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/Alignment.h" 18 #include "llvm/Support/DataTypes.h" 19 #include <cassert> 20 #include <vector> 21 22 namespace llvm { 23 class raw_ostream; 24 class MachineFunction; 25 class MachineBasicBlock; 26 class BitVector; 27 class AllocaInst; 28 29 /// The CalleeSavedInfo class tracks the information need to locate where a 30 /// callee saved register is in the current frame. 31 /// Callee saved reg can also be saved to a different register rather than 32 /// on the stack by setting DstReg instead of FrameIdx. 33 class CalleeSavedInfo { 34 unsigned Reg; 35 union { 36 int FrameIdx; 37 unsigned DstReg; 38 }; 39 /// Flag indicating whether the register is actually restored in the epilog. 40 /// In most cases, if a register is saved, it is also restored. There are 41 /// some situations, though, when this is not the case. For example, the 42 /// LR register on ARM is usually saved, but on exit from the function its 43 /// saved value may be loaded directly into PC. Since liveness tracking of 44 /// physical registers treats callee-saved registers are live outside of 45 /// the function, LR would be treated as live-on-exit, even though in these 46 /// scenarios it is not. This flag is added to indicate that the saved 47 /// register described by this object is not restored in the epilog. 48 /// The long-term solution is to model the liveness of callee-saved registers 49 /// by implicit uses on the return instructions, however, the required 50 /// changes in the ARM backend would be quite extensive. 51 bool Restored; 52 /// Flag indicating whether the register is spilled to stack or another 53 /// register. 54 bool SpilledToReg; 55 56 public: 57 explicit CalleeSavedInfo(unsigned R, int FI = 0) Reg(R)58 : Reg(R), FrameIdx(FI), Restored(true), SpilledToReg(false) {} 59 60 // Accessors. getReg()61 unsigned getReg() const { return Reg; } getFrameIdx()62 int getFrameIdx() const { return FrameIdx; } getDstReg()63 unsigned getDstReg() const { return DstReg; } setFrameIdx(int FI)64 void setFrameIdx(int FI) { 65 FrameIdx = FI; 66 SpilledToReg = false; 67 } setDstReg(unsigned SpillReg)68 void setDstReg(unsigned SpillReg) { 69 DstReg = SpillReg; 70 SpilledToReg = true; 71 } isRestored()72 bool isRestored() const { return Restored; } setRestored(bool R)73 void setRestored(bool R) { Restored = R; } isSpilledToReg()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 106 class MachineFrameInfo { 107 public: 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 }; 120 121 private: 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 zero-extended. 180 bool isSExt = false; 181 182 uint8_t SSPLayout; 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) SPOffsetStackObject187 : SPOffset(SPOffset), Size(Size), Alignment(Alignment), 188 isImmutable(IsImmutable), isSpillSlot(IsSpillSlot), StackID(StackID), 189 Alloca(Alloca), isAliased(IsAliased), SSPLayout(SSPLK_None) {} 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 public: MachineFrameInfo(unsigned StackAlignment,bool StackRealignable,bool ForcedRealign)339 explicit MachineFrameInfo(unsigned StackAlignment, bool StackRealignable, 340 bool ForcedRealign) 341 : StackAlignment(assumeAligned(StackAlignment)), 342 StackRealignable(StackRealignable), ForcedRealign(ForcedRealign) {} 343 344 /// Return true if there are any stack objects in this function. hasStackObjects()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. hasVarSizedObjects()350 bool hasVarSizedObjects() const { return HasVarSizedObjects; } 351 352 /// Return the index for the stack protector object. getStackProtectorIndex()353 int getStackProtectorIndex() const { return StackProtectorIdx; } setStackProtectorIndex(int I)354 void setStackProtectorIndex(int I) { StackProtectorIdx = I; } hasStackProtectorIndex()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. getFunctionContextIndex()359 int getFunctionContextIndex() const { return FunctionContextIdx; } setFunctionContextIndex(int I)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. isFrameAddressTaken()365 bool isFrameAddressTaken() const { return FrameAddressTaken; } setFrameAddressIsTaken(bool T)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. isReturnAddressTaken()371 bool isReturnAddressTaken() const { return ReturnAddressTaken; } setReturnAddressIsTaken(bool s)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. hasStackMap()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. hasPatchPoint()383 bool hasPatchPoint() const { return HasPatchPoint; } 384 void setHasPatchPoint(bool s = true) { HasPatchPoint = s; } 385 386 /// Return the minimum frame object index. getObjectIndexBegin()387 int getObjectIndexBegin() const { return -NumFixedObjects; } 388 389 /// Return one past the maximum frame object index. getObjectIndexEnd()390 int getObjectIndexEnd() const { return (int)Objects.size()-NumFixedObjects; } 391 392 /// Return the number of fixed objects. getNumFixedObjects()393 unsigned getNumFixedObjects() const { return NumFixedObjects; } 394 395 /// Return the number of objects. getNumObjects()396 unsigned getNumObjects() const { return Objects.size(); } 397 398 /// Map a frame index into the local object block mapLocalFrameObject(int ObjectIndex,int64_t Offset)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. getLocalFrameObjectMap(int i)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. getLocalFrameObjectCount()412 int64_t getLocalFrameObjectCount() const { return LocalFrameObjects.size(); } 413 414 /// Set the size of the local object blob. setLocalFrameSize(int64_t sz)415 void setLocalFrameSize(int64_t sz) { LocalFrameSize = sz; } 416 417 /// Get the size of the local object blob. getLocalFrameSize()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. setLocalFrameMaxAlign(Align Alignment)422 void setLocalFrameMaxAlign(Align Alignment) { 423 LocalFrameMaxAlign = Alignment; 424 } 425 426 /// Return the required alignment of the local object blob. getLocalFrameMaxAlign()427 Align getLocalFrameMaxAlign() const { return LocalFrameMaxAlign; } 428 429 /// Get whether the local allocation blob should be allocated together or 430 /// let PEI allocate the locals in it directly. getUseLocalStackAllocationBlock()431 bool getUseLocalStackAllocationBlock() const { 432 return UseLocalStackAllocationBlock; 433 } 434 435 /// setUseLocalStackAllocationBlock - Set whether the local allocation blob 436 /// should be allocated together or let PEI allocate the locals in it 437 /// directly. setUseLocalStackAllocationBlock(bool v)438 void setUseLocalStackAllocationBlock(bool v) { 439 UseLocalStackAllocationBlock = v; 440 } 441 442 /// Return true if the object was pre-allocated into the local block. isObjectPreAllocated(int ObjectIdx)443 bool isObjectPreAllocated(int ObjectIdx) const { 444 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() && 445 "Invalid Object Idx!"); 446 return Objects[ObjectIdx+NumFixedObjects].PreAllocated; 447 } 448 449 /// Return the size of the specified object. getObjectSize(int ObjectIdx)450 int64_t getObjectSize(int ObjectIdx) const { 451 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() && 452 "Invalid Object Idx!"); 453 return Objects[ObjectIdx+NumFixedObjects].Size; 454 } 455 456 /// Change the size of the specified stack object. setObjectSize(int ObjectIdx,int64_t Size)457 void setObjectSize(int ObjectIdx, int64_t Size) { 458 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() && 459 "Invalid Object Idx!"); 460 Objects[ObjectIdx+NumFixedObjects].Size = Size; 461 } 462 getObjectAlignment(int ObjectIdx)463 LLVM_ATTRIBUTE_DEPRECATED(inline unsigned getObjectAlignment(int ObjectIdx) 464 const, 465 "Use getObjectAlign instead") { 466 return getObjectAlign(ObjectIdx).value(); 467 } 468 469 /// Return the alignment of the specified stack object. getObjectAlign(int ObjectIdx)470 Align getObjectAlign(int ObjectIdx) const { 471 assert(unsigned(ObjectIdx + NumFixedObjects) < Objects.size() && 472 "Invalid Object Idx!"); 473 return Objects[ObjectIdx + NumFixedObjects].Alignment; 474 } 475 476 /// setObjectAlignment - Change the alignment of the specified stack object. setObjectAlignment(int ObjectIdx,Align Alignment)477 void setObjectAlignment(int ObjectIdx, Align Alignment) { 478 assert(unsigned(ObjectIdx + NumFixedObjects) < Objects.size() && 479 "Invalid Object Idx!"); 480 Objects[ObjectIdx + NumFixedObjects].Alignment = Alignment; 481 482 // Only ensure max alignment for the default stack. 483 if (getStackID(ObjectIdx) == 0) 484 ensureMaxAlignment(Alignment); 485 } 486 setObjectAlignment(int ObjectIdx,unsigned Align)487 LLVM_ATTRIBUTE_DEPRECATED(inline void setObjectAlignment(int ObjectIdx, 488 unsigned Align), 489 "Use the version that takes Align instead") { 490 setObjectAlignment(ObjectIdx, assumeAligned(Align)); 491 } 492 493 /// Return the underlying Alloca of the specified 494 /// stack object if it exists. Returns 0 if none exists. getObjectAllocation(int ObjectIdx)495 const AllocaInst* getObjectAllocation(int ObjectIdx) const { 496 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() && 497 "Invalid Object Idx!"); 498 return Objects[ObjectIdx+NumFixedObjects].Alloca; 499 } 500 501 /// Return the assigned stack offset of the specified object 502 /// from the incoming stack pointer. getObjectOffset(int ObjectIdx)503 int64_t getObjectOffset(int ObjectIdx) const { 504 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() && 505 "Invalid Object Idx!"); 506 assert(!isDeadObjectIndex(ObjectIdx) && 507 "Getting frame offset for a dead object?"); 508 return Objects[ObjectIdx+NumFixedObjects].SPOffset; 509 } 510 isObjectZExt(int ObjectIdx)511 bool isObjectZExt(int ObjectIdx) const { 512 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() && 513 "Invalid Object Idx!"); 514 return Objects[ObjectIdx+NumFixedObjects].isZExt; 515 } 516 setObjectZExt(int ObjectIdx,bool IsZExt)517 void setObjectZExt(int ObjectIdx, bool IsZExt) { 518 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() && 519 "Invalid Object Idx!"); 520 Objects[ObjectIdx+NumFixedObjects].isZExt = IsZExt; 521 } 522 isObjectSExt(int ObjectIdx)523 bool isObjectSExt(int ObjectIdx) const { 524 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() && 525 "Invalid Object Idx!"); 526 return Objects[ObjectIdx+NumFixedObjects].isSExt; 527 } 528 setObjectSExt(int ObjectIdx,bool IsSExt)529 void setObjectSExt(int ObjectIdx, bool IsSExt) { 530 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() && 531 "Invalid Object Idx!"); 532 Objects[ObjectIdx+NumFixedObjects].isSExt = IsSExt; 533 } 534 535 /// Set the stack frame offset of the specified object. The 536 /// offset is relative to the stack pointer on entry to the function. setObjectOffset(int ObjectIdx,int64_t SPOffset)537 void setObjectOffset(int ObjectIdx, int64_t SPOffset) { 538 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() && 539 "Invalid Object Idx!"); 540 assert(!isDeadObjectIndex(ObjectIdx) && 541 "Setting frame offset for a dead object?"); 542 Objects[ObjectIdx+NumFixedObjects].SPOffset = SPOffset; 543 } 544 getObjectSSPLayout(int ObjectIdx)545 SSPLayoutKind getObjectSSPLayout(int ObjectIdx) const { 546 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() && 547 "Invalid Object Idx!"); 548 return (SSPLayoutKind)Objects[ObjectIdx+NumFixedObjects].SSPLayout; 549 } 550 setObjectSSPLayout(int ObjectIdx,SSPLayoutKind Kind)551 void setObjectSSPLayout(int ObjectIdx, SSPLayoutKind Kind) { 552 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() && 553 "Invalid Object Idx!"); 554 assert(!isDeadObjectIndex(ObjectIdx) && 555 "Setting SSP layout for a dead object?"); 556 Objects[ObjectIdx+NumFixedObjects].SSPLayout = Kind; 557 } 558 559 /// Return the number of bytes that must be allocated to hold 560 /// all of the fixed size frame objects. This is only valid after 561 /// Prolog/Epilog code insertion has finalized the stack frame layout. getStackSize()562 uint64_t getStackSize() const { return StackSize; } 563 564 /// Set the size of the stack. setStackSize(uint64_t Size)565 void setStackSize(uint64_t Size) { StackSize = Size; } 566 567 /// Estimate and return the size of the stack frame. 568 uint64_t estimateStackSize(const MachineFunction &MF) const; 569 570 /// Return the correction for frame offsets. getOffsetAdjustment()571 int getOffsetAdjustment() const { return OffsetAdjustment; } 572 573 /// Set the correction for frame offsets. setOffsetAdjustment(int Adj)574 void setOffsetAdjustment(int Adj) { OffsetAdjustment = Adj; } 575 576 /// Return the alignment in bytes that this function must be aligned to, 577 /// which is greater than the default stack alignment provided by the target. getMaxAlignment()578 LLVM_ATTRIBUTE_DEPRECATED(unsigned getMaxAlignment() const, 579 "Use getMaxAlign instead") { 580 return MaxAlignment.value(); 581 } 582 /// Return the alignment in bytes that this function must be aligned to, 583 /// which is greater than the default stack alignment provided by the target. getMaxAlign()584 Align getMaxAlign() const { return MaxAlignment; } 585 586 /// Make sure the function is at least Align bytes aligned. 587 void ensureMaxAlignment(Align Alignment); 588 ensureMaxAlignment(unsigned Align)589 LLVM_ATTRIBUTE_DEPRECATED(inline void ensureMaxAlignment(unsigned Align), 590 "Use the version that uses Align instead") { 591 ensureMaxAlignment(assumeAligned(Align)); 592 } 593 594 /// Return true if this function adjusts the stack -- e.g., 595 /// when calling another function. This is only valid during and after 596 /// prolog/epilog code insertion. adjustsStack()597 bool adjustsStack() const { return AdjustsStack; } setAdjustsStack(bool V)598 void setAdjustsStack(bool V) { AdjustsStack = V; } 599 600 /// Return true if the current function has any function calls. hasCalls()601 bool hasCalls() const { return HasCalls; } setHasCalls(bool V)602 void setHasCalls(bool V) { HasCalls = V; } 603 604 /// Returns true if the function contains opaque dynamic stack adjustments. hasOpaqueSPAdjustment()605 bool hasOpaqueSPAdjustment() const { return HasOpaqueSPAdjustment; } setHasOpaqueSPAdjustment(bool B)606 void setHasOpaqueSPAdjustment(bool B) { HasOpaqueSPAdjustment = B; } 607 608 /// Returns true if the function contains operations which will lower down to 609 /// instructions which manipulate the stack pointer. hasCopyImplyingStackAdjustment()610 bool hasCopyImplyingStackAdjustment() const { 611 return HasCopyImplyingStackAdjustment; 612 } setHasCopyImplyingStackAdjustment(bool B)613 void setHasCopyImplyingStackAdjustment(bool B) { 614 HasCopyImplyingStackAdjustment = B; 615 } 616 617 /// Returns true if the function calls the llvm.va_start intrinsic. hasVAStart()618 bool hasVAStart() const { return HasVAStart; } setHasVAStart(bool B)619 void setHasVAStart(bool B) { HasVAStart = B; } 620 621 /// Returns true if the function is variadic and contains a musttail call. hasMustTailInVarArgFunc()622 bool hasMustTailInVarArgFunc() const { return HasMustTailInVarArgFunc; } setHasMustTailInVarArgFunc(bool B)623 void setHasMustTailInVarArgFunc(bool B) { HasMustTailInVarArgFunc = B; } 624 625 /// Returns true if the function contains a tail call. hasTailCall()626 bool hasTailCall() const { return HasTailCall; } setHasTailCall()627 void setHasTailCall() { HasTailCall = true; } 628 629 /// Computes the maximum size of a callframe and the AdjustsStack property. 630 /// This only works for targets defining 631 /// TargetInstrInfo::getCallFrameSetupOpcode(), getCallFrameDestroyOpcode(), 632 /// and getFrameSize(). 633 /// This is usually computed by the prologue epilogue inserter but some 634 /// targets may call this to compute it earlier. 635 void computeMaxCallFrameSize(const MachineFunction &MF); 636 637 /// Return the maximum size of a call frame that must be 638 /// allocated for an outgoing function call. This is only available if 639 /// CallFrameSetup/Destroy pseudo instructions are used by the target, and 640 /// then only during or after prolog/epilog code insertion. 641 /// getMaxCallFrameSize()642 unsigned getMaxCallFrameSize() const { 643 // TODO: Enable this assert when targets are fixed. 644 //assert(isMaxCallFrameSizeComputed() && "MaxCallFrameSize not computed yet"); 645 if (!isMaxCallFrameSizeComputed()) 646 return 0; 647 return MaxCallFrameSize; 648 } isMaxCallFrameSizeComputed()649 bool isMaxCallFrameSizeComputed() const { 650 return MaxCallFrameSize != ~0u; 651 } setMaxCallFrameSize(unsigned S)652 void setMaxCallFrameSize(unsigned S) { MaxCallFrameSize = S; } 653 654 /// Returns how many bytes of callee-saved registers the target pushed in the 655 /// prologue. Only used for debug info. getCVBytesOfCalleeSavedRegisters()656 unsigned getCVBytesOfCalleeSavedRegisters() const { 657 return CVBytesOfCalleeSavedRegisters; 658 } setCVBytesOfCalleeSavedRegisters(unsigned S)659 void setCVBytesOfCalleeSavedRegisters(unsigned S) { 660 CVBytesOfCalleeSavedRegisters = S; 661 } 662 663 /// Create a new object at a fixed location on the stack. 664 /// All fixed objects should be created before other objects are created for 665 /// efficiency. By default, fixed objects are not pointed to by LLVM IR 666 /// values. This returns an index with a negative value. 667 int CreateFixedObject(uint64_t Size, int64_t SPOffset, bool IsImmutable, 668 bool isAliased = false); 669 670 /// Create a spill slot at a fixed location on the stack. 671 /// Returns an index with a negative value. 672 int CreateFixedSpillStackObject(uint64_t Size, int64_t SPOffset, 673 bool IsImmutable = false); 674 675 /// Returns true if the specified index corresponds to a fixed stack object. isFixedObjectIndex(int ObjectIdx)676 bool isFixedObjectIndex(int ObjectIdx) const { 677 return ObjectIdx < 0 && (ObjectIdx >= -(int)NumFixedObjects); 678 } 679 680 /// Returns true if the specified index corresponds 681 /// to an object that might be pointed to by an LLVM IR value. isAliasedObjectIndex(int ObjectIdx)682 bool isAliasedObjectIndex(int ObjectIdx) const { 683 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() && 684 "Invalid Object Idx!"); 685 return Objects[ObjectIdx+NumFixedObjects].isAliased; 686 } 687 688 /// Returns true if the specified index corresponds to an immutable object. isImmutableObjectIndex(int ObjectIdx)689 bool isImmutableObjectIndex(int ObjectIdx) const { 690 // Tail calling functions can clobber their function arguments. 691 if (HasTailCall) 692 return false; 693 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() && 694 "Invalid Object Idx!"); 695 return Objects[ObjectIdx+NumFixedObjects].isImmutable; 696 } 697 698 /// Marks the immutability of an object. setIsImmutableObjectIndex(int ObjectIdx,bool IsImmutable)699 void setIsImmutableObjectIndex(int ObjectIdx, bool IsImmutable) { 700 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() && 701 "Invalid Object Idx!"); 702 Objects[ObjectIdx+NumFixedObjects].isImmutable = IsImmutable; 703 } 704 705 /// Returns true if the specified index corresponds to a spill slot. isSpillSlotObjectIndex(int ObjectIdx)706 bool isSpillSlotObjectIndex(int ObjectIdx) const { 707 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() && 708 "Invalid Object Idx!"); 709 return Objects[ObjectIdx+NumFixedObjects].isSpillSlot; 710 } 711 isStatepointSpillSlotObjectIndex(int ObjectIdx)712 bool isStatepointSpillSlotObjectIndex(int ObjectIdx) const { 713 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() && 714 "Invalid Object Idx!"); 715 return Objects[ObjectIdx+NumFixedObjects].isStatepointSpillSlot; 716 } 717 718 /// \see StackID getStackID(int ObjectIdx)719 uint8_t getStackID(int ObjectIdx) const { 720 return Objects[ObjectIdx+NumFixedObjects].StackID; 721 } 722 723 /// \see StackID setStackID(int ObjectIdx,uint8_t ID)724 void setStackID(int ObjectIdx, uint8_t ID) { 725 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() && 726 "Invalid Object Idx!"); 727 Objects[ObjectIdx+NumFixedObjects].StackID = ID; 728 // If ID > 0, MaxAlignment may now be overly conservative. 729 // If ID == 0, MaxAlignment will need to be updated separately. 730 } 731 732 /// Returns true if the specified index corresponds to a dead object. isDeadObjectIndex(int ObjectIdx)733 bool isDeadObjectIndex(int ObjectIdx) const { 734 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() && 735 "Invalid Object Idx!"); 736 return Objects[ObjectIdx+NumFixedObjects].Size == ~0ULL; 737 } 738 739 /// Returns true if the specified index corresponds to a variable sized 740 /// object. isVariableSizedObjectIndex(int ObjectIdx)741 bool isVariableSizedObjectIndex(int ObjectIdx) const { 742 assert(unsigned(ObjectIdx + NumFixedObjects) < Objects.size() && 743 "Invalid Object Idx!"); 744 return Objects[ObjectIdx + NumFixedObjects].Size == 0; 745 } 746 markAsStatepointSpillSlotObjectIndex(int ObjectIdx)747 void markAsStatepointSpillSlotObjectIndex(int ObjectIdx) { 748 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() && 749 "Invalid Object Idx!"); 750 Objects[ObjectIdx+NumFixedObjects].isStatepointSpillSlot = true; 751 assert(isStatepointSpillSlotObjectIndex(ObjectIdx) && "inconsistent"); 752 } 753 754 /// Create a new statically sized stack object, returning 755 /// a nonnegative identifier to represent it. 756 int CreateStackObject(uint64_t Size, Align Alignment, bool isSpillSlot, 757 const AllocaInst *Alloca = nullptr, uint8_t ID = 0); 758 LLVM_ATTRIBUTE_DEPRECATED( 759 inline int CreateStackObject(uint64_t Size, unsigned Alignment, 760 bool isSpillSlot, 761 const AllocaInst *Alloca = nullptr, 762 uint8_t ID = 0), 763 "Use CreateStackObject that takes an Align instead") { 764 return CreateStackObject(Size, assumeAligned(Alignment), isSpillSlot, 765 Alloca, ID); 766 } 767 768 /// Create a new statically sized stack object that represents a spill slot, 769 /// returning a nonnegative identifier to represent it. 770 int CreateSpillStackObject(uint64_t Size, Align Alignment); 771 LLVM_ATTRIBUTE_DEPRECATED( CreateSpillStackObject(uint64_t Size,unsigned Alignment)772 inline int CreateSpillStackObject(uint64_t Size, unsigned Alignment), 773 "Use CreateSpillStackObject that takes an Align instead") { 774 return CreateSpillStackObject(Size, assumeAligned(Alignment)); 775 } 776 777 /// Remove or mark dead a statically sized stack object. RemoveStackObject(int ObjectIdx)778 void RemoveStackObject(int ObjectIdx) { 779 // Mark it dead. 780 Objects[ObjectIdx+NumFixedObjects].Size = ~0ULL; 781 } 782 783 /// Notify the MachineFrameInfo object that a variable sized object has been 784 /// created. This must be created whenever a variable sized object is 785 /// created, whether or not the index returned is actually used. 786 int CreateVariableSizedObject(Align Alignment, const AllocaInst *Alloca); 787 /// FIXME: Remove this function when transition to Align is over. CreateVariableSizedObject(unsigned Alignment,const AllocaInst * Alloca)788 LLVM_ATTRIBUTE_DEPRECATED(int CreateVariableSizedObject( 789 unsigned Alignment, const AllocaInst *Alloca), 790 "Use the version that takes an Align instead") { 791 return CreateVariableSizedObject(assumeAligned(Alignment), Alloca); 792 } 793 794 /// Returns a reference to call saved info vector for the current function. getCalleeSavedInfo()795 const std::vector<CalleeSavedInfo> &getCalleeSavedInfo() const { 796 return CSInfo; 797 } 798 /// \copydoc getCalleeSavedInfo() getCalleeSavedInfo()799 std::vector<CalleeSavedInfo> &getCalleeSavedInfo() { return CSInfo; } 800 801 /// Used by prolog/epilog inserter to set the function's callee saved 802 /// information. setCalleeSavedInfo(std::vector<CalleeSavedInfo> CSI)803 void setCalleeSavedInfo(std::vector<CalleeSavedInfo> CSI) { 804 CSInfo = std::move(CSI); 805 } 806 807 /// Has the callee saved info been calculated yet? isCalleeSavedInfoValid()808 bool isCalleeSavedInfoValid() const { return CSIValid; } 809 setCalleeSavedInfoValid(bool v)810 void setCalleeSavedInfoValid(bool v) { CSIValid = v; } 811 getSavePoint()812 MachineBasicBlock *getSavePoint() const { return Save; } setSavePoint(MachineBasicBlock * NewSave)813 void setSavePoint(MachineBasicBlock *NewSave) { Save = NewSave; } getRestorePoint()814 MachineBasicBlock *getRestorePoint() const { return Restore; } setRestorePoint(MachineBasicBlock * NewRestore)815 void setRestorePoint(MachineBasicBlock *NewRestore) { Restore = NewRestore; } 816 817 /// Return a set of physical registers that are pristine. 818 /// 819 /// Pristine registers hold a value that is useless to the current function, 820 /// but that must be preserved - they are callee saved registers that are not 821 /// saved. 822 /// 823 /// Before the PrologueEpilogueInserter has placed the CSR spill code, this 824 /// method always returns an empty set. 825 BitVector getPristineRegs(const MachineFunction &MF) const; 826 827 /// Used by the MachineFunction printer to print information about 828 /// stack objects. Implemented in MachineFunction.cpp. 829 void print(const MachineFunction &MF, raw_ostream &OS) const; 830 831 /// dump - Print the function to stderr. 832 void dump(const MachineFunction &MF) const; 833 }; 834 835 } // End llvm namespace 836 837 #endif 838