1 //===-- llvm/CodeGen/MachineRegisterInfo.h ----------------------*- 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 defines the MachineRegisterInfo class.
12 //===----------------------------------------------------------------------===//
14 #ifndef LLVM_CODEGEN_MACHINEREGISTERINFO_H
15 #define LLVM_CODEGEN_MACHINEREGISTERINFO_H
17 #include "llvm/Target/TargetRegisterInfo.h"
18 #include "llvm/ADT/BitVector.h"
19 #include "llvm/ADT/IndexedMap.h"
24 /// MachineRegisterInfo - Keep track of information for virtual and physical
25 /// registers, including vreg register classes, use/def chains for registers,
27 class MachineRegisterInfo {
28 /// IsSSA - True when the machine function is in SSA form and virtual
29 /// registers have a single def.
32 /// VRegInfo - Information we keep for each virtual register.
34 /// Each element in this list contains the register class of the vreg and the
35 /// start of the use/def list for the register.
36 IndexedMap<std::pair<const TargetRegisterClass*, MachineOperand*>,
37 VirtReg2IndexFunctor> VRegInfo;
39 /// RegAllocHints - This vector records register allocation hints for virtual
40 /// registers. For each virtual register, it keeps a register and hint type
41 /// pair making up the allocation hint. Hint type is target specific except
42 /// for the value 0 which means the second value of the pair is the preferred
43 /// register for allocation. For example, if the hint is <0, 1024>, it means
44 /// the allocator should prefer the physical register allocated to the virtual
45 /// register of the hint.
46 IndexedMap<std::pair<unsigned, unsigned>, VirtReg2IndexFunctor> RegAllocHints;
48 /// PhysRegUseDefLists - This is an array of the head of the use/def list for
49 /// physical registers.
50 MachineOperand **PhysRegUseDefLists;
52 /// UsedPhysRegs - This is a bit vector that is computed and set by the
53 /// register allocator, and must be kept up to date by passes that run after
54 /// register allocation (though most don't modify this). This is used
55 /// so that the code generator knows which callee save registers to save and
56 /// for other target specific uses.
57 BitVector UsedPhysRegs;
59 /// LiveIns/LiveOuts - Keep track of the physical registers that are
60 /// livein/liveout of the function. Live in values are typically arguments in
61 /// registers, live out values are typically return values in registers.
62 /// LiveIn values are allowed to have virtual registers associated with them,
63 /// stored in the second element.
64 std::vector<std::pair<unsigned, unsigned> > LiveIns;
65 std::vector<unsigned> LiveOuts;
67 MachineRegisterInfo(const MachineRegisterInfo&); // DO NOT IMPLEMENT
68 void operator=(const MachineRegisterInfo&); // DO NOT IMPLEMENT
70 explicit MachineRegisterInfo(const TargetRegisterInfo &TRI);
71 ~MachineRegisterInfo();
73 //===--------------------------------------------------------------------===//
75 //===--------------------------------------------------------------------===//
77 // isSSA - Returns true when the machine function is in SSA form. Early
78 // passes require the machine function to be in SSA form where every virtual
79 // register has a single defining instruction.
81 // The TwoAddressInstructionPass and PHIElimination passes take the machine
82 // function out of SSA form when they introduce multiple defs per virtual
84 bool isSSA() const { return IsSSA; }
86 // leaveSSA - Indicates that the machine function is no longer in SSA form.
87 void leaveSSA() { IsSSA = false; }
89 //===--------------------------------------------------------------------===//
91 //===--------------------------------------------------------------------===//
93 /// reg_begin/reg_end - Provide iteration support to walk over all definitions
94 /// and uses of a register within the MachineFunction that corresponds to this
95 /// MachineRegisterInfo object.
96 template<bool Uses, bool Defs, bool SkipDebug>
97 class defusechain_iterator;
99 /// reg_iterator/reg_begin/reg_end - Walk all defs and uses of the specified
101 typedef defusechain_iterator<true,true,false> reg_iterator;
102 reg_iterator reg_begin(unsigned RegNo) const {
103 return reg_iterator(getRegUseDefListHead(RegNo));
105 static reg_iterator reg_end() { return reg_iterator(0); }
107 /// reg_empty - Return true if there are no instructions using or defining the
108 /// specified register (it may be live-in).
109 bool reg_empty(unsigned RegNo) const { return reg_begin(RegNo) == reg_end(); }
111 /// reg_nodbg_iterator/reg_nodbg_begin/reg_nodbg_end - Walk all defs and uses
112 /// of the specified register, skipping those marked as Debug.
113 typedef defusechain_iterator<true,true,true> reg_nodbg_iterator;
114 reg_nodbg_iterator reg_nodbg_begin(unsigned RegNo) const {
115 return reg_nodbg_iterator(getRegUseDefListHead(RegNo));
117 static reg_nodbg_iterator reg_nodbg_end() { return reg_nodbg_iterator(0); }
119 /// reg_nodbg_empty - Return true if the only instructions using or defining
120 /// Reg are Debug instructions.
121 bool reg_nodbg_empty(unsigned RegNo) const {
122 return reg_nodbg_begin(RegNo) == reg_nodbg_end();
125 /// def_iterator/def_begin/def_end - Walk all defs of the specified register.
126 typedef defusechain_iterator<false,true,false> def_iterator;
127 def_iterator def_begin(unsigned RegNo) const {
128 return def_iterator(getRegUseDefListHead(RegNo));
130 static def_iterator def_end() { return def_iterator(0); }
132 /// def_empty - Return true if there are no instructions defining the
133 /// specified register (it may be live-in).
134 bool def_empty(unsigned RegNo) const { return def_begin(RegNo) == def_end(); }
136 /// use_iterator/use_begin/use_end - Walk all uses of the specified register.
137 typedef defusechain_iterator<true,false,false> use_iterator;
138 use_iterator use_begin(unsigned RegNo) const {
139 return use_iterator(getRegUseDefListHead(RegNo));
141 static use_iterator use_end() { return use_iterator(0); }
143 /// use_empty - Return true if there are no instructions using the specified
145 bool use_empty(unsigned RegNo) const { return use_begin(RegNo) == use_end(); }
147 /// hasOneUse - Return true if there is exactly one instruction using the
148 /// specified register.
149 bool hasOneUse(unsigned RegNo) const;
151 /// use_nodbg_iterator/use_nodbg_begin/use_nodbg_end - Walk all uses of the
152 /// specified register, skipping those marked as Debug.
153 typedef defusechain_iterator<true,false,true> use_nodbg_iterator;
154 use_nodbg_iterator use_nodbg_begin(unsigned RegNo) const {
155 return use_nodbg_iterator(getRegUseDefListHead(RegNo));
157 static use_nodbg_iterator use_nodbg_end() { return use_nodbg_iterator(0); }
159 /// use_nodbg_empty - Return true if there are no non-Debug instructions
160 /// using the specified register.
161 bool use_nodbg_empty(unsigned RegNo) const {
162 return use_nodbg_begin(RegNo) == use_nodbg_end();
165 /// hasOneNonDBGUse - Return true if there is exactly one non-Debug
166 /// instruction using the specified register.
167 bool hasOneNonDBGUse(unsigned RegNo) const;
169 /// replaceRegWith - Replace all instances of FromReg with ToReg in the
170 /// machine function. This is like llvm-level X->replaceAllUsesWith(Y),
171 /// except that it also changes any definitions of the register as well.
172 void replaceRegWith(unsigned FromReg, unsigned ToReg);
174 /// getRegUseDefListHead - Return the head pointer for the register use/def
175 /// list for the specified virtual or physical register.
176 MachineOperand *&getRegUseDefListHead(unsigned RegNo) {
177 if (TargetRegisterInfo::isVirtualRegister(RegNo))
178 return VRegInfo[RegNo].second;
179 return PhysRegUseDefLists[RegNo];
182 MachineOperand *getRegUseDefListHead(unsigned RegNo) const {
183 if (TargetRegisterInfo::isVirtualRegister(RegNo))
184 return VRegInfo[RegNo].second;
185 return PhysRegUseDefLists[RegNo];
188 /// getVRegDef - Return the machine instr that defines the specified virtual
189 /// register or null if none is found. This assumes that the code is in SSA
190 /// form, so there should only be one definition.
191 MachineInstr *getVRegDef(unsigned Reg) const;
193 /// clearKillFlags - Iterate over all the uses of the given register and
194 /// clear the kill flag from the MachineOperand. This function is used by
195 /// optimization passes which extend register lifetimes and need only
196 /// preserve conservative kill flag information.
197 void clearKillFlags(unsigned Reg) const;
200 void dumpUses(unsigned RegNo) const;
203 //===--------------------------------------------------------------------===//
204 // Virtual Register Info
205 //===--------------------------------------------------------------------===//
207 /// getRegClass - Return the register class of the specified virtual register.
209 const TargetRegisterClass *getRegClass(unsigned Reg) const {
210 return VRegInfo[Reg].first;
213 /// setRegClass - Set the register class of the specified virtual register.
215 void setRegClass(unsigned Reg, const TargetRegisterClass *RC);
217 /// constrainRegClass - Constrain the register class of the specified virtual
218 /// register to be a common subclass of RC and the current register class,
219 /// but only if the new class has at least MinNumRegs registers. Return the
220 /// new register class, or NULL if no such class exists.
221 /// This should only be used when the constraint is known to be trivial, like
222 /// GR32 -> GR32_NOSP. Beware of increasing register pressure.
224 const TargetRegisterClass *constrainRegClass(unsigned Reg,
225 const TargetRegisterClass *RC,
226 unsigned MinNumRegs = 0);
228 /// recomputeRegClass - Try to find a legal super-class of Reg's register
229 /// class that still satisfies the constraints from the instructions using
230 /// Reg. Returns true if Reg was upgraded.
232 /// This method can be used after constraints have been removed from a
233 /// virtual register, for example after removing instructions or splitting
236 bool recomputeRegClass(unsigned Reg, const TargetMachine&);
238 /// createVirtualRegister - Create and return a new virtual register in the
239 /// function with the specified register class.
241 unsigned createVirtualRegister(const TargetRegisterClass *RegClass);
243 /// getNumVirtRegs - Return the number of virtual registers created.
245 unsigned getNumVirtRegs() const { return VRegInfo.size(); }
247 /// setRegAllocationHint - Specify a register allocation hint for the
248 /// specified virtual register.
249 void setRegAllocationHint(unsigned Reg, unsigned Type, unsigned PrefReg) {
250 RegAllocHints[Reg].first = Type;
251 RegAllocHints[Reg].second = PrefReg;
254 /// getRegAllocationHint - Return the register allocation hint for the
255 /// specified virtual register.
256 std::pair<unsigned, unsigned>
257 getRegAllocationHint(unsigned Reg) const {
258 return RegAllocHints[Reg];
261 /// getSimpleHint - Return the preferred register allocation hint, or 0 if a
262 /// standard simple hint (Type == 0) is not set.
263 unsigned getSimpleHint(unsigned Reg) const {
264 std::pair<unsigned, unsigned> Hint = getRegAllocationHint(Reg);
265 return Hint.first ? 0 : Hint.second;
269 //===--------------------------------------------------------------------===//
270 // Physical Register Use Info
271 //===--------------------------------------------------------------------===//
273 /// isPhysRegUsed - Return true if the specified register is used in this
274 /// function. This only works after register allocation.
275 bool isPhysRegUsed(unsigned Reg) const { return UsedPhysRegs[Reg]; }
277 /// setPhysRegUsed - Mark the specified register used in this function.
278 /// This should only be called during and after register allocation.
279 void setPhysRegUsed(unsigned Reg) { UsedPhysRegs[Reg] = true; }
281 /// addPhysRegsUsed - Mark the specified registers used in this function.
282 /// This should only be called during and after register allocation.
283 void addPhysRegsUsed(const BitVector &Regs) { UsedPhysRegs |= Regs; }
285 /// setPhysRegUnused - Mark the specified register unused in this function.
286 /// This should only be called during and after register allocation.
287 void setPhysRegUnused(unsigned Reg) { UsedPhysRegs[Reg] = false; }
289 /// closePhysRegsUsed - Expand UsedPhysRegs to its transitive closure over
290 /// subregisters. That means that if R is used, so are all subregisters.
291 void closePhysRegsUsed(const TargetRegisterInfo&);
293 //===--------------------------------------------------------------------===//
294 // LiveIn/LiveOut Management
295 //===--------------------------------------------------------------------===//
297 /// addLiveIn/Out - Add the specified register as a live in/out. Note that it
298 /// is an error to add the same register to the same set more than once.
299 void addLiveIn(unsigned Reg, unsigned vreg = 0) {
300 LiveIns.push_back(std::make_pair(Reg, vreg));
302 void addLiveOut(unsigned Reg) { LiveOuts.push_back(Reg); }
304 // Iteration support for live in/out sets. These sets are kept in sorted
305 // order by their register number.
306 typedef std::vector<std::pair<unsigned,unsigned> >::const_iterator
308 typedef std::vector<unsigned>::const_iterator liveout_iterator;
309 livein_iterator livein_begin() const { return LiveIns.begin(); }
310 livein_iterator livein_end() const { return LiveIns.end(); }
311 bool livein_empty() const { return LiveIns.empty(); }
312 liveout_iterator liveout_begin() const { return LiveOuts.begin(); }
313 liveout_iterator liveout_end() const { return LiveOuts.end(); }
314 bool liveout_empty() const { return LiveOuts.empty(); }
316 bool isLiveIn(unsigned Reg) const;
317 bool isLiveOut(unsigned Reg) const;
319 /// getLiveInPhysReg - If VReg is a live-in virtual register, return the
320 /// corresponding live-in physical register.
321 unsigned getLiveInPhysReg(unsigned VReg) const;
323 /// getLiveInVirtReg - If PReg is a live-in physical register, return the
324 /// corresponding live-in physical register.
325 unsigned getLiveInVirtReg(unsigned PReg) const;
327 /// EmitLiveInCopies - Emit copies to initialize livein virtual registers
328 /// into the given entry block.
329 void EmitLiveInCopies(MachineBasicBlock *EntryMBB,
330 const TargetRegisterInfo &TRI,
331 const TargetInstrInfo &TII);
334 void HandleVRegListReallocation();
337 /// defusechain_iterator - This class provides iterator support for machine
338 /// operands in the function that use or define a specific register. If
339 /// ReturnUses is true it returns uses of registers, if ReturnDefs is true it
340 /// returns defs. If neither are true then you are silly and it always
341 /// returns end(). If SkipDebug is true it skips uses marked Debug
342 /// when incrementing.
343 template<bool ReturnUses, bool ReturnDefs, bool SkipDebug>
344 class defusechain_iterator
345 : public std::iterator<std::forward_iterator_tag, MachineInstr, ptrdiff_t> {
347 explicit defusechain_iterator(MachineOperand *op) : Op(op) {
348 // If the first node isn't one we're interested in, advance to one that
349 // we are interested in.
351 if ((!ReturnUses && op->isUse()) ||
352 (!ReturnDefs && op->isDef()) ||
353 (SkipDebug && op->isDebug()))
357 friend class MachineRegisterInfo;
359 typedef std::iterator<std::forward_iterator_tag,
360 MachineInstr, ptrdiff_t>::reference reference;
361 typedef std::iterator<std::forward_iterator_tag,
362 MachineInstr, ptrdiff_t>::pointer pointer;
364 defusechain_iterator(const defusechain_iterator &I) : Op(I.Op) {}
365 defusechain_iterator() : Op(0) {}
367 bool operator==(const defusechain_iterator &x) const {
370 bool operator!=(const defusechain_iterator &x) const {
371 return !operator==(x);
374 /// atEnd - return true if this iterator is equal to reg_end() on the value.
375 bool atEnd() const { return Op == 0; }
377 // Iterator traversal: forward iteration only
378 defusechain_iterator &operator++() { // Preincrement
379 assert(Op && "Cannot increment end iterator!");
380 Op = Op->getNextOperandForReg();
382 // If this is an operand we don't care about, skip it.
383 while (Op && ((!ReturnUses && Op->isUse()) ||
384 (!ReturnDefs && Op->isDef()) ||
385 (SkipDebug && Op->isDebug())))
386 Op = Op->getNextOperandForReg();
390 defusechain_iterator operator++(int) { // Postincrement
391 defusechain_iterator tmp = *this; ++*this; return tmp;
394 /// skipInstruction - move forward until reaching a different instruction.
395 /// Return the skipped instruction that is no longer pointed to, or NULL if
396 /// already pointing to end().
397 MachineInstr *skipInstruction() {
399 MachineInstr *MI = Op->getParent();
401 while (Op && Op->getParent() == MI);
405 MachineOperand &getOperand() const {
406 assert(Op && "Cannot dereference end iterator!");
410 /// getOperandNo - Return the operand # of this MachineOperand in its
412 unsigned getOperandNo() const {
413 assert(Op && "Cannot dereference end iterator!");
414 return Op - &Op->getParent()->getOperand(0);
417 // Retrieve a reference to the current operand.
418 MachineInstr &operator*() const {
419 assert(Op && "Cannot dereference end iterator!");
420 return *Op->getParent();
423 MachineInstr *operator->() const {
424 assert(Op && "Cannot dereference end iterator!");
425 return Op->getParent();
431 } // End llvm namespace