1 //===-- CodeGen/MachineFrameInfo.h - Abstract Stack Frame Rep. --*- 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 // The file defines the MachineFrameInfo class.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #ifndef LLVM_CODEGEN_MACHINEFRAMEINFO_H
15 #define LLVM_CODEGEN_MACHINEFRAMEINFO_H
16 
17 #include "llvm/ADT/SmallVector.h"
18 #include "llvm/Support/DataTypes.h"
19 #include <cassert>
20 #include <vector>
21 
22 namespace llvm {
23 class raw_ostream;
24 class DataLayout;
25 class TargetRegisterClass;
26 class Type;
27 class MachineFunction;
28 class MachineBasicBlock;
29 class TargetFrameLowering;
30 class TargetMachine;
31 class BitVector;
32 class Value;
33 class AllocaInst;
34 
35 /// The CalleeSavedInfo class tracks the information need to locate where a
36 /// callee saved register is in the current frame.
37 class CalleeSavedInfo {
38   unsigned Reg;
39   int FrameIdx;
40 
41 public:
42   explicit CalleeSavedInfo(unsigned R, int FI = 0)
Reg(R)43   : Reg(R), FrameIdx(FI) {}
44 
45   // Accessors.
getReg()46   unsigned getReg()                        const { return Reg; }
getFrameIdx()47   int getFrameIdx()                        const { return FrameIdx; }
setFrameIdx(int FI)48   void setFrameIdx(int FI)                       { FrameIdx = FI; }
49 };
50 
51 /// The MachineFrameInfo class represents an abstract stack frame until
52 /// prolog/epilog code is inserted.  This class is key to allowing stack frame
53 /// representation optimizations, such as frame pointer elimination.  It also
54 /// allows more mundane (but still important) optimizations, such as reordering
55 /// of abstract objects on the stack frame.
56 ///
57 /// To support this, the class assigns unique integer identifiers to stack
58 /// objects requested clients.  These identifiers are negative integers for
59 /// fixed stack objects (such as arguments passed on the stack) or nonnegative
60 /// for objects that may be reordered.  Instructions which refer to stack
61 /// objects use a special MO_FrameIndex operand to represent these frame
62 /// indexes.
63 ///
64 /// Because this class keeps track of all references to the stack frame, it
65 /// knows when a variable sized object is allocated on the stack.  This is the
66 /// sole condition which prevents frame pointer elimination, which is an
67 /// important optimization on register-poor architectures.  Because original
68 /// variable sized alloca's in the source program are the only source of
69 /// variable sized stack objects, it is safe to decide whether there will be
70 /// any variable sized objects before all stack objects are known (for
71 /// example, register allocator spill code never needs variable sized
72 /// objects).
73 ///
74 /// When prolog/epilog code emission is performed, the final stack frame is
75 /// built and the machine instructions are modified to refer to the actual
76 /// stack offsets of the object, eliminating all MO_FrameIndex operands from
77 /// the program.
78 ///
79 /// @brief Abstract Stack Frame Information
80 class MachineFrameInfo {
81 
82   // Represent a single object allocated on the stack.
83   struct StackObject {
84     // The offset of this object from the stack pointer on entry to
85     // the function.  This field has no meaning for a variable sized element.
86     int64_t SPOffset;
87 
88     // The size of this object on the stack. 0 means a variable sized object,
89     // ~0ULL means a dead object.
90     uint64_t Size;
91 
92     // The required alignment of this stack slot.
93     unsigned Alignment;
94 
95     // If true, the value of the stack object is set before
96     // entering the function and is not modified inside the function. By
97     // default, fixed objects are immutable unless marked otherwise.
98     bool isImmutable;
99 
100     // If true the stack object is used as spill slot. It
101     // cannot alias any other memory objects.
102     bool isSpillSlot;
103 
104     /// If this stack object is originated from an Alloca instruction
105     /// this value saves the original IR allocation. Can be NULL.
106     const AllocaInst *Alloca;
107 
108     // If true, the object was mapped into the local frame
109     // block and doesn't need additional handling for allocation beyond that.
110     bool PreAllocated;
111 
112     // If true, an LLVM IR value might point to this object.
113     // Normally, spill slots and fixed-offset objects don't alias IR-accessible
114     // objects, but there are exceptions (on PowerPC, for example, some byval
115     // arguments have ABI-prescribed offsets).
116     bool isAliased;
117 
StackObjectStackObject118     StackObject(uint64_t Sz, unsigned Al, int64_t SP, bool IM,
119                 bool isSS, const AllocaInst *Val, bool A)
120       : SPOffset(SP), Size(Sz), Alignment(Al), isImmutable(IM),
121         isSpillSlot(isSS), Alloca(Val), PreAllocated(false), isAliased(A) {}
122   };
123 
124   /// The alignment of the stack.
125   unsigned StackAlignment;
126 
127   /// Can the stack be realigned.
128   /// Targets that set this to false don't have the ability to overalign
129   /// their stack frame, and thus, overaligned allocas are all treated
130   /// as dynamic allocations and the target must handle them as part
131   /// of DYNAMIC_STACKALLOC lowering.
132   /// FIXME: There is room for improvement in this case, in terms of
133   /// grouping overaligned allocas into a "secondary stack frame" and
134   /// then only use a single alloca to allocate this frame and only a
135   /// single virtual register to access it. Currently, without such an
136   /// optimization, each such alloca gets it's own dynamic
137   /// realignment.
138   bool StackRealignable;
139 
140   /// The list of stack objects allocated.
141   std::vector<StackObject> Objects;
142 
143   /// This contains the number of fixed objects contained on
144   /// the stack.  Because fixed objects are stored at a negative index in the
145   /// Objects list, this is also the index to the 0th object in the list.
146   unsigned NumFixedObjects;
147 
148   /// This boolean keeps track of whether any variable
149   /// sized objects have been allocated yet.
150   bool HasVarSizedObjects;
151 
152   /// This boolean keeps track of whether there is a call
153   /// to builtin \@llvm.frameaddress.
154   bool FrameAddressTaken;
155 
156   /// This boolean keeps track of whether there is a call
157   /// to builtin \@llvm.returnaddress.
158   bool ReturnAddressTaken;
159 
160   /// This boolean keeps track of whether there is a call
161   /// to builtin \@llvm.experimental.stackmap.
162   bool HasStackMap;
163 
164   /// This boolean keeps track of whether there is a call
165   /// to builtin \@llvm.experimental.patchpoint.
166   bool HasPatchPoint;
167 
168   /// The prolog/epilog code inserter calculates the final stack
169   /// offsets for all of the fixed size objects, updating the Objects list
170   /// above.  It then updates StackSize to contain the number of bytes that need
171   /// to be allocated on entry to the function.
172   uint64_t StackSize;
173 
174   /// The amount that a frame offset needs to be adjusted to
175   /// have the actual offset from the stack/frame pointer.  The exact usage of
176   /// this is target-dependent, but it is typically used to adjust between
177   /// SP-relative and FP-relative offsets.  E.G., if objects are accessed via
178   /// SP then OffsetAdjustment is zero; if FP is used, OffsetAdjustment is set
179   /// to the distance between the initial SP and the value in FP.  For many
180   /// targets, this value is only used when generating debug info (via
181   /// TargetRegisterInfo::getFrameIndexReference); when generating code, the
182   /// corresponding adjustments are performed directly.
183   int OffsetAdjustment;
184 
185   /// The prolog/epilog code inserter may process objects that require greater
186   /// alignment than the default alignment the target provides.
187   /// To handle this, MaxAlignment is set to the maximum alignment
188   /// needed by the objects on the current frame.  If this is greater than the
189   /// native alignment maintained by the compiler, dynamic alignment code will
190   /// be needed.
191   ///
192   unsigned MaxAlignment;
193 
194   /// Set to true if this function adjusts the stack -- e.g.,
195   /// when calling another function. This is only valid during and after
196   /// prolog/epilog code insertion.
197   bool AdjustsStack;
198 
199   /// Set to true if this function has any function calls.
200   bool HasCalls;
201 
202   /// The frame index for the stack protector.
203   int StackProtectorIdx;
204 
205   /// The frame index for the function context. Used for SjLj exceptions.
206   int FunctionContextIdx;
207 
208   /// This contains the size of the largest call frame if the target uses frame
209   /// setup/destroy pseudo instructions (as defined in the TargetFrameInfo
210   /// class).  This information is important for frame pointer elimination.
211   /// It is only valid during and after prolog/epilog code insertion.
212   unsigned MaxCallFrameSize;
213 
214   /// The prolog/epilog code inserter fills in this vector with each
215   /// callee saved register saved in the frame.  Beyond its use by the prolog/
216   /// epilog code inserter, this data used for debug info and exception
217   /// handling.
218   std::vector<CalleeSavedInfo> CSInfo;
219 
220   /// Has CSInfo been set yet?
221   bool CSIValid;
222 
223   /// References to frame indices which are mapped
224   /// into the local frame allocation block. <FrameIdx, LocalOffset>
225   SmallVector<std::pair<int, int64_t>, 32> LocalFrameObjects;
226 
227   /// Size of the pre-allocated local frame block.
228   int64_t LocalFrameSize;
229 
230   /// Required alignment of the local object blob, which is the strictest
231   /// alignment of any object in it.
232   unsigned LocalFrameMaxAlign;
233 
234   /// Whether the local object blob needs to be allocated together. If not,
235   /// PEI should ignore the isPreAllocated flags on the stack objects and
236   /// just allocate them normally.
237   bool UseLocalStackAllocationBlock;
238 
239   /// Whether the "realign-stack" option is on.
240   bool RealignOption;
241 
242   /// True if the function dynamically adjusts the stack pointer through some
243   /// opaque mechanism like inline assembly or Win32 EH.
244   bool HasOpaqueSPAdjustment;
245 
246   /// True if the function contains a call to the llvm.vastart intrinsic.
247   bool HasVAStart;
248 
249   /// True if this is a varargs function that contains a musttail call.
250   bool HasMustTailInVarArgFunc;
251 
252   /// True if this function contains a tail call. If so immutable objects like
253   /// function arguments are no longer so. A tail call *can* override fixed
254   /// stack objects like arguments so we can't treat them as immutable.
255   bool HasTailCall;
256 
257   /// Not null, if shrink-wrapping found a better place for the prologue.
258   MachineBasicBlock *Save;
259   /// Not null, if shrink-wrapping found a better place for the epilogue.
260   MachineBasicBlock *Restore;
261 
262 public:
MachineFrameInfo(unsigned StackAlign,bool isStackRealign,bool RealignOpt)263   explicit MachineFrameInfo(unsigned StackAlign, bool isStackRealign,
264                             bool RealignOpt)
265       : StackAlignment(StackAlign), StackRealignable(isStackRealign),
266         RealignOption(RealignOpt) {
267     StackSize = NumFixedObjects = OffsetAdjustment = MaxAlignment = 0;
268     HasVarSizedObjects = false;
269     FrameAddressTaken = false;
270     ReturnAddressTaken = false;
271     HasStackMap = false;
272     HasPatchPoint = false;
273     AdjustsStack = false;
274     HasCalls = false;
275     StackProtectorIdx = -1;
276     FunctionContextIdx = -1;
277     MaxCallFrameSize = 0;
278     CSIValid = false;
279     LocalFrameSize = 0;
280     LocalFrameMaxAlign = 0;
281     UseLocalStackAllocationBlock = false;
282     HasOpaqueSPAdjustment = false;
283     HasVAStart = false;
284     HasMustTailInVarArgFunc = false;
285     Save = nullptr;
286     Restore = nullptr;
287     HasTailCall = false;
288   }
289 
290   /// Return true if there are any stack objects in this function.
hasStackObjects()291   bool hasStackObjects() const { return !Objects.empty(); }
292 
293   /// This method may be called any time after instruction
294   /// selection is complete to determine if the stack frame for this function
295   /// contains any variable sized objects.
hasVarSizedObjects()296   bool hasVarSizedObjects() const { return HasVarSizedObjects; }
297 
298   /// Return the index for the stack protector object.
getStackProtectorIndex()299   int getStackProtectorIndex() const { return StackProtectorIdx; }
setStackProtectorIndex(int I)300   void setStackProtectorIndex(int I) { StackProtectorIdx = I; }
hasStackProtectorIndex()301   bool hasStackProtectorIndex() const { return StackProtectorIdx != -1; }
302 
303   /// Return the index for the function context object.
304   /// This object is used for SjLj exceptions.
getFunctionContextIndex()305   int getFunctionContextIndex() const { return FunctionContextIdx; }
setFunctionContextIndex(int I)306   void setFunctionContextIndex(int I) { FunctionContextIdx = I; }
307 
308   /// This method may be called any time after instruction
309   /// selection is complete to determine if there is a call to
310   /// \@llvm.frameaddress in this function.
isFrameAddressTaken()311   bool isFrameAddressTaken() const { return FrameAddressTaken; }
setFrameAddressIsTaken(bool T)312   void setFrameAddressIsTaken(bool T) { FrameAddressTaken = T; }
313 
314   /// This method may be called any time after
315   /// instruction selection is complete to determine if there is a call to
316   /// \@llvm.returnaddress in this function.
isReturnAddressTaken()317   bool isReturnAddressTaken() const { return ReturnAddressTaken; }
setReturnAddressIsTaken(bool s)318   void setReturnAddressIsTaken(bool s) { ReturnAddressTaken = s; }
319 
320   /// This method may be called any time after instruction
321   /// selection is complete to determine if there is a call to builtin
322   /// \@llvm.experimental.stackmap.
hasStackMap()323   bool hasStackMap() const { return HasStackMap; }
324   void setHasStackMap(bool s = true) { HasStackMap = s; }
325 
326   /// This method may be called any time after instruction
327   /// selection is complete to determine if there is a call to builtin
328   /// \@llvm.experimental.patchpoint.
hasPatchPoint()329   bool hasPatchPoint() const { return HasPatchPoint; }
330   void setHasPatchPoint(bool s = true) { HasPatchPoint = s; }
331 
332   /// Return the minimum frame object index.
getObjectIndexBegin()333   int getObjectIndexBegin() const { return -NumFixedObjects; }
334 
335   /// Return one past the maximum frame object index.
getObjectIndexEnd()336   int getObjectIndexEnd() const { return (int)Objects.size()-NumFixedObjects; }
337 
338   /// Return the number of fixed objects.
getNumFixedObjects()339   unsigned getNumFixedObjects() const { return NumFixedObjects; }
340 
341   /// Return the number of objects.
getNumObjects()342   unsigned getNumObjects() const { return Objects.size(); }
343 
344   /// Map a frame index into the local object block
mapLocalFrameObject(int ObjectIndex,int64_t Offset)345   void mapLocalFrameObject(int ObjectIndex, int64_t Offset) {
346     LocalFrameObjects.push_back(std::pair<int, int64_t>(ObjectIndex, Offset));
347     Objects[ObjectIndex + NumFixedObjects].PreAllocated = true;
348   }
349 
350   /// Get the local offset mapping for a for an object.
getLocalFrameObjectMap(int i)351   std::pair<int, int64_t> getLocalFrameObjectMap(int i) const {
352     assert (i >= 0 && (unsigned)i < LocalFrameObjects.size() &&
353             "Invalid local object reference!");
354     return LocalFrameObjects[i];
355   }
356 
357   /// Return the number of objects allocated into the local object block.
getLocalFrameObjectCount()358   int64_t getLocalFrameObjectCount() const { return LocalFrameObjects.size(); }
359 
360   /// Set the size of the local object blob.
setLocalFrameSize(int64_t sz)361   void setLocalFrameSize(int64_t sz) { LocalFrameSize = sz; }
362 
363   /// Get the size of the local object blob.
getLocalFrameSize()364   int64_t getLocalFrameSize() const { return LocalFrameSize; }
365 
366   /// Required alignment of the local object blob,
367   /// which is the strictest alignment of any object in it.
setLocalFrameMaxAlign(unsigned Align)368   void setLocalFrameMaxAlign(unsigned Align) { LocalFrameMaxAlign = Align; }
369 
370   /// Return the required alignment of the local object blob.
getLocalFrameMaxAlign()371   unsigned getLocalFrameMaxAlign() const { return LocalFrameMaxAlign; }
372 
373   /// Get whether the local allocation blob should be allocated together or
374   /// let PEI allocate the locals in it directly.
getUseLocalStackAllocationBlock()375   bool getUseLocalStackAllocationBlock() const {
376     return UseLocalStackAllocationBlock;
377   }
378 
379   /// setUseLocalStackAllocationBlock - Set whether the local allocation blob
380   /// should be allocated together or let PEI allocate the locals in it
381   /// directly.
setUseLocalStackAllocationBlock(bool v)382   void setUseLocalStackAllocationBlock(bool v) {
383     UseLocalStackAllocationBlock = v;
384   }
385 
386   /// Return true if the object was pre-allocated into the local block.
isObjectPreAllocated(int ObjectIdx)387   bool isObjectPreAllocated(int ObjectIdx) const {
388     assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
389            "Invalid Object Idx!");
390     return Objects[ObjectIdx+NumFixedObjects].PreAllocated;
391   }
392 
393   /// Return the size of the specified object.
getObjectSize(int ObjectIdx)394   int64_t getObjectSize(int ObjectIdx) const {
395     assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
396            "Invalid Object Idx!");
397     return Objects[ObjectIdx+NumFixedObjects].Size;
398   }
399 
400   /// Change the size of the specified stack object.
setObjectSize(int ObjectIdx,int64_t Size)401   void setObjectSize(int ObjectIdx, int64_t Size) {
402     assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
403            "Invalid Object Idx!");
404     Objects[ObjectIdx+NumFixedObjects].Size = Size;
405   }
406 
407   /// Return the alignment of the specified stack object.
getObjectAlignment(int ObjectIdx)408   unsigned getObjectAlignment(int ObjectIdx) const {
409     assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
410            "Invalid Object Idx!");
411     return Objects[ObjectIdx+NumFixedObjects].Alignment;
412   }
413 
414   /// setObjectAlignment - Change the alignment of the specified stack object.
setObjectAlignment(int ObjectIdx,unsigned Align)415   void setObjectAlignment(int ObjectIdx, unsigned Align) {
416     assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
417            "Invalid Object Idx!");
418     Objects[ObjectIdx+NumFixedObjects].Alignment = Align;
419     ensureMaxAlignment(Align);
420   }
421 
422   /// Return the underlying Alloca of the specified
423   /// stack object if it exists. Returns 0 if none exists.
getObjectAllocation(int ObjectIdx)424   const AllocaInst* getObjectAllocation(int ObjectIdx) const {
425     assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
426            "Invalid Object Idx!");
427     return Objects[ObjectIdx+NumFixedObjects].Alloca;
428   }
429 
430   /// Return the assigned stack offset of the specified object
431   /// from the incoming stack pointer.
getObjectOffset(int ObjectIdx)432   int64_t getObjectOffset(int ObjectIdx) const {
433     assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
434            "Invalid Object Idx!");
435     assert(!isDeadObjectIndex(ObjectIdx) &&
436            "Getting frame offset for a dead object?");
437     return Objects[ObjectIdx+NumFixedObjects].SPOffset;
438   }
439 
440   /// Set the stack frame offset of the specified object. The
441   /// offset is relative to the stack pointer on entry to the function.
setObjectOffset(int ObjectIdx,int64_t SPOffset)442   void setObjectOffset(int ObjectIdx, int64_t SPOffset) {
443     assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
444            "Invalid Object Idx!");
445     assert(!isDeadObjectIndex(ObjectIdx) &&
446            "Setting frame offset for a dead object?");
447     Objects[ObjectIdx+NumFixedObjects].SPOffset = SPOffset;
448   }
449 
450   /// Return the number of bytes that must be allocated to hold
451   /// all of the fixed size frame objects.  This is only valid after
452   /// Prolog/Epilog code insertion has finalized the stack frame layout.
getStackSize()453   uint64_t getStackSize() const { return StackSize; }
454 
455   /// Set the size of the stack.
setStackSize(uint64_t Size)456   void setStackSize(uint64_t Size) { StackSize = Size; }
457 
458   /// Estimate and return the size of the stack frame.
459   unsigned estimateStackSize(const MachineFunction &MF) const;
460 
461   /// Return the correction for frame offsets.
getOffsetAdjustment()462   int getOffsetAdjustment() const { return OffsetAdjustment; }
463 
464   /// Set the correction for frame offsets.
setOffsetAdjustment(int Adj)465   void setOffsetAdjustment(int Adj) { OffsetAdjustment = Adj; }
466 
467   /// Return the alignment in bytes that this function must be aligned to,
468   /// which is greater than the default stack alignment provided by the target.
getMaxAlignment()469   unsigned getMaxAlignment() const { return MaxAlignment; }
470 
471   /// Make sure the function is at least Align bytes aligned.
472   void ensureMaxAlignment(unsigned Align);
473 
474   /// Return true if this function adjusts the stack -- e.g.,
475   /// when calling another function. This is only valid during and after
476   /// prolog/epilog code insertion.
adjustsStack()477   bool adjustsStack() const { return AdjustsStack; }
setAdjustsStack(bool V)478   void setAdjustsStack(bool V) { AdjustsStack = V; }
479 
480   /// Return true if the current function has any function calls.
hasCalls()481   bool hasCalls() const { return HasCalls; }
setHasCalls(bool V)482   void setHasCalls(bool V) { HasCalls = V; }
483 
484   /// Returns true if the function contains opaque dynamic stack adjustments.
hasOpaqueSPAdjustment()485   bool hasOpaqueSPAdjustment() const { return HasOpaqueSPAdjustment; }
setHasOpaqueSPAdjustment(bool B)486   void setHasOpaqueSPAdjustment(bool B) { HasOpaqueSPAdjustment = B; }
487 
488   /// Returns true if the function calls the llvm.va_start intrinsic.
hasVAStart()489   bool hasVAStart() const { return HasVAStart; }
setHasVAStart(bool B)490   void setHasVAStart(bool B) { HasVAStart = B; }
491 
492   /// Returns true if the function is variadic and contains a musttail call.
hasMustTailInVarArgFunc()493   bool hasMustTailInVarArgFunc() const { return HasMustTailInVarArgFunc; }
setHasMustTailInVarArgFunc(bool B)494   void setHasMustTailInVarArgFunc(bool B) { HasMustTailInVarArgFunc = B; }
495 
496   /// Returns true if the function contains a tail call.
hasTailCall()497   bool hasTailCall() const { return HasTailCall; }
setHasTailCall()498   void setHasTailCall() { HasTailCall = true; }
499 
500   /// Return the maximum size of a call frame that must be
501   /// allocated for an outgoing function call.  This is only available if
502   /// CallFrameSetup/Destroy pseudo instructions are used by the target, and
503   /// then only during or after prolog/epilog code insertion.
504   ///
getMaxCallFrameSize()505   unsigned getMaxCallFrameSize() const { return MaxCallFrameSize; }
setMaxCallFrameSize(unsigned S)506   void setMaxCallFrameSize(unsigned S) { MaxCallFrameSize = S; }
507 
508   /// Create a new object at a fixed location on the stack.
509   /// All fixed objects should be created before other objects are created for
510   /// efficiency. By default, fixed objects are not pointed to by LLVM IR
511   /// values. This returns an index with a negative value.
512   int CreateFixedObject(uint64_t Size, int64_t SPOffset, bool Immutable,
513                         bool isAliased = false);
514 
515   /// Create a spill slot at a fixed location on the stack.
516   /// Returns an index with a negative value.
517   int CreateFixedSpillStackObject(uint64_t Size, int64_t SPOffset);
518 
519   /// Returns true if the specified index corresponds to a fixed stack object.
isFixedObjectIndex(int ObjectIdx)520   bool isFixedObjectIndex(int ObjectIdx) const {
521     return ObjectIdx < 0 && (ObjectIdx >= -(int)NumFixedObjects);
522   }
523 
524   /// Returns true if the specified index corresponds
525   /// to an object that might be pointed to by an LLVM IR value.
isAliasedObjectIndex(int ObjectIdx)526   bool isAliasedObjectIndex(int ObjectIdx) const {
527     assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
528            "Invalid Object Idx!");
529     return Objects[ObjectIdx+NumFixedObjects].isAliased;
530   }
531 
532   /// isImmutableObjectIndex - Returns true if the specified index corresponds
533   /// to an immutable object.
isImmutableObjectIndex(int ObjectIdx)534   bool isImmutableObjectIndex(int ObjectIdx) const {
535     // Tail calling functions can clobber their function arguments.
536     if (HasTailCall)
537       return false;
538     assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
539            "Invalid Object Idx!");
540     return Objects[ObjectIdx+NumFixedObjects].isImmutable;
541   }
542 
543   /// Returns true if the specified index corresponds to a spill slot.
isSpillSlotObjectIndex(int ObjectIdx)544   bool isSpillSlotObjectIndex(int ObjectIdx) const {
545     assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
546            "Invalid Object Idx!");
547     return Objects[ObjectIdx+NumFixedObjects].isSpillSlot;
548   }
549 
550   /// Returns true if the specified index corresponds to a dead object.
isDeadObjectIndex(int ObjectIdx)551   bool isDeadObjectIndex(int ObjectIdx) const {
552     assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
553            "Invalid Object Idx!");
554     return Objects[ObjectIdx+NumFixedObjects].Size == ~0ULL;
555   }
556 
557   /// Returns true if the specified index corresponds to a variable sized
558   /// object.
isVariableSizedObjectIndex(int ObjectIdx)559   bool isVariableSizedObjectIndex(int ObjectIdx) const {
560     assert(unsigned(ObjectIdx + NumFixedObjects) < Objects.size() &&
561            "Invalid Object Idx!");
562     return Objects[ObjectIdx + NumFixedObjects].Size == 0;
563   }
564 
565   /// Create a new statically sized stack object, returning
566   /// a nonnegative identifier to represent it.
567   int CreateStackObject(uint64_t Size, unsigned Alignment, bool isSS,
568                         const AllocaInst *Alloca = nullptr);
569 
570   /// Create a new statically sized stack object that represents a spill slot,
571   /// returning a nonnegative identifier to represent it.
572   int CreateSpillStackObject(uint64_t Size, unsigned Alignment);
573 
574   /// Remove or mark dead a statically sized stack object.
RemoveStackObject(int ObjectIdx)575   void RemoveStackObject(int ObjectIdx) {
576     // Mark it dead.
577     Objects[ObjectIdx+NumFixedObjects].Size = ~0ULL;
578   }
579 
580   /// Notify the MachineFrameInfo object that a variable sized object has been
581   /// created.  This must be created whenever a variable sized object is
582   /// created, whether or not the index returned is actually used.
583   int CreateVariableSizedObject(unsigned Alignment, const AllocaInst *Alloca);
584 
585   /// Returns a reference to call saved info vector for the current function.
getCalleeSavedInfo()586   const std::vector<CalleeSavedInfo> &getCalleeSavedInfo() const {
587     return CSInfo;
588   }
589 
590   /// Used by prolog/epilog inserter to set the function's callee saved
591   /// information.
setCalleeSavedInfo(const std::vector<CalleeSavedInfo> & CSI)592   void setCalleeSavedInfo(const std::vector<CalleeSavedInfo> &CSI) {
593     CSInfo = CSI;
594   }
595 
596   /// Has the callee saved info been calculated yet?
isCalleeSavedInfoValid()597   bool isCalleeSavedInfoValid() const { return CSIValid; }
598 
setCalleeSavedInfoValid(bool v)599   void setCalleeSavedInfoValid(bool v) { CSIValid = v; }
600 
getSavePoint()601   MachineBasicBlock *getSavePoint() const { return Save; }
setSavePoint(MachineBasicBlock * NewSave)602   void setSavePoint(MachineBasicBlock *NewSave) { Save = NewSave; }
getRestorePoint()603   MachineBasicBlock *getRestorePoint() const { return Restore; }
setRestorePoint(MachineBasicBlock * NewRestore)604   void setRestorePoint(MachineBasicBlock *NewRestore) { Restore = NewRestore; }
605 
606   /// Return a set of physical registers that are pristine.
607   ///
608   /// Pristine registers hold a value that is useless to the current function,
609   /// but that must be preserved - they are callee saved registers that are not
610   /// saved.
611   ///
612   /// Before the PrologueEpilogueInserter has placed the CSR spill code, this
613   /// method always returns an empty set.
614   BitVector getPristineRegs(const MachineFunction &MF) const;
615 
616   /// Used by the MachineFunction printer to print information about
617   /// stack objects. Implemented in MachineFunction.cpp.
618   void print(const MachineFunction &MF, raw_ostream &OS) const;
619 
620   /// dump - Print the function to stderr.
621   void dump(const MachineFunction &MF) const;
622 };
623 
624 } // End llvm namespace
625 
626 #endif
627