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/CodeGen/Register.h"
18#include "llvm/CodeGen/TargetFrameLowering.h"
19#include "llvm/Support/Alignment.h"
20#include <cassert>
21#include <vector>
22
23namespace llvm {
24class raw_ostream;
25class MachineFunction;
26class MachineBasicBlock;
27class BitVector;
28class AllocaInst;
29
30/// The CalleeSavedInfo class tracks the information need to locate where a
31/// callee saved register is in the current frame.
32/// Callee saved reg can also be saved to a different register rather than
33/// on the stack by setting DstReg instead of FrameIdx.
34class CalleeSavedInfo {
35 Register Reg;
36 union {
37 int FrameIdx;
38 unsigned DstReg;
39 };
40 /// Flag indicating whether the register is actually restored in the epilog.
41 /// In most cases, if a register is saved, it is also restored. There are
42 /// some situations, though, when this is not the case. For example, the
43 /// LR register on ARM is usually saved, but on exit from the function its
44 /// saved value may be loaded directly into PC. Since liveness tracking of
45 /// physical registers treats callee-saved registers are live outside of
46 /// the function, LR would be treated as live-on-exit, even though in these
47 /// scenarios it is not. This flag is added to indicate that the saved
48 /// register described by this object is not restored in the epilog.
49 /// The long-term solution is to model the liveness of callee-saved registers
50 /// by implicit uses on the return instructions, however, the required
51 /// changes in the ARM backend would be quite extensive.
52 bool Restored = true;
53 /// Flag indicating whether the register is spilled to stack or another
54 /// register.
55 bool SpilledToReg = false;
56
57public:
58 explicit CalleeSavedInfo(unsigned R, int FI = 0) : Reg(R), FrameIdx(FI) {}
59
60 // Accessors.
61 Register getReg() const { return Reg; }
62 int getFrameIdx() const { return FrameIdx; }
63 unsigned getDstReg() const { return DstReg; }
64 void setFrameIdx(int FI) {
65 FrameIdx = FI;
66 SpilledToReg = false;
67 }
68 void setDstReg(Register SpillReg) {
69 DstReg = SpillReg;
70 SpilledToReg = true;
71 }
72 bool isRestored() const { return Restored; }
73 void setRestored(bool R) { Restored = R; }
74 bool isSpilledToReg() const { return SpilledToReg; }
75};
76
77/// The MachineFrameInfo class represents an abstract stack frame until
78/// prolog/epilog code is inserted. This class is key to allowing stack frame
79/// representation optimizations, such as frame pointer elimination. It also
80/// allows more mundane (but still important) optimizations, such as reordering
81/// of abstract objects on the stack frame.
82///
83/// To support this, the class assigns unique integer identifiers to stack
84/// objects requested clients. These identifiers are negative integers for
85/// fixed stack objects (such as arguments passed on the stack) or nonnegative
86/// for objects that may be reordered. Instructions which refer to stack
87/// objects use a special MO_FrameIndex operand to represent these frame
88/// indexes.
89///
90/// Because this class keeps track of all references to the stack frame, it
91/// knows when a variable sized object is allocated on the stack. This is the
92/// sole condition which prevents frame pointer elimination, which is an
93/// important optimization on register-poor architectures. Because original
94/// variable sized alloca's in the source program are the only source of
95/// variable sized stack objects, it is safe to decide whether there will be
96/// any variable sized objects before all stack objects are known (for
97/// example, register allocator spill code never needs variable sized
98/// objects).
99///
100/// When prolog/epilog code emission is performed, the final stack frame is
101/// built and the machine instructions are modified to refer to the actual
102/// stack offsets of the object, eliminating all MO_FrameIndex operands from
103/// the program.
104///
105/// Abstract Stack Frame Information
106class MachineFrameInfo {
107public:
108 /// Stack Smashing Protection (SSP) rules require that vulnerable stack
109 /// allocations are located close the stack protector.
110 enum SSPLayoutKind {
111 SSPLK_None, ///< Did not trigger a stack protector. No effect on data
112 ///< layout.
113 SSPLK_LargeArray, ///< Array or nested array >= SSP-buffer-size. Closest
114 ///< to the stack protector.
115 SSPLK_SmallArray, ///< Array or nested array < SSP-buffer-size. 2nd closest
116 ///< to the stack protector.
117 SSPLK_AddrOf ///< The address of this allocation is exposed and
118 ///< triggered protection. 3rd closest to the protector.
119 };
120
121private:
122 // Represent a single object allocated on the stack.
123 struct StackObject {
124 // The offset of this object from the stack pointer on entry to
125 // the function. This field has no meaning for a variable sized element.
126 int64_t SPOffset;
127
128 // The size of this object on the stack. 0 means a variable sized object,
129 // ~0ULL means a dead object.
130 uint64_t Size;
131
132 // The required alignment of this stack slot.
133 Align Alignment;
134
135 // If true, the value of the stack object is set before
136 // entering the function and is not modified inside the function. By
137 // default, fixed objects are immutable unless marked otherwise.
138 bool isImmutable;
139
140 // If true the stack object is used as spill slot. It
141 // cannot alias any other memory objects.
142 bool isSpillSlot;
143
144 /// If true, this stack slot is used to spill a value (could be deopt
145 /// and/or GC related) over a statepoint. We know that the address of the
146 /// slot can't alias any LLVM IR value. This is very similar to a Spill
147 /// Slot, but is created by statepoint lowering is SelectionDAG, not the
148 /// register allocator.
149 bool isStatepointSpillSlot = false;
150
151 /// Identifier for stack memory type analagous to address space. If this is
152 /// non-0, the meaning is target defined. Offsets cannot be directly
153 /// compared between objects with different stack IDs. The object may not
154 /// necessarily reside in the same contiguous memory block as other stack
155 /// objects. Objects with differing stack IDs should not be merged or
156 /// replaced substituted for each other.
157 //
158 /// It is assumed a target uses consecutive, increasing stack IDs starting
159 /// from 1.
160 uint8_t StackID;
161
162 /// If this stack object is originated from an Alloca instruction
163 /// this value saves the original IR allocation. Can be NULL.
164 const AllocaInst *Alloca;
165
166 // If true, the object was mapped into the local frame
167 // block and doesn't need additional handling for allocation beyond that.
168 bool PreAllocated = false;
169
170 // If true, an LLVM IR value might point to this object.
171 // Normally, spill slots and fixed-offset objects don't alias IR-accessible
172 // objects, but there are exceptions (on PowerPC, for example, some byval
173 // arguments have ABI-prescribed offsets).
174 bool isAliased;
175
176 /// If true, the object has been zero-extended.
177 bool isZExt = false;
178
179 /// If true, the object has been sign-extended.
180 bool isSExt = false;
181
182 uint8_t SSPLayout = SSPLK_None;
183
184 StackObject(uint64_t Size, Align Alignment, int64_t SPOffset,
185 bool IsImmutable, bool IsSpillSlot, const AllocaInst *Alloca,
186 bool IsAliased, uint8_t StackID = 0)
187 : SPOffset(SPOffset), Size(Size), Alignment(Alignment),
188 isImmutable(IsImmutable), isSpillSlot(IsSpillSlot), StackID(StackID),
189 Alloca(Alloca), isAliased(IsAliased) {}
190 };
191
192 /// The alignment of the stack.
193 Align 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 Align MaxAlignment;
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 Align LocalFrameMaxAlign;
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 /// Size of the UnsafeStack Frame
339 uint64_t UnsafeStackSize = 0;
340
341public:
342 explicit MachineFrameInfo(Align StackAlignment, bool StackRealignable,
343 bool ForcedRealign)
344 : StackAlignment(StackAlignment),
345 StackRealignable(StackRealignable), ForcedRealign(ForcedRealign) {}
346
347 MachineFrameInfo(const MachineFrameInfo &) = delete;
348
349 /// Return true if there are any stack objects in this function.
350 bool hasStackObjects() const { return !Objects.empty(); }
351
352 /// This method may be called any time after instruction
353 /// selection is complete to determine if the stack frame for this function
354 /// contains any variable sized objects.
355 bool hasVarSizedObjects() const { return HasVarSizedObjects; }
356
357 /// Return the index for the stack protector object.
358 int getStackProtectorIndex() const { return StackProtectorIdx; }
359 void setStackProtectorIndex(int I) { StackProtectorIdx = I; }
360 bool hasStackProtectorIndex() const { return StackProtectorIdx != -1; }
361
362 /// Return the index for the function context object.
363 /// This object is used for SjLj exceptions.
364 int getFunctionContextIndex() const { return FunctionContextIdx; }
365 void setFunctionContextIndex(int I) { FunctionContextIdx = I; }
366 bool hasFunctionContextIndex() const { return FunctionContextIdx != -1; }
367
368 /// This method may be called any time after instruction
369 /// selection is complete to determine if there is a call to
370 /// \@llvm.frameaddress in this function.
371 bool isFrameAddressTaken() const { return FrameAddressTaken; }
372 void setFrameAddressIsTaken(bool T) { FrameAddressTaken = T; }
373
374 /// This method may be called any time after
375 /// instruction selection is complete to determine if there is a call to
376 /// \@llvm.returnaddress in this function.
377 bool isReturnAddressTaken() const { return ReturnAddressTaken; }
378 void setReturnAddressIsTaken(bool s) { ReturnAddressTaken = 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.stackmap.
383 bool hasStackMap() const { return HasStackMap; }
384 void setHasStackMap(bool s = true) { HasStackMap = s; }
385
386 /// This method may be called any time after instruction
387 /// selection is complete to determine if there is a call to builtin
388 /// \@llvm.experimental.patchpoint.
389 bool hasPatchPoint() const { return HasPatchPoint; }
390 void setHasPatchPoint(bool s = true) { HasPatchPoint = s; }
391
392 /// Return true if this function requires a split stack prolog, even if it
393 /// uses no stack space. This is only meaningful for functions where
394 /// MachineFunction::shouldSplitStack() returns true.
395 //
396 // For non-leaf functions we have to allow for the possibility that the call
397 // is to a non-split function, as in PR37807. This function could also take
398 // the address of a non-split function. When the linker tries to adjust its
399 // non-existent prologue, it would fail with an error. Mark the object file so
400 // that such failures are not errors. See this Go language bug-report
401 // https://go-review.googlesource.com/c/go/+/148819/
402 bool needsSplitStackProlog() const {
403 return getStackSize() != 0 || hasTailCall();
404 }
405
406 /// Return the minimum frame object index.
407 int getObjectIndexBegin() const { return -NumFixedObjects; }
408
409 /// Return one past the maximum frame object index.
410 int getObjectIndexEnd() const { return (int)Objects.size()-NumFixedObjects; }
411
412 /// Return the number of fixed objects.
413 unsigned getNumFixedObjects() const { return NumFixedObjects; }
414
415 /// Return the number of objects.
416 unsigned getNumObjects() const { return Objects.size(); }
417
418 /// Map a frame index into the local object block
419 void mapLocalFrameObject(int ObjectIndex, int64_t Offset) {
420 LocalFrameObjects.push_back(Elt: std::pair<int, int64_t>(ObjectIndex, Offset));
421 Objects[ObjectIndex + NumFixedObjects].PreAllocated = true;
422 }
423
424 /// Get the local offset mapping for a for an object.
425 std::pair<int, int64_t> getLocalFrameObjectMap(int i) const {
426 assert (i >= 0 && (unsigned)i < LocalFrameObjects.size() &&
427 "Invalid local object reference!");
428 return LocalFrameObjects[i];
429 }
430
431 /// Return the number of objects allocated into the local object block.
432 int64_t getLocalFrameObjectCount() const { return LocalFrameObjects.size(); }
433
434 /// Set the size of the local object blob.
435 void setLocalFrameSize(int64_t sz) { LocalFrameSize = sz; }
436
437 /// Get the size of the local object blob.
438 int64_t getLocalFrameSize() const { return LocalFrameSize; }
439
440 /// Required alignment of the local object blob,
441 /// which is the strictest alignment of any object in it.
442 void setLocalFrameMaxAlign(Align Alignment) {
443 LocalFrameMaxAlign = Alignment;
444 }
445
446 /// Return the required alignment of the local object blob.
447 Align getLocalFrameMaxAlign() const { return LocalFrameMaxAlign; }
448
449 /// Get whether the local allocation blob should be allocated together or
450 /// let PEI allocate the locals in it directly.
451 bool getUseLocalStackAllocationBlock() const {
452 return UseLocalStackAllocationBlock;
453 }
454
455 /// setUseLocalStackAllocationBlock - Set whether the local allocation blob
456 /// should be allocated together or let PEI allocate the locals in it
457 /// directly.
458 void setUseLocalStackAllocationBlock(bool v) {
459 UseLocalStackAllocationBlock = v;
460 }
461
462 /// Return true if the object was pre-allocated into the local block.
463 bool isObjectPreAllocated(int ObjectIdx) const {
464 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
465 "Invalid Object Idx!");
466 return Objects[ObjectIdx+NumFixedObjects].PreAllocated;
467 }
468
469 /// Return the size of the specified object.
470 int64_t getObjectSize(int ObjectIdx) const {
471 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
472 "Invalid Object Idx!");
473 return Objects[ObjectIdx+NumFixedObjects].Size;
474 }
475
476 /// Change the size of the specified stack object.
477 void setObjectSize(int ObjectIdx, int64_t Size) {
478 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
479 "Invalid Object Idx!");
480 Objects[ObjectIdx+NumFixedObjects].Size = Size;
481 }
482
483 /// Return the alignment of the specified stack object.
484 Align getObjectAlign(int ObjectIdx) const {
485 assert(unsigned(ObjectIdx + NumFixedObjects) < Objects.size() &&
486 "Invalid Object Idx!");
487 return Objects[ObjectIdx + NumFixedObjects].Alignment;
488 }
489
490 /// Should this stack ID be considered in MaxAlignment.
491 bool contributesToMaxAlignment(uint8_t StackID) {
492 return StackID == TargetStackID::Default ||
493 StackID == TargetStackID::ScalableVector;
494 }
495
496 /// setObjectAlignment - Change the alignment of the specified stack object.
497 void setObjectAlignment(int ObjectIdx, Align Alignment) {
498 assert(unsigned(ObjectIdx + NumFixedObjects) < Objects.size() &&
499 "Invalid Object Idx!");
500 Objects[ObjectIdx + NumFixedObjects].Alignment = Alignment;
501
502 // Only ensure max alignment for the default and scalable vector stack.
503 uint8_t StackID = getStackID(ObjectIdx);
504 if (contributesToMaxAlignment(StackID))
505 ensureMaxAlignment(Alignment);
506 }
507
508 /// Return the underlying Alloca of the specified
509 /// stack object if it exists. Returns 0 if none exists.
510 const AllocaInst* getObjectAllocation(int ObjectIdx) const {
511 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
512 "Invalid Object Idx!");
513 return Objects[ObjectIdx+NumFixedObjects].Alloca;
514 }
515
516 /// Remove the underlying Alloca of the specified stack object if it
517 /// exists. This generally should not be used and is for reduction tooling.
518 void clearObjectAllocation(int ObjectIdx) {
519 assert(unsigned(ObjectIdx + NumFixedObjects) < Objects.size() &&
520 "Invalid Object Idx!");
521 Objects[ObjectIdx + NumFixedObjects].Alloca = nullptr;
522 }
523
524 /// Return the assigned stack offset of the specified object
525 /// from the incoming stack pointer.
526 int64_t getObjectOffset(int ObjectIdx) const {
527 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
528 "Invalid Object Idx!");
529 assert(!isDeadObjectIndex(ObjectIdx) &&
530 "Getting frame offset for a dead object?");
531 return Objects[ObjectIdx+NumFixedObjects].SPOffset;
532 }
533
534 bool isObjectZExt(int ObjectIdx) const {
535 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
536 "Invalid Object Idx!");
537 return Objects[ObjectIdx+NumFixedObjects].isZExt;
538 }
539
540 void setObjectZExt(int ObjectIdx, bool IsZExt) {
541 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
542 "Invalid Object Idx!");
543 Objects[ObjectIdx+NumFixedObjects].isZExt = IsZExt;
544 }
545
546 bool isObjectSExt(int ObjectIdx) const {
547 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
548 "Invalid Object Idx!");
549 return Objects[ObjectIdx+NumFixedObjects].isSExt;
550 }
551
552 void setObjectSExt(int ObjectIdx, bool IsSExt) {
553 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
554 "Invalid Object Idx!");
555 Objects[ObjectIdx+NumFixedObjects].isSExt = IsSExt;
556 }
557
558 /// Set the stack frame offset of the specified object. The
559 /// offset is relative to the stack pointer on entry to the function.
560 void setObjectOffset(int ObjectIdx, int64_t SPOffset) {
561 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
562 "Invalid Object Idx!");
563 assert(!isDeadObjectIndex(ObjectIdx) &&
564 "Setting frame offset for a dead object?");
565 Objects[ObjectIdx+NumFixedObjects].SPOffset = SPOffset;
566 }
567
568 SSPLayoutKind getObjectSSPLayout(int ObjectIdx) const {
569 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
570 "Invalid Object Idx!");
571 return (SSPLayoutKind)Objects[ObjectIdx+NumFixedObjects].SSPLayout;
572 }
573
574 void setObjectSSPLayout(int ObjectIdx, SSPLayoutKind Kind) {
575 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
576 "Invalid Object Idx!");
577 assert(!isDeadObjectIndex(ObjectIdx) &&
578 "Setting SSP layout for a dead object?");
579 Objects[ObjectIdx+NumFixedObjects].SSPLayout = Kind;
580 }
581
582 /// Return the number of bytes that must be allocated to hold
583 /// all of the fixed size frame objects. This is only valid after
584 /// Prolog/Epilog code insertion has finalized the stack frame layout.
585 uint64_t getStackSize() const { return StackSize; }
586
587 /// Set the size of the stack.
588 void setStackSize(uint64_t Size) { StackSize = Size; }
589
590 /// Estimate and return the size of the stack frame.
591 uint64_t estimateStackSize(const MachineFunction &MF) const;
592
593 /// Return the correction for frame offsets.
594 int getOffsetAdjustment() const { return OffsetAdjustment; }
595
596 /// Set the correction for frame offsets.
597 void setOffsetAdjustment(int Adj) { OffsetAdjustment = Adj; }
598
599 /// Return the alignment in bytes that this function must be aligned to,
600 /// which is greater than the default stack alignment provided by the target.
601 Align getMaxAlign() const { return MaxAlignment; }
602
603 /// Make sure the function is at least Align bytes aligned.
604 void ensureMaxAlignment(Align Alignment);
605
606 /// Return true if this function adjusts the stack -- e.g.,
607 /// when calling another function. This is only valid during and after
608 /// prolog/epilog code insertion.
609 bool adjustsStack() const { return AdjustsStack; }
610 void setAdjustsStack(bool V) { AdjustsStack = V; }
611
612 /// Return true if the current function has any function calls.
613 bool hasCalls() const { return HasCalls; }
614 void setHasCalls(bool V) { HasCalls = V; }
615
616 /// Returns true if the function contains opaque dynamic stack adjustments.
617 bool hasOpaqueSPAdjustment() const { return HasOpaqueSPAdjustment; }
618 void setHasOpaqueSPAdjustment(bool B) { HasOpaqueSPAdjustment = B; }
619
620 /// Returns true if the function contains operations which will lower down to
621 /// instructions which manipulate the stack pointer.
622 bool hasCopyImplyingStackAdjustment() const {
623 return HasCopyImplyingStackAdjustment;
624 }
625 void setHasCopyImplyingStackAdjustment(bool B) {
626 HasCopyImplyingStackAdjustment = B;
627 }
628
629 /// Returns true if the function calls the llvm.va_start intrinsic.
630 bool hasVAStart() const { return HasVAStart; }
631 void setHasVAStart(bool B) { HasVAStart = B; }
632
633 /// Returns true if the function is variadic and contains a musttail call.
634 bool hasMustTailInVarArgFunc() const { return HasMustTailInVarArgFunc; }
635 void setHasMustTailInVarArgFunc(bool B) { HasMustTailInVarArgFunc = B; }
636
637 /// Returns true if the function contains a tail call.
638 bool hasTailCall() const { return HasTailCall; }
639 void setHasTailCall(bool V = true) { HasTailCall = V; }
640
641 /// Computes the maximum size of a callframe and the AdjustsStack property.
642 /// This only works for targets defining
643 /// TargetInstrInfo::getCallFrameSetupOpcode(), getCallFrameDestroyOpcode(),
644 /// and getFrameSize().
645 /// This is usually computed by the prologue epilogue inserter but some
646 /// targets may call this to compute it earlier.
647 void computeMaxCallFrameSize(const MachineFunction &MF);
648
649 /// Return the maximum size of a call frame that must be
650 /// allocated for an outgoing function call. This is only available if
651 /// CallFrameSetup/Destroy pseudo instructions are used by the target, and
652 /// then only during or after prolog/epilog code insertion.
653 ///
654 unsigned getMaxCallFrameSize() const {
655 // TODO: Enable this assert when targets are fixed.
656 //assert(isMaxCallFrameSizeComputed() && "MaxCallFrameSize not computed yet");
657 if (!isMaxCallFrameSizeComputed())
658 return 0;
659 return MaxCallFrameSize;
660 }
661 bool isMaxCallFrameSizeComputed() const {
662 return MaxCallFrameSize != ~0u;
663 }
664 void setMaxCallFrameSize(unsigned S) { MaxCallFrameSize = S; }
665
666 /// Returns how many bytes of callee-saved registers the target pushed in the
667 /// prologue. Only used for debug info.
668 unsigned getCVBytesOfCalleeSavedRegisters() const {
669 return CVBytesOfCalleeSavedRegisters;
670 }
671 void setCVBytesOfCalleeSavedRegisters(unsigned S) {
672 CVBytesOfCalleeSavedRegisters = S;
673 }
674
675 /// Create a new object at a fixed location on the stack.
676 /// All fixed objects should be created before other objects are created for
677 /// efficiency. By default, fixed objects are not pointed to by LLVM IR
678 /// values. This returns an index with a negative value.
679 int CreateFixedObject(uint64_t Size, int64_t SPOffset, bool IsImmutable,
680 bool isAliased = false);
681
682 /// Create a spill slot at a fixed location on the stack.
683 /// Returns an index with a negative value.
684 int CreateFixedSpillStackObject(uint64_t Size, int64_t SPOffset,
685 bool IsImmutable = false);
686
687 /// Returns true if the specified index corresponds to a fixed stack object.
688 bool isFixedObjectIndex(int ObjectIdx) const {
689 return ObjectIdx < 0 && (ObjectIdx >= -(int)NumFixedObjects);
690 }
691
692 /// Returns true if the specified index corresponds
693 /// to an object that might be pointed to by an LLVM IR value.
694 bool isAliasedObjectIndex(int ObjectIdx) const {
695 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
696 "Invalid Object Idx!");
697 return Objects[ObjectIdx+NumFixedObjects].isAliased;
698 }
699
700 /// Returns true if the specified index corresponds to an immutable object.
701 bool isImmutableObjectIndex(int ObjectIdx) const {
702 // Tail calling functions can clobber their function arguments.
703 if (HasTailCall)
704 return false;
705 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
706 "Invalid Object Idx!");
707 return Objects[ObjectIdx+NumFixedObjects].isImmutable;
708 }
709
710 /// Marks the immutability of an object.
711 void setIsImmutableObjectIndex(int ObjectIdx, bool IsImmutable) {
712 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
713 "Invalid Object Idx!");
714 Objects[ObjectIdx+NumFixedObjects].isImmutable = IsImmutable;
715 }
716
717 /// Returns true if the specified index corresponds to a spill slot.
718 bool isSpillSlotObjectIndex(int ObjectIdx) const {
719 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
720 "Invalid Object Idx!");
721 return Objects[ObjectIdx+NumFixedObjects].isSpillSlot;
722 }
723
724 bool isStatepointSpillSlotObjectIndex(int ObjectIdx) const {
725 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
726 "Invalid Object Idx!");
727 return Objects[ObjectIdx+NumFixedObjects].isStatepointSpillSlot;
728 }
729
730 /// \see StackID
731 uint8_t getStackID(int ObjectIdx) const {
732 return Objects[ObjectIdx+NumFixedObjects].StackID;
733 }
734
735 /// \see StackID
736 void setStackID(int ObjectIdx, uint8_t ID) {
737 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
738 "Invalid Object Idx!");
739 Objects[ObjectIdx+NumFixedObjects].StackID = ID;
740 // If ID > 0, MaxAlignment may now be overly conservative.
741 // If ID == 0, MaxAlignment will need to be updated separately.
742 }
743
744 /// Returns true if the specified index corresponds to a dead object.
745 bool isDeadObjectIndex(int ObjectIdx) const {
746 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
747 "Invalid Object Idx!");
748 return Objects[ObjectIdx+NumFixedObjects].Size == ~0ULL;
749 }
750
751 /// Returns true if the specified index corresponds to a variable sized
752 /// object.
753 bool isVariableSizedObjectIndex(int ObjectIdx) const {
754 assert(unsigned(ObjectIdx + NumFixedObjects) < Objects.size() &&
755 "Invalid Object Idx!");
756 return Objects[ObjectIdx + NumFixedObjects].Size == 0;
757 }
758
759 void markAsStatepointSpillSlotObjectIndex(int ObjectIdx) {
760 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
761 "Invalid Object Idx!");
762 Objects[ObjectIdx+NumFixedObjects].isStatepointSpillSlot = true;
763 assert(isStatepointSpillSlotObjectIndex(ObjectIdx) && "inconsistent");
764 }
765
766 /// Create a new statically sized stack object, returning
767 /// a nonnegative identifier to represent it.
768 int CreateStackObject(uint64_t Size, Align Alignment, bool isSpillSlot,
769 const AllocaInst *Alloca = nullptr, uint8_t ID = 0);
770
771 /// Create a new statically sized stack object that represents a spill slot,
772 /// returning a nonnegative identifier to represent it.
773 int CreateSpillStackObject(uint64_t Size, Align Alignment);
774
775 /// Remove or mark dead a statically sized stack object.
776 void RemoveStackObject(int ObjectIdx) {
777 // Mark it dead.
778 Objects[ObjectIdx+NumFixedObjects].Size = ~0ULL;
779 }
780
781 /// Notify the MachineFrameInfo object that a variable sized object has been
782 /// created. This must be created whenever a variable sized object is
783 /// created, whether or not the index returned is actually used.
784 int CreateVariableSizedObject(Align Alignment, const AllocaInst *Alloca);
785
786 /// Returns a reference to call saved info vector for the current function.
787 const std::vector<CalleeSavedInfo> &getCalleeSavedInfo() const {
788 return CSInfo;
789 }
790 /// \copydoc getCalleeSavedInfo()
791 std::vector<CalleeSavedInfo> &getCalleeSavedInfo() { return CSInfo; }
792
793 /// Used by prolog/epilog inserter to set the function's callee saved
794 /// information.
795 void setCalleeSavedInfo(std::vector<CalleeSavedInfo> CSI) {
796 CSInfo = std::move(CSI);
797 }
798
799 /// Has the callee saved info been calculated yet?
800 bool isCalleeSavedInfoValid() const { return CSIValid; }
801
802 void setCalleeSavedInfoValid(bool v) { CSIValid = v; }
803
804 MachineBasicBlock *getSavePoint() const { return Save; }
805 void setSavePoint(MachineBasicBlock *NewSave) { Save = NewSave; }
806 MachineBasicBlock *getRestorePoint() const { return Restore; }
807 void setRestorePoint(MachineBasicBlock *NewRestore) { Restore = NewRestore; }
808
809 uint64_t getUnsafeStackSize() const { return UnsafeStackSize; }
810 void setUnsafeStackSize(uint64_t Size) { UnsafeStackSize = Size; }
811
812 /// Return a set of physical registers that are pristine.
813 ///
814 /// Pristine registers hold a value that is useless to the current function,
815 /// but that must be preserved - they are callee saved registers that are not
816 /// saved.
817 ///
818 /// Before the PrologueEpilogueInserter has placed the CSR spill code, this
819 /// method always returns an empty set.
820 BitVector getPristineRegs(const MachineFunction &MF) const;
821
822 /// Used by the MachineFunction printer to print information about
823 /// stack objects. Implemented in MachineFunction.cpp.
824 void print(const MachineFunction &MF, raw_ostream &OS) const;
825
826 /// dump - Print the function to stderr.
827 void dump(const MachineFunction &MF) const;
828};
829
830} // End llvm namespace
831
832#endif
833

source code of llvm/include/llvm/CodeGen/MachineFrameInfo.h