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 "llvm/Support/Compiler.h"
21#include <cassert>
22#include <vector>
23
24namespace llvm {
25class raw_ostream;
26class MachineFunction;
27class MachineBasicBlock;
28class BitVector;
29class AllocaInst;
30
31/// The CalleeSavedInfo class tracks the information need to locate where a
32/// callee saved register is in the current frame.
33/// Callee saved reg can also be saved to a different register rather than
34/// on the stack by setting DstReg instead of FrameIdx.
35class CalleeSavedInfo {
36 MCRegister Reg;
37 union {
38 int FrameIdx;
39 unsigned DstReg;
40 };
41 /// Flag indicating whether the register is actually restored in the epilog.
42 /// In most cases, if a register is saved, it is also restored. There are
43 /// some situations, though, when this is not the case. For example, the
44 /// LR register on ARM is usually saved, but on exit from the function its
45 /// saved value may be loaded directly into PC. Since liveness tracking of
46 /// physical registers treats callee-saved registers are live outside of
47 /// the function, LR would be treated as live-on-exit, even though in these
48 /// scenarios it is not. This flag is added to indicate that the saved
49 /// register described by this object is not restored in the epilog.
50 /// The long-term solution is to model the liveness of callee-saved registers
51 /// by implicit uses on the return instructions, however, the required
52 /// changes in the ARM backend would be quite extensive.
53 bool Restored = true;
54 /// Flag indicating whether the register is spilled to stack or another
55 /// register.
56 bool SpilledToReg = false;
57
58public:
59 explicit CalleeSavedInfo(MCRegister R, int FI = 0) : Reg(R), FrameIdx(FI) {}
60
61 // Accessors.
62 MCRegister getReg() const { return Reg; }
63 int getFrameIdx() const { return FrameIdx; }
64 MCRegister getDstReg() const { return DstReg; }
65 void setReg(MCRegister R) { Reg = R; }
66 void setFrameIdx(int FI) {
67 FrameIdx = FI;
68 SpilledToReg = false;
69 }
70 void setDstReg(MCRegister SpillReg) {
71 DstReg = SpillReg.id();
72 SpilledToReg = true;
73 }
74 bool isRestored() const { return Restored; }
75 void setRestored(bool R) { Restored = R; }
76 bool isSpilledToReg() const { return SpilledToReg; }
77};
78
79/// The MachineFrameInfo class represents an abstract stack frame until
80/// prolog/epilog code is inserted. This class is key to allowing stack frame
81/// representation optimizations, such as frame pointer elimination. It also
82/// allows more mundane (but still important) optimizations, such as reordering
83/// of abstract objects on the stack frame.
84///
85/// To support this, the class assigns unique integer identifiers to stack
86/// objects requested clients. These identifiers are negative integers for
87/// fixed stack objects (such as arguments passed on the stack) or nonnegative
88/// for objects that may be reordered. Instructions which refer to stack
89/// objects use a special MO_FrameIndex operand to represent these frame
90/// indexes.
91///
92/// Because this class keeps track of all references to the stack frame, it
93/// knows when a variable sized object is allocated on the stack. This is the
94/// sole condition which prevents frame pointer elimination, which is an
95/// important optimization on register-poor architectures. Because original
96/// variable sized alloca's in the source program are the only source of
97/// variable sized stack objects, it is safe to decide whether there will be
98/// any variable sized objects before all stack objects are known (for
99/// example, register allocator spill code never needs variable sized
100/// objects).
101///
102/// When prolog/epilog code emission is performed, the final stack frame is
103/// built and the machine instructions are modified to refer to the actual
104/// stack offsets of the object, eliminating all MO_FrameIndex operands from
105/// the program.
106///
107/// Abstract Stack Frame Information
108class MachineFrameInfo {
109public:
110 /// Stack Smashing Protection (SSP) rules require that vulnerable stack
111 /// allocations are located close the stack protector.
112 enum SSPLayoutKind {
113 SSPLK_None, ///< Did not trigger a stack protector. No effect on data
114 ///< layout.
115 SSPLK_LargeArray, ///< Array or nested array >= SSP-buffer-size. Closest
116 ///< to the stack protector.
117 SSPLK_SmallArray, ///< Array or nested array < SSP-buffer-size. 2nd closest
118 ///< to the stack protector.
119 SSPLK_AddrOf ///< The address of this allocation is exposed and
120 ///< triggered protection. 3rd closest to the protector.
121 };
122
123private:
124 // Represent a single object allocated on the stack.
125 struct StackObject {
126 // The offset of this object from the stack pointer on entry to
127 // the function. This field has no meaning for a variable sized element.
128 int64_t SPOffset;
129
130 // The size of this object on the stack. 0 means a variable sized object,
131 // ~0ULL means a dead object.
132 uint64_t Size;
133
134 // The required alignment of this stack slot.
135 Align Alignment;
136
137 // If true, the value of the stack object is set before
138 // entering the function and is not modified inside the function. By
139 // default, fixed objects are immutable unless marked otherwise.
140 bool isImmutable;
141
142 // If true the stack object is used as spill slot. It
143 // cannot alias any other memory objects.
144 bool isSpillSlot;
145
146 /// If true, this stack slot is used to spill a value (could be deopt
147 /// and/or GC related) over a statepoint. We know that the address of the
148 /// slot can't alias any LLVM IR value. This is very similar to a Spill
149 /// Slot, but is created by statepoint lowering is SelectionDAG, not the
150 /// register allocator.
151 bool isStatepointSpillSlot = false;
152
153 /// Identifier for stack memory type analagous to address space. If this is
154 /// non-0, the meaning is target defined. Offsets cannot be directly
155 /// compared between objects with different stack IDs. The object may not
156 /// necessarily reside in the same contiguous memory block as other stack
157 /// objects. Objects with differing stack IDs should not be merged or
158 /// replaced substituted for each other.
159 //
160 /// It is assumed a target uses consecutive, increasing stack IDs starting
161 /// from 1.
162 uint8_t StackID;
163
164 /// If this stack object is originated from an Alloca instruction
165 /// this value saves the original IR allocation. Can be NULL.
166 const AllocaInst *Alloca;
167
168 // If true, the object was mapped into the local frame
169 // block and doesn't need additional handling for allocation beyond that.
170 bool PreAllocated = false;
171
172 // If true, an LLVM IR value might point to this object.
173 // Normally, spill slots and fixed-offset objects don't alias IR-accessible
174 // objects, but there are exceptions (on PowerPC, for example, some byval
175 // arguments have ABI-prescribed offsets).
176 bool isAliased;
177
178 /// If true, the object has been zero-extended.
179 bool isZExt = false;
180
181 /// If true, the object has been sign-extended.
182 bool isSExt = false;
183
184 uint8_t SSPLayout = SSPLK_None;
185
186 StackObject(uint64_t Size, Align Alignment, int64_t SPOffset,
187 bool IsImmutable, bool IsSpillSlot, const AllocaInst *Alloca,
188 bool IsAliased, uint8_t StackID = 0)
189 : SPOffset(SPOffset), Size(Size), Alignment(Alignment),
190 isImmutable(IsImmutable), isSpillSlot(IsSpillSlot), StackID(StackID),
191 Alloca(Alloca), isAliased(IsAliased) {}
192 };
193
194 /// The alignment of the stack.
195 Align StackAlignment;
196
197 /// Can the stack be realigned. This can be false if the target does not
198 /// support stack realignment, or if the user asks us not to realign the
199 /// stack. In this situation, overaligned allocas are all treated as dynamic
200 /// allocations and the target must handle them as part of DYNAMIC_STACKALLOC
201 /// lowering. All non-alloca stack objects have their alignment clamped to the
202 /// base ABI stack alignment.
203 /// FIXME: There is room for improvement in this case, in terms of
204 /// grouping overaligned allocas into a "secondary stack frame" and
205 /// then only use a single alloca to allocate this frame and only a
206 /// single virtual register to access it. Currently, without such an
207 /// optimization, each such alloca gets its own dynamic realignment.
208 bool StackRealignable;
209
210 /// Whether the function has the \c alignstack attribute.
211 bool ForcedRealign;
212
213 /// The list of stack objects allocated.
214 std::vector<StackObject> Objects;
215
216 /// This contains the number of fixed objects contained on
217 /// the stack. Because fixed objects are stored at a negative index in the
218 /// Objects list, this is also the index to the 0th object in the list.
219 unsigned NumFixedObjects = 0;
220
221 /// This boolean keeps track of whether any variable
222 /// sized objects have been allocated yet.
223 bool HasVarSizedObjects = false;
224
225 /// This boolean keeps track of whether there is a call
226 /// to builtin \@llvm.frameaddress.
227 bool FrameAddressTaken = false;
228
229 /// This boolean keeps track of whether there is a call
230 /// to builtin \@llvm.returnaddress.
231 bool ReturnAddressTaken = false;
232
233 /// This boolean keeps track of whether there is a call
234 /// to builtin \@llvm.experimental.stackmap.
235 bool HasStackMap = false;
236
237 /// This boolean keeps track of whether there is a call
238 /// to builtin \@llvm.experimental.patchpoint.
239 bool HasPatchPoint = false;
240
241 /// The prolog/epilog code inserter calculates the final stack
242 /// offsets for all of the fixed size objects, updating the Objects list
243 /// above. It then updates StackSize to contain the number of bytes that need
244 /// to be allocated on entry to the function.
245 uint64_t StackSize = 0;
246
247 /// The amount that a frame offset needs to be adjusted to
248 /// have the actual offset from the stack/frame pointer. The exact usage of
249 /// this is target-dependent, but it is typically used to adjust between
250 /// SP-relative and FP-relative offsets. E.G., if objects are accessed via
251 /// SP then OffsetAdjustment is zero; if FP is used, OffsetAdjustment is set
252 /// to the distance between the initial SP and the value in FP. For many
253 /// targets, this value is only used when generating debug info (via
254 /// TargetRegisterInfo::getFrameIndexReference); when generating code, the
255 /// corresponding adjustments are performed directly.
256 int64_t OffsetAdjustment = 0;
257
258 /// The prolog/epilog code inserter may process objects that require greater
259 /// alignment than the default alignment the target provides.
260 /// To handle this, MaxAlignment is set to the maximum alignment
261 /// needed by the objects on the current frame. If this is greater than the
262 /// native alignment maintained by the compiler, dynamic alignment code will
263 /// be needed.
264 ///
265 Align MaxAlignment;
266
267 /// Set to true if this function adjusts the stack -- e.g.,
268 /// when calling another function. This is only valid during and after
269 /// prolog/epilog code insertion.
270 bool AdjustsStack = false;
271
272 /// Set to true if this function has any function calls.
273 bool HasCalls = false;
274
275 /// The frame index for the stack protector.
276 int StackProtectorIdx = -1;
277
278 /// The frame index for the function context. Used for SjLj exceptions.
279 int FunctionContextIdx = -1;
280
281 /// This contains the size of the largest call frame if the target uses frame
282 /// setup/destroy pseudo instructions (as defined in the TargetFrameInfo
283 /// class). This information is important for frame pointer elimination.
284 /// It is only valid during and after prolog/epilog code insertion.
285 uint64_t MaxCallFrameSize = ~UINT64_C(0);
286
287 /// The number of bytes of callee saved registers that the target wants to
288 /// report for the current function in the CodeView S_FRAMEPROC record.
289 unsigned CVBytesOfCalleeSavedRegisters = 0;
290
291 /// The prolog/epilog code inserter fills in this vector with each
292 /// callee saved register saved in either the frame or a different
293 /// register. Beyond its use by the prolog/ epilog code inserter,
294 /// this data is used for debug info and exception handling.
295 std::vector<CalleeSavedInfo> CSInfo;
296
297 /// Has CSInfo been set yet?
298 bool CSIValid = false;
299
300 /// References to frame indices which are mapped
301 /// into the local frame allocation block. <FrameIdx, LocalOffset>
302 SmallVector<std::pair<int, int64_t>, 32> LocalFrameObjects;
303
304 /// Size of the pre-allocated local frame block.
305 int64_t LocalFrameSize = 0;
306
307 /// Required alignment of the local object blob, which is the strictest
308 /// alignment of any object in it.
309 Align LocalFrameMaxAlign;
310
311 /// Whether the local object blob needs to be allocated together. If not,
312 /// PEI should ignore the isPreAllocated flags on the stack objects and
313 /// just allocate them normally.
314 bool UseLocalStackAllocationBlock = false;
315
316 /// True if the function dynamically adjusts the stack pointer through some
317 /// opaque mechanism like inline assembly or Win32 EH.
318 bool HasOpaqueSPAdjustment = false;
319
320 /// True if the function contains operations which will lower down to
321 /// instructions which manipulate the stack pointer.
322 bool HasCopyImplyingStackAdjustment = false;
323
324 /// True if the function contains a call to the llvm.vastart intrinsic.
325 bool HasVAStart = false;
326
327 /// True if this is a varargs function that contains a musttail call.
328 bool HasMustTailInVarArgFunc = false;
329
330 /// True if this function contains a tail call. If so immutable objects like
331 /// function arguments are no longer so. A tail call *can* override fixed
332 /// stack objects like arguments so we can't treat them as immutable.
333 bool HasTailCall = false;
334
335 /// Not null, if shrink-wrapping found a better place for the prologue.
336 MachineBasicBlock *Save = nullptr;
337 /// Not null, if shrink-wrapping found a better place for the epilogue.
338 MachineBasicBlock *Restore = nullptr;
339
340 /// Size of the UnsafeStack Frame
341 uint64_t UnsafeStackSize = 0;
342
343public:
344 explicit MachineFrameInfo(Align StackAlignment, bool StackRealignable,
345 bool ForcedRealign)
346 : StackAlignment(StackAlignment),
347 StackRealignable(StackRealignable), ForcedRealign(ForcedRealign) {}
348
349 MachineFrameInfo(const MachineFrameInfo &) = delete;
350
351 bool isStackRealignable() const { return StackRealignable; }
352
353 /// Return true if there are any stack objects in this function.
354 bool hasStackObjects() const { return !Objects.empty(); }
355
356 /// This method may be called any time after instruction
357 /// selection is complete to determine if the stack frame for this function
358 /// contains any variable sized objects.
359 bool hasVarSizedObjects() const { return HasVarSizedObjects; }
360
361 /// Return the index for the stack protector object.
362 int getStackProtectorIndex() const { return StackProtectorIdx; }
363 void setStackProtectorIndex(int I) { StackProtectorIdx = I; }
364 bool hasStackProtectorIndex() const { return StackProtectorIdx != -1; }
365
366 /// Return the index for the function context object.
367 /// This object is used for SjLj exceptions.
368 int getFunctionContextIndex() const { return FunctionContextIdx; }
369 void setFunctionContextIndex(int I) { FunctionContextIdx = I; }
370 bool hasFunctionContextIndex() const { return FunctionContextIdx != -1; }
371
372 /// This method may be called any time after instruction
373 /// selection is complete to determine if there is a call to
374 /// \@llvm.frameaddress in this function.
375 bool isFrameAddressTaken() const { return FrameAddressTaken; }
376 void setFrameAddressIsTaken(bool T) { FrameAddressTaken = T; }
377
378 /// This method may be called any time after
379 /// instruction selection is complete to determine if there is a call to
380 /// \@llvm.returnaddress in this function.
381 bool isReturnAddressTaken() const { return ReturnAddressTaken; }
382 void setReturnAddressIsTaken(bool s) { ReturnAddressTaken = s; }
383
384 /// This method may be called any time after instruction
385 /// selection is complete to determine if there is a call to builtin
386 /// \@llvm.experimental.stackmap.
387 bool hasStackMap() const { return HasStackMap; }
388 void setHasStackMap(bool s = true) { HasStackMap = s; }
389
390 /// This method may be called any time after instruction
391 /// selection is complete to determine if there is a call to builtin
392 /// \@llvm.experimental.patchpoint.
393 bool hasPatchPoint() const { return HasPatchPoint; }
394 void setHasPatchPoint(bool s = true) { HasPatchPoint = s; }
395
396 /// Return true if this function requires a split stack prolog, even if it
397 /// uses no stack space. This is only meaningful for functions where
398 /// MachineFunction::shouldSplitStack() returns true.
399 //
400 // For non-leaf functions we have to allow for the possibility that the call
401 // is to a non-split function, as in PR37807. This function could also take
402 // the address of a non-split function. When the linker tries to adjust its
403 // non-existent prologue, it would fail with an error. Mark the object file so
404 // that such failures are not errors. See this Go language bug-report
405 // https://go-review.googlesource.com/c/go/+/148819/
406 bool needsSplitStackProlog() const {
407 return getStackSize() != 0 || hasTailCall();
408 }
409
410 /// Return the minimum frame object index.
411 int getObjectIndexBegin() const { return -NumFixedObjects; }
412
413 /// Return one past the maximum frame object index.
414 int getObjectIndexEnd() const { return (int)Objects.size()-NumFixedObjects; }
415
416 /// Return the number of fixed objects.
417 unsigned getNumFixedObjects() const { return NumFixedObjects; }
418
419 /// Return the number of objects.
420 unsigned getNumObjects() const { return Objects.size(); }
421
422 /// Map a frame index into the local object block
423 void mapLocalFrameObject(int ObjectIndex, int64_t Offset) {
424 LocalFrameObjects.push_back(Elt: std::pair<int, int64_t>(ObjectIndex, Offset));
425 Objects[ObjectIndex + NumFixedObjects].PreAllocated = true;
426 }
427
428 /// Get the local offset mapping for a for an object.
429 std::pair<int, int64_t> getLocalFrameObjectMap(int i) const {
430 assert (i >= 0 && (unsigned)i < LocalFrameObjects.size() &&
431 "Invalid local object reference!");
432 return LocalFrameObjects[i];
433 }
434
435 /// Return the number of objects allocated into the local object block.
436 int64_t getLocalFrameObjectCount() const { return LocalFrameObjects.size(); }
437
438 /// Set the size of the local object blob.
439 void setLocalFrameSize(int64_t sz) { LocalFrameSize = sz; }
440
441 /// Get the size of the local object blob.
442 int64_t getLocalFrameSize() const { return LocalFrameSize; }
443
444 /// Required alignment of the local object blob,
445 /// which is the strictest alignment of any object in it.
446 void setLocalFrameMaxAlign(Align Alignment) {
447 LocalFrameMaxAlign = Alignment;
448 }
449
450 /// Return the required alignment of the local object blob.
451 Align getLocalFrameMaxAlign() const { return LocalFrameMaxAlign; }
452
453 /// Get whether the local allocation blob should be allocated together or
454 /// let PEI allocate the locals in it directly.
455 bool getUseLocalStackAllocationBlock() const {
456 return UseLocalStackAllocationBlock;
457 }
458
459 /// setUseLocalStackAllocationBlock - Set whether the local allocation blob
460 /// should be allocated together or let PEI allocate the locals in it
461 /// directly.
462 void setUseLocalStackAllocationBlock(bool v) {
463 UseLocalStackAllocationBlock = v;
464 }
465
466 /// Return true if the object was pre-allocated into the local block.
467 bool isObjectPreAllocated(int ObjectIdx) const {
468 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
469 "Invalid Object Idx!");
470 return Objects[ObjectIdx+NumFixedObjects].PreAllocated;
471 }
472
473 /// Return the size of the specified object.
474 int64_t getObjectSize(int ObjectIdx) const {
475 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
476 "Invalid Object Idx!");
477 return Objects[ObjectIdx+NumFixedObjects].Size;
478 }
479
480 /// Change the size of the specified stack object.
481 void setObjectSize(int ObjectIdx, int64_t Size) {
482 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
483 "Invalid Object Idx!");
484 Objects[ObjectIdx+NumFixedObjects].Size = Size;
485 }
486
487 /// Return the alignment of the specified stack object.
488 Align getObjectAlign(int ObjectIdx) const {
489 assert(unsigned(ObjectIdx + NumFixedObjects) < Objects.size() &&
490 "Invalid Object Idx!");
491 return Objects[ObjectIdx + NumFixedObjects].Alignment;
492 }
493
494 /// Should this stack ID be considered in MaxAlignment.
495 bool contributesToMaxAlignment(uint8_t StackID) {
496 return StackID == TargetStackID::Default ||
497 StackID == TargetStackID::ScalableVector;
498 }
499
500 /// setObjectAlignment - Change the alignment of the specified stack object.
501 void setObjectAlignment(int ObjectIdx, Align Alignment) {
502 assert(unsigned(ObjectIdx + NumFixedObjects) < Objects.size() &&
503 "Invalid Object Idx!");
504 Objects[ObjectIdx + NumFixedObjects].Alignment = Alignment;
505
506 // Only ensure max alignment for the default and scalable vector stack.
507 uint8_t StackID = getStackID(ObjectIdx);
508 if (contributesToMaxAlignment(StackID))
509 ensureMaxAlignment(Alignment);
510 }
511
512 /// Return the underlying Alloca of the specified
513 /// stack object if it exists. Returns 0 if none exists.
514 const AllocaInst* getObjectAllocation(int ObjectIdx) const {
515 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
516 "Invalid Object Idx!");
517 return Objects[ObjectIdx+NumFixedObjects].Alloca;
518 }
519
520 /// Remove the underlying Alloca of the specified stack object if it
521 /// exists. This generally should not be used and is for reduction tooling.
522 void clearObjectAllocation(int ObjectIdx) {
523 assert(unsigned(ObjectIdx + NumFixedObjects) < Objects.size() &&
524 "Invalid Object Idx!");
525 Objects[ObjectIdx + NumFixedObjects].Alloca = nullptr;
526 }
527
528 /// Return the assigned stack offset of the specified object
529 /// from the incoming stack pointer.
530 int64_t getObjectOffset(int ObjectIdx) const {
531 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
532 "Invalid Object Idx!");
533 assert(!isDeadObjectIndex(ObjectIdx) &&
534 "Getting frame offset for a dead object?");
535 return Objects[ObjectIdx+NumFixedObjects].SPOffset;
536 }
537
538 bool isObjectZExt(int ObjectIdx) const {
539 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
540 "Invalid Object Idx!");
541 return Objects[ObjectIdx+NumFixedObjects].isZExt;
542 }
543
544 void setObjectZExt(int ObjectIdx, bool IsZExt) {
545 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
546 "Invalid Object Idx!");
547 Objects[ObjectIdx+NumFixedObjects].isZExt = IsZExt;
548 }
549
550 bool isObjectSExt(int ObjectIdx) const {
551 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
552 "Invalid Object Idx!");
553 return Objects[ObjectIdx+NumFixedObjects].isSExt;
554 }
555
556 void setObjectSExt(int ObjectIdx, bool IsSExt) {
557 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
558 "Invalid Object Idx!");
559 Objects[ObjectIdx+NumFixedObjects].isSExt = IsSExt;
560 }
561
562 /// Set the stack frame offset of the specified object. The
563 /// offset is relative to the stack pointer on entry to the function.
564 void setObjectOffset(int ObjectIdx, int64_t SPOffset) {
565 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
566 "Invalid Object Idx!");
567 assert(!isDeadObjectIndex(ObjectIdx) &&
568 "Setting frame offset for a dead object?");
569 Objects[ObjectIdx+NumFixedObjects].SPOffset = SPOffset;
570 }
571
572 SSPLayoutKind getObjectSSPLayout(int ObjectIdx) const {
573 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
574 "Invalid Object Idx!");
575 return (SSPLayoutKind)Objects[ObjectIdx+NumFixedObjects].SSPLayout;
576 }
577
578 void setObjectSSPLayout(int ObjectIdx, SSPLayoutKind Kind) {
579 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
580 "Invalid Object Idx!");
581 assert(!isDeadObjectIndex(ObjectIdx) &&
582 "Setting SSP layout for a dead object?");
583 Objects[ObjectIdx+NumFixedObjects].SSPLayout = Kind;
584 }
585
586 /// Return the number of bytes that must be allocated to hold
587 /// all of the fixed size frame objects. This is only valid after
588 /// Prolog/Epilog code insertion has finalized the stack frame layout.
589 uint64_t getStackSize() const { return StackSize; }
590
591 /// Set the size of the stack.
592 void setStackSize(uint64_t Size) { StackSize = Size; }
593
594 /// Estimate and return the size of the stack frame.
595 LLVM_ABI uint64_t estimateStackSize(const MachineFunction &MF) const;
596
597 /// Return the correction for frame offsets.
598 int64_t getOffsetAdjustment() const { return OffsetAdjustment; }
599
600 /// Set the correction for frame offsets.
601 void setOffsetAdjustment(int64_t Adj) { OffsetAdjustment = Adj; }
602
603 /// Return the alignment in bytes that this function must be aligned to,
604 /// which is greater than the default stack alignment provided by the target.
605 Align getMaxAlign() const { return MaxAlignment; }
606
607 /// Make sure the function is at least Align bytes aligned.
608 LLVM_ABI void ensureMaxAlignment(Align Alignment);
609
610 /// Return true if stack realignment is forced by function attributes or if
611 /// the stack alignment.
612 bool shouldRealignStack() const {
613 return ForcedRealign || MaxAlignment > StackAlignment;
614 }
615
616 /// Return true if this function adjusts the stack -- e.g.,
617 /// when calling another function. This is only valid during and after
618 /// prolog/epilog code insertion.
619 bool adjustsStack() const { return AdjustsStack; }
620 void setAdjustsStack(bool V) { AdjustsStack = V; }
621
622 /// Return true if the current function has any function calls.
623 bool hasCalls() const { return HasCalls; }
624 void setHasCalls(bool V) { HasCalls = V; }
625
626 /// Returns true if the function contains opaque dynamic stack adjustments.
627 bool hasOpaqueSPAdjustment() const { return HasOpaqueSPAdjustment; }
628 void setHasOpaqueSPAdjustment(bool B) { HasOpaqueSPAdjustment = B; }
629
630 /// Returns true if the function contains operations which will lower down to
631 /// instructions which manipulate the stack pointer.
632 bool hasCopyImplyingStackAdjustment() const {
633 return HasCopyImplyingStackAdjustment;
634 }
635 void setHasCopyImplyingStackAdjustment(bool B) {
636 HasCopyImplyingStackAdjustment = B;
637 }
638
639 /// Returns true if the function calls the llvm.va_start intrinsic.
640 bool hasVAStart() const { return HasVAStart; }
641 void setHasVAStart(bool B) { HasVAStart = B; }
642
643 /// Returns true if the function is variadic and contains a musttail call.
644 bool hasMustTailInVarArgFunc() const { return HasMustTailInVarArgFunc; }
645 void setHasMustTailInVarArgFunc(bool B) { HasMustTailInVarArgFunc = B; }
646
647 /// Returns true if the function contains a tail call.
648 bool hasTailCall() const { return HasTailCall; }
649 void setHasTailCall(bool V = true) { HasTailCall = V; }
650
651 /// Computes the maximum size of a callframe.
652 /// This only works for targets defining
653 /// TargetInstrInfo::getCallFrameSetupOpcode(), getCallFrameDestroyOpcode(),
654 /// and getFrameSize().
655 /// This is usually computed by the prologue epilogue inserter but some
656 /// targets may call this to compute it earlier.
657 /// If FrameSDOps is passed, the frame instructions in the MF will be
658 /// inserted into it.
659 LLVM_ABI void computeMaxCallFrameSize(
660 MachineFunction &MF,
661 std::vector<MachineBasicBlock::iterator> *FrameSDOps = nullptr);
662
663 /// Return the maximum size of a call frame that must be
664 /// allocated for an outgoing function call. This is only available if
665 /// CallFrameSetup/Destroy pseudo instructions are used by the target, and
666 /// then only during or after prolog/epilog code insertion.
667 ///
668 uint64_t getMaxCallFrameSize() const {
669 // TODO: Enable this assert when targets are fixed.
670 //assert(isMaxCallFrameSizeComputed() && "MaxCallFrameSize not computed yet");
671 if (!isMaxCallFrameSizeComputed())
672 return 0;
673 return MaxCallFrameSize;
674 }
675 bool isMaxCallFrameSizeComputed() const {
676 return MaxCallFrameSize != ~UINT64_C(0);
677 }
678 void setMaxCallFrameSize(uint64_t S) { MaxCallFrameSize = S; }
679
680 /// Returns how many bytes of callee-saved registers the target pushed in the
681 /// prologue. Only used for debug info.
682 unsigned getCVBytesOfCalleeSavedRegisters() const {
683 return CVBytesOfCalleeSavedRegisters;
684 }
685 void setCVBytesOfCalleeSavedRegisters(unsigned S) {
686 CVBytesOfCalleeSavedRegisters = S;
687 }
688
689 /// Create a new object at a fixed location on the stack.
690 /// All fixed objects should be created before other objects are created for
691 /// efficiency. By default, fixed objects are not pointed to by LLVM IR
692 /// values. This returns an index with a negative value.
693 LLVM_ABI int CreateFixedObject(uint64_t Size, int64_t SPOffset,
694 bool IsImmutable, bool isAliased = false);
695
696 /// Create a spill slot at a fixed location on the stack.
697 /// Returns an index with a negative value.
698 LLVM_ABI int CreateFixedSpillStackObject(uint64_t Size, int64_t SPOffset,
699 bool IsImmutable = false);
700
701 /// Returns true if the specified index corresponds to a fixed stack object.
702 bool isFixedObjectIndex(int ObjectIdx) const {
703 return ObjectIdx < 0 && (ObjectIdx >= -(int)NumFixedObjects);
704 }
705
706 /// Returns true if the specified index corresponds
707 /// to an object that might be pointed to by an LLVM IR value.
708 bool isAliasedObjectIndex(int ObjectIdx) const {
709 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
710 "Invalid Object Idx!");
711 return Objects[ObjectIdx+NumFixedObjects].isAliased;
712 }
713
714 /// Set "maybe pointed to by an LLVM IR value" for an object.
715 void setIsAliasedObjectIndex(int ObjectIdx, bool IsAliased) {
716 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
717 "Invalid Object Idx!");
718 Objects[ObjectIdx+NumFixedObjects].isAliased = IsAliased;
719 }
720
721 /// Returns true if the specified index corresponds to an immutable object.
722 bool isImmutableObjectIndex(int ObjectIdx) const {
723 // Tail calling functions can clobber their function arguments.
724 if (HasTailCall)
725 return false;
726 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
727 "Invalid Object Idx!");
728 return Objects[ObjectIdx+NumFixedObjects].isImmutable;
729 }
730
731 /// Marks the immutability of an object.
732 void setIsImmutableObjectIndex(int ObjectIdx, bool IsImmutable) {
733 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
734 "Invalid Object Idx!");
735 Objects[ObjectIdx+NumFixedObjects].isImmutable = IsImmutable;
736 }
737
738 /// Returns true if the specified index corresponds to a spill slot.
739 bool isSpillSlotObjectIndex(int ObjectIdx) const {
740 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
741 "Invalid Object Idx!");
742 return Objects[ObjectIdx+NumFixedObjects].isSpillSlot;
743 }
744
745 bool isStatepointSpillSlotObjectIndex(int ObjectIdx) const {
746 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
747 "Invalid Object Idx!");
748 return Objects[ObjectIdx+NumFixedObjects].isStatepointSpillSlot;
749 }
750
751 /// \see StackID
752 uint8_t getStackID(int ObjectIdx) const {
753 return Objects[ObjectIdx+NumFixedObjects].StackID;
754 }
755
756 /// \see StackID
757 void setStackID(int ObjectIdx, uint8_t ID) {
758 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
759 "Invalid Object Idx!");
760 Objects[ObjectIdx+NumFixedObjects].StackID = ID;
761 // If ID > 0, MaxAlignment may now be overly conservative.
762 // If ID == 0, MaxAlignment will need to be updated separately.
763 }
764
765 /// Returns true if the specified index corresponds to a dead object.
766 bool isDeadObjectIndex(int ObjectIdx) const {
767 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
768 "Invalid Object Idx!");
769 return Objects[ObjectIdx+NumFixedObjects].Size == ~0ULL;
770 }
771
772 /// Returns true if the specified index corresponds to a variable sized
773 /// object.
774 bool isVariableSizedObjectIndex(int ObjectIdx) const {
775 assert(unsigned(ObjectIdx + NumFixedObjects) < Objects.size() &&
776 "Invalid Object Idx!");
777 return Objects[ObjectIdx + NumFixedObjects].Size == 0;
778 }
779
780 void markAsStatepointSpillSlotObjectIndex(int ObjectIdx) {
781 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
782 "Invalid Object Idx!");
783 Objects[ObjectIdx+NumFixedObjects].isStatepointSpillSlot = true;
784 assert(isStatepointSpillSlotObjectIndex(ObjectIdx) && "inconsistent");
785 }
786
787 /// Create a new statically sized stack object, returning
788 /// a nonnegative identifier to represent it.
789 LLVM_ABI int CreateStackObject(uint64_t Size, Align Alignment,
790 bool isSpillSlot,
791 const AllocaInst *Alloca = nullptr,
792 uint8_t ID = 0);
793
794 /// Create a new statically sized stack object that represents a spill slot,
795 /// returning a nonnegative identifier to represent it.
796 LLVM_ABI int CreateSpillStackObject(uint64_t Size, Align Alignment);
797
798 /// Remove or mark dead a statically sized stack object.
799 void RemoveStackObject(int ObjectIdx) {
800 // Mark it dead.
801 Objects[ObjectIdx+NumFixedObjects].Size = ~0ULL;
802 }
803
804 /// Notify the MachineFrameInfo object that a variable sized object has been
805 /// created. This must be created whenever a variable sized object is
806 /// created, whether or not the index returned is actually used.
807 LLVM_ABI int CreateVariableSizedObject(Align Alignment,
808 const AllocaInst *Alloca);
809
810 /// Returns a reference to call saved info vector for the current function.
811 const std::vector<CalleeSavedInfo> &getCalleeSavedInfo() const {
812 return CSInfo;
813 }
814 /// \copydoc getCalleeSavedInfo()
815 std::vector<CalleeSavedInfo> &getCalleeSavedInfo() { return CSInfo; }
816
817 /// Used by prolog/epilog inserter to set the function's callee saved
818 /// information.
819 void setCalleeSavedInfo(std::vector<CalleeSavedInfo> CSI) {
820 CSInfo = std::move(CSI);
821 }
822
823 /// Has the callee saved info been calculated yet?
824 bool isCalleeSavedInfoValid() const { return CSIValid; }
825
826 void setCalleeSavedInfoValid(bool v) { CSIValid = v; }
827
828 MachineBasicBlock *getSavePoint() const { return Save; }
829 void setSavePoint(MachineBasicBlock *NewSave) { Save = NewSave; }
830 MachineBasicBlock *getRestorePoint() const { return Restore; }
831 void setRestorePoint(MachineBasicBlock *NewRestore) { Restore = NewRestore; }
832
833 uint64_t getUnsafeStackSize() const { return UnsafeStackSize; }
834 void setUnsafeStackSize(uint64_t Size) { UnsafeStackSize = Size; }
835
836 /// Return a set of physical registers that are pristine.
837 ///
838 /// Pristine registers hold a value that is useless to the current function,
839 /// but that must be preserved - they are callee saved registers that are not
840 /// saved.
841 ///
842 /// Before the PrologueEpilogueInserter has placed the CSR spill code, this
843 /// method always returns an empty set.
844 LLVM_ABI BitVector getPristineRegs(const MachineFunction &MF) const;
845
846 /// Used by the MachineFunction printer to print information about
847 /// stack objects. Implemented in MachineFunction.cpp.
848 LLVM_ABI void print(const MachineFunction &MF, raw_ostream &OS) const;
849
850 /// dump - Print the function to stderr.
851 LLVM_ABI void dump(const MachineFunction &MF) const;
852};
853
854} // End llvm namespace
855
856#endif
857