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MachineFrameInfo.h
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1 //===-- CodeGen/MachineFrameInfo.h - Abstract Stack Frame Rep. --*- C++ -*-===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // The file defines the MachineFrameInfo class.
10 //
11 //===----------------------------------------------------------------------===//
12 
13 #ifndef LLVM_CODEGEN_MACHINEFRAMEINFO_H
14 #define LLVM_CODEGEN_MACHINEFRAMEINFO_H
15 
16 #include "llvm/ADT/SmallVector.h"
17 #include "llvm/Support/DataTypes.h"
18 #include <cassert>
19 #include <vector>
20 
21 namespace llvm {
22 class raw_ostream;
23 class MachineFunction;
24 class MachineBasicBlock;
25 class BitVector;
26 class AllocaInst;
27 
28 /// The CalleeSavedInfo class tracks the information need to locate where a
29 /// callee saved register is in the current frame.
30 /// Callee saved reg can also be saved to a different register rather than
31 /// on the stack by setting DstReg instead of FrameIdx.
33  unsigned Reg;
34  union {
35  int FrameIdx;
36  unsigned DstReg;
37  };
38  /// Flag indicating whether the register is actually restored in the epilog.
39  /// In most cases, if a register is saved, it is also restored. There are
40  /// some situations, though, when this is not the case. For example, the
41  /// LR register on ARM is usually saved, but on exit from the function its
42  /// saved value may be loaded directly into PC. Since liveness tracking of
43  /// physical registers treats callee-saved registers are live outside of
44  /// the function, LR would be treated as live-on-exit, even though in these
45  /// scenarios it is not. This flag is added to indicate that the saved
46  /// register described by this object is not restored in the epilog.
47  /// The long-term solution is to model the liveness of callee-saved registers
48  /// by implicit uses on the return instructions, however, the required
49  /// changes in the ARM backend would be quite extensive.
50  bool Restored;
51  /// Flag indicating whether the register is spilled to stack or another
52  /// register.
53  bool SpilledToReg;
54 
55 public:
56  explicit CalleeSavedInfo(unsigned R, int FI = 0)
57  : Reg(R), FrameIdx(FI), Restored(true), SpilledToReg(false) {}
58 
59  // Accessors.
60  unsigned getReg() const { return Reg; }
61  int getFrameIdx() const { return FrameIdx; }
62  unsigned getDstReg() const { return DstReg; }
63  void setFrameIdx(int FI) {
64  FrameIdx = FI;
65  SpilledToReg = false;
66  }
67  void setDstReg(unsigned SpillReg) {
68  DstReg = SpillReg;
69  SpilledToReg = true;
70  }
71  bool isRestored() const { return Restored; }
72  void setRestored(bool R) { Restored = R; }
73  bool isSpilledToReg() const { return SpilledToReg; }
74 };
75 
76 /// The MachineFrameInfo class represents an abstract stack frame until
77 /// prolog/epilog code is inserted. This class is key to allowing stack frame
78 /// representation optimizations, such as frame pointer elimination. It also
79 /// allows more mundane (but still important) optimizations, such as reordering
80 /// of abstract objects on the stack frame.
81 ///
82 /// To support this, the class assigns unique integer identifiers to stack
83 /// objects requested clients. These identifiers are negative integers for
84 /// fixed stack objects (such as arguments passed on the stack) or nonnegative
85 /// for objects that may be reordered. Instructions which refer to stack
86 /// objects use a special MO_FrameIndex operand to represent these frame
87 /// indexes.
88 ///
89 /// Because this class keeps track of all references to the stack frame, it
90 /// knows when a variable sized object is allocated on the stack. This is the
91 /// sole condition which prevents frame pointer elimination, which is an
92 /// important optimization on register-poor architectures. Because original
93 /// variable sized alloca's in the source program are the only source of
94 /// variable sized stack objects, it is safe to decide whether there will be
95 /// any variable sized objects before all stack objects are known (for
96 /// example, register allocator spill code never needs variable sized
97 /// objects).
98 ///
99 /// When prolog/epilog code emission is performed, the final stack frame is
100 /// built and the machine instructions are modified to refer to the actual
101 /// stack offsets of the object, eliminating all MO_FrameIndex operands from
102 /// the program.
103 ///
104 /// Abstract Stack Frame Information
106 public:
107  /// Stack Smashing Protection (SSP) rules require that vulnerable stack
108  /// allocations are located close the stack protector.
110  SSPLK_None, ///< Did not trigger a stack protector. No effect on data
111  ///< layout.
112  SSPLK_LargeArray, ///< Array or nested array >= SSP-buffer-size. Closest
113  ///< to the stack protector.
114  SSPLK_SmallArray, ///< Array or nested array < SSP-buffer-size. 2nd closest
115  ///< to the stack protector.
116  SSPLK_AddrOf ///< The address of this allocation is exposed and
117  ///< triggered protection. 3rd closest to the protector.
118  };
119 
120 private:
121  // Represent a single object allocated on the stack.
122  struct StackObject {
123  // The offset of this object from the stack pointer on entry to
124  // the function. This field has no meaning for a variable sized element.
125  int64_t SPOffset;
126 
127  // The size of this object on the stack. 0 means a variable sized object,
128  // ~0ULL means a dead object.
129  uint64_t Size;
130 
131  // The required alignment of this stack slot.
132  unsigned Alignment;
133 
134  // If true, the value of the stack object is set before
135  // entering the function and is not modified inside the function. By
136  // default, fixed objects are immutable unless marked otherwise.
137  bool isImmutable;
138 
139  // If true the stack object is used as spill slot. It
140  // cannot alias any other memory objects.
141  bool isSpillSlot;
142 
143  /// If true, this stack slot is used to spill a value (could be deopt
144  /// and/or GC related) over a statepoint. We know that the address of the
145  /// slot can't alias any LLVM IR value. This is very similar to a Spill
146  /// Slot, but is created by statepoint lowering is SelectionDAG, not the
147  /// register allocator.
148  bool isStatepointSpillSlot = false;
149 
150  /// Identifier for stack memory type analagous to address space. If this is
151  /// non-0, the meaning is target defined. Offsets cannot be directly
152  /// compared between objects with different stack IDs. The object may not
153  /// necessarily reside in the same contiguous memory block as other stack
154  /// objects. Objects with differing stack IDs should not be merged or
155  /// replaced substituted for each other.
156  //
157  /// It is assumed a target uses consecutive, increasing stack IDs starting
158  /// from 1.
159  uint8_t StackID;
160 
161  /// If this stack object is originated from an Alloca instruction
162  /// this value saves the original IR allocation. Can be NULL.
163  const AllocaInst *Alloca;
164 
165  // If true, the object was mapped into the local frame
166  // block and doesn't need additional handling for allocation beyond that.
167  bool PreAllocated = false;
168 
169  // If true, an LLVM IR value might point to this object.
170  // Normally, spill slots and fixed-offset objects don't alias IR-accessible
171  // objects, but there are exceptions (on PowerPC, for example, some byval
172  // arguments have ABI-prescribed offsets).
173  bool isAliased;
174 
175  /// If true, the object has been zero-extended.
176  bool isZExt = false;
177 
178  /// If true, the object has been zero-extended.
179  bool isSExt = false;
180 
181  uint8_t SSPLayout;
182 
183  StackObject(uint64_t Size, unsigned Alignment, int64_t SPOffset,
184  bool IsImmutable, bool IsSpillSlot, const AllocaInst *Alloca,
185  bool IsAliased, uint8_t StackID = 0)
186  : SPOffset(SPOffset), Size(Size), Alignment(Alignment),
187  isImmutable(IsImmutable), isSpillSlot(IsSpillSlot),
188  StackID(StackID), Alloca(Alloca), isAliased(IsAliased),
189  SSPLayout(SSPLK_None) {}
190  };
191 
192  /// The alignment of the stack.
193  unsigned StackAlignment;
194 
195  /// Can the stack be realigned. This can be false if the target does not
196  /// support stack realignment, or if the user asks us not to realign the
197  /// stack. In this situation, overaligned allocas are all treated as dynamic
198  /// allocations and the target must handle them as part of DYNAMIC_STACKALLOC
199  /// lowering. All non-alloca stack objects have their alignment clamped to the
200  /// base ABI stack alignment.
201  /// FIXME: There is room for improvement in this case, in terms of
202  /// grouping overaligned allocas into a "secondary stack frame" and
203  /// then only use a single alloca to allocate this frame and only a
204  /// single virtual register to access it. Currently, without such an
205  /// optimization, each such alloca gets its own dynamic realignment.
206  bool StackRealignable;
207 
208  /// Whether the function has the \c alignstack attribute.
209  bool ForcedRealign;
210 
211  /// The list of stack objects allocated.
212  std::vector<StackObject> Objects;
213 
214  /// This contains the number of fixed objects contained on
215  /// the stack. Because fixed objects are stored at a negative index in the
216  /// Objects list, this is also the index to the 0th object in the list.
217  unsigned NumFixedObjects = 0;
218 
219  /// This boolean keeps track of whether any variable
220  /// sized objects have been allocated yet.
221  bool HasVarSizedObjects = false;
222 
223  /// This boolean keeps track of whether there is a call
224  /// to builtin \@llvm.frameaddress.
225  bool FrameAddressTaken = false;
226 
227  /// This boolean keeps track of whether there is a call
228  /// to builtin \@llvm.returnaddress.
229  bool ReturnAddressTaken = false;
230 
231  /// This boolean keeps track of whether there is a call
232  /// to builtin \@llvm.experimental.stackmap.
233  bool HasStackMap = false;
234 
235  /// This boolean keeps track of whether there is a call
236  /// to builtin \@llvm.experimental.patchpoint.
237  bool HasPatchPoint = false;
238 
239  /// The prolog/epilog code inserter calculates the final stack
240  /// offsets for all of the fixed size objects, updating the Objects list
241  /// above. It then updates StackSize to contain the number of bytes that need
242  /// to be allocated on entry to the function.
243  uint64_t StackSize = 0;
244 
245  /// The amount that a frame offset needs to be adjusted to
246  /// have the actual offset from the stack/frame pointer. The exact usage of
247  /// this is target-dependent, but it is typically used to adjust between
248  /// SP-relative and FP-relative offsets. E.G., if objects are accessed via
249  /// SP then OffsetAdjustment is zero; if FP is used, OffsetAdjustment is set
250  /// to the distance between the initial SP and the value in FP. For many
251  /// targets, this value is only used when generating debug info (via
252  /// TargetRegisterInfo::getFrameIndexReference); when generating code, the
253  /// corresponding adjustments are performed directly.
254  int OffsetAdjustment = 0;
255 
256  /// The prolog/epilog code inserter may process objects that require greater
257  /// alignment than the default alignment the target provides.
258  /// To handle this, MaxAlignment is set to the maximum alignment
259  /// needed by the objects on the current frame. If this is greater than the
260  /// native alignment maintained by the compiler, dynamic alignment code will
261  /// be needed.
262  ///
263  unsigned MaxAlignment = 0;
264 
265  /// Set to true if this function adjusts the stack -- e.g.,
266  /// when calling another function. This is only valid during and after
267  /// prolog/epilog code insertion.
268  bool AdjustsStack = false;
269 
270  /// Set to true if this function has any function calls.
271  bool HasCalls = false;
272 
273  /// The frame index for the stack protector.
274  int StackProtectorIdx = -1;
275 
276  /// The frame index for the function context. Used for SjLj exceptions.
277  int FunctionContextIdx = -1;
278 
279  /// This contains the size of the largest call frame if the target uses frame
280  /// setup/destroy pseudo instructions (as defined in the TargetFrameInfo
281  /// class). This information is important for frame pointer elimination.
282  /// It is only valid during and after prolog/epilog code insertion.
283  unsigned MaxCallFrameSize = ~0u;
284 
285  /// The number of bytes of callee saved registers that the target wants to
286  /// report for the current function in the CodeView S_FRAMEPROC record.
287  unsigned CVBytesOfCalleeSavedRegisters = 0;
288 
289  /// The prolog/epilog code inserter fills in this vector with each
290  /// callee saved register saved in either the frame or a different
291  /// register. Beyond its use by the prolog/ epilog code inserter,
292  /// this data is used for debug info and exception handling.
293  std::vector<CalleeSavedInfo> CSInfo;
294 
295  /// Has CSInfo been set yet?
296  bool CSIValid = false;
297 
298  /// References to frame indices which are mapped
299  /// into the local frame allocation block. <FrameIdx, LocalOffset>
300  SmallVector<std::pair<int, int64_t>, 32> LocalFrameObjects;
301 
302  /// Size of the pre-allocated local frame block.
303  int64_t LocalFrameSize = 0;
304 
305  /// Required alignment of the local object blob, which is the strictest
306  /// alignment of any object in it.
307  unsigned LocalFrameMaxAlign = 0;
308 
309  /// Whether the local object blob needs to be allocated together. If not,
310  /// PEI should ignore the isPreAllocated flags on the stack objects and
311  /// just allocate them normally.
312  bool UseLocalStackAllocationBlock = false;
313 
314  /// True if the function dynamically adjusts the stack pointer through some
315  /// opaque mechanism like inline assembly or Win32 EH.
316  bool HasOpaqueSPAdjustment = false;
317 
318  /// True if the function contains operations which will lower down to
319  /// instructions which manipulate the stack pointer.
320  bool HasCopyImplyingStackAdjustment = false;
321 
322  /// True if the function contains a call to the llvm.vastart intrinsic.
323  bool HasVAStart = false;
324 
325  /// True if this is a varargs function that contains a musttail call.
326  bool HasMustTailInVarArgFunc = false;
327 
328  /// True if this function contains a tail call. If so immutable objects like
329  /// function arguments are no longer so. A tail call *can* override fixed
330  /// stack objects like arguments so we can't treat them as immutable.
331  bool HasTailCall = false;
332 
333  /// Not null, if shrink-wrapping found a better place for the prologue.
334  MachineBasicBlock *Save = nullptr;
335  /// Not null, if shrink-wrapping found a better place for the epilogue.
336  MachineBasicBlock *Restore = nullptr;
337 
338 public:
339  explicit MachineFrameInfo(unsigned StackAlignment, bool StackRealignable,
340  bool ForcedRealign)
341  : StackAlignment(StackAlignment), StackRealignable(StackRealignable),
342  ForcedRealign(ForcedRealign) {}
343 
344  /// Return true if there are any stack objects in this function.
345  bool hasStackObjects() const { return !Objects.empty(); }
346 
347  /// This method may be called any time after instruction
348  /// selection is complete to determine if the stack frame for this function
349  /// contains any variable sized objects.
350  bool hasVarSizedObjects() const { return HasVarSizedObjects; }
351 
352  /// Return the index for the stack protector object.
353  int getStackProtectorIndex() const { return StackProtectorIdx; }
354  void setStackProtectorIndex(int I) { StackProtectorIdx = I; }
355  bool hasStackProtectorIndex() const { return StackProtectorIdx != -1; }
356 
357  /// Return the index for the function context object.
358  /// This object is used for SjLj exceptions.
359  int getFunctionContextIndex() const { return FunctionContextIdx; }
360  void setFunctionContextIndex(int I) { FunctionContextIdx = I; }
361 
362  /// This method may be called any time after instruction
363  /// selection is complete to determine if there is a call to
364  /// \@llvm.frameaddress in this function.
365  bool isFrameAddressTaken() const { return FrameAddressTaken; }
366  void setFrameAddressIsTaken(bool T) { FrameAddressTaken = T; }
367 
368  /// This method may be called any time after
369  /// instruction selection is complete to determine if there is a call to
370  /// \@llvm.returnaddress in this function.
371  bool isReturnAddressTaken() const { return ReturnAddressTaken; }
372  void setReturnAddressIsTaken(bool s) { ReturnAddressTaken = s; }
373 
374  /// This method may be called any time after instruction
375  /// selection is complete to determine if there is a call to builtin
376  /// \@llvm.experimental.stackmap.
377  bool hasStackMap() const { return HasStackMap; }
378  void setHasStackMap(bool s = true) { HasStackMap = s; }
379 
380  /// This method may be called any time after instruction
381  /// selection is complete to determine if there is a call to builtin
382  /// \@llvm.experimental.patchpoint.
383  bool hasPatchPoint() const { return HasPatchPoint; }
384  void setHasPatchPoint(bool s = true) { HasPatchPoint = s; }
385 
386  /// Return the minimum frame object index.
387  int getObjectIndexBegin() const { return -NumFixedObjects; }
388 
389  /// Return one past the maximum frame object index.
390  int getObjectIndexEnd() const { return (int)Objects.size()-NumFixedObjects; }
391 
392  /// Return the number of fixed objects.
393  unsigned getNumFixedObjects() const { return NumFixedObjects; }
394 
395  /// Return the number of objects.
396  unsigned getNumObjects() const { return Objects.size(); }
397 
398  /// Map a frame index into the local object block
399  void mapLocalFrameObject(int ObjectIndex, int64_t Offset) {
400  LocalFrameObjects.push_back(std::pair<int, int64_t>(ObjectIndex, Offset));
401  Objects[ObjectIndex + NumFixedObjects].PreAllocated = true;
402  }
403 
404  /// Get the local offset mapping for a for an object.
405  std::pair<int, int64_t> getLocalFrameObjectMap(int i) const {
406  assert (i >= 0 && (unsigned)i < LocalFrameObjects.size() &&
407  "Invalid local object reference!");
408  return LocalFrameObjects[i];
409  }
410 
411  /// Return the number of objects allocated into the local object block.
412  int64_t getLocalFrameObjectCount() const { return LocalFrameObjects.size(); }
413 
414  /// Set the size of the local object blob.
415  void setLocalFrameSize(int64_t sz) { LocalFrameSize = sz; }
416 
417  /// Get the size of the local object blob.
418  int64_t getLocalFrameSize() const { return LocalFrameSize; }
419 
420  /// Required alignment of the local object blob,
421  /// which is the strictest alignment of any object in it.
422  void setLocalFrameMaxAlign(unsigned Align) { LocalFrameMaxAlign = Align; }
423 
424  /// Return the required alignment of the local object blob.
425  unsigned getLocalFrameMaxAlign() const { return LocalFrameMaxAlign; }
426 
427  /// Get whether the local allocation blob should be allocated together or
428  /// let PEI allocate the locals in it directly.
430  return UseLocalStackAllocationBlock;
431  }
432 
433  /// setUseLocalStackAllocationBlock - Set whether the local allocation blob
434  /// should be allocated together or let PEI allocate the locals in it
435  /// directly.
437  UseLocalStackAllocationBlock = v;
438  }
439 
440  /// Return true if the object was pre-allocated into the local block.
441  bool isObjectPreAllocated(int ObjectIdx) const {
442  assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
443  "Invalid Object Idx!");
444  return Objects[ObjectIdx+NumFixedObjects].PreAllocated;
445  }
446 
447  /// Return the size of the specified object.
448  int64_t getObjectSize(int ObjectIdx) const {
449  assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
450  "Invalid Object Idx!");
451  return Objects[ObjectIdx+NumFixedObjects].Size;
452  }
453 
454  /// Change the size of the specified stack object.
455  void setObjectSize(int ObjectIdx, int64_t Size) {
456  assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
457  "Invalid Object Idx!");
458  Objects[ObjectIdx+NumFixedObjects].Size = Size;
459  }
460 
461  /// Return the alignment of the specified stack object.
462  unsigned getObjectAlignment(int ObjectIdx) const {
463  assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
464  "Invalid Object Idx!");
465  return Objects[ObjectIdx+NumFixedObjects].Alignment;
466  }
467 
468  /// setObjectAlignment - Change the alignment of the specified stack object.
469  void setObjectAlignment(int ObjectIdx, unsigned Align) {
470  assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
471  "Invalid Object Idx!");
472  Objects[ObjectIdx+NumFixedObjects].Alignment = Align;
473 
474  // Only ensure max alignment for the default stack.
475  if (getStackID(ObjectIdx) == 0)
476  ensureMaxAlignment(Align);
477  }
478 
479  /// Return the underlying Alloca of the specified
480  /// stack object if it exists. Returns 0 if none exists.
481  const AllocaInst* getObjectAllocation(int ObjectIdx) const {
482  assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
483  "Invalid Object Idx!");
484  return Objects[ObjectIdx+NumFixedObjects].Alloca;
485  }
486 
487  /// Return the assigned stack offset of the specified object
488  /// from the incoming stack pointer.
489  int64_t getObjectOffset(int ObjectIdx) const {
490  assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
491  "Invalid Object Idx!");
492  assert(!isDeadObjectIndex(ObjectIdx) &&
493  "Getting frame offset for a dead object?");
494  return Objects[ObjectIdx+NumFixedObjects].SPOffset;
495  }
496 
497  bool isObjectZExt(int ObjectIdx) const {
498  assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
499  "Invalid Object Idx!");
500  return Objects[ObjectIdx+NumFixedObjects].isZExt;
501  }
502 
503  void setObjectZExt(int ObjectIdx, bool IsZExt) {
504  assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
505  "Invalid Object Idx!");
506  Objects[ObjectIdx+NumFixedObjects].isZExt = IsZExt;
507  }
508 
509  bool isObjectSExt(int ObjectIdx) const {
510  assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
511  "Invalid Object Idx!");
512  return Objects[ObjectIdx+NumFixedObjects].isSExt;
513  }
514 
515  void setObjectSExt(int ObjectIdx, bool IsSExt) {
516  assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
517  "Invalid Object Idx!");
518  Objects[ObjectIdx+NumFixedObjects].isSExt = IsSExt;
519  }
520 
521  /// Set the stack frame offset of the specified object. The
522  /// offset is relative to the stack pointer on entry to the function.
523  void setObjectOffset(int ObjectIdx, int64_t SPOffset) {
524  assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
525  "Invalid Object Idx!");
526  assert(!isDeadObjectIndex(ObjectIdx) &&
527  "Setting frame offset for a dead object?");
528  Objects[ObjectIdx+NumFixedObjects].SPOffset = SPOffset;
529  }
530 
531  SSPLayoutKind getObjectSSPLayout(int ObjectIdx) const {
532  assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
533  "Invalid Object Idx!");
534  return (SSPLayoutKind)Objects[ObjectIdx+NumFixedObjects].SSPLayout;
535  }
536 
537  void setObjectSSPLayout(int ObjectIdx, SSPLayoutKind Kind) {
538  assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
539  "Invalid Object Idx!");
540  assert(!isDeadObjectIndex(ObjectIdx) &&
541  "Setting SSP layout for a dead object?");
542  Objects[ObjectIdx+NumFixedObjects].SSPLayout = Kind;
543  }
544 
545  /// Return the number of bytes that must be allocated to hold
546  /// all of the fixed size frame objects. This is only valid after
547  /// Prolog/Epilog code insertion has finalized the stack frame layout.
548  uint64_t getStackSize() const { return StackSize; }
549 
550  /// Set the size of the stack.
551  void setStackSize(uint64_t Size) { StackSize = Size; }
552 
553  /// Estimate and return the size of the stack frame.
554  unsigned estimateStackSize(const MachineFunction &MF) const;
555 
556  /// Return the correction for frame offsets.
557  int getOffsetAdjustment() const { return OffsetAdjustment; }
558 
559  /// Set the correction for frame offsets.
560  void setOffsetAdjustment(int Adj) { OffsetAdjustment = Adj; }
561 
562  /// Return the alignment in bytes that this function must be aligned to,
563  /// which is greater than the default stack alignment provided by the target.
564  unsigned getMaxAlignment() const { return MaxAlignment; }
565 
566  /// Make sure the function is at least Align bytes aligned.
567  void ensureMaxAlignment(unsigned Align);
568 
569  /// Return true if this function adjusts the stack -- e.g.,
570  /// when calling another function. This is only valid during and after
571  /// prolog/epilog code insertion.
572  bool adjustsStack() const { return AdjustsStack; }
573  void setAdjustsStack(bool V) { AdjustsStack = V; }
574 
575  /// Return true if the current function has any function calls.
576  bool hasCalls() const { return HasCalls; }
577  void setHasCalls(bool V) { HasCalls = V; }
578 
579  /// Returns true if the function contains opaque dynamic stack adjustments.
580  bool hasOpaqueSPAdjustment() const { return HasOpaqueSPAdjustment; }
581  void setHasOpaqueSPAdjustment(bool B) { HasOpaqueSPAdjustment = B; }
582 
583  /// Returns true if the function contains operations which will lower down to
584  /// instructions which manipulate the stack pointer.
586  return HasCopyImplyingStackAdjustment;
587  }
589  HasCopyImplyingStackAdjustment = B;
590  }
591 
592  /// Returns true if the function calls the llvm.va_start intrinsic.
593  bool hasVAStart() const { return HasVAStart; }
594  void setHasVAStart(bool B) { HasVAStart = B; }
595 
596  /// Returns true if the function is variadic and contains a musttail call.
597  bool hasMustTailInVarArgFunc() const { return HasMustTailInVarArgFunc; }
598  void setHasMustTailInVarArgFunc(bool B) { HasMustTailInVarArgFunc = B; }
599 
600  /// Returns true if the function contains a tail call.
601  bool hasTailCall() const { return HasTailCall; }
602  void setHasTailCall() { HasTailCall = true; }
603 
604  /// Computes the maximum size of a callframe and the AdjustsStack property.
605  /// This only works for targets defining
606  /// TargetInstrInfo::getCallFrameSetupOpcode(), getCallFrameDestroyOpcode(),
607  /// and getFrameSize().
608  /// This is usually computed by the prologue epilogue inserter but some
609  /// targets may call this to compute it earlier.
610  void computeMaxCallFrameSize(const MachineFunction &MF);
611 
612  /// Return the maximum size of a call frame that must be
613  /// allocated for an outgoing function call. This is only available if
614  /// CallFrameSetup/Destroy pseudo instructions are used by the target, and
615  /// then only during or after prolog/epilog code insertion.
616  ///
617  unsigned getMaxCallFrameSize() const {
618  // TODO: Enable this assert when targets are fixed.
619  //assert(isMaxCallFrameSizeComputed() && "MaxCallFrameSize not computed yet");
620  if (!isMaxCallFrameSizeComputed())
621  return 0;
622  return MaxCallFrameSize;
623  }
625  return MaxCallFrameSize != ~0u;
626  }
627  void setMaxCallFrameSize(unsigned S) { MaxCallFrameSize = S; }
628 
629  /// Returns how many bytes of callee-saved registers the target pushed in the
630  /// prologue. Only used for debug info.
632  return CVBytesOfCalleeSavedRegisters;
633  }
635  CVBytesOfCalleeSavedRegisters = S;
636  }
637 
638  /// Create a new object at a fixed location on the stack.
639  /// All fixed objects should be created before other objects are created for
640  /// efficiency. By default, fixed objects are not pointed to by LLVM IR
641  /// values. This returns an index with a negative value.
642  int CreateFixedObject(uint64_t Size, int64_t SPOffset, bool IsImmutable,
643  bool isAliased = false);
644 
645  /// Create a spill slot at a fixed location on the stack.
646  /// Returns an index with a negative value.
647  int CreateFixedSpillStackObject(uint64_t Size, int64_t SPOffset,
648  bool IsImmutable = false);
649 
650  /// Returns true if the specified index corresponds to a fixed stack object.
651  bool isFixedObjectIndex(int ObjectIdx) const {
652  return ObjectIdx < 0 && (ObjectIdx >= -(int)NumFixedObjects);
653  }
654 
655  /// Returns true if the specified index corresponds
656  /// to an object that might be pointed to by an LLVM IR value.
657  bool isAliasedObjectIndex(int ObjectIdx) const {
658  assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
659  "Invalid Object Idx!");
660  return Objects[ObjectIdx+NumFixedObjects].isAliased;
661  }
662 
663  /// Returns true if the specified index corresponds to an immutable object.
664  bool isImmutableObjectIndex(int ObjectIdx) const {
665  // Tail calling functions can clobber their function arguments.
666  if (HasTailCall)
667  return false;
668  assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
669  "Invalid Object Idx!");
670  return Objects[ObjectIdx+NumFixedObjects].isImmutable;
671  }
672 
673  /// Marks the immutability of an object.
674  void setIsImmutableObjectIndex(int ObjectIdx, bool IsImmutable) {
675  assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
676  "Invalid Object Idx!");
677  Objects[ObjectIdx+NumFixedObjects].isImmutable = IsImmutable;
678  }
679 
680  /// Returns true if the specified index corresponds to a spill slot.
681  bool isSpillSlotObjectIndex(int ObjectIdx) const {
682  assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
683  "Invalid Object Idx!");
684  return Objects[ObjectIdx+NumFixedObjects].isSpillSlot;
685  }
686 
687  bool isStatepointSpillSlotObjectIndex(int ObjectIdx) const {
688  assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
689  "Invalid Object Idx!");
690  return Objects[ObjectIdx+NumFixedObjects].isStatepointSpillSlot;
691  }
692 
693  /// \see StackID
694  uint8_t getStackID(int ObjectIdx) const {
695  return Objects[ObjectIdx+NumFixedObjects].StackID;
696  }
697 
698  /// \see StackID
699  void setStackID(int ObjectIdx, uint8_t ID) {
700  assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
701  "Invalid Object Idx!");
702  Objects[ObjectIdx+NumFixedObjects].StackID = ID;
703  // If ID > 0, MaxAlignment may now be overly conservative.
704  // If ID == 0, MaxAlignment will need to be updated separately.
705  }
706 
707  /// Returns true if the specified index corresponds to a dead object.
708  bool isDeadObjectIndex(int ObjectIdx) const {
709  assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
710  "Invalid Object Idx!");
711  return Objects[ObjectIdx+NumFixedObjects].Size == ~0ULL;
712  }
713 
714  /// Returns true if the specified index corresponds to a variable sized
715  /// object.
716  bool isVariableSizedObjectIndex(int ObjectIdx) const {
717  assert(unsigned(ObjectIdx + NumFixedObjects) < Objects.size() &&
718  "Invalid Object Idx!");
719  return Objects[ObjectIdx + NumFixedObjects].Size == 0;
720  }
721 
723  assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
724  "Invalid Object Idx!");
725  Objects[ObjectIdx+NumFixedObjects].isStatepointSpillSlot = true;
726  assert(isStatepointSpillSlotObjectIndex(ObjectIdx) && "inconsistent");
727  }
728 
729  /// Create a new statically sized stack object, returning
730  /// a nonnegative identifier to represent it.
731  int CreateStackObject(uint64_t Size, unsigned Alignment, bool isSpillSlot,
732  const AllocaInst *Alloca = nullptr, uint8_t ID = 0);
733 
734  /// Create a new statically sized stack object that represents a spill slot,
735  /// returning a nonnegative identifier to represent it.
736  int CreateSpillStackObject(uint64_t Size, unsigned Alignment);
737 
738  /// Remove or mark dead a statically sized stack object.
739  void RemoveStackObject(int ObjectIdx) {
740  // Mark it dead.
741  Objects[ObjectIdx+NumFixedObjects].Size = ~0ULL;
742  }
743 
744  /// Notify the MachineFrameInfo object that a variable sized object has been
745  /// created. This must be created whenever a variable sized object is
746  /// created, whether or not the index returned is actually used.
747  int CreateVariableSizedObject(unsigned Alignment, const AllocaInst *Alloca);
748 
749  /// Returns a reference to call saved info vector for the current function.
750  const std::vector<CalleeSavedInfo> &getCalleeSavedInfo() const {
751  return CSInfo;
752  }
753  /// \copydoc getCalleeSavedInfo()
754  std::vector<CalleeSavedInfo> &getCalleeSavedInfo() { return CSInfo; }
755 
756  /// Used by prolog/epilog inserter to set the function's callee saved
757  /// information.
758  void setCalleeSavedInfo(const std::vector<CalleeSavedInfo> &CSI) {
759  CSInfo = CSI;
760  }
761 
762  /// Has the callee saved info been calculated yet?
763  bool isCalleeSavedInfoValid() const { return CSIValid; }
764 
765  void setCalleeSavedInfoValid(bool v) { CSIValid = v; }
766 
767  MachineBasicBlock *getSavePoint() const { return Save; }
768  void setSavePoint(MachineBasicBlock *NewSave) { Save = NewSave; }
769  MachineBasicBlock *getRestorePoint() const { return Restore; }
770  void setRestorePoint(MachineBasicBlock *NewRestore) { Restore = NewRestore; }
771 
772  /// Return a set of physical registers that are pristine.
773  ///
774  /// Pristine registers hold a value that is useless to the current function,
775  /// but that must be preserved - they are callee saved registers that are not
776  /// saved.
777  ///
778  /// Before the PrologueEpilogueInserter has placed the CSR spill code, this
779  /// method always returns an empty set.
780  BitVector getPristineRegs(const MachineFunction &MF) const;
781 
782  /// Used by the MachineFunction printer to print information about
783  /// stack objects. Implemented in MachineFunction.cpp.
784  void print(const MachineFunction &MF, raw_ostream &OS) const;
785 
786  /// dump - Print the function to stderr.
787  void dump(const MachineFunction &MF) const;
788 };
789 
790 } // End llvm namespace
791 
792 #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)
bool isSpilledToReg() const
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)
This class represents lattice values for constants.
Definition: AllocatorList.h:23
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.
void setDstReg(unsigned SpillReg)
bool adjustsStack() const
Return true if this function adjusts the stack – e.g., when calling another function.
block Block Frequency true
unsigned getDstReg() const
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)
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 getCVBytesOfCalleeSavedRegisters() const
Returns how many bytes of callee-saved registers the target pushed in the prologue.
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:52
This struct is a compact representation of a valid (non-zero power of two) alignment.
Definition: Alignment.h:40
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:837
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 setCVBytesOfCalleeSavedRegisters(unsigned S)
uint32_t Size
Definition: Profile.cpp:46
void setIsImmutableObjectIndex(int ObjectIdx, bool IsImmutable)
Marks the immutability of an object.
uint8_t getStackID(int ObjectIdx) const
MachineBasicBlock * getSavePoint() const
assert(ImpDefSCC.getReg()==AMDGPU::SCC &&ImpDefSCC.isDef())
void setReturnAddressIsTaken(bool s)
This class implements an extremely fast bulk output stream that can only output to a stream...
Definition: raw_ostream.h:45
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:59