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1 //===- CodeGen/MachineInstrBuilder.h - Simplify creation of MIs --*- 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 exposes a function named BuildMI, which is useful for dramatically
11 // simplifying how MachineInstr's are created.  It allows use of code like this:
12 //
13 //   M = BuildMI(MBB, MI, DL, TII.get(X86::ADD8rr), Dst)
14 //           .addReg(argVal1)
15 //           .addReg(argVal2);
16 //
17 //===----------------------------------------------------------------------===//
18 
19 #ifndef LLVM_CODEGEN_MACHINEINSTRBUILDER_H
20 #define LLVM_CODEGEN_MACHINEINSTRBUILDER_H
21 
22 #include "llvm/ADT/ArrayRef.h"
23 #include "llvm/CodeGen/GlobalISel/Utils.h"
24 #include "llvm/CodeGen/MachineBasicBlock.h"
25 #include "llvm/CodeGen/MachineFunction.h"
26 #include "llvm/CodeGen/MachineInstr.h"
27 #include "llvm/CodeGen/MachineInstrBundle.h"
28 #include "llvm/CodeGen/MachineOperand.h"
29 #include "llvm/CodeGen/TargetRegisterInfo.h"
30 #include "llvm/IR/InstrTypes.h"
31 #include "llvm/IR/Intrinsics.h"
32 #include "llvm/Support/ErrorHandling.h"
33 #include <cassert>
34 #include <cstdint>
35 #include <utility>
36 
37 namespace llvm {
38 
39 class MCInstrDesc;
40 class MDNode;
41 
42 namespace RegState {
43 
44   enum {
45     Define         = 0x2,
46     Implicit       = 0x4,
47     Kill           = 0x8,
48     Dead           = 0x10,
49     Undef          = 0x20,
50     EarlyClobber   = 0x40,
51     Debug          = 0x80,
52     InternalRead   = 0x100,
53     Renamable      = 0x200,
54     DefineNoRead   = Define | Undef,
55     ImplicitDefine = Implicit | Define,
56     ImplicitKill   = Implicit | Kill
57   };
58 
59 } // end namespace RegState
60 
61 class MachineInstrBuilder {
62   MachineFunction *MF = nullptr;
63   MachineInstr *MI = nullptr;
64 
65 public:
66   MachineInstrBuilder() = default;
67 
68   /// Create a MachineInstrBuilder for manipulating an existing instruction.
69   /// F must be the machine function that was used to allocate I.
MachineInstrBuilder(MachineFunction & F,MachineInstr * I)70   MachineInstrBuilder(MachineFunction &F, MachineInstr *I) : MF(&F), MI(I) {}
MachineInstrBuilder(MachineFunction & F,MachineBasicBlock::iterator I)71   MachineInstrBuilder(MachineFunction &F, MachineBasicBlock::iterator I)
72       : MF(&F), MI(&*I) {}
73 
74   /// Allow automatic conversion to the machine instruction we are working on.
75   operator MachineInstr*() const { return MI; }
76   MachineInstr *operator->() const { return MI; }
iterator()77   operator MachineBasicBlock::iterator() const { return MI; }
78 
79   /// If conversion operators fail, use this method to get the MachineInstr
80   /// explicitly.
getInstr()81   MachineInstr *getInstr() const { return MI; }
82 
83   /// Add a new virtual register operand.
84   const MachineInstrBuilder &addReg(unsigned RegNo, unsigned flags = 0,
85                                     unsigned SubReg = 0) const {
86     assert((flags & 0x1) == 0 &&
87            "Passing in 'true' to addReg is forbidden! Use enums instead.");
88     MI->addOperand(*MF, MachineOperand::CreateReg(RegNo,
89                                                flags & RegState::Define,
90                                                flags & RegState::Implicit,
91                                                flags & RegState::Kill,
92                                                flags & RegState::Dead,
93                                                flags & RegState::Undef,
94                                                flags & RegState::EarlyClobber,
95                                                SubReg,
96                                                flags & RegState::Debug,
97                                                flags & RegState::InternalRead,
98                                                flags & RegState::Renamable));
99     return *this;
100   }
101 
102   /// Add a virtual register definition operand.
103   const MachineInstrBuilder &addDef(unsigned RegNo, unsigned Flags = 0,
104                                     unsigned SubReg = 0) const {
105     return addReg(RegNo, Flags | RegState::Define, SubReg);
106   }
107 
108   /// Add a virtual register use operand. It is an error for Flags to contain
109   /// `RegState::Define` when calling this function.
110   const MachineInstrBuilder &addUse(unsigned RegNo, unsigned Flags = 0,
111                                     unsigned SubReg = 0) const {
112     assert(!(Flags & RegState::Define) &&
113            "Misleading addUse defines register, use addReg instead.");
114     return addReg(RegNo, Flags, SubReg);
115   }
116 
117   /// Add a new immediate operand.
addImm(int64_t Val)118   const MachineInstrBuilder &addImm(int64_t Val) const {
119     MI->addOperand(*MF, MachineOperand::CreateImm(Val));
120     return *this;
121   }
122 
addCImm(const ConstantInt * Val)123   const MachineInstrBuilder &addCImm(const ConstantInt *Val) const {
124     MI->addOperand(*MF, MachineOperand::CreateCImm(Val));
125     return *this;
126   }
127 
addFPImm(const ConstantFP * Val)128   const MachineInstrBuilder &addFPImm(const ConstantFP *Val) const {
129     MI->addOperand(*MF, MachineOperand::CreateFPImm(Val));
130     return *this;
131   }
132 
133   const MachineInstrBuilder &addMBB(MachineBasicBlock *MBB,
134                                     unsigned char TargetFlags = 0) const {
135     MI->addOperand(*MF, MachineOperand::CreateMBB(MBB, TargetFlags));
136     return *this;
137   }
138 
addFrameIndex(int Idx)139   const MachineInstrBuilder &addFrameIndex(int Idx) const {
140     MI->addOperand(*MF, MachineOperand::CreateFI(Idx));
141     return *this;
142   }
143 
144   const MachineInstrBuilder &addConstantPoolIndex(unsigned Idx,
145                                                   int Offset = 0,
146                                           unsigned char TargetFlags = 0) const {
147     MI->addOperand(*MF, MachineOperand::CreateCPI(Idx, Offset, TargetFlags));
148     return *this;
149   }
150 
151   const MachineInstrBuilder &addTargetIndex(unsigned Idx, int64_t Offset = 0,
152                                           unsigned char TargetFlags = 0) const {
153     MI->addOperand(*MF, MachineOperand::CreateTargetIndex(Idx, Offset,
154                                                           TargetFlags));
155     return *this;
156   }
157 
158   const MachineInstrBuilder &addJumpTableIndex(unsigned Idx,
159                                           unsigned char TargetFlags = 0) const {
160     MI->addOperand(*MF, MachineOperand::CreateJTI(Idx, TargetFlags));
161     return *this;
162   }
163 
164   const MachineInstrBuilder &addGlobalAddress(const GlobalValue *GV,
165                                               int64_t Offset = 0,
166                                           unsigned char TargetFlags = 0) const {
167     MI->addOperand(*MF, MachineOperand::CreateGA(GV, Offset, TargetFlags));
168     return *this;
169   }
170 
171   const MachineInstrBuilder &addExternalSymbol(const char *FnName,
172                                           unsigned char TargetFlags = 0) const {
173     MI->addOperand(*MF, MachineOperand::CreateES(FnName, TargetFlags));
174     return *this;
175   }
176 
177   const MachineInstrBuilder &addBlockAddress(const BlockAddress *BA,
178                                              int64_t Offset = 0,
179                                           unsigned char TargetFlags = 0) const {
180     MI->addOperand(*MF, MachineOperand::CreateBA(BA, Offset, TargetFlags));
181     return *this;
182   }
183 
addRegMask(const uint32_t * Mask)184   const MachineInstrBuilder &addRegMask(const uint32_t *Mask) const {
185     MI->addOperand(*MF, MachineOperand::CreateRegMask(Mask));
186     return *this;
187   }
188 
addMemOperand(MachineMemOperand * MMO)189   const MachineInstrBuilder &addMemOperand(MachineMemOperand *MMO) const {
190     MI->addMemOperand(*MF, MMO);
191     return *this;
192   }
193 
setMemRefs(MachineInstr::mmo_iterator b,MachineInstr::mmo_iterator e)194   const MachineInstrBuilder &setMemRefs(MachineInstr::mmo_iterator b,
195                                         MachineInstr::mmo_iterator e) const {
196     MI->setMemRefs(b, e);
197     return *this;
198   }
199 
setMemRefs(std::pair<MachineInstr::mmo_iterator,unsigned> MemOperandsRef)200   const MachineInstrBuilder &setMemRefs(std::pair<MachineInstr::mmo_iterator,
201                                         unsigned> MemOperandsRef) const {
202     MI->setMemRefs(MemOperandsRef);
203     return *this;
204   }
205 
add(const MachineOperand & MO)206   const MachineInstrBuilder &add(const MachineOperand &MO) const {
207     MI->addOperand(*MF, MO);
208     return *this;
209   }
210 
add(ArrayRef<MachineOperand> MOs)211   const MachineInstrBuilder &add(ArrayRef<MachineOperand> MOs) const {
212     for (const MachineOperand &MO : MOs) {
213       MI->addOperand(*MF, MO);
214     }
215     return *this;
216   }
217 
addMetadata(const MDNode * MD)218   const MachineInstrBuilder &addMetadata(const MDNode *MD) const {
219     MI->addOperand(*MF, MachineOperand::CreateMetadata(MD));
220     assert((MI->isDebugValue() ? static_cast<bool>(MI->getDebugVariable())
221                                : true) &&
222            "first MDNode argument of a DBG_VALUE not a variable");
223     assert((MI->isDebugLabel() ? static_cast<bool>(MI->getDebugLabel())
224                                : true) &&
225            "first MDNode argument of a DBG_LABEL not a label");
226     return *this;
227   }
228 
addCFIIndex(unsigned CFIIndex)229   const MachineInstrBuilder &addCFIIndex(unsigned CFIIndex) const {
230     MI->addOperand(*MF, MachineOperand::CreateCFIIndex(CFIIndex));
231     return *this;
232   }
233 
addIntrinsicID(Intrinsic::ID ID)234   const MachineInstrBuilder &addIntrinsicID(Intrinsic::ID ID) const {
235     MI->addOperand(*MF, MachineOperand::CreateIntrinsicID(ID));
236     return *this;
237   }
238 
addPredicate(CmpInst::Predicate Pred)239   const MachineInstrBuilder &addPredicate(CmpInst::Predicate Pred) const {
240     MI->addOperand(*MF, MachineOperand::CreatePredicate(Pred));
241     return *this;
242   }
243 
244   const MachineInstrBuilder &addSym(MCSymbol *Sym,
245                                     unsigned char TargetFlags = 0) const {
246     MI->addOperand(*MF, MachineOperand::CreateMCSymbol(Sym, TargetFlags));
247     return *this;
248   }
249 
setMIFlags(unsigned Flags)250   const MachineInstrBuilder &setMIFlags(unsigned Flags) const {
251     MI->setFlags(Flags);
252     return *this;
253   }
254 
setMIFlag(MachineInstr::MIFlag Flag)255   const MachineInstrBuilder &setMIFlag(MachineInstr::MIFlag Flag) const {
256     MI->setFlag(Flag);
257     return *this;
258   }
259 
260   // Add a displacement from an existing MachineOperand with an added offset.
261   const MachineInstrBuilder &addDisp(const MachineOperand &Disp, int64_t off,
262                                      unsigned char TargetFlags = 0) const {
263     // If caller specifies new TargetFlags then use it, otherwise the
264     // default behavior is to copy the target flags from the existing
265     // MachineOperand. This means if the caller wants to clear the
266     // target flags it needs to do so explicitly.
267     if (0 == TargetFlags)
268       TargetFlags = Disp.getTargetFlags();
269 
270     switch (Disp.getType()) {
271       default:
272         llvm_unreachable("Unhandled operand type in addDisp()");
273       case MachineOperand::MO_Immediate:
274         return addImm(Disp.getImm() + off);
275       case MachineOperand::MO_ConstantPoolIndex:
276         return addConstantPoolIndex(Disp.getIndex(), Disp.getOffset() + off,
277                                     TargetFlags);
278       case MachineOperand::MO_GlobalAddress:
279         return addGlobalAddress(Disp.getGlobal(), Disp.getOffset() + off,
280                                 TargetFlags);
281     }
282   }
283 
284   /// Copy all the implicit operands from OtherMI onto this one.
285   const MachineInstrBuilder &
copyImplicitOps(const MachineInstr & OtherMI)286   copyImplicitOps(const MachineInstr &OtherMI) const {
287     MI->copyImplicitOps(*MF, OtherMI);
288     return *this;
289   }
290 
constrainAllUses(const TargetInstrInfo & TII,const TargetRegisterInfo & TRI,const RegisterBankInfo & RBI)291   bool constrainAllUses(const TargetInstrInfo &TII,
292                         const TargetRegisterInfo &TRI,
293                         const RegisterBankInfo &RBI) const {
294     return constrainSelectedInstRegOperands(*MI, TII, TRI, RBI);
295   }
296 };
297 
298 /// Builder interface. Specify how to create the initial instruction itself.
BuildMI(MachineFunction & MF,const DebugLoc & DL,const MCInstrDesc & MCID)299 inline MachineInstrBuilder BuildMI(MachineFunction &MF, const DebugLoc &DL,
300                                    const MCInstrDesc &MCID) {
301   return MachineInstrBuilder(MF, MF.CreateMachineInstr(MCID, DL));
302 }
303 
304 /// This version of the builder sets up the first operand as a
305 /// destination virtual register.
BuildMI(MachineFunction & MF,const DebugLoc & DL,const MCInstrDesc & MCID,unsigned DestReg)306 inline MachineInstrBuilder BuildMI(MachineFunction &MF, const DebugLoc &DL,
307                                    const MCInstrDesc &MCID, unsigned DestReg) {
308   return MachineInstrBuilder(MF, MF.CreateMachineInstr(MCID, DL))
309            .addReg(DestReg, RegState::Define);
310 }
311 
312 /// This version of the builder inserts the newly-built instruction before
313 /// the given position in the given MachineBasicBlock, and sets up the first
314 /// operand as a destination virtual register.
BuildMI(MachineBasicBlock & BB,MachineBasicBlock::iterator I,const DebugLoc & DL,const MCInstrDesc & MCID,unsigned DestReg)315 inline MachineInstrBuilder BuildMI(MachineBasicBlock &BB,
316                                    MachineBasicBlock::iterator I,
317                                    const DebugLoc &DL, const MCInstrDesc &MCID,
318                                    unsigned DestReg) {
319   MachineFunction &MF = *BB.getParent();
320   MachineInstr *MI = MF.CreateMachineInstr(MCID, DL);
321   BB.insert(I, MI);
322   return MachineInstrBuilder(MF, MI).addReg(DestReg, RegState::Define);
323 }
324 
325 /// This version of the builder inserts the newly-built instruction before
326 /// the given position in the given MachineBasicBlock, and sets up the first
327 /// operand as a destination virtual register.
328 ///
329 /// If \c I is inside a bundle, then the newly inserted \a MachineInstr is
330 /// added to the same bundle.
BuildMI(MachineBasicBlock & BB,MachineBasicBlock::instr_iterator I,const DebugLoc & DL,const MCInstrDesc & MCID,unsigned DestReg)331 inline MachineInstrBuilder BuildMI(MachineBasicBlock &BB,
332                                    MachineBasicBlock::instr_iterator I,
333                                    const DebugLoc &DL, const MCInstrDesc &MCID,
334                                    unsigned DestReg) {
335   MachineFunction &MF = *BB.getParent();
336   MachineInstr *MI = MF.CreateMachineInstr(MCID, DL);
337   BB.insert(I, MI);
338   return MachineInstrBuilder(MF, MI).addReg(DestReg, RegState::Define);
339 }
340 
BuildMI(MachineBasicBlock & BB,MachineInstr & I,const DebugLoc & DL,const MCInstrDesc & MCID,unsigned DestReg)341 inline MachineInstrBuilder BuildMI(MachineBasicBlock &BB, MachineInstr &I,
342                                    const DebugLoc &DL, const MCInstrDesc &MCID,
343                                    unsigned DestReg) {
344   // Calling the overload for instr_iterator is always correct.  However, the
345   // definition is not available in headers, so inline the check.
346   if (I.isInsideBundle())
347     return BuildMI(BB, MachineBasicBlock::instr_iterator(I), DL, MCID, DestReg);
348   return BuildMI(BB, MachineBasicBlock::iterator(I), DL, MCID, DestReg);
349 }
350 
BuildMI(MachineBasicBlock & BB,MachineInstr * I,const DebugLoc & DL,const MCInstrDesc & MCID,unsigned DestReg)351 inline MachineInstrBuilder BuildMI(MachineBasicBlock &BB, MachineInstr *I,
352                                    const DebugLoc &DL, const MCInstrDesc &MCID,
353                                    unsigned DestReg) {
354   return BuildMI(BB, *I, DL, MCID, DestReg);
355 }
356 
357 /// This version of the builder inserts the newly-built instruction before the
358 /// given position in the given MachineBasicBlock, and does NOT take a
359 /// destination register.
BuildMI(MachineBasicBlock & BB,MachineBasicBlock::iterator I,const DebugLoc & DL,const MCInstrDesc & MCID)360 inline MachineInstrBuilder BuildMI(MachineBasicBlock &BB,
361                                    MachineBasicBlock::iterator I,
362                                    const DebugLoc &DL,
363                                    const MCInstrDesc &MCID) {
364   MachineFunction &MF = *BB.getParent();
365   MachineInstr *MI = MF.CreateMachineInstr(MCID, DL);
366   BB.insert(I, MI);
367   return MachineInstrBuilder(MF, MI);
368 }
369 
BuildMI(MachineBasicBlock & BB,MachineBasicBlock::instr_iterator I,const DebugLoc & DL,const MCInstrDesc & MCID)370 inline MachineInstrBuilder BuildMI(MachineBasicBlock &BB,
371                                    MachineBasicBlock::instr_iterator I,
372                                    const DebugLoc &DL,
373                                    const MCInstrDesc &MCID) {
374   MachineFunction &MF = *BB.getParent();
375   MachineInstr *MI = MF.CreateMachineInstr(MCID, DL);
376   BB.insert(I, MI);
377   return MachineInstrBuilder(MF, MI);
378 }
379 
BuildMI(MachineBasicBlock & BB,MachineInstr & I,const DebugLoc & DL,const MCInstrDesc & MCID)380 inline MachineInstrBuilder BuildMI(MachineBasicBlock &BB, MachineInstr &I,
381                                    const DebugLoc &DL,
382                                    const MCInstrDesc &MCID) {
383   // Calling the overload for instr_iterator is always correct.  However, the
384   // definition is not available in headers, so inline the check.
385   if (I.isInsideBundle())
386     return BuildMI(BB, MachineBasicBlock::instr_iterator(I), DL, MCID);
387   return BuildMI(BB, MachineBasicBlock::iterator(I), DL, MCID);
388 }
389 
BuildMI(MachineBasicBlock & BB,MachineInstr * I,const DebugLoc & DL,const MCInstrDesc & MCID)390 inline MachineInstrBuilder BuildMI(MachineBasicBlock &BB, MachineInstr *I,
391                                    const DebugLoc &DL,
392                                    const MCInstrDesc &MCID) {
393   return BuildMI(BB, *I, DL, MCID);
394 }
395 
396 /// This version of the builder inserts the newly-built instruction at the end
397 /// of the given MachineBasicBlock, and does NOT take a destination register.
BuildMI(MachineBasicBlock * BB,const DebugLoc & DL,const MCInstrDesc & MCID)398 inline MachineInstrBuilder BuildMI(MachineBasicBlock *BB, const DebugLoc &DL,
399                                    const MCInstrDesc &MCID) {
400   return BuildMI(*BB, BB->end(), DL, MCID);
401 }
402 
403 /// This version of the builder inserts the newly-built instruction at the
404 /// end of the given MachineBasicBlock, and sets up the first operand as a
405 /// destination virtual register.
BuildMI(MachineBasicBlock * BB,const DebugLoc & DL,const MCInstrDesc & MCID,unsigned DestReg)406 inline MachineInstrBuilder BuildMI(MachineBasicBlock *BB, const DebugLoc &DL,
407                                    const MCInstrDesc &MCID, unsigned DestReg) {
408   return BuildMI(*BB, BB->end(), DL, MCID, DestReg);
409 }
410 
411 /// This version of the builder builds a DBG_VALUE intrinsic
412 /// for either a value in a register or a register-indirect
413 /// address.  The convention is that a DBG_VALUE is indirect iff the
414 /// second operand is an immediate.
415 MachineInstrBuilder BuildMI(MachineFunction &MF, const DebugLoc &DL,
416                             const MCInstrDesc &MCID, bool IsIndirect,
417                             unsigned Reg, const MDNode *Variable,
418                             const MDNode *Expr);
419 
420 /// This version of the builder builds a DBG_VALUE intrinsic
421 /// for a MachineOperand.
422 MachineInstrBuilder BuildMI(MachineFunction &MF, const DebugLoc &DL,
423                             const MCInstrDesc &MCID, bool IsIndirect,
424                             MachineOperand &MO, const MDNode *Variable,
425                             const MDNode *Expr);
426 
427 /// This version of the builder builds a DBG_VALUE intrinsic
428 /// for either a value in a register or a register-indirect
429 /// address and inserts it at position I.
430 MachineInstrBuilder BuildMI(MachineBasicBlock &BB,
431                             MachineBasicBlock::iterator I, const DebugLoc &DL,
432                             const MCInstrDesc &MCID, bool IsIndirect,
433                             unsigned Reg, const MDNode *Variable,
434                             const MDNode *Expr);
435 
436 /// This version of the builder builds a DBG_VALUE intrinsic
437 /// for a machine operand and inserts it at position I.
438 MachineInstrBuilder BuildMI(MachineBasicBlock &BB,
439                             MachineBasicBlock::iterator I, const DebugLoc &DL,
440                             const MCInstrDesc &MCID, bool IsIndirect,
441                             MachineOperand &MO, const MDNode *Variable,
442                             const MDNode *Expr);
443 
444 /// Clone a DBG_VALUE whose value has been spilled to FrameIndex.
445 MachineInstr *buildDbgValueForSpill(MachineBasicBlock &BB,
446                                     MachineBasicBlock::iterator I,
447                                     const MachineInstr &Orig, int FrameIndex);
448 
449 /// Update a DBG_VALUE whose value has been spilled to FrameIndex. Useful when
450 /// modifying an instruction in place while iterating over a basic block.
451 void updateDbgValueForSpill(MachineInstr &Orig, int FrameIndex);
452 
getDefRegState(bool B)453 inline unsigned getDefRegState(bool B) {
454   return B ? RegState::Define : 0;
455 }
getImplRegState(bool B)456 inline unsigned getImplRegState(bool B) {
457   return B ? RegState::Implicit : 0;
458 }
getKillRegState(bool B)459 inline unsigned getKillRegState(bool B) {
460   return B ? RegState::Kill : 0;
461 }
getDeadRegState(bool B)462 inline unsigned getDeadRegState(bool B) {
463   return B ? RegState::Dead : 0;
464 }
getUndefRegState(bool B)465 inline unsigned getUndefRegState(bool B) {
466   return B ? RegState::Undef : 0;
467 }
getInternalReadRegState(bool B)468 inline unsigned getInternalReadRegState(bool B) {
469   return B ? RegState::InternalRead : 0;
470 }
getDebugRegState(bool B)471 inline unsigned getDebugRegState(bool B) {
472   return B ? RegState::Debug : 0;
473 }
getRenamableRegState(bool B)474 inline unsigned getRenamableRegState(bool B) {
475   return B ? RegState::Renamable : 0;
476 }
477 
478 /// Get all register state flags from machine operand \p RegOp.
getRegState(const MachineOperand & RegOp)479 inline unsigned getRegState(const MachineOperand &RegOp) {
480   assert(RegOp.isReg() && "Not a register operand");
481   return getDefRegState(RegOp.isDef())                    |
482          getImplRegState(RegOp.isImplicit())              |
483          getKillRegState(RegOp.isKill())                  |
484          getDeadRegState(RegOp.isDead())                  |
485          getUndefRegState(RegOp.isUndef())                |
486          getInternalReadRegState(RegOp.isInternalRead())  |
487          getDebugRegState(RegOp.isDebug())                |
488          getRenamableRegState(
489              TargetRegisterInfo::isPhysicalRegister(RegOp.getReg()) &&
490              RegOp.isRenamable());
491 }
492 
493 /// Helper class for constructing bundles of MachineInstrs.
494 ///
495 /// MIBundleBuilder can create a bundle from scratch by inserting new
496 /// MachineInstrs one at a time, or it can create a bundle from a sequence of
497 /// existing MachineInstrs in a basic block.
498 class MIBundleBuilder {
499   MachineBasicBlock &MBB;
500   MachineBasicBlock::instr_iterator Begin;
501   MachineBasicBlock::instr_iterator End;
502 
503 public:
504   /// Create an MIBundleBuilder that inserts instructions into a new bundle in
505   /// BB above the bundle or instruction at Pos.
MIBundleBuilder(MachineBasicBlock & BB,MachineBasicBlock::iterator Pos)506   MIBundleBuilder(MachineBasicBlock &BB, MachineBasicBlock::iterator Pos)
507       : MBB(BB), Begin(Pos.getInstrIterator()), End(Begin) {}
508 
509   /// Create a bundle from the sequence of instructions between B and E.
MIBundleBuilder(MachineBasicBlock & BB,MachineBasicBlock::iterator B,MachineBasicBlock::iterator E)510   MIBundleBuilder(MachineBasicBlock &BB, MachineBasicBlock::iterator B,
511                   MachineBasicBlock::iterator E)
512       : MBB(BB), Begin(B.getInstrIterator()), End(E.getInstrIterator()) {
513     assert(B != E && "No instructions to bundle");
514     ++B;
515     while (B != E) {
516       MachineInstr &MI = *B;
517       ++B;
518       MI.bundleWithPred();
519     }
520   }
521 
522   /// Create an MIBundleBuilder representing an existing instruction or bundle
523   /// that has MI as its head.
MIBundleBuilder(MachineInstr * MI)524   explicit MIBundleBuilder(MachineInstr *MI)
525       : MBB(*MI->getParent()), Begin(MI),
526         End(getBundleEnd(MI->getIterator())) {}
527 
528   /// Return a reference to the basic block containing this bundle.
getMBB()529   MachineBasicBlock &getMBB() const { return MBB; }
530 
531   /// Return true if no instructions have been inserted in this bundle yet.
532   /// Empty bundles aren't representable in a MachineBasicBlock.
empty()533   bool empty() const { return Begin == End; }
534 
535   /// Return an iterator to the first bundled instruction.
begin()536   MachineBasicBlock::instr_iterator begin() const { return Begin; }
537 
538   /// Return an iterator beyond the last bundled instruction.
end()539   MachineBasicBlock::instr_iterator end() const { return End; }
540 
541   /// Insert MI into this bundle before I which must point to an instruction in
542   /// the bundle, or end().
insert(MachineBasicBlock::instr_iterator I,MachineInstr * MI)543   MIBundleBuilder &insert(MachineBasicBlock::instr_iterator I,
544                           MachineInstr *MI) {
545     MBB.insert(I, MI);
546     if (I == Begin) {
547       if (!empty())
548         MI->bundleWithSucc();
549       Begin = MI->getIterator();
550       return *this;
551     }
552     if (I == End) {
553       MI->bundleWithPred();
554       return *this;
555     }
556     // MI was inserted in the middle of the bundle, so its neighbors' flags are
557     // already fine. Update MI's bundle flags manually.
558     MI->setFlag(MachineInstr::BundledPred);
559     MI->setFlag(MachineInstr::BundledSucc);
560     return *this;
561   }
562 
563   /// Insert MI into MBB by prepending it to the instructions in the bundle.
564   /// MI will become the first instruction in the bundle.
prepend(MachineInstr * MI)565   MIBundleBuilder &prepend(MachineInstr *MI) {
566     return insert(begin(), MI);
567   }
568 
569   /// Insert MI into MBB by appending it to the instructions in the bundle.
570   /// MI will become the last instruction in the bundle.
append(MachineInstr * MI)571   MIBundleBuilder &append(MachineInstr *MI) {
572     return insert(end(), MI);
573   }
574 };
575 
576 } // end namespace llvm
577 
578 #endif // LLVM_CODEGEN_MACHINEINSTRBUILDER_H
579