr *getEmptyKey() {
583     return 0;
584   }
585 
586   static inline MachineInstr *getTombstoneKey() {
587     return reinterpret_cast<MachineInstr*>(-1);
588   }
589 
590   static unsigned getHashValue(const MachineInstr* const &MI);
591 
592   static bool isEqual(const MachineInstr* const &LHS,
593                       const MachineInstr* const &RHS) {
594     if (RHS == getEmptyKey() || RHS == getTombstoneKey() ||
595         LHS == getEmptyKey() || LHS == getTombstoneKey())
596       return LHS == RHS;
597     return LHS->isIdenticalTo(RHS, MachineInstr::IgnoreVRegDefs);
598   }
599 };
600 
601 //===----------------------------------------------------------------------===//
602 // Debugging Support
603 
604 inline raw_ostream& operator<<(raw_ostream &OS, const MachineInstr &MI) {
605   MI.print(OS);
606   return OS;
607 }
608 
609 } // End llvm namespace
610 
611 #endif
612