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/ADT/SmallVector.h"
20 #include "llvm/CodeGen/MachineBasicBlock.h"
21 #include "llvm/CodeGen/ValueTypes.h"
28 class MachineFunction;
34 class TargetRegisterClass;
37 /// TargetRegisterDesc - This record contains all of the information known about
38 /// a particular register. The AliasSet field (if not null) contains a pointer
39 /// to a Zero terminated array of registers that this register aliases. This is
40 /// needed for architectures like X86 which have AL alias AX alias EAX.
41 /// Registers that this does not apply to simply should set this to null.
42 /// The SubRegs field is a zero terminated array of registers that are
43 /// sub-registers of the specific register, e.g. AL, AH are sub-registers of AX.
44 /// The ImmsubRegs field is a subset of SubRegs. It includes only the immediate
45 /// sub-registers. e.g. EAX has only one immediate sub-register of AX, not AH,
46 /// AL which are immediate sub-registers of AX. The SuperRegs field is a zero
47 /// terminated array of registers that are super-registers of the specific
48 /// register, e.g. RAX, EAX, are super-registers of AX.
50 struct TargetRegisterDesc {
51 const char *AsmName; // Assembly language name for the register
52 const char *Name; // Printable name for the reg (for debugging)
53 const unsigned *AliasSet; // Register Alias Set, described above
54 const unsigned *SubRegs; // Sub-register set, described above
55 const unsigned *ImmSubRegs; // Immediate sub-register set, described above
56 const unsigned *SuperRegs; // Super-register set, described above
59 class TargetRegisterClass {
61 typedef const unsigned* iterator;
62 typedef const unsigned* const_iterator;
64 typedef const MVT* vt_iterator;
65 typedef const TargetRegisterClass* const * sc_iterator;
69 const vt_iterator VTs;
70 const sc_iterator SubClasses;
71 const sc_iterator SuperClasses;
72 const sc_iterator SubRegClasses;
73 const sc_iterator SuperRegClasses;
74 const unsigned RegSize, Alignment; // Size & Alignment of register in bytes
76 const iterator RegsBegin, RegsEnd;
78 TargetRegisterClass(unsigned id,
80 const TargetRegisterClass * const *subcs,
81 const TargetRegisterClass * const *supcs,
82 const TargetRegisterClass * const *subregcs,
83 const TargetRegisterClass * const *superregcs,
84 unsigned RS, unsigned Al, int CC,
85 iterator RB, iterator RE)
86 : ID(id), VTs(vts), SubClasses(subcs), SuperClasses(supcs),
87 SubRegClasses(subregcs), SuperRegClasses(superregcs),
88 RegSize(RS), Alignment(Al), CopyCost(CC), RegsBegin(RB), RegsEnd(RE) {}
89 virtual ~TargetRegisterClass() {} // Allow subclasses
91 /// getID() - Return the register class ID number.
93 unsigned getID() const { return ID; }
95 /// begin/end - Return all of the registers in this class.
97 iterator begin() const { return RegsBegin; }
98 iterator end() const { return RegsEnd; }
100 /// getNumRegs - Return the number of registers in this class.
102 unsigned getNumRegs() const { return (unsigned)(RegsEnd-RegsBegin); }
104 /// getRegister - Return the specified register in the class.
106 unsigned getRegister(unsigned i) const {
107 assert(i < getNumRegs() && "Register number out of range!");
111 /// contains - Return true if the specified register is included in this
113 bool contains(unsigned Reg) const {
114 for (iterator I = begin(), E = end(); I != E; ++I)
115 if (*I == Reg) return true;
119 /// hasType - return true if this TargetRegisterClass has the ValueType vt.
121 bool hasType(MVT vt) const {
122 for(int i = 0; VTs[i] != MVT::Other; ++i)
128 /// vt_begin / vt_end - Loop over all of the value types that can be
129 /// represented by values in this register class.
130 vt_iterator vt_begin() const {
134 vt_iterator vt_end() const {
136 while (*I != MVT::Other) ++I;
140 /// hasSubClass - return true if the specified TargetRegisterClass is a
141 /// sub-register class of this TargetRegisterClass.
142 bool hasSubClass(const TargetRegisterClass *cs) const {
143 for (int i = 0; SubClasses[i] != NULL; ++i)
144 if (SubClasses[i] == cs)
149 /// subclasses_begin / subclasses_end - Loop over all of the sub-classes of
150 /// this register class.
151 sc_iterator subclasses_begin() const {
155 sc_iterator subclasses_end() const {
156 sc_iterator I = SubClasses;
157 while (*I != NULL) ++I;
161 /// hasSuperClass - return true if the specified TargetRegisterClass is a
162 /// super-register class of this TargetRegisterClass.
163 bool hasSuperClass(const TargetRegisterClass *cs) const {
164 for (int i = 0; SuperClasses[i] != NULL; ++i)
165 if (SuperClasses[i] == cs)
170 /// superclasses_begin / superclasses_end - Loop over all of the super-classes
171 /// of this register class.
172 sc_iterator superclasses_begin() const {
176 sc_iterator superclasses_end() const {
177 sc_iterator I = SuperClasses;
178 while (*I != NULL) ++I;
182 /// hasSubRegClass - return true if the specified TargetRegisterClass is a
183 /// class of a sub-register class for this TargetRegisterClass.
184 bool hasSubRegClass(const TargetRegisterClass *cs) const {
185 for (int i = 0; SubRegClasses[i] != NULL; ++i)
186 if (SubRegClasses[i] == cs)
191 /// hasClassForSubReg - return true if the specified TargetRegisterClass is a
192 /// class of a sub-register class for this TargetRegisterClass.
193 bool hasClassForSubReg(unsigned SubReg) const {
195 for (unsigned i = 0; SubRegClasses[i] != NULL; ++i)
201 /// getClassForSubReg - return theTargetRegisterClass for the sub-register
202 /// at idx for this TargetRegisterClass.
203 sc_iterator getClassForSubReg(unsigned SubReg) const {
205 for (unsigned i = 0; SubRegClasses[i] != NULL; ++i)
207 return &SubRegClasses[i];
208 assert(0 && "Invalid subregister index for register class");
212 /// subregclasses_begin / subregclasses_end - Loop over all of
213 /// the subregister classes of this register class.
214 sc_iterator subregclasses_begin() const {
215 return SubRegClasses;
218 sc_iterator subregclasses_end() const {
219 sc_iterator I = SubRegClasses;
220 while (*I != NULL) ++I;
224 /// superregclasses_begin / superregclasses_end - Loop over all of
225 /// the superregister classes of this register class.
226 sc_iterator superregclasses_begin() const {
227 return SuperRegClasses;
230 sc_iterator superregclasses_end() const {
231 sc_iterator I = SuperRegClasses;
232 while (*I != NULL) ++I;
236 /// allocation_order_begin/end - These methods define a range of registers
237 /// which specify the registers in this class that are valid to register
238 /// allocate, and the preferred order to allocate them in. For example,
239 /// callee saved registers should be at the end of the list, because it is
240 /// cheaper to allocate caller saved registers.
242 /// These methods take a MachineFunction argument, which can be used to tune
243 /// the allocatable registers based on the characteristics of the function.
244 /// One simple example is that the frame pointer register can be used if
245 /// frame-pointer-elimination is performed.
247 /// By default, these methods return all registers in the class.
249 virtual iterator allocation_order_begin(const MachineFunction &MF) const {
252 virtual iterator allocation_order_end(const MachineFunction &MF) const {
258 /// getSize - Return the size of the register in bytes, which is also the size
259 /// of a stack slot allocated to hold a spilled copy of this register.
260 unsigned getSize() const { return RegSize; }
262 /// getAlignment - Return the minimum required alignment for a register of
264 unsigned getAlignment() const { return Alignment; }
266 /// getCopyCost - Return the cost of copying a value between two registers in
268 int getCopyCost() const { return CopyCost; }
272 /// TargetRegisterInfo base class - We assume that the target defines a static
273 /// array of TargetRegisterDesc objects that represent all of the machine
274 /// registers that the target has. As such, we simply have to track a pointer
275 /// to this array so that we can turn register number into a register
278 class TargetRegisterInfo {
280 typedef const TargetRegisterClass * const * regclass_iterator;
282 const TargetRegisterDesc *Desc; // Pointer to the descriptor array
283 unsigned NumRegs; // Number of entries in the array
285 regclass_iterator RegClassBegin, RegClassEnd; // List of regclasses
287 int CallFrameSetupOpcode, CallFrameDestroyOpcode;
289 TargetRegisterInfo(const TargetRegisterDesc *D, unsigned NR,
290 regclass_iterator RegClassBegin,
291 regclass_iterator RegClassEnd,
292 int CallFrameSetupOpcode = -1,
293 int CallFrameDestroyOpcode = -1);
294 virtual ~TargetRegisterInfo();
297 enum { // Define some target independent constants
298 /// NoRegister - This physical register is not a real target register. It
299 /// is useful as a sentinal.
302 /// FirstVirtualRegister - This is the first register number that is
303 /// considered to be a 'virtual' register, which is part of the SSA
304 /// namespace. This must be the same for all targets, which means that each
305 /// target is limited to 1024 registers.
306 FirstVirtualRegister = 1024
309 /// isPhysicalRegister - Return true if the specified register number is in
310 /// the physical register namespace.
311 static bool isPhysicalRegister(unsigned Reg) {
312 assert(Reg && "this is not a register!");
313 return Reg < FirstVirtualRegister;
316 /// isVirtualRegister - Return true if the specified register number is in
317 /// the virtual register namespace.
318 static bool isVirtualRegister(unsigned Reg) {
319 assert(Reg && "this is not a register!");
320 return Reg >= FirstVirtualRegister;
323 /// getPhysicalRegisterRegClass - Returns the Register Class of a physical
324 /// register of the given type. If type is MVT::Other, then just return any
325 /// register class the register belongs to.
326 const TargetRegisterClass *getPhysicalRegisterRegClass(unsigned Reg,
327 MVT VT = MVT::Other) const;
329 /// getAllocatableSet - Returns a bitset indexed by register number
330 /// indicating if a register is allocatable or not. If a register class is
331 /// specified, returns the subset for the class.
332 BitVector getAllocatableSet(MachineFunction &MF,
333 const TargetRegisterClass *RC = NULL) const;
335 const TargetRegisterDesc &operator[](unsigned RegNo) const {
336 assert(RegNo < NumRegs &&
337 "Attempting to access record for invalid register number!");
341 /// Provide a get method, equivalent to [], but more useful if we have a
342 /// pointer to this object.
344 const TargetRegisterDesc &get(unsigned RegNo) const {
345 return operator[](RegNo);
348 /// getAliasSet - Return the set of registers aliased by the specified
349 /// register, or a null list of there are none. The list returned is zero
352 const unsigned *getAliasSet(unsigned RegNo) const {
353 return get(RegNo).AliasSet;
356 /// getSubRegisters - Return the list of registers that are sub-registers of
357 /// the specified register, or a null list of there are none. The list
358 /// returned is zero terminated and sorted according to super-sub register
359 /// relations. e.g. X86::RAX's sub-register list is EAX, AX, AL, AH.
361 const unsigned *getSubRegisters(unsigned RegNo) const {
362 return get(RegNo).SubRegs;
365 /// getImmediateSubRegisters - Return the set of registers that are immediate
366 /// sub-registers of the specified register, or a null list of there are none.
367 /// The list returned is zero terminated.
369 const unsigned *getImmediateSubRegisters(unsigned RegNo) const {
370 return get(RegNo).ImmSubRegs;
373 /// getSuperRegisters - Return the list of registers that are super-registers
374 /// of the specified register, or a null list of there are none. The list
375 /// returned is zero terminated and sorted according to super-sub register
376 /// relations. e.g. X86::AL's super-register list is RAX, EAX, AX.
378 const unsigned *getSuperRegisters(unsigned RegNo) const {
379 return get(RegNo).SuperRegs;
382 /// getAsmName - Return the symbolic target-specific name for the
383 /// specified physical register.
384 const char *getAsmName(unsigned RegNo) const {
385 return get(RegNo).AsmName;
388 /// getName - Return the human-readable symbolic target-specific name for the
389 /// specified physical register.
390 const char *getName(unsigned RegNo) const {
391 return get(RegNo).Name;
394 /// getNumRegs - Return the number of registers this target has (useful for
395 /// sizing arrays holding per register information)
396 unsigned getNumRegs() const {
400 /// areAliases - Returns true if the two registers alias each other, false
402 bool areAliases(unsigned regA, unsigned regB) const {
403 for (const unsigned *Alias = getAliasSet(regA); *Alias; ++Alias)
404 if (*Alias == regB) return true;
408 /// regsOverlap - Returns true if the two registers are equal or alias each
409 /// other. The registers may be virtual register.
410 bool regsOverlap(unsigned regA, unsigned regB) const {
414 if (isVirtualRegister(regA) || isVirtualRegister(regB))
416 return areAliases(regA, regB);
419 /// isSubRegister - Returns true if regB is a sub-register of regA.
421 bool isSubRegister(unsigned regA, unsigned regB) const {
422 for (const unsigned *SR = getSubRegisters(regA); *SR; ++SR)
423 if (*SR == regB) return true;
427 /// isSuperRegister - Returns true if regB is a super-register of regA.
429 bool isSuperRegister(unsigned regA, unsigned regB) const {
430 for (const unsigned *SR = getSuperRegisters(regA); *SR; ++SR)
431 if (*SR == regB) return true;
435 /// getCalleeSavedRegs - Return a null-terminated list of all of the
436 /// callee saved registers on this target. The register should be in the
437 /// order of desired callee-save stack frame offset. The first register is
438 /// closed to the incoming stack pointer if stack grows down, and vice versa.
439 virtual const unsigned* getCalleeSavedRegs(const MachineFunction *MF = 0)
442 /// getCalleeSavedRegClasses - Return a null-terminated list of the preferred
443 /// register classes to spill each callee saved register with. The order and
444 /// length of this list match the getCalleeSaveRegs() list.
445 virtual const TargetRegisterClass* const *getCalleeSavedRegClasses(
446 const MachineFunction *MF) const =0;
448 /// getReservedRegs - Returns a bitset indexed by physical register number
449 /// indicating if a register is a special register that has particular uses
450 /// and should be considered unavailable at all times, e.g. SP, RA. This is
451 /// used by register scavenger to determine what registers are free.
452 virtual BitVector getReservedRegs(const MachineFunction &MF) const = 0;
454 /// getSubReg - Returns the physical register number of sub-register "Index"
455 /// for physical register RegNo.
456 virtual unsigned getSubReg(unsigned RegNo, unsigned Index) const = 0;
458 //===--------------------------------------------------------------------===//
459 // Register Class Information
462 /// Register class iterators
464 regclass_iterator regclass_begin() const { return RegClassBegin; }
465 regclass_iterator regclass_end() const { return RegClassEnd; }
467 unsigned getNumRegClasses() const {
468 return (unsigned)(regclass_end()-regclass_begin());
471 /// getRegClass - Returns the register class associated with the enumeration
472 /// value. See class TargetOperandInfo.
473 const TargetRegisterClass *getRegClass(unsigned i) const {
474 assert(i <= getNumRegClasses() && "Register Class ID out of range");
475 return i ? RegClassBegin[i - 1] : NULL;
478 //===--------------------------------------------------------------------===//
479 // Interfaces used by the register allocator and stack frame
480 // manipulation passes to move data around between registers,
481 // immediates and memory. FIXME: Move these to TargetInstrInfo.h.
484 /// getCrossCopyRegClass - Returns a legal register class to copy a register
485 /// in the specified class to or from. Returns NULL if it is possible to copy
486 /// between a two registers of the specified class.
487 virtual const TargetRegisterClass *
488 getCrossCopyRegClass(const TargetRegisterClass *RC) const {
492 /// targetHandlesStackFrameRounding - Returns true if the target is
493 /// responsible for rounding up the stack frame (probably at emitPrologue
495 virtual bool targetHandlesStackFrameRounding() const {
499 /// requiresRegisterScavenging - returns true if the target requires (and can
500 /// make use of) the register scavenger.
501 virtual bool requiresRegisterScavenging(const MachineFunction &MF) const {
505 /// hasFP - Return true if the specified function should have a dedicated
506 /// frame pointer register. For most targets this is true only if the function
507 /// has variable sized allocas or if frame pointer elimination is disabled.
508 virtual bool hasFP(const MachineFunction &MF) const = 0;
510 // hasReservedCallFrame - Under normal circumstances, when a frame pointer is
511 // not required, we reserve argument space for call sites in the function
512 // immediately on entry to the current function. This eliminates the need for
513 // add/sub sp brackets around call sites. Returns true if the call frame is
514 // included as part of the stack frame.
515 virtual bool hasReservedCallFrame(MachineFunction &MF) const {
519 /// getCallFrameSetup/DestroyOpcode - These methods return the opcode of the
520 /// frame setup/destroy instructions if they exist (-1 otherwise). Some
521 /// targets use pseudo instructions in order to abstract away the difference
522 /// between operating with a frame pointer and operating without, through the
523 /// use of these two instructions.
525 int getCallFrameSetupOpcode() const { return CallFrameSetupOpcode; }
526 int getCallFrameDestroyOpcode() const { return CallFrameDestroyOpcode; }
529 /// eliminateCallFramePseudoInstr - This method is called during prolog/epilog
530 /// code insertion to eliminate call frame setup and destroy pseudo
531 /// instructions (but only if the Target is using them). It is responsible
532 /// for eliminating these instructions, replacing them with concrete
533 /// instructions. This method need only be implemented if using call frame
534 /// setup/destroy pseudo instructions.
537 eliminateCallFramePseudoInstr(MachineFunction &MF,
538 MachineBasicBlock &MBB,
539 MachineBasicBlock::iterator MI) const {
540 assert(getCallFrameSetupOpcode()== -1 && getCallFrameDestroyOpcode()== -1 &&
541 "eliminateCallFramePseudoInstr must be implemented if using"
542 " call frame setup/destroy pseudo instructions!");
543 assert(0 && "Call Frame Pseudo Instructions do not exist on this target!");
546 /// processFunctionBeforeCalleeSavedScan - This method is called immediately
547 /// before PrologEpilogInserter scans the physical registers used to determine
548 /// what callee saved registers should be spilled. This method is optional.
549 virtual void processFunctionBeforeCalleeSavedScan(MachineFunction &MF,
550 RegScavenger *RS = NULL) const {
554 /// processFunctionBeforeFrameFinalized - This method is called immediately
555 /// before the specified functions frame layout (MF.getFrameInfo()) is
556 /// finalized. Once the frame is finalized, MO_FrameIndex operands are
557 /// replaced with direct constants. This method is optional.
559 virtual void processFunctionBeforeFrameFinalized(MachineFunction &MF) const {
562 /// eliminateFrameIndex - This method must be overriden to eliminate abstract
563 /// frame indices from instructions which may use them. The instruction
564 /// referenced by the iterator contains an MO_FrameIndex operand which must be
565 /// eliminated by this method. This method may modify or replace the
566 /// specified instruction, as long as it keeps the iterator pointing the the
567 /// finished product. SPAdj is the SP adjustment due to call frame setup
568 /// instruction. The return value is the number of instructions added to
569 /// (negative if removed from) the basic block.
571 virtual void eliminateFrameIndex(MachineBasicBlock::iterator MI,
572 int SPAdj, RegScavenger *RS=NULL) const = 0;
574 /// emitProlog/emitEpilog - These methods insert prolog and epilog code into
575 /// the function. The return value is the number of instructions
576 /// added to (negative if removed from) the basic block (entry for prologue).
578 virtual void emitPrologue(MachineFunction &MF) const = 0;
579 virtual void emitEpilogue(MachineFunction &MF,
580 MachineBasicBlock &MBB) const = 0;
582 //===--------------------------------------------------------------------===//
583 /// Debug information queries.
585 /// getDwarfRegNum - Map a target register to an equivalent dwarf register
586 /// number. Returns -1 if there is no equivalent value. The second
587 /// parameter allows targets to use different numberings for EH info and
589 virtual int getDwarfRegNum(unsigned RegNum, bool isEH) const = 0;
591 /// getFrameRegister - This method should return the register used as a base
592 /// for values allocated in the current stack frame.
593 virtual unsigned getFrameRegister(MachineFunction &MF) const = 0;
595 /// getFrameIndexOffset - Returns the displacement from the frame register to
596 /// the stack frame of the specified index.
597 virtual int getFrameIndexOffset(MachineFunction &MF, int FI) const;
599 /// getRARegister - This method should return the register where the return
600 /// address can be found.
601 virtual unsigned getRARegister() const = 0;
603 /// getInitialFrameState - Returns a list of machine moves that are assumed
604 /// on entry to all functions. Note that LabelID is ignored (assumed to be
605 /// the beginning of the function.)
606 virtual void getInitialFrameState(std::vector<MachineMove> &Moves) const;
609 // This is useful when building IndexedMaps keyed on virtual registers
610 struct VirtReg2IndexFunctor : std::unary_function<unsigned, unsigned> {
611 unsigned operator()(unsigned Reg) const {
612 return Reg - TargetRegisterInfo::FirstVirtualRegister;
616 } // End llvm namespace