1 //=== Target/TargetRegisterInfo.h - Target Register Information -*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file describes an abstract interface used to get information about a
11 // target machines register file. This information is used for a variety of
12 // purposed, especially register allocation.
14 //===----------------------------------------------------------------------===//
16 #ifndef LLVM_TARGET_TARGETREGISTERINFO_H
17 #define LLVM_TARGET_TARGETREGISTERINFO_H
19 #include "llvm/CodeGen/MachineBasicBlock.h"
20 #include "llvm/CodeGen/ValueTypes.h"
21 #include "llvm/ADT/DenseSet.h"
28 class MachineFunction;
31 template<class T> class SmallVectorImpl;
33 /// TargetRegisterDesc - This record contains all of the information known about
34 /// a particular register. The AliasSet field (if not null) contains a pointer
35 /// to a Zero terminated array of registers that this register aliases. This is
36 /// needed for architectures like X86 which have AL alias AX alias EAX.
37 /// Registers that this does not apply to simply should set this to null.
38 /// The SubRegs field is a zero terminated array of registers that are
39 /// sub-registers of the specific register, e.g. AL, AH are sub-registers of AX.
40 /// The SuperRegs field is a zero terminated array of registers that are
41 /// super-registers of the specific register, e.g. RAX, EAX, are super-registers
44 struct TargetRegisterDesc {
45 const char *Name; // Printable name for the reg (for debugging)
46 const unsigned *AliasSet; // Register Alias Set, described above
47 const unsigned *SubRegs; // Sub-register set, described above
48 const unsigned *SuperRegs; // Super-register set, described above
51 class TargetRegisterClass {
53 typedef const unsigned* iterator;
54 typedef const unsigned* const_iterator;
56 typedef const EVT* vt_iterator;
57 typedef const TargetRegisterClass* const * sc_iterator;
61 const vt_iterator VTs;
62 const sc_iterator SubClasses;
63 const sc_iterator SuperClasses;
64 const sc_iterator SubRegClasses;
65 const sc_iterator SuperRegClasses;
66 const unsigned RegSize, Alignment; // Size & Alignment of register in bytes
68 const iterator RegsBegin, RegsEnd;
69 DenseSet<unsigned> RegSet;
71 TargetRegisterClass(unsigned id,
74 const TargetRegisterClass * const *subcs,
75 const TargetRegisterClass * const *supcs,
76 const TargetRegisterClass * const *subregcs,
77 const TargetRegisterClass * const *superregcs,
78 unsigned RS, unsigned Al, int CC,
79 iterator RB, iterator RE)
80 : ID(id), Name(name), VTs(vts), SubClasses(subcs), SuperClasses(supcs),
81 SubRegClasses(subregcs), SuperRegClasses(superregcs),
82 RegSize(RS), Alignment(Al), CopyCost(CC), RegsBegin(RB), RegsEnd(RE) {
83 for (iterator I = RegsBegin, E = RegsEnd; I != E; ++I)
86 virtual ~TargetRegisterClass() {} // Allow subclasses
88 /// getID() - Return the register class ID number.
90 unsigned getID() const { return ID; }
92 /// getName() - Return the register class name for debugging.
94 const char *getName() const { return Name; }
96 /// begin/end - Return all of the registers in this class.
98 iterator begin() const { return RegsBegin; }
99 iterator end() const { return RegsEnd; }
101 /// getNumRegs - Return the number of registers in this class.
103 unsigned getNumRegs() const { return (unsigned)(RegsEnd-RegsBegin); }
105 /// getRegister - Return the specified register in the class.
107 unsigned getRegister(unsigned i) const {
108 assert(i < getNumRegs() && "Register number out of range!");
112 /// contains - Return true if the specified register is included in this
113 /// register class. This does not include virtual registers.
114 bool contains(unsigned Reg) const {
115 return RegSet.count(Reg);
118 /// contains - Return true if both registers are in this class.
119 bool contains(unsigned Reg1, unsigned Reg2) const {
120 return contains(Reg1) && contains(Reg2);
123 /// hasType - return true if this TargetRegisterClass has the ValueType vt.
125 bool hasType(EVT vt) const {
126 for(int i = 0; VTs[i] != MVT::Other; ++i)
132 /// vt_begin / vt_end - Loop over all of the value types that can be
133 /// represented by values in this register class.
134 vt_iterator vt_begin() const {
138 vt_iterator vt_end() const {
140 while (*I != MVT::Other) ++I;
144 /// subregclasses_begin / subregclasses_end - Loop over all of
145 /// the subreg register classes of this register class.
146 sc_iterator subregclasses_begin() const {
147 return SubRegClasses;
150 sc_iterator subregclasses_end() const {
151 sc_iterator I = SubRegClasses;
152 while (*I != NULL) ++I;
156 /// getSubRegisterRegClass - Return the register class of subregisters with
157 /// index SubIdx, or NULL if no such class exists.
158 const TargetRegisterClass* getSubRegisterRegClass(unsigned SubIdx) const {
159 assert(SubIdx>0 && "Invalid subregister index");
160 return SubRegClasses[SubIdx-1];
163 /// superregclasses_begin / superregclasses_end - Loop over all of
164 /// the superreg register classes of this register class.
165 sc_iterator superregclasses_begin() const {
166 return SuperRegClasses;
169 sc_iterator superregclasses_end() const {
170 sc_iterator I = SuperRegClasses;
171 while (*I != NULL) ++I;
175 /// hasSubClass - return true if the specified TargetRegisterClass
176 /// is a proper subset of this TargetRegisterClass.
177 bool hasSubClass(const TargetRegisterClass *cs) const {
178 for (int i = 0; SubClasses[i] != NULL; ++i)
179 if (SubClasses[i] == cs)
184 /// subclasses_begin / subclasses_end - Loop over all of the classes
185 /// that are proper subsets of this register class.
186 sc_iterator subclasses_begin() const {
190 sc_iterator subclasses_end() const {
191 sc_iterator I = SubClasses;
192 while (*I != NULL) ++I;
196 /// hasSuperClass - return true if the specified TargetRegisterClass is a
197 /// proper superset of this TargetRegisterClass.
198 bool hasSuperClass(const TargetRegisterClass *cs) const {
199 for (int i = 0; SuperClasses[i] != NULL; ++i)
200 if (SuperClasses[i] == cs)
205 /// superclasses_begin / superclasses_end - Loop over all of the classes
206 /// that are proper supersets of this register class.
207 sc_iterator superclasses_begin() const {
211 sc_iterator superclasses_end() const {
212 sc_iterator I = SuperClasses;
213 while (*I != NULL) ++I;
217 /// isASubClass - return true if this TargetRegisterClass is a subset
218 /// class of at least one other TargetRegisterClass.
219 bool isASubClass() const {
220 return SuperClasses[0] != 0;
223 /// allocation_order_begin/end - These methods define a range of registers
224 /// which specify the registers in this class that are valid to register
225 /// allocate, and the preferred order to allocate them in. For example,
226 /// callee saved registers should be at the end of the list, because it is
227 /// cheaper to allocate caller saved registers.
229 /// These methods take a MachineFunction argument, which can be used to tune
230 /// the allocatable registers based on the characteristics of the function,
231 /// subtarget, or other criteria.
233 /// Register allocators should account for the fact that an allocation
234 /// order iterator may return a reserved register and always check
235 /// if the register is allocatable (getAllocatableSet()) before using it.
237 /// By default, these methods return all registers in the class.
239 virtual iterator allocation_order_begin(const MachineFunction &MF) const {
242 virtual iterator allocation_order_end(const MachineFunction &MF) const {
246 /// getSize - Return the size of the register in bytes, which is also the size
247 /// of a stack slot allocated to hold a spilled copy of this register.
248 unsigned getSize() const { return RegSize; }
250 /// getAlignment - Return the minimum required alignment for a register of
252 unsigned getAlignment() const { return Alignment; }
254 /// getCopyCost - Return the cost of copying a value between two registers in
255 /// this class. A negative number means the register class is very expensive
256 /// to copy e.g. status flag register classes.
257 int getCopyCost() const { return CopyCost; }
261 /// TargetRegisterInfo base class - We assume that the target defines a static
262 /// array of TargetRegisterDesc objects that represent all of the machine
263 /// registers that the target has. As such, we simply have to track a pointer
264 /// to this array so that we can turn register number into a register
267 class TargetRegisterInfo {
269 const unsigned* SubregHash;
270 const unsigned SubregHashSize;
271 const unsigned* AliasesHash;
272 const unsigned AliasesHashSize;
274 typedef const TargetRegisterClass * const * regclass_iterator;
276 const TargetRegisterDesc *Desc; // Pointer to the descriptor array
277 const char *const *SubRegIndexNames; // Names of subreg indexes.
278 unsigned NumRegs; // Number of entries in the array
280 regclass_iterator RegClassBegin, RegClassEnd; // List of regclasses
282 int CallFrameSetupOpcode, CallFrameDestroyOpcode;
285 TargetRegisterInfo(const TargetRegisterDesc *D, unsigned NR,
286 regclass_iterator RegClassBegin,
287 regclass_iterator RegClassEnd,
288 const char *const *subregindexnames,
289 int CallFrameSetupOpcode = -1,
290 int CallFrameDestroyOpcode = -1,
291 const unsigned* subregs = 0,
292 const unsigned subregsize = 0,
293 const unsigned* aliases = 0,
294 const unsigned aliasessize = 0);
295 virtual ~TargetRegisterInfo();
298 enum { // Define some target independent constants
299 /// NoRegister - This physical register is not a real target register. It
300 /// is useful as a sentinal.
303 /// FirstVirtualRegister - This is the first register number that is
304 /// considered to be a 'virtual' register, which is part of the SSA
305 /// namespace. This must be the same for all targets, which means that each
306 /// target is limited to this fixed number of registers.
307 FirstVirtualRegister = 16384
310 /// isPhysicalRegister - Return true if the specified register number is in
311 /// the physical register namespace.
312 static bool isPhysicalRegister(unsigned Reg) {
313 assert(Reg && "this is not a register!");
314 return Reg < FirstVirtualRegister;
317 /// isVirtualRegister - Return true if the specified register number is in
318 /// the virtual register namespace.
319 static bool isVirtualRegister(unsigned Reg) {
320 assert(Reg && "this is not a register!");
321 return Reg >= FirstVirtualRegister;
324 /// getMinimalPhysRegClass - Returns the Register Class of a physical
325 /// register of the given type, picking the most sub register class of
326 /// the right type that contains this physreg.
327 const TargetRegisterClass *
328 getMinimalPhysRegClass(unsigned Reg, EVT VT = MVT::Other) const;
330 /// getAllocatableSet - Returns a bitset indexed by register number
331 /// indicating if a register is allocatable or not. If a register class is
332 /// specified, returns the subset for the class.
333 BitVector getAllocatableSet(const MachineFunction &MF,
334 const TargetRegisterClass *RC = NULL) const;
336 const TargetRegisterDesc &operator[](unsigned RegNo) const {
337 assert(RegNo < NumRegs &&
338 "Attempting to access record for invalid register number!");
342 /// Provide a get method, equivalent to [], but more useful if we have a
343 /// pointer to this object.
345 const TargetRegisterDesc &get(unsigned RegNo) const {
346 return operator[](RegNo);
349 /// getAliasSet - Return the set of registers aliased by the specified
350 /// register, or a null list of there are none. The list returned is zero
353 const unsigned *getAliasSet(unsigned RegNo) const {
354 return get(RegNo).AliasSet;
357 /// getSubRegisters - Return the list of registers that are sub-registers of
358 /// the specified register, or a null list of there are none. The list
359 /// returned is zero terminated and sorted according to super-sub register
360 /// relations. e.g. X86::RAX's sub-register list is EAX, AX, AL, AH.
362 const unsigned *getSubRegisters(unsigned RegNo) const {
363 return get(RegNo).SubRegs;
366 /// getSuperRegisters - Return the list of registers that are super-registers
367 /// of the specified register, or a null list of there are none. The list
368 /// returned is zero terminated and sorted according to super-sub register
369 /// relations. e.g. X86::AL's super-register list is RAX, EAX, AX.
371 const unsigned *getSuperRegisters(unsigned RegNo) const {
372 return get(RegNo).SuperRegs;
375 /// getName - Return the human-readable symbolic target-specific name for the
376 /// specified physical register.
377 const char *getName(unsigned RegNo) const {
378 return get(RegNo).Name;
381 /// getNumRegs - Return the number of registers this target has (useful for
382 /// sizing arrays holding per register information)
383 unsigned getNumRegs() const {
387 /// getSubRegIndexName - Return the human-readable symbolic target-specific
388 /// name for the specified SubRegIndex.
389 const char *getSubRegIndexName(unsigned SubIdx) const {
390 assert(SubIdx && "This is not a subregister index");
391 return SubRegIndexNames[SubIdx-1];
394 /// regsOverlap - Returns true if the two registers are equal or alias each
395 /// other. The registers may be virtual register.
396 bool regsOverlap(unsigned regA, unsigned regB) const {
400 if (isVirtualRegister(regA) || isVirtualRegister(regB))
403 // regA and regB are distinct physical registers. Do they alias?
404 size_t index = (regA + regB * 37) & (AliasesHashSize-1);
405 unsigned ProbeAmt = 0;
406 while (AliasesHash[index*2] != 0 &&
407 AliasesHash[index*2+1] != 0) {
408 if (AliasesHash[index*2] == regA && AliasesHash[index*2+1] == regB)
411 index = (index + ProbeAmt) & (AliasesHashSize-1);
418 /// isSubRegister - Returns true if regB is a sub-register of regA.
420 bool isSubRegister(unsigned regA, unsigned regB) const {
421 // SubregHash is a simple quadratically probed hash table.
422 size_t index = (regA + regB * 37) & (SubregHashSize-1);
423 unsigned ProbeAmt = 2;
424 while (SubregHash[index*2] != 0 &&
425 SubregHash[index*2+1] != 0) {
426 if (SubregHash[index*2] == regA && SubregHash[index*2+1] == regB)
429 index = (index + ProbeAmt) & (SubregHashSize-1);
436 /// isSuperRegister - Returns true if regB is a super-register of regA.
438 bool isSuperRegister(unsigned regA, unsigned regB) const {
439 return isSubRegister(regB, regA);
442 /// getCalleeSavedRegs - Return a null-terminated list of all of the
443 /// callee saved registers on this target. The register should be in the
444 /// order of desired callee-save stack frame offset. The first register is
445 /// closed to the incoming stack pointer if stack grows down, and vice versa.
446 virtual const unsigned* getCalleeSavedRegs(const MachineFunction *MF = 0)
450 /// getReservedRegs - Returns a bitset indexed by physical register number
451 /// indicating if a register is a special register that has particular uses
452 /// and should be considered unavailable at all times, e.g. SP, RA. This is
453 /// used by register scavenger to determine what registers are free.
454 virtual BitVector getReservedRegs(const MachineFunction &MF) const = 0;
456 /// getSubReg - Returns the physical register number of sub-register "Index"
457 /// for physical register RegNo. Return zero if the sub-register does not
459 virtual unsigned getSubReg(unsigned RegNo, unsigned Index) const = 0;
461 /// getSubRegIndex - For a given register pair, return the sub-register index
462 /// if the second register is a sub-register of the first. Return zero
464 virtual unsigned getSubRegIndex(unsigned RegNo, unsigned SubRegNo) const = 0;
466 /// getMatchingSuperReg - Return a super-register of the specified register
467 /// Reg so its sub-register of index SubIdx is Reg.
468 unsigned getMatchingSuperReg(unsigned Reg, unsigned SubIdx,
469 const TargetRegisterClass *RC) const {
470 for (const unsigned *SRs = getSuperRegisters(Reg); unsigned SR = *SRs;++SRs)
471 if (Reg == getSubReg(SR, SubIdx) && RC->contains(SR))
476 /// canCombineSubRegIndices - Given a register class and a list of
477 /// subregister indices, return true if it's possible to combine the
478 /// subregister indices into one that corresponds to a larger
479 /// subregister. Return the new subregister index by reference. Note the
480 /// new index may be zero if the given subregisters can be combined to
481 /// form the whole register.
482 virtual bool canCombineSubRegIndices(const TargetRegisterClass *RC,
483 SmallVectorImpl<unsigned> &SubIndices,
484 unsigned &NewSubIdx) const {
488 /// getMatchingSuperRegClass - Return a subclass of the specified register
489 /// class A so that each register in it has a sub-register of the
490 /// specified sub-register index which is in the specified register class B.
491 virtual const TargetRegisterClass *
492 getMatchingSuperRegClass(const TargetRegisterClass *A,
493 const TargetRegisterClass *B, unsigned Idx) const {
497 /// composeSubRegIndices - Return the subregister index you get from composing
498 /// two subregister indices.
500 /// If R:a:b is the same register as R:c, then composeSubRegIndices(a, b)
501 /// returns c. Note that composeSubRegIndices does not tell you about illegal
502 /// compositions. If R does not have a subreg a, or R:a does not have a subreg
503 /// b, composeSubRegIndices doesn't tell you.
505 /// The ARM register Q0 has two D subregs dsub_0:D0 and dsub_1:D1. It also has
506 /// ssub_0:S0 - ssub_3:S3 subregs.
507 /// If you compose subreg indices dsub_1, ssub_0 you get ssub_2.
509 virtual unsigned composeSubRegIndices(unsigned a, unsigned b) const {
510 // This default implementation is correct for most targets.
514 //===--------------------------------------------------------------------===//
515 // Register Class Information
518 /// Register class iterators
520 regclass_iterator regclass_begin() const { return RegClassBegin; }
521 regclass_iterator regclass_end() const { return RegClassEnd; }
523 unsigned getNumRegClasses() const {
524 return (unsigned)(regclass_end()-regclass_begin());
527 /// getRegClass - Returns the register class associated with the enumeration
528 /// value. See class TargetOperandInfo.
529 const TargetRegisterClass *getRegClass(unsigned i) const {
530 assert(i < getNumRegClasses() && "Register Class ID out of range");
531 return RegClassBegin[i];
534 /// getPointerRegClass - Returns a TargetRegisterClass used for pointer
535 /// values. If a target supports multiple different pointer register classes,
536 /// kind specifies which one is indicated.
537 virtual const TargetRegisterClass *getPointerRegClass(unsigned Kind=0) const {
538 assert(0 && "Target didn't implement getPointerRegClass!");
539 return 0; // Must return a value in order to compile with VS 2005
542 /// getCrossCopyRegClass - Returns a legal register class to copy a register
543 /// in the specified class to or from. Returns NULL if it is possible to copy
544 /// between a two registers of the specified class.
545 virtual const TargetRegisterClass *
546 getCrossCopyRegClass(const TargetRegisterClass *RC) const {
550 /// getAllocationOrder - Returns the register allocation order for a specified
551 /// register class in the form of a pair of TargetRegisterClass iterators.
552 virtual std::pair<TargetRegisterClass::iterator,TargetRegisterClass::iterator>
553 getAllocationOrder(const TargetRegisterClass *RC,
554 unsigned HintType, unsigned HintReg,
555 const MachineFunction &MF) const {
556 return std::make_pair(RC->allocation_order_begin(MF),
557 RC->allocation_order_end(MF));
560 /// ResolveRegAllocHint - Resolves the specified register allocation hint
561 /// to a physical register. Returns the physical register if it is successful.
562 virtual unsigned ResolveRegAllocHint(unsigned Type, unsigned Reg,
563 const MachineFunction &MF) const {
564 if (Type == 0 && Reg && isPhysicalRegister(Reg))
569 /// UpdateRegAllocHint - A callback to allow target a chance to update
570 /// register allocation hints when a register is "changed" (e.g. coalesced)
571 /// to another register. e.g. On ARM, some virtual registers should target
572 /// register pairs, if one of pair is coalesced to another register, the
573 /// allocation hint of the other half of the pair should be changed to point
574 /// to the new register.
575 virtual void UpdateRegAllocHint(unsigned Reg, unsigned NewReg,
576 MachineFunction &MF) const {
580 /// requiresRegisterScavenging - returns true if the target requires (and can
581 /// make use of) the register scavenger.
582 virtual bool requiresRegisterScavenging(const MachineFunction &MF) const {
586 /// requiresFrameIndexScavenging - returns true if the target requires post
587 /// PEI scavenging of registers for materializing frame index constants.
588 virtual bool requiresFrameIndexScavenging(const MachineFunction &MF) const {
592 /// requiresVirtualBaseRegisters - Returns true if the target wants the
593 /// LocalStackAllocation pass to be run and virtual base registers
594 /// used for more efficient stack access.
595 virtual bool requiresVirtualBaseRegisters(const MachineFunction &MF) const {
599 /// hasReservedSpillSlot - Return true if target has reserved a spill slot in
600 /// the stack frame of the given function for the specified register. e.g. On
601 /// x86, if the frame register is required, the first fixed stack object is
602 /// reserved as its spill slot. This tells PEI not to create a new stack frame
603 /// object for the given register. It should be called only after
604 /// processFunctionBeforeCalleeSavedScan().
605 virtual bool hasReservedSpillSlot(const MachineFunction &MF, unsigned Reg,
606 int &FrameIdx) const {
610 /// needsStackRealignment - true if storage within the function requires the
611 /// stack pointer to be aligned more than the normal calling convention calls
613 virtual bool needsStackRealignment(const MachineFunction &MF) const {
617 /// getFrameIndexInstrOffset - Get the offset from the referenced frame
618 /// index in the instruction, if the is one.
619 virtual int64_t getFrameIndexInstrOffset(const MachineInstr *MI,
624 /// needsFrameBaseReg - Returns true if the instruction's frame index
625 /// reference would be better served by a base register other than FP
626 /// or SP. Used by LocalStackFrameAllocation to determine which frame index
627 /// references it should create new base registers for.
628 virtual bool needsFrameBaseReg(MachineInstr *MI, int64_t Offset) const {
632 /// materializeFrameBaseRegister - Insert defining instruction(s) for
633 /// BaseReg to be a pointer to FrameIdx before insertion point I.
634 virtual void materializeFrameBaseRegister(MachineBasicBlock::iterator I,
635 unsigned BaseReg, int FrameIdx,
636 int64_t Offset) const {
637 assert(0 && "materializeFrameBaseRegister does not exist on this target");
640 /// resolveFrameIndex - Resolve a frame index operand of an instruction
641 /// to reference the indicated base register plus offset instead.
642 virtual void resolveFrameIndex(MachineBasicBlock::iterator I,
643 unsigned BaseReg, int64_t Offset) const {
644 assert(0 && "resolveFrameIndex does not exist on this target");
647 /// isFrameOffsetLegal - Determine whether a given offset immediate is
648 /// encodable to resolve a frame index.
649 virtual bool isFrameOffsetLegal(const MachineInstr *MI,
650 int64_t Offset) const {
651 assert(0 && "isFrameOffsetLegal does not exist on this target");
652 return false; // Must return a value in order to compile with VS 2005
655 /// getCallFrameSetup/DestroyOpcode - These methods return the opcode of the
656 /// frame setup/destroy instructions if they exist (-1 otherwise). Some
657 /// targets use pseudo instructions in order to abstract away the difference
658 /// between operating with a frame pointer and operating without, through the
659 /// use of these two instructions.
661 int getCallFrameSetupOpcode() const { return CallFrameSetupOpcode; }
662 int getCallFrameDestroyOpcode() const { return CallFrameDestroyOpcode; }
664 /// eliminateCallFramePseudoInstr - This method is called during prolog/epilog
665 /// code insertion to eliminate call frame setup and destroy pseudo
666 /// instructions (but only if the Target is using them). It is responsible
667 /// for eliminating these instructions, replacing them with concrete
668 /// instructions. This method need only be implemented if using call frame
669 /// setup/destroy pseudo instructions.
672 eliminateCallFramePseudoInstr(MachineFunction &MF,
673 MachineBasicBlock &MBB,
674 MachineBasicBlock::iterator MI) const {
675 assert(getCallFrameSetupOpcode()== -1 && getCallFrameDestroyOpcode()== -1 &&
676 "eliminateCallFramePseudoInstr must be implemented if using"
677 " call frame setup/destroy pseudo instructions!");
678 assert(0 && "Call Frame Pseudo Instructions do not exist on this target!");
681 /// processFunctionBeforeCalleeSavedScan - This method is called immediately
682 /// before PrologEpilogInserter scans the physical registers used to determine
683 /// what callee saved registers should be spilled. This method is optional.
684 virtual void processFunctionBeforeCalleeSavedScan(MachineFunction &MF,
685 RegScavenger *RS = NULL) const {
689 /// processFunctionBeforeFrameFinalized - This method is called immediately
690 /// before the specified function's frame layout (MF.getFrameInfo()) is
691 /// finalized. Once the frame is finalized, MO_FrameIndex operands are
692 /// replaced with direct constants. This method is optional.
694 virtual void processFunctionBeforeFrameFinalized(MachineFunction &MF) const {
697 /// saveScavengerRegister - Spill the register so it can be used by the
698 /// register scavenger. Return true if the register was spilled, false
699 /// otherwise. If this function does not spill the register, the scavenger
700 /// will instead spill it to the emergency spill slot.
702 virtual bool saveScavengerRegister(MachineBasicBlock &MBB,
703 MachineBasicBlock::iterator I,
704 MachineBasicBlock::iterator &UseMI,
705 const TargetRegisterClass *RC,
706 unsigned Reg) const {
710 /// eliminateFrameIndex - This method must be overriden to eliminate abstract
711 /// frame indices from instructions which may use them. The instruction
712 /// referenced by the iterator contains an MO_FrameIndex operand which must be
713 /// eliminated by this method. This method may modify or replace the
714 /// specified instruction, as long as it keeps the iterator pointing at the
715 /// finished product. SPAdj is the SP adjustment due to call frame setup
717 virtual void eliminateFrameIndex(MachineBasicBlock::iterator MI,
718 int SPAdj, RegScavenger *RS=NULL) const = 0;
720 //===--------------------------------------------------------------------===//
721 /// Debug information queries.
723 /// getDwarfRegNum - Map a target register to an equivalent dwarf register
724 /// number. Returns -1 if there is no equivalent value. The second
725 /// parameter allows targets to use different numberings for EH info and
727 virtual int getDwarfRegNum(unsigned RegNum, bool isEH) const = 0;
729 /// getFrameRegister - This method should return the register used as a base
730 /// for values allocated in the current stack frame.
731 virtual unsigned getFrameRegister(const MachineFunction &MF) const = 0;
733 /// getFrameIndexOffset - Returns the displacement from the frame register to
734 /// the stack frame of the specified index.
735 virtual int getFrameIndexOffset(const MachineFunction &MF, int FI) const;
737 /// getFrameIndexReference - This method should return the base register
738 /// and offset used to reference a frame index location. The offset is
739 /// returned directly, and the base register is returned via FrameReg.
740 virtual int getFrameIndexReference(const MachineFunction &MF, int FI,
741 unsigned &FrameReg) const {
742 // By default, assume all frame indices are referenced via whatever
743 // getFrameRegister() says. The target can override this if it's doing
744 // something different.
745 FrameReg = getFrameRegister(MF);
746 return getFrameIndexOffset(MF, FI);
749 /// getRARegister - This method should return the register where the return
750 /// address can be found.
751 virtual unsigned getRARegister() const = 0;
753 /// getInitialFrameState - Returns a list of machine moves that are assumed
754 /// on entry to all functions. Note that LabelID is ignored (assumed to be
755 /// the beginning of the function.)
756 virtual void getInitialFrameState(std::vector<MachineMove> &Moves) const;
760 // This is useful when building IndexedMaps keyed on virtual registers
761 struct VirtReg2IndexFunctor : public std::unary_function<unsigned, unsigned> {
762 unsigned operator()(unsigned Reg) const {
763 return Reg - TargetRegisterInfo::FirstVirtualRegister;
767 /// getCommonSubClass - find the largest common subclass of A and B. Return NULL
768 /// if there is no common subclass.
769 const TargetRegisterClass *getCommonSubClass(const TargetRegisterClass *A,
770 const TargetRegisterClass *B);
772 } // End llvm namespace