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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