LLVM  8.0.0svn
MachineFrameInfo.h
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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 MachineFunction;
25 class MachineBasicBlock;
26 class BitVector;
27 class AllocaInst;
28 
29 /// The CalleeSavedInfo class tracks the information need to locate where a
30 /// callee saved register is in the current frame.
32  unsigned Reg;
33  int FrameIdx;
34  /// Flag indicating whether the register is actually restored in the epilog.
35  /// In most cases, if a register is saved, it is also restored. There are
36  /// some situations, though, when this is not the case. For example, the
37  /// LR register on ARM is usually saved, but on exit from the function its
38  /// saved value may be loaded directly into PC. Since liveness tracking of
39  /// physical registers treats callee-saved registers are live outside of
40  /// the function, LR would be treated as live-on-exit, even though in these
41  /// scenarios it is not. This flag is added to indicate that the saved
42  /// register described by this object is not restored in the epilog.
43  /// The long-term solution is to model the liveness of callee-saved registers
44  /// by implicit uses on the return instructions, however, the required
45  /// changes in the ARM backend would be quite extensive.
46  bool Restored;
47 
48 public:
49  explicit CalleeSavedInfo(unsigned R, int FI = 0)
50  : Reg(R), FrameIdx(FI), Restored(true) {}
51 
52  // Accessors.
53  unsigned getReg() const { return Reg; }
54  int getFrameIdx() const { return FrameIdx; }
55  void setFrameIdx(int FI) { FrameIdx = FI; }
56  bool isRestored() const { return Restored; }
57  void setRestored(bool R) { Restored = R; }
58 };
59 
60 /// The MachineFrameInfo class represents an abstract stack frame until
61 /// prolog/epilog code is inserted. This class is key to allowing stack frame
62 /// representation optimizations, such as frame pointer elimination. It also
63 /// allows more mundane (but still important) optimizations, such as reordering
64 /// of abstract objects on the stack frame.
65 ///
66 /// To support this, the class assigns unique integer identifiers to stack
67 /// objects requested clients. These identifiers are negative integers for
68 /// fixed stack objects (such as arguments passed on the stack) or nonnegative
69 /// for objects that may be reordered. Instructions which refer to stack
70 /// objects use a special MO_FrameIndex operand to represent these frame
71 /// indexes.
72 ///
73 /// Because this class keeps track of all references to the stack frame, it
74 /// knows when a variable sized object is allocated on the stack. This is the
75 /// sole condition which prevents frame pointer elimination, which is an
76 /// important optimization on register-poor architectures. Because original
77 /// variable sized alloca's in the source program are the only source of
78 /// variable sized stack objects, it is safe to decide whether there will be
79 /// any variable sized objects before all stack objects are known (for
80 /// example, register allocator spill code never needs variable sized
81 /// objects).
82 ///
83 /// When prolog/epilog code emission is performed, the final stack frame is
84 /// built and the machine instructions are modified to refer to the actual
85 /// stack offsets of the object, eliminating all MO_FrameIndex operands from
86 /// the program.
87 ///
88 /// Abstract Stack Frame Information
90 public:
91  /// Stack Smashing Protection (SSP) rules require that vulnerable stack
92  /// allocations are located close the stack protector.
94  SSPLK_None, ///< Did not trigger a stack protector. No effect on data
95  ///< layout.
96  SSPLK_LargeArray, ///< Array or nested array >= SSP-buffer-size. Closest
97  ///< to the stack protector.
98  SSPLK_SmallArray, ///< Array or nested array < SSP-buffer-size. 2nd closest
99  ///< to the stack protector.
100  SSPLK_AddrOf ///< The address of this allocation is exposed and
101  ///< triggered protection. 3rd closest to the protector.
102  };
103 
104 private:
105  // Represent a single object allocated on the stack.
106  struct StackObject {
107  // The offset of this object from the stack pointer on entry to
108  // the function. This field has no meaning for a variable sized element.
109  int64_t SPOffset;
110 
111  // The size of this object on the stack. 0 means a variable sized object,
112  // ~0ULL means a dead object.
113  uint64_t Size;
114 
115  // The required alignment of this stack slot.
116  unsigned Alignment;
117 
118  // If true, the value of the stack object is set before
119  // entering the function and is not modified inside the function. By
120  // default, fixed objects are immutable unless marked otherwise.
121  bool isImmutable;
122 
123  // If true the stack object is used as spill slot. It
124  // cannot alias any other memory objects.
125  bool isSpillSlot;
126 
127  /// If true, this stack slot is used to spill a value (could be deopt
128  /// and/or GC related) over a statepoint. We know that the address of the
129  /// slot can't alias any LLVM IR value. This is very similar to a Spill
130  /// Slot, but is created by statepoint lowering is SelectionDAG, not the
131  /// register allocator.
132  bool isStatepointSpillSlot = false;
133 
134  /// Identifier for stack memory type analagous to address space. If this is
135  /// non-0, the meaning is target defined. Offsets cannot be directly
136  /// compared between objects with different stack IDs. The object may not
137  /// necessarily reside in the same contiguous memory block as other stack
138  /// objects. Objects with differing stack IDs should not be merged or
139  /// replaced substituted for each other.
140  //
141  /// It is assumed a target uses consecutive, increasing stack IDs starting
142  /// from 1.
143  uint8_t StackID;
144 
145  /// If this stack object is originated from an Alloca instruction
146  /// this value saves the original IR allocation. Can be NULL.
147  const AllocaInst *Alloca;
148 
149  // If true, the object was mapped into the local frame
150  // block and doesn't need additional handling for allocation beyond that.
151  bool PreAllocated = false;
152 
153  // If true, an LLVM IR value might point to this object.
154  // Normally, spill slots and fixed-offset objects don't alias IR-accessible
155  // objects, but there are exceptions (on PowerPC, for example, some byval
156  // arguments have ABI-prescribed offsets).
157  bool isAliased;
158 
159  /// If true, the object has been zero-extended.
160  bool isZExt = false;
161 
162  /// If true, the object has been zero-extended.
163  bool isSExt = false;
164 
165  uint8_t SSPLayout;
166 
167  StackObject(uint64_t Size, unsigned Alignment, int64_t SPOffset,
168  bool IsImmutable, bool IsSpillSlot, const AllocaInst *Alloca,
169  bool IsAliased, uint8_t StackID = 0)
170  : SPOffset(SPOffset), Size(Size), Alignment(Alignment),
171  isImmutable(IsImmutable), isSpillSlot(IsSpillSlot),
172  StackID(StackID), Alloca(Alloca), isAliased(IsAliased),
173  SSPLayout(SSPLK_None) {}
174  };
175 
176  /// The alignment of the stack.
177  unsigned StackAlignment;
178 
179  /// Can the stack be realigned. This can be false if the target does not
180  /// support stack realignment, or if the user asks us not to realign the
181  /// stack. In this situation, overaligned allocas are all treated as dynamic
182  /// allocations and the target must handle them as part of DYNAMIC_STACKALLOC
183  /// lowering. All non-alloca stack objects have their alignment clamped to the
184  /// base ABI stack alignment.
185  /// FIXME: There is room for improvement in this case, in terms of
186  /// grouping overaligned allocas into a "secondary stack frame" and
187  /// then only use a single alloca to allocate this frame and only a
188  /// single virtual register to access it. Currently, without such an
189  /// optimization, each such alloca gets its own dynamic realignment.
190  bool StackRealignable;
191 
192  /// Whether the function has the \c alignstack attribute.
193  bool ForcedRealign;
194 
195  /// The list of stack objects allocated.
196  std::vector<StackObject> Objects;
197 
198  /// This contains the number of fixed objects contained on
199  /// the stack. Because fixed objects are stored at a negative index in the
200  /// Objects list, this is also the index to the 0th object in the list.
201  unsigned NumFixedObjects = 0;
202 
203  /// This boolean keeps track of whether any variable
204  /// sized objects have been allocated yet.
205  bool HasVarSizedObjects = false;
206 
207  /// This boolean keeps track of whether there is a call
208  /// to builtin \@llvm.frameaddress.
209  bool FrameAddressTaken = false;
210 
211  /// This boolean keeps track of whether there is a call
212  /// to builtin \@llvm.returnaddress.
213  bool ReturnAddressTaken = false;
214 
215  /// This boolean keeps track of whether there is a call
216  /// to builtin \@llvm.experimental.stackmap.
217  bool HasStackMap = false;
218 
219  /// This boolean keeps track of whether there is a call
220  /// to builtin \@llvm.experimental.patchpoint.
221  bool HasPatchPoint = false;
222 
223  /// The prolog/epilog code inserter calculates the final stack
224  /// offsets for all of the fixed size objects, updating the Objects list
225  /// above. It then updates StackSize to contain the number of bytes that need
226  /// to be allocated on entry to the function.
227  uint64_t StackSize = 0;
228 
229  /// The amount that a frame offset needs to be adjusted to
230  /// have the actual offset from the stack/frame pointer. The exact usage of
231  /// this is target-dependent, but it is typically used to adjust between
232  /// SP-relative and FP-relative offsets. E.G., if objects are accessed via
233  /// SP then OffsetAdjustment is zero; if FP is used, OffsetAdjustment is set
234  /// to the distance between the initial SP and the value in FP. For many
235  /// targets, this value is only used when generating debug info (via
236  /// TargetRegisterInfo::getFrameIndexReference); when generating code, the
237  /// corresponding adjustments are performed directly.
238  int OffsetAdjustment = 0;
239 
240  /// The prolog/epilog code inserter may process objects that require greater
241  /// alignment than the default alignment the target provides.
242  /// To handle this, MaxAlignment is set to the maximum alignment
243  /// needed by the objects on the current frame. If this is greater than the
244  /// native alignment maintained by the compiler, dynamic alignment code will
245  /// be needed.
246  ///
247  unsigned MaxAlignment = 0;
248 
249  /// Set to true if this function adjusts the stack -- e.g.,
250  /// when calling another function. This is only valid during and after
251  /// prolog/epilog code insertion.
252  bool AdjustsStack = false;
253 
254  /// Set to true if this function has any function calls.
255  bool HasCalls = false;
256 
257  /// The frame index for the stack protector.
258  int StackProtectorIdx = -1;
259 
260  /// The frame index for the function context. Used for SjLj exceptions.
261  int FunctionContextIdx = -1;
262 
263  /// This contains the size of the largest call frame if the target uses frame
264  /// setup/destroy pseudo instructions (as defined in the TargetFrameInfo
265  /// class). This information is important for frame pointer elimination.
266  /// It is only valid during and after prolog/epilog code insertion.
267  unsigned MaxCallFrameSize = ~0u;
268 
269  /// The prolog/epilog code inserter fills in this vector with each
270  /// callee saved register saved in the frame. Beyond its use by the prolog/
271  /// epilog code inserter, this data used for debug info and exception
272  /// handling.
273  std::vector<CalleeSavedInfo> CSInfo;
274 
275  /// Has CSInfo been set yet?
276  bool CSIValid = false;
277 
278  /// References to frame indices which are mapped
279  /// into the local frame allocation block. <FrameIdx, LocalOffset>
280  SmallVector<std::pair<int, int64_t>, 32> LocalFrameObjects;
281 
282  /// Size of the pre-allocated local frame block.
283  int64_t LocalFrameSize = 0;
284 
285  /// Required alignment of the local object blob, which is the strictest
286  /// alignment of any object in it.
287  unsigned LocalFrameMaxAlign = 0;
288 
289  /// Whether the local object blob needs to be allocated together. If not,
290  /// PEI should ignore the isPreAllocated flags on the stack objects and
291  /// just allocate them normally.
292  bool UseLocalStackAllocationBlock = false;
293 
294  /// True if the function dynamically adjusts the stack pointer through some
295  /// opaque mechanism like inline assembly or Win32 EH.
296  bool HasOpaqueSPAdjustment = false;
297 
298  /// True if the function contains operations which will lower down to
299  /// instructions which manipulate the stack pointer.
300  bool HasCopyImplyingStackAdjustment = false;
301 
302  /// True if the function contains a call to the llvm.vastart intrinsic.
303  bool HasVAStart = false;
304 
305  /// True if this is a varargs function that contains a musttail call.
306  bool HasMustTailInVarArgFunc = false;
307 
308  /// True if this function contains a tail call. If so immutable objects like
309  /// function arguments are no longer so. A tail call *can* override fixed
310  /// stack objects like arguments so we can't treat them as immutable.
311  bool HasTailCall = false;
312 
313  /// Not null, if shrink-wrapping found a better place for the prologue.
314  MachineBasicBlock *Save = nullptr;
315  /// Not null, if shrink-wrapping found a better place for the epilogue.
316  MachineBasicBlock *Restore = nullptr;
317 
318 public:
319  explicit MachineFrameInfo(unsigned StackAlignment, bool StackRealignable,
320  bool ForcedRealign)
321  : StackAlignment(StackAlignment), StackRealignable(StackRealignable),
322  ForcedRealign(ForcedRealign) {}
323 
324  /// Return true if there are any stack objects in this function.
325  bool hasStackObjects() const { return !Objects.empty(); }
326 
327  /// This method may be called any time after instruction
328  /// selection is complete to determine if the stack frame for this function
329  /// contains any variable sized objects.
330  bool hasVarSizedObjects() const { return HasVarSizedObjects; }
331 
332  /// Return the index for the stack protector object.
333  int getStackProtectorIndex() const { return StackProtectorIdx; }
334  void setStackProtectorIndex(int I) { StackProtectorIdx = I; }
335  bool hasStackProtectorIndex() const { return StackProtectorIdx != -1; }
336 
337  /// Return the index for the function context object.
338  /// This object is used for SjLj exceptions.
339  int getFunctionContextIndex() const { return FunctionContextIdx; }
340  void setFunctionContextIndex(int I) { FunctionContextIdx = I; }
341 
342  /// This method may be called any time after instruction
343  /// selection is complete to determine if there is a call to
344  /// \@llvm.frameaddress in this function.
345  bool isFrameAddressTaken() const { return FrameAddressTaken; }
346  void setFrameAddressIsTaken(bool T) { FrameAddressTaken = T; }
347 
348  /// This method may be called any time after
349  /// instruction selection is complete to determine if there is a call to
350  /// \@llvm.returnaddress in this function.
351  bool isReturnAddressTaken() const { return ReturnAddressTaken; }
352  void setReturnAddressIsTaken(bool s) { ReturnAddressTaken = s; }
353 
354  /// This method may be called any time after instruction
355  /// selection is complete to determine if there is a call to builtin
356  /// \@llvm.experimental.stackmap.
357  bool hasStackMap() const { return HasStackMap; }
358  void setHasStackMap(bool s = true) { HasStackMap = s; }
359 
360  /// This method may be called any time after instruction
361  /// selection is complete to determine if there is a call to builtin
362  /// \@llvm.experimental.patchpoint.
363  bool hasPatchPoint() const { return HasPatchPoint; }
364  void setHasPatchPoint(bool s = true) { HasPatchPoint = s; }
365 
366  /// Return the minimum frame object index.
367  int getObjectIndexBegin() const { return -NumFixedObjects; }
368 
369  /// Return one past the maximum frame object index.
370  int getObjectIndexEnd() const { return (int)Objects.size()-NumFixedObjects; }
371 
372  /// Return the number of fixed objects.
373  unsigned getNumFixedObjects() const { return NumFixedObjects; }
374 
375  /// Return the number of objects.
376  unsigned getNumObjects() const { return Objects.size(); }
377 
378  /// Map a frame index into the local object block
379  void mapLocalFrameObject(int ObjectIndex, int64_t Offset) {
380  LocalFrameObjects.push_back(std::pair<int, int64_t>(ObjectIndex, Offset));
381  Objects[ObjectIndex + NumFixedObjects].PreAllocated = true;
382  }
383 
384  /// Get the local offset mapping for a for an object.
385  std::pair<int, int64_t> getLocalFrameObjectMap(int i) const {
386  assert (i >= 0 && (unsigned)i < LocalFrameObjects.size() &&
387  "Invalid local object reference!");
388  return LocalFrameObjects[i];
389  }
390 
391  /// Return the number of objects allocated into the local object block.
392  int64_t getLocalFrameObjectCount() const { return LocalFrameObjects.size(); }
393 
394  /// Set the size of the local object blob.
395  void setLocalFrameSize(int64_t sz) { LocalFrameSize = sz; }
396 
397  /// Get the size of the local object blob.
398  int64_t getLocalFrameSize() const { return LocalFrameSize; }
399 
400  /// Required alignment of the local object blob,
401  /// which is the strictest alignment of any object in it.
402  void setLocalFrameMaxAlign(unsigned Align) { LocalFrameMaxAlign = Align; }
403 
404  /// Return the required alignment of the local object blob.
405  unsigned getLocalFrameMaxAlign() const { return LocalFrameMaxAlign; }
406 
407  /// Get whether the local allocation blob should be allocated together or
408  /// let PEI allocate the locals in it directly.
410  return UseLocalStackAllocationBlock;
411  }
412 
413  /// setUseLocalStackAllocationBlock - Set whether the local allocation blob
414  /// should be allocated together or let PEI allocate the locals in it
415  /// directly.
417  UseLocalStackAllocationBlock = v;
418  }
419 
420  /// Return true if the object was pre-allocated into the local block.
421  bool isObjectPreAllocated(int ObjectIdx) const {
422  assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
423  "Invalid Object Idx!");
424  return Objects[ObjectIdx+NumFixedObjects].PreAllocated;
425  }
426 
427  /// Return the size of the specified object.
428  int64_t getObjectSize(int ObjectIdx) const {
429  assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
430  "Invalid Object Idx!");
431  return Objects[ObjectIdx+NumFixedObjects].Size;
432  }
433 
434  /// Change the size of the specified stack object.
435  void setObjectSize(int ObjectIdx, int64_t Size) {
436  assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
437  "Invalid Object Idx!");
438  Objects[ObjectIdx+NumFixedObjects].Size = Size;
439  }
440 
441  /// Return the alignment of the specified stack object.
442  unsigned getObjectAlignment(int ObjectIdx) const {
443  assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
444  "Invalid Object Idx!");
445  return Objects[ObjectIdx+NumFixedObjects].Alignment;
446  }
447 
448  /// setObjectAlignment - Change the alignment of the specified stack object.
449  void setObjectAlignment(int ObjectIdx, unsigned Align) {
450  assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
451  "Invalid Object Idx!");
452  Objects[ObjectIdx+NumFixedObjects].Alignment = Align;
453  ensureMaxAlignment(Align);
454  }
455 
456  /// Return the underlying Alloca of the specified
457  /// stack object if it exists. Returns 0 if none exists.
458  const AllocaInst* getObjectAllocation(int ObjectIdx) const {
459  assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
460  "Invalid Object Idx!");
461  return Objects[ObjectIdx+NumFixedObjects].Alloca;
462  }
463 
464  /// Return the assigned stack offset of the specified object
465  /// from the incoming stack pointer.
466  int64_t getObjectOffset(int ObjectIdx) const {
467  assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
468  "Invalid Object Idx!");
469  assert(!isDeadObjectIndex(ObjectIdx) &&
470  "Getting frame offset for a dead object?");
471  return Objects[ObjectIdx+NumFixedObjects].SPOffset;
472  }
473 
474  bool isObjectZExt(int ObjectIdx) const {
475  assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
476  "Invalid Object Idx!");
477  return Objects[ObjectIdx+NumFixedObjects].isZExt;
478  }
479 
480  void setObjectZExt(int ObjectIdx, bool IsZExt) {
481  assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
482  "Invalid Object Idx!");
483  Objects[ObjectIdx+NumFixedObjects].isZExt = IsZExt;
484  }
485 
486  bool isObjectSExt(int ObjectIdx) const {
487  assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
488  "Invalid Object Idx!");
489  return Objects[ObjectIdx+NumFixedObjects].isSExt;
490  }
491 
492  void setObjectSExt(int ObjectIdx, bool IsSExt) {
493  assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
494  "Invalid Object Idx!");
495  Objects[ObjectIdx+NumFixedObjects].isSExt = IsSExt;
496  }
497 
498  /// Set the stack frame offset of the specified object. The
499  /// offset is relative to the stack pointer on entry to the function.
500  void setObjectOffset(int ObjectIdx, int64_t SPOffset) {
501  assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
502  "Invalid Object Idx!");
503  assert(!isDeadObjectIndex(ObjectIdx) &&
504  "Setting frame offset for a dead object?");
505  Objects[ObjectIdx+NumFixedObjects].SPOffset = SPOffset;
506  }
507 
508  SSPLayoutKind getObjectSSPLayout(int ObjectIdx) const {
509  assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
510  "Invalid Object Idx!");
511  return (SSPLayoutKind)Objects[ObjectIdx+NumFixedObjects].SSPLayout;
512  }
513 
514  void setObjectSSPLayout(int ObjectIdx, SSPLayoutKind Kind) {
515  assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
516  "Invalid Object Idx!");
517  assert(!isDeadObjectIndex(ObjectIdx) &&
518  "Setting SSP layout for a dead object?");
519  Objects[ObjectIdx+NumFixedObjects].SSPLayout = Kind;
520  }
521 
522  /// Return the number of bytes that must be allocated to hold
523  /// all of the fixed size frame objects. This is only valid after
524  /// Prolog/Epilog code insertion has finalized the stack frame layout.
525  uint64_t getStackSize() const { return StackSize; }
526 
527  /// Set the size of the stack.
528  void setStackSize(uint64_t Size) { StackSize = Size; }
529 
530  /// Estimate and return the size of the stack frame.
531  unsigned estimateStackSize(const MachineFunction &MF) const;
532 
533  /// Return the correction for frame offsets.
534  int getOffsetAdjustment() const { return OffsetAdjustment; }
535 
536  /// Set the correction for frame offsets.
537  void setOffsetAdjustment(int Adj) { OffsetAdjustment = Adj; }
538 
539  /// Return the alignment in bytes that this function must be aligned to,
540  /// which is greater than the default stack alignment provided by the target.
541  unsigned getMaxAlignment() const { return MaxAlignment; }
542 
543  /// Make sure the function is at least Align bytes aligned.
544  void ensureMaxAlignment(unsigned Align);
545 
546  /// Return true if this function adjusts the stack -- e.g.,
547  /// when calling another function. This is only valid during and after
548  /// prolog/epilog code insertion.
549  bool adjustsStack() const { return AdjustsStack; }
550  void setAdjustsStack(bool V) { AdjustsStack = V; }
551 
552  /// Return true if the current function has any function calls.
553  bool hasCalls() const { return HasCalls; }
554  void setHasCalls(bool V) { HasCalls = V; }
555 
556  /// Returns true if the function contains opaque dynamic stack adjustments.
557  bool hasOpaqueSPAdjustment() const { return HasOpaqueSPAdjustment; }
558  void setHasOpaqueSPAdjustment(bool B) { HasOpaqueSPAdjustment = B; }
559 
560  /// Returns true if the function contains operations which will lower down to
561  /// instructions which manipulate the stack pointer.
563  return HasCopyImplyingStackAdjustment;
564  }
566  HasCopyImplyingStackAdjustment = B;
567  }
568 
569  /// Returns true if the function calls the llvm.va_start intrinsic.
570  bool hasVAStart() const { return HasVAStart; }
571  void setHasVAStart(bool B) { HasVAStart = B; }
572 
573  /// Returns true if the function is variadic and contains a musttail call.
574  bool hasMustTailInVarArgFunc() const { return HasMustTailInVarArgFunc; }
575  void setHasMustTailInVarArgFunc(bool B) { HasMustTailInVarArgFunc = B; }
576 
577  /// Returns true if the function contains a tail call.
578  bool hasTailCall() const { return HasTailCall; }
579  void setHasTailCall() { HasTailCall = true; }
580 
581  /// Computes the maximum size of a callframe and the AdjustsStack property.
582  /// This only works for targets defining
583  /// TargetInstrInfo::getCallFrameSetupOpcode(), getCallFrameDestroyOpcode(),
584  /// and getFrameSize().
585  /// This is usually computed by the prologue epilogue inserter but some
586  /// targets may call this to compute it earlier.
587  void computeMaxCallFrameSize(const MachineFunction &MF);
588 
589  /// Return the maximum size of a call frame that must be
590  /// allocated for an outgoing function call. This is only available if
591  /// CallFrameSetup/Destroy pseudo instructions are used by the target, and
592  /// then only during or after prolog/epilog code insertion.
593  ///
594  unsigned getMaxCallFrameSize() const {
595  // TODO: Enable this assert when targets are fixed.
596  //assert(isMaxCallFrameSizeComputed() && "MaxCallFrameSize not computed yet");
597  if (!isMaxCallFrameSizeComputed())
598  return 0;
599  return MaxCallFrameSize;
600  }
602  return MaxCallFrameSize != ~0u;
603  }
604  void setMaxCallFrameSize(unsigned S) { MaxCallFrameSize = S; }
605 
606  /// Create a new object at a fixed location on the stack.
607  /// All fixed objects should be created before other objects are created for
608  /// efficiency. By default, fixed objects are not pointed to by LLVM IR
609  /// values. This returns an index with a negative value.
610  int CreateFixedObject(uint64_t Size, int64_t SPOffset, bool IsImmutable,
611  bool isAliased = false);
612 
613  /// Create a spill slot at a fixed location on the stack.
614  /// Returns an index with a negative value.
615  int CreateFixedSpillStackObject(uint64_t Size, int64_t SPOffset,
616  bool IsImmutable = false);
617 
618  /// Returns true if the specified index corresponds to a fixed stack object.
619  bool isFixedObjectIndex(int ObjectIdx) const {
620  return ObjectIdx < 0 && (ObjectIdx >= -(int)NumFixedObjects);
621  }
622 
623  /// Returns true if the specified index corresponds
624  /// to an object that might be pointed to by an LLVM IR value.
625  bool isAliasedObjectIndex(int ObjectIdx) const {
626  assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
627  "Invalid Object Idx!");
628  return Objects[ObjectIdx+NumFixedObjects].isAliased;
629  }
630 
631  /// Returns true if the specified index corresponds to an immutable object.
632  bool isImmutableObjectIndex(int ObjectIdx) const {
633  // Tail calling functions can clobber their function arguments.
634  if (HasTailCall)
635  return false;
636  assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
637  "Invalid Object Idx!");
638  return Objects[ObjectIdx+NumFixedObjects].isImmutable;
639  }
640 
641  /// Marks the immutability of an object.
642  void setIsImmutableObjectIndex(int ObjectIdx, bool IsImmutable) {
643  assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
644  "Invalid Object Idx!");
645  Objects[ObjectIdx+NumFixedObjects].isImmutable = IsImmutable;
646  }
647 
648  /// Returns true if the specified index corresponds to a spill slot.
649  bool isSpillSlotObjectIndex(int ObjectIdx) const {
650  assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
651  "Invalid Object Idx!");
652  return Objects[ObjectIdx+NumFixedObjects].isSpillSlot;
653  }
654 
655  bool isStatepointSpillSlotObjectIndex(int ObjectIdx) const {
656  assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
657  "Invalid Object Idx!");
658  return Objects[ObjectIdx+NumFixedObjects].isStatepointSpillSlot;
659  }
660 
661  /// \see StackID
662  uint8_t getStackID(int ObjectIdx) const {
663  return Objects[ObjectIdx+NumFixedObjects].StackID;
664  }
665 
666  /// \see StackID
667  void setStackID(int ObjectIdx, uint8_t ID) {
668  assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
669  "Invalid Object Idx!");
670  Objects[ObjectIdx+NumFixedObjects].StackID = ID;
671  }
672 
673  /// Returns true if the specified index corresponds to a dead object.
674  bool isDeadObjectIndex(int ObjectIdx) const {
675  assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
676  "Invalid Object Idx!");
677  return Objects[ObjectIdx+NumFixedObjects].Size == ~0ULL;
678  }
679 
680  /// Returns true if the specified index corresponds to a variable sized
681  /// object.
682  bool isVariableSizedObjectIndex(int ObjectIdx) const {
683  assert(unsigned(ObjectIdx + NumFixedObjects) < Objects.size() &&
684  "Invalid Object Idx!");
685  return Objects[ObjectIdx + NumFixedObjects].Size == 0;
686  }
687 
689  assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
690  "Invalid Object Idx!");
691  Objects[ObjectIdx+NumFixedObjects].isStatepointSpillSlot = true;
692  assert(isStatepointSpillSlotObjectIndex(ObjectIdx) && "inconsistent");
693  }
694 
695  /// Create a new statically sized stack object, returning
696  /// a nonnegative identifier to represent it.
697  int CreateStackObject(uint64_t Size, unsigned Alignment, bool isSpillSlot,
698  const AllocaInst *Alloca = nullptr, uint8_t ID = 0);
699 
700  /// Create a new statically sized stack object that represents a spill slot,
701  /// returning a nonnegative identifier to represent it.
702  int CreateSpillStackObject(uint64_t Size, unsigned Alignment);
703 
704  /// Remove or mark dead a statically sized stack object.
705  void RemoveStackObject(int ObjectIdx) {
706  // Mark it dead.
707  Objects[ObjectIdx+NumFixedObjects].Size = ~0ULL;
708  }
709 
710  /// Notify the MachineFrameInfo object that a variable sized object has been
711  /// created. This must be created whenever a variable sized object is
712  /// created, whether or not the index returned is actually used.
713  int CreateVariableSizedObject(unsigned Alignment, const AllocaInst *Alloca);
714 
715  /// Returns a reference to call saved info vector for the current function.
716  const std::vector<CalleeSavedInfo> &getCalleeSavedInfo() const {
717  return CSInfo;
718  }
719  /// \copydoc getCalleeSavedInfo()
720  std::vector<CalleeSavedInfo> &getCalleeSavedInfo() { return CSInfo; }
721 
722  /// Used by prolog/epilog inserter to set the function's callee saved
723  /// information.
724  void setCalleeSavedInfo(const std::vector<CalleeSavedInfo> &CSI) {
725  CSInfo = CSI;
726  }
727 
728  /// Has the callee saved info been calculated yet?
729  bool isCalleeSavedInfoValid() const { return CSIValid; }
730 
731  void setCalleeSavedInfoValid(bool v) { CSIValid = v; }
732 
733  MachineBasicBlock *getSavePoint() const { return Save; }
734  void setSavePoint(MachineBasicBlock *NewSave) { Save = NewSave; }
735  MachineBasicBlock *getRestorePoint() const { return Restore; }
736  void setRestorePoint(MachineBasicBlock *NewRestore) { Restore = NewRestore; }
737 
738  /// Return a set of physical registers that are pristine.
739  ///
740  /// Pristine registers hold a value that is useless to the current function,
741  /// but that must be preserved - they are callee saved registers that are not
742  /// saved.
743  ///
744  /// Before the PrologueEpilogueInserter has placed the CSR spill code, this
745  /// method always returns an empty set.
746  BitVector getPristineRegs(const MachineFunction &MF) const;
747 
748  /// Used by the MachineFunction printer to print information about
749  /// stack objects. Implemented in MachineFunction.cpp.
750  void print(const MachineFunction &MF, raw_ostream &OS) const;
751 
752  /// dump - Print the function to stderr.
753  void dump(const MachineFunction &MF) const;
754 };
755 
756 } // End llvm namespace
757 
758 #endif
void setHasStackMap(bool s=true)
void setFrameAddressIsTaken(bool T)
unsigned getNumFixedObjects() const
Return the number of fixed objects.
constexpr char Align[]
Key for Kernel::Arg::Metadata::mAlign.
bool isCalleeSavedInfoValid() const
Has the callee saved info been calculated yet?
void setSavePoint(MachineBasicBlock *NewSave)
void setObjectZExt(int ObjectIdx, bool IsZExt)
bool hasStackMap() const
This method may be called any time after instruction selection is complete to determine if there is a...
void setRestorePoint(MachineBasicBlock *NewRestore)
void mapLocalFrameObject(int ObjectIndex, int64_t Offset)
Map a frame index into the local object block.
int getFunctionContextIndex() const
Return the index for the function context object.
void setCalleeSavedInfoValid(bool v)
Compute iterated dominance frontiers using a linear time algorithm.
Definition: AllocatorList.h:24
unsigned getNumObjects() const
Return the number of objects.
bool hasVAStart() const
Returns true if the function calls the llvm.va_start intrinsic.
bool hasStackProtectorIndex() const
bool hasStackObjects() const
Return true if there are any stack objects in this function.
bool isDeadObjectIndex(int ObjectIdx) const
Returns true if the specified index corresponds to a dead object.
bool hasOpaqueSPAdjustment() const
Returns true if the function contains opaque dynamic stack adjustments.
int64_t getLocalFrameSize() const
Get the size of the local object blob.
bool adjustsStack() const
Return true if this function adjusts the stack – e.g., when calling another function.
block Block Frequency true
bool isVariableSizedObjectIndex(int ObjectIdx) const
Returns true if the specified index corresponds to a variable sized object.
bool isFrameAddressTaken() const
This method may be called any time after instruction selection is complete to determine if there is a...
std::pair< int, int64_t > getLocalFrameObjectMap(int i) const
Get the local offset mapping for a for an object.
void setHasPatchPoint(bool s=true)
void setLocalFrameSize(int64_t sz)
Set the size of the local object blob.
void setUseLocalStackAllocationBlock(bool v)
setUseLocalStackAllocationBlock - Set whether the local allocation blob should be allocated together ...
MachineBasicBlock * getRestorePoint() const
int64_t getObjectOffset(int ObjectIdx) const
Return the assigned stack offset of the specified object from the incoming stack pointer.
bool isObjectSExt(int ObjectIdx) const
The MachineFrameInfo class represents an abstract stack frame until prolog/epilog code is inserted...
bool hasVarSizedObjects() const
This method may be called any time after instruction selection is complete to determine if the stack ...
void setFunctionContextIndex(int I)
bool isImmutableObjectIndex(int ObjectIdx) const
Returns true if the specified index corresponds to an immutable object.
bool isObjectZExt(int ObjectIdx) const
bool getUseLocalStackAllocationBlock() const
Get whether the local allocation blob should be allocated together or let PEI allocate the locals in ...
void setHasMustTailInVarArgFunc(bool B)
#define T
int getObjectIndexBegin() const
Return the minimum frame object index.
bool isObjectPreAllocated(int ObjectIdx) const
Return true if the object was pre-allocated into the local block.
void setLocalFrameMaxAlign(unsigned Align)
Required alignment of the local object blob, which is the strictest alignment of any object in it...
int getObjectIndexEnd() const
Return one past the maximum frame object index.
SSPLayoutKind getObjectSSPLayout(int ObjectIdx) const
void setHasCopyImplyingStackAdjustment(bool B)
bool hasCopyImplyingStackAdjustment() const
Returns true if the function contains operations which will lower down to instructions which manipula...
void setObjectSExt(int ObjectIdx, bool IsSExt)
void setStackProtectorIndex(int I)
int64_t getObjectSize(int ObjectIdx) const
Return the size of the specified object.
void setHasOpaqueSPAdjustment(bool B)
void setObjectSSPLayout(int ObjectIdx, SSPLayoutKind Kind)
unsigned getObjectAlignment(int ObjectIdx) const
Return the alignment of the specified stack object.
static GCRegistry::Add< OcamlGC > B("ocaml", "ocaml 3.10-compatible GC")
void dump(const SparseBitVector< ElementSize > &LHS, raw_ostream &out)
void RemoveStackObject(int ObjectIdx)
Remove or mark dead a statically sized stack object.
void setStackSize(uint64_t Size)
Set the size of the stack.
bool isFixedObjectIndex(int ObjectIdx) const
Returns true if the specified index corresponds to a fixed stack object.
int getStackProtectorIndex() const
Return the index for the stack protector object.
unsigned getMaxAlignment() const
Return the alignment in bytes that this function must be aligned to, which is greater than the defaul...
static void print(raw_ostream &Out, object::Archive::Kind Kind, T Val)
MachineFrameInfo(unsigned StackAlignment, bool StackRealignable, bool ForcedRealign)
void setObjectSize(int ObjectIdx, int64_t Size)
Change the size of the specified stack object.
void setStackID(int ObjectIdx, uint8_t ID)
size_t size() const
Definition: SmallVector.h:53
void markAsStatepointSpillSlotObjectIndex(int ObjectIdx)
CalleeSavedInfo(unsigned R, int FI=0)
unsigned getMaxCallFrameSize() const
Return the maximum size of a call frame that must be allocated for an outgoing function call...
This is a &#39;vector&#39; (really, a variable-sized array), optimized for the case when the array is small...
Definition: SmallVector.h:847
SSPLayoutKind
Stack Smashing Protection (SSP) rules require that vulnerable stack allocations are located close the...
void setOffsetAdjustment(int Adj)
Set the correction for frame offsets.
bool hasMustTailInVarArgFunc() const
Returns true if the function is variadic and contains a musttail call.
The CalleeSavedInfo class tracks the information need to locate where a callee saved register is in t...
bool isStatepointSpillSlotObjectIndex(int ObjectIdx) const
const AllocaInst * getObjectAllocation(int ObjectIdx) const
Return the underlying Alloca of the specified stack object if it exists.
void setCalleeSavedInfo(const std::vector< CalleeSavedInfo > &CSI)
Used by prolog/epilog inserter to set the function&#39;s callee saved information.
const std::vector< CalleeSavedInfo > & getCalleeSavedInfo() const
Returns a reference to call saved info vector for the current function.
bool isAliasedObjectIndex(int ObjectIdx) const
Returns true if the specified index corresponds to an object that might be pointed to by an LLVM IR v...
bool isReturnAddressTaken() const
This method may be called any time after instruction selection is complete to determine if there is a...
#define I(x, y, z)
Definition: MD5.cpp:58
void setMaxCallFrameSize(unsigned S)
unsigned getLocalFrameMaxAlign() const
Return the required alignment of the local object blob.
int getOffsetAdjustment() const
Return the correction for frame offsets.
void setIsImmutableObjectIndex(int ObjectIdx, bool IsImmutable)
Marks the immutability of an object.
const unsigned Kind
uint8_t getStackID(int ObjectIdx) const
MachineBasicBlock * getSavePoint() const
assert(ImpDefSCC.getReg()==AMDGPU::SCC &&ImpDefSCC.isDef())
void setReturnAddressIsTaken(bool s)
constexpr char Size[]
Key for Kernel::Arg::Metadata::mSize.
This class implements an extremely fast bulk output stream that can only output to a stream...
Definition: raw_ostream.h:46
bool isMaxCallFrameSizeComputed() const
void setObjectOffset(int ObjectIdx, int64_t SPOffset)
Set the stack frame offset of the specified object.
bool hasPatchPoint() const
This method may be called any time after instruction selection is complete to determine if there is a...
int64_t getLocalFrameObjectCount() const
Return the number of objects allocated into the local object block.
unsigned getReg() const
bool hasTailCall() const
Returns true if the function contains a tail call.
void setObjectAlignment(int ObjectIdx, unsigned Align)
setObjectAlignment - Change the alignment of the specified stack object.
uint64_t getStackSize() const
Return the number of bytes that must be allocated to hold all of the fixed size frame objects...
std::vector< CalleeSavedInfo > & getCalleeSavedInfo()
bool isSpillSlotObjectIndex(int ObjectIdx) const
Returns true if the specified index corresponds to a spill slot.
bool hasCalls() const
Return true if the current function has any function calls.
an instruction to allocate memory on the stack
Definition: Instructions.h:60