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/Support/Alignment.h" 19 #include "llvm/Support/DataTypes.h" 20 #include <cassert> 21 #include <vector> 22 23 namespace llvm { 24 class raw_ostream; 25 class MachineFunction; 26 class MachineBasicBlock; 27 class BitVector; 28 class 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. 34 class 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; 53 /// Flag indicating whether the register is spilled to stack or another 54 /// register. 55 bool SpilledToReg; 56 57 public: 58 explicit CalleeSavedInfo(unsigned R, int FI = 0) Reg(R)59 : Reg(R), FrameIdx(FI), Restored(true), SpilledToReg(false) {} 60 61 // Accessors. getReg()62 Register getReg() const { return Reg; } getFrameIdx()63 int getFrameIdx() const { return FrameIdx; } getDstReg()64 unsigned getDstReg() const { return DstReg; } setFrameIdx(int FI)65 void setFrameIdx(int FI) { 66 FrameIdx = FI; 67 SpilledToReg = false; 68 } setDstReg(Register SpillReg)69 void setDstReg(Register SpillReg) { 70 DstReg = SpillReg; 71 SpilledToReg = true; 72 } isRestored()73 bool isRestored() const { return Restored; } setRestored(bool R)74 void setRestored(bool R) { Restored = R; } isSpilledToReg()75 bool isSpilledToReg() const { return SpilledToReg; } 76 }; 77 78 /// The MachineFrameInfo class represents an abstract stack frame until 79 /// prolog/epilog code is inserted. This class is key to allowing stack frame 80 /// representation optimizations, such as frame pointer elimination. It also 81 /// allows more mundane (but still important) optimizations, such as reordering 82 /// of abstract objects on the stack frame. 83 /// 84 /// To support this, the class assigns unique integer identifiers to stack 85 /// objects requested clients. These identifiers are negative integers for 86 /// fixed stack objects (such as arguments passed on the stack) or nonnegative 87 /// for objects that may be reordered. Instructions which refer to stack 88 /// objects use a special MO_FrameIndex operand to represent these frame 89 /// indexes. 90 /// 91 /// Because this class keeps track of all references to the stack frame, it 92 /// knows when a variable sized object is allocated on the stack. This is the 93 /// sole condition which prevents frame pointer elimination, which is an 94 /// important optimization on register-poor architectures. Because original 95 /// variable sized alloca's in the source program are the only source of 96 /// variable sized stack objects, it is safe to decide whether there will be 97 /// any variable sized objects before all stack objects are known (for 98 /// example, register allocator spill code never needs variable sized 99 /// objects). 100 /// 101 /// When prolog/epilog code emission is performed, the final stack frame is 102 /// built and the machine instructions are modified to refer to the actual 103 /// stack offsets of the object, eliminating all MO_FrameIndex operands from 104 /// the program. 105 /// 106 /// Abstract Stack Frame Information 107 class MachineFrameInfo { 108 public: 109 /// Stack Smashing Protection (SSP) rules require that vulnerable stack 110 /// allocations are located close the stack protector. 111 enum SSPLayoutKind { 112 SSPLK_None, ///< Did not trigger a stack protector. No effect on data 113 ///< layout. 114 SSPLK_LargeArray, ///< Array or nested array >= SSP-buffer-size. Closest 115 ///< to the stack protector. 116 SSPLK_SmallArray, ///< Array or nested array < SSP-buffer-size. 2nd closest 117 ///< to the stack protector. 118 SSPLK_AddrOf ///< The address of this allocation is exposed and 119 ///< triggered protection. 3rd closest to the protector. 120 }; 121 122 private: 123 // Represent a single object allocated on the stack. 124 struct StackObject { 125 // The offset of this object from the stack pointer on entry to 126 // the function. This field has no meaning for a variable sized element. 127 int64_t SPOffset; 128 129 // The size of this object on the stack. 0 means a variable sized object, 130 // ~0ULL means a dead object. 131 uint64_t Size; 132 133 // The required alignment of this stack slot. 134 Align Alignment; 135 136 // If true, the value of the stack object is set before 137 // entering the function and is not modified inside the function. By 138 // default, fixed objects are immutable unless marked otherwise. 139 bool isImmutable; 140 141 // If true the stack object is used as spill slot. It 142 // cannot alias any other memory objects. 143 bool isSpillSlot; 144 145 /// If true, this stack slot is used to spill a value (could be deopt 146 /// and/or GC related) over a statepoint. We know that the address of the 147 /// slot can't alias any LLVM IR value. This is very similar to a Spill 148 /// Slot, but is created by statepoint lowering is SelectionDAG, not the 149 /// register allocator. 150 bool isStatepointSpillSlot = false; 151 152 /// Identifier for stack memory type analagous to address space. If this is 153 /// non-0, the meaning is target defined. Offsets cannot be directly 154 /// compared between objects with different stack IDs. The object may not 155 /// necessarily reside in the same contiguous memory block as other stack 156 /// objects. Objects with differing stack IDs should not be merged or 157 /// replaced substituted for each other. 158 // 159 /// It is assumed a target uses consecutive, increasing stack IDs starting 160 /// from 1. 161 uint8_t StackID; 162 163 /// If this stack object is originated from an Alloca instruction 164 /// this value saves the original IR allocation. Can be NULL. 165 const AllocaInst *Alloca; 166 167 // If true, the object was mapped into the local frame 168 // block and doesn't need additional handling for allocation beyond that. 169 bool PreAllocated = false; 170 171 // If true, an LLVM IR value might point to this object. 172 // Normally, spill slots and fixed-offset objects don't alias IR-accessible 173 // objects, but there are exceptions (on PowerPC, for example, some byval 174 // arguments have ABI-prescribed offsets). 175 bool isAliased; 176 177 /// If true, the object has been zero-extended. 178 bool isZExt = false; 179 180 /// If true, the object has been sign-extended. 181 bool isSExt = false; 182 183 uint8_t SSPLayout; 184 185 StackObject(uint64_t Size, Align Alignment, int64_t SPOffset, 186 bool IsImmutable, bool IsSpillSlot, const AllocaInst *Alloca, 187 bool IsAliased, uint8_t StackID = 0) SPOffsetStackObject188 : SPOffset(SPOffset), Size(Size), Alignment(Alignment), 189 isImmutable(IsImmutable), isSpillSlot(IsSpillSlot), StackID(StackID), 190 Alloca(Alloca), isAliased(IsAliased), SSPLayout(SSPLK_None) {} 191 }; 192 193 /// The alignment of the stack. 194 Align StackAlignment; 195 196 /// Can the stack be realigned. This can be false if the target does not 197 /// support stack realignment, or if the user asks us not to realign the 198 /// stack. In this situation, overaligned allocas are all treated as dynamic 199 /// allocations and the target must handle them as part of DYNAMIC_STACKALLOC 200 /// lowering. All non-alloca stack objects have their alignment clamped to the 201 /// base ABI stack alignment. 202 /// FIXME: There is room for improvement in this case, in terms of 203 /// grouping overaligned allocas into a "secondary stack frame" and 204 /// then only use a single alloca to allocate this frame and only a 205 /// single virtual register to access it. Currently, without such an 206 /// optimization, each such alloca gets its own dynamic realignment. 207 bool StackRealignable; 208 209 /// Whether the function has the \c alignstack attribute. 210 bool ForcedRealign; 211 212 /// The list of stack objects allocated. 213 std::vector<StackObject> Objects; 214 215 /// This contains the number of fixed objects contained on 216 /// the stack. Because fixed objects are stored at a negative index in the 217 /// Objects list, this is also the index to the 0th object in the list. 218 unsigned NumFixedObjects = 0; 219 220 /// This boolean keeps track of whether any variable 221 /// sized objects have been allocated yet. 222 bool HasVarSizedObjects = false; 223 224 /// This boolean keeps track of whether there is a call 225 /// to builtin \@llvm.frameaddress. 226 bool FrameAddressTaken = false; 227 228 /// This boolean keeps track of whether there is a call 229 /// to builtin \@llvm.returnaddress. 230 bool ReturnAddressTaken = false; 231 232 /// This boolean keeps track of whether there is a call 233 /// to builtin \@llvm.experimental.stackmap. 234 bool HasStackMap = false; 235 236 /// This boolean keeps track of whether there is a call 237 /// to builtin \@llvm.experimental.patchpoint. 238 bool HasPatchPoint = false; 239 240 /// The prolog/epilog code inserter calculates the final stack 241 /// offsets for all of the fixed size objects, updating the Objects list 242 /// above. It then updates StackSize to contain the number of bytes that need 243 /// to be allocated on entry to the function. 244 uint64_t StackSize = 0; 245 246 /// The amount that a frame offset needs to be adjusted to 247 /// have the actual offset from the stack/frame pointer. The exact usage of 248 /// this is target-dependent, but it is typically used to adjust between 249 /// SP-relative and FP-relative offsets. E.G., if objects are accessed via 250 /// SP then OffsetAdjustment is zero; if FP is used, OffsetAdjustment is set 251 /// to the distance between the initial SP and the value in FP. For many 252 /// targets, this value is only used when generating debug info (via 253 /// TargetRegisterInfo::getFrameIndexReference); when generating code, the 254 /// corresponding adjustments are performed directly. 255 int OffsetAdjustment = 0; 256 257 /// The prolog/epilog code inserter may process objects that require greater 258 /// alignment than the default alignment the target provides. 259 /// To handle this, MaxAlignment is set to the maximum alignment 260 /// needed by the objects on the current frame. If this is greater than the 261 /// native alignment maintained by the compiler, dynamic alignment code will 262 /// be needed. 263 /// 264 Align MaxAlignment; 265 266 /// Set to true if this function adjusts the stack -- e.g., 267 /// when calling another function. This is only valid during and after 268 /// prolog/epilog code insertion. 269 bool AdjustsStack = false; 270 271 /// Set to true if this function has any function calls. 272 bool HasCalls = false; 273 274 /// The frame index for the stack protector. 275 int StackProtectorIdx = -1; 276 277 /// The frame index for the function context. Used for SjLj exceptions. 278 int FunctionContextIdx = -1; 279 280 /// This contains the size of the largest call frame if the target uses frame 281 /// setup/destroy pseudo instructions (as defined in the TargetFrameInfo 282 /// class). This information is important for frame pointer elimination. 283 /// It is only valid during and after prolog/epilog code insertion. 284 unsigned MaxCallFrameSize = ~0u; 285 286 /// The number of bytes of callee saved registers that the target wants to 287 /// report for the current function in the CodeView S_FRAMEPROC record. 288 unsigned CVBytesOfCalleeSavedRegisters = 0; 289 290 /// The prolog/epilog code inserter fills in this vector with each 291 /// callee saved register saved in either the frame or a different 292 /// register. Beyond its use by the prolog/ epilog code inserter, 293 /// this data is used for debug info and exception handling. 294 std::vector<CalleeSavedInfo> CSInfo; 295 296 /// Has CSInfo been set yet? 297 bool CSIValid = false; 298 299 /// References to frame indices which are mapped 300 /// into the local frame allocation block. <FrameIdx, LocalOffset> 301 SmallVector<std::pair<int, int64_t>, 32> LocalFrameObjects; 302 303 /// Size of the pre-allocated local frame block. 304 int64_t LocalFrameSize = 0; 305 306 /// Required alignment of the local object blob, which is the strictest 307 /// alignment of any object in it. 308 Align LocalFrameMaxAlign; 309 310 /// Whether the local object blob needs to be allocated together. If not, 311 /// PEI should ignore the isPreAllocated flags on the stack objects and 312 /// just allocate them normally. 313 bool UseLocalStackAllocationBlock = false; 314 315 /// True if the function dynamically adjusts the stack pointer through some 316 /// opaque mechanism like inline assembly or Win32 EH. 317 bool HasOpaqueSPAdjustment = false; 318 319 /// True if the function contains operations which will lower down to 320 /// instructions which manipulate the stack pointer. 321 bool HasCopyImplyingStackAdjustment = false; 322 323 /// True if the function contains a call to the llvm.vastart intrinsic. 324 bool HasVAStart = false; 325 326 /// True if this is a varargs function that contains a musttail call. 327 bool HasMustTailInVarArgFunc = false; 328 329 /// True if this function contains a tail call. If so immutable objects like 330 /// function arguments are no longer so. A tail call *can* override fixed 331 /// stack objects like arguments so we can't treat them as immutable. 332 bool HasTailCall = false; 333 334 /// Not null, if shrink-wrapping found a better place for the prologue. 335 MachineBasicBlock *Save = nullptr; 336 /// Not null, if shrink-wrapping found a better place for the epilogue. 337 MachineBasicBlock *Restore = nullptr; 338 339 public: MachineFrameInfo(unsigned StackAlignment,bool StackRealignable,bool ForcedRealign)340 explicit MachineFrameInfo(unsigned StackAlignment, bool StackRealignable, 341 bool ForcedRealign) 342 : StackAlignment(assumeAligned(StackAlignment)), 343 StackRealignable(StackRealignable), ForcedRealign(ForcedRealign) {} 344 345 MachineFrameInfo(const MachineFrameInfo &) = delete; 346 347 /// Return true if there are any stack objects in this function. hasStackObjects()348 bool hasStackObjects() const { return !Objects.empty(); } 349 350 /// This method may be called any time after instruction 351 /// selection is complete to determine if the stack frame for this function 352 /// contains any variable sized objects. hasVarSizedObjects()353 bool hasVarSizedObjects() const { return HasVarSizedObjects; } 354 355 /// Return the index for the stack protector object. getStackProtectorIndex()356 int getStackProtectorIndex() const { return StackProtectorIdx; } setStackProtectorIndex(int I)357 void setStackProtectorIndex(int I) { StackProtectorIdx = I; } hasStackProtectorIndex()358 bool hasStackProtectorIndex() const { return StackProtectorIdx != -1; } 359 360 /// Return the index for the function context object. 361 /// This object is used for SjLj exceptions. getFunctionContextIndex()362 int getFunctionContextIndex() const { return FunctionContextIdx; } setFunctionContextIndex(int I)363 void setFunctionContextIndex(int I) { FunctionContextIdx = I; } 364 365 /// This method may be called any time after instruction 366 /// selection is complete to determine if there is a call to 367 /// \@llvm.frameaddress in this function. isFrameAddressTaken()368 bool isFrameAddressTaken() const { return FrameAddressTaken; } setFrameAddressIsTaken(bool T)369 void setFrameAddressIsTaken(bool T) { FrameAddressTaken = T; } 370 371 /// This method may be called any time after 372 /// instruction selection is complete to determine if there is a call to 373 /// \@llvm.returnaddress in this function. isReturnAddressTaken()374 bool isReturnAddressTaken() const { return ReturnAddressTaken; } setReturnAddressIsTaken(bool s)375 void setReturnAddressIsTaken(bool s) { ReturnAddressTaken = s; } 376 377 /// This method may be called any time after instruction 378 /// selection is complete to determine if there is a call to builtin 379 /// \@llvm.experimental.stackmap. hasStackMap()380 bool hasStackMap() const { return HasStackMap; } 381 void setHasStackMap(bool s = true) { HasStackMap = s; } 382 383 /// This method may be called any time after instruction 384 /// selection is complete to determine if there is a call to builtin 385 /// \@llvm.experimental.patchpoint. hasPatchPoint()386 bool hasPatchPoint() const { return HasPatchPoint; } 387 void setHasPatchPoint(bool s = true) { HasPatchPoint = s; } 388 389 /// Return the minimum frame object index. getObjectIndexBegin()390 int getObjectIndexBegin() const { return -NumFixedObjects; } 391 392 /// Return one past the maximum frame object index. getObjectIndexEnd()393 int getObjectIndexEnd() const { return (int)Objects.size()-NumFixedObjects; } 394 395 /// Return the number of fixed objects. getNumFixedObjects()396 unsigned getNumFixedObjects() const { return NumFixedObjects; } 397 398 /// Return the number of objects. getNumObjects()399 unsigned getNumObjects() const { return Objects.size(); } 400 401 /// Map a frame index into the local object block mapLocalFrameObject(int ObjectIndex,int64_t Offset)402 void mapLocalFrameObject(int ObjectIndex, int64_t Offset) { 403 LocalFrameObjects.push_back(std::pair<int, int64_t>(ObjectIndex, Offset)); 404 Objects[ObjectIndex + NumFixedObjects].PreAllocated = true; 405 } 406 407 /// Get the local offset mapping for a for an object. getLocalFrameObjectMap(int i)408 std::pair<int, int64_t> getLocalFrameObjectMap(int i) const { 409 assert (i >= 0 && (unsigned)i < LocalFrameObjects.size() && 410 "Invalid local object reference!"); 411 return LocalFrameObjects[i]; 412 } 413 414 /// Return the number of objects allocated into the local object block. getLocalFrameObjectCount()415 int64_t getLocalFrameObjectCount() const { return LocalFrameObjects.size(); } 416 417 /// Set the size of the local object blob. setLocalFrameSize(int64_t sz)418 void setLocalFrameSize(int64_t sz) { LocalFrameSize = sz; } 419 420 /// Get the size of the local object blob. getLocalFrameSize()421 int64_t getLocalFrameSize() const { return LocalFrameSize; } 422 423 /// Required alignment of the local object blob, 424 /// which is the strictest alignment of any object in it. setLocalFrameMaxAlign(Align Alignment)425 void setLocalFrameMaxAlign(Align Alignment) { 426 LocalFrameMaxAlign = Alignment; 427 } 428 429 /// Return the required alignment of the local object blob. getLocalFrameMaxAlign()430 Align getLocalFrameMaxAlign() const { return LocalFrameMaxAlign; } 431 432 /// Get whether the local allocation blob should be allocated together or 433 /// let PEI allocate the locals in it directly. getUseLocalStackAllocationBlock()434 bool getUseLocalStackAllocationBlock() const { 435 return UseLocalStackAllocationBlock; 436 } 437 438 /// setUseLocalStackAllocationBlock - Set whether the local allocation blob 439 /// should be allocated together or let PEI allocate the locals in it 440 /// directly. setUseLocalStackAllocationBlock(bool v)441 void setUseLocalStackAllocationBlock(bool v) { 442 UseLocalStackAllocationBlock = v; 443 } 444 445 /// Return true if the object was pre-allocated into the local block. isObjectPreAllocated(int ObjectIdx)446 bool isObjectPreAllocated(int ObjectIdx) const { 447 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() && 448 "Invalid Object Idx!"); 449 return Objects[ObjectIdx+NumFixedObjects].PreAllocated; 450 } 451 452 /// Return the size of the specified object. getObjectSize(int ObjectIdx)453 int64_t getObjectSize(int ObjectIdx) const { 454 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() && 455 "Invalid Object Idx!"); 456 return Objects[ObjectIdx+NumFixedObjects].Size; 457 } 458 459 /// Change the size of the specified stack object. setObjectSize(int ObjectIdx,int64_t Size)460 void setObjectSize(int ObjectIdx, int64_t Size) { 461 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() && 462 "Invalid Object Idx!"); 463 Objects[ObjectIdx+NumFixedObjects].Size = Size; 464 } 465 466 /// Return the alignment of the specified stack object. getObjectAlign(int ObjectIdx)467 Align getObjectAlign(int ObjectIdx) const { 468 assert(unsigned(ObjectIdx + NumFixedObjects) < Objects.size() && 469 "Invalid Object Idx!"); 470 return Objects[ObjectIdx + NumFixedObjects].Alignment; 471 } 472 473 /// setObjectAlignment - Change the alignment of the specified stack object. setObjectAlignment(int ObjectIdx,Align Alignment)474 void setObjectAlignment(int ObjectIdx, Align Alignment) { 475 assert(unsigned(ObjectIdx + NumFixedObjects) < Objects.size() && 476 "Invalid Object Idx!"); 477 Objects[ObjectIdx + NumFixedObjects].Alignment = Alignment; 478 479 // Only ensure max alignment for the default stack. 480 if (getStackID(ObjectIdx) == 0) 481 ensureMaxAlignment(Alignment); 482 } 483 484 /// Return the underlying Alloca of the specified 485 /// stack object if it exists. Returns 0 if none exists. getObjectAllocation(int ObjectIdx)486 const AllocaInst* getObjectAllocation(int ObjectIdx) const { 487 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() && 488 "Invalid Object Idx!"); 489 return Objects[ObjectIdx+NumFixedObjects].Alloca; 490 } 491 492 /// Return the assigned stack offset of the specified object 493 /// from the incoming stack pointer. getObjectOffset(int ObjectIdx)494 int64_t getObjectOffset(int ObjectIdx) const { 495 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() && 496 "Invalid Object Idx!"); 497 assert(!isDeadObjectIndex(ObjectIdx) && 498 "Getting frame offset for a dead object?"); 499 return Objects[ObjectIdx+NumFixedObjects].SPOffset; 500 } 501 isObjectZExt(int ObjectIdx)502 bool isObjectZExt(int ObjectIdx) const { 503 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() && 504 "Invalid Object Idx!"); 505 return Objects[ObjectIdx+NumFixedObjects].isZExt; 506 } 507 setObjectZExt(int ObjectIdx,bool IsZExt)508 void setObjectZExt(int ObjectIdx, bool IsZExt) { 509 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() && 510 "Invalid Object Idx!"); 511 Objects[ObjectIdx+NumFixedObjects].isZExt = IsZExt; 512 } 513 isObjectSExt(int ObjectIdx)514 bool isObjectSExt(int ObjectIdx) const { 515 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() && 516 "Invalid Object Idx!"); 517 return Objects[ObjectIdx+NumFixedObjects].isSExt; 518 } 519 setObjectSExt(int ObjectIdx,bool IsSExt)520 void setObjectSExt(int ObjectIdx, bool IsSExt) { 521 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() && 522 "Invalid Object Idx!"); 523 Objects[ObjectIdx+NumFixedObjects].isSExt = IsSExt; 524 } 525 526 /// Set the stack frame offset of the specified object. The 527 /// offset is relative to the stack pointer on entry to the function. setObjectOffset(int ObjectIdx,int64_t SPOffset)528 void setObjectOffset(int ObjectIdx, int64_t SPOffset) { 529 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() && 530 "Invalid Object Idx!"); 531 assert(!isDeadObjectIndex(ObjectIdx) && 532 "Setting frame offset for a dead object?"); 533 Objects[ObjectIdx+NumFixedObjects].SPOffset = SPOffset; 534 } 535 getObjectSSPLayout(int ObjectIdx)536 SSPLayoutKind getObjectSSPLayout(int ObjectIdx) const { 537 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() && 538 "Invalid Object Idx!"); 539 return (SSPLayoutKind)Objects[ObjectIdx+NumFixedObjects].SSPLayout; 540 } 541 setObjectSSPLayout(int ObjectIdx,SSPLayoutKind Kind)542 void setObjectSSPLayout(int ObjectIdx, SSPLayoutKind Kind) { 543 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() && 544 "Invalid Object Idx!"); 545 assert(!isDeadObjectIndex(ObjectIdx) && 546 "Setting SSP layout for a dead object?"); 547 Objects[ObjectIdx+NumFixedObjects].SSPLayout = Kind; 548 } 549 550 /// Return the number of bytes that must be allocated to hold 551 /// all of the fixed size frame objects. This is only valid after 552 /// Prolog/Epilog code insertion has finalized the stack frame layout. getStackSize()553 uint64_t getStackSize() const { return StackSize; } 554 555 /// Set the size of the stack. setStackSize(uint64_t Size)556 void setStackSize(uint64_t Size) { StackSize = Size; } 557 558 /// Estimate and return the size of the stack frame. 559 uint64_t estimateStackSize(const MachineFunction &MF) const; 560 561 /// Return the correction for frame offsets. getOffsetAdjustment()562 int getOffsetAdjustment() const { return OffsetAdjustment; } 563 564 /// Set the correction for frame offsets. setOffsetAdjustment(int Adj)565 void setOffsetAdjustment(int Adj) { OffsetAdjustment = Adj; } 566 567 /// Return the alignment in bytes that this function must be aligned to, 568 /// which is greater than the default stack alignment provided by the target. getMaxAlign()569 Align getMaxAlign() const { return MaxAlignment; } 570 571 /// Make sure the function is at least Align bytes aligned. 572 void ensureMaxAlignment(Align Alignment); 573 574 /// Return true if this function adjusts the stack -- e.g., 575 /// when calling another function. This is only valid during and after 576 /// prolog/epilog code insertion. adjustsStack()577 bool adjustsStack() const { return AdjustsStack; } setAdjustsStack(bool V)578 void setAdjustsStack(bool V) { AdjustsStack = V; } 579 580 /// Return true if the current function has any function calls. hasCalls()581 bool hasCalls() const { return HasCalls; } setHasCalls(bool V)582 void setHasCalls(bool V) { HasCalls = V; } 583 584 /// Returns true if the function contains opaque dynamic stack adjustments. hasOpaqueSPAdjustment()585 bool hasOpaqueSPAdjustment() const { return HasOpaqueSPAdjustment; } setHasOpaqueSPAdjustment(bool B)586 void setHasOpaqueSPAdjustment(bool B) { HasOpaqueSPAdjustment = B; } 587 588 /// Returns true if the function contains operations which will lower down to 589 /// instructions which manipulate the stack pointer. hasCopyImplyingStackAdjustment()590 bool hasCopyImplyingStackAdjustment() const { 591 return HasCopyImplyingStackAdjustment; 592 } setHasCopyImplyingStackAdjustment(bool B)593 void setHasCopyImplyingStackAdjustment(bool B) { 594 HasCopyImplyingStackAdjustment = B; 595 } 596 597 /// Returns true if the function calls the llvm.va_start intrinsic. hasVAStart()598 bool hasVAStart() const { return HasVAStart; } setHasVAStart(bool B)599 void setHasVAStart(bool B) { HasVAStart = B; } 600 601 /// Returns true if the function is variadic and contains a musttail call. hasMustTailInVarArgFunc()602 bool hasMustTailInVarArgFunc() const { return HasMustTailInVarArgFunc; } setHasMustTailInVarArgFunc(bool B)603 void setHasMustTailInVarArgFunc(bool B) { HasMustTailInVarArgFunc = B; } 604 605 /// Returns true if the function contains a tail call. hasTailCall()606 bool hasTailCall() const { return HasTailCall; } 607 void setHasTailCall(bool V = true) { HasTailCall = V; } 608 609 /// Computes the maximum size of a callframe and the AdjustsStack property. 610 /// This only works for targets defining 611 /// TargetInstrInfo::getCallFrameSetupOpcode(), getCallFrameDestroyOpcode(), 612 /// and getFrameSize(). 613 /// This is usually computed by the prologue epilogue inserter but some 614 /// targets may call this to compute it earlier. 615 void computeMaxCallFrameSize(const MachineFunction &MF); 616 617 /// Return the maximum size of a call frame that must be 618 /// allocated for an outgoing function call. This is only available if 619 /// CallFrameSetup/Destroy pseudo instructions are used by the target, and 620 /// then only during or after prolog/epilog code insertion. 621 /// getMaxCallFrameSize()622 unsigned getMaxCallFrameSize() const { 623 // TODO: Enable this assert when targets are fixed. 624 //assert(isMaxCallFrameSizeComputed() && "MaxCallFrameSize not computed yet"); 625 if (!isMaxCallFrameSizeComputed()) 626 return 0; 627 return MaxCallFrameSize; 628 } isMaxCallFrameSizeComputed()629 bool isMaxCallFrameSizeComputed() const { 630 return MaxCallFrameSize != ~0u; 631 } setMaxCallFrameSize(unsigned S)632 void setMaxCallFrameSize(unsigned S) { MaxCallFrameSize = S; } 633 634 /// Returns how many bytes of callee-saved registers the target pushed in the 635 /// prologue. Only used for debug info. getCVBytesOfCalleeSavedRegisters()636 unsigned getCVBytesOfCalleeSavedRegisters() const { 637 return CVBytesOfCalleeSavedRegisters; 638 } setCVBytesOfCalleeSavedRegisters(unsigned S)639 void setCVBytesOfCalleeSavedRegisters(unsigned S) { 640 CVBytesOfCalleeSavedRegisters = S; 641 } 642 643 /// Create a new object at a fixed location on the stack. 644 /// All fixed objects should be created before other objects are created for 645 /// efficiency. By default, fixed objects are not pointed to by LLVM IR 646 /// values. This returns an index with a negative value. 647 int CreateFixedObject(uint64_t Size, int64_t SPOffset, bool IsImmutable, 648 bool isAliased = false); 649 650 /// Create a spill slot at a fixed location on the stack. 651 /// Returns an index with a negative value. 652 int CreateFixedSpillStackObject(uint64_t Size, int64_t SPOffset, 653 bool IsImmutable = false); 654 655 /// Returns true if the specified index corresponds to a fixed stack object. isFixedObjectIndex(int ObjectIdx)656 bool isFixedObjectIndex(int ObjectIdx) const { 657 return ObjectIdx < 0 && (ObjectIdx >= -(int)NumFixedObjects); 658 } 659 660 /// Returns true if the specified index corresponds 661 /// to an object that might be pointed to by an LLVM IR value. isAliasedObjectIndex(int ObjectIdx)662 bool isAliasedObjectIndex(int ObjectIdx) const { 663 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() && 664 "Invalid Object Idx!"); 665 return Objects[ObjectIdx+NumFixedObjects].isAliased; 666 } 667 668 /// Returns true if the specified index corresponds to an immutable object. isImmutableObjectIndex(int ObjectIdx)669 bool isImmutableObjectIndex(int ObjectIdx) const { 670 // Tail calling functions can clobber their function arguments. 671 if (HasTailCall) 672 return false; 673 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() && 674 "Invalid Object Idx!"); 675 return Objects[ObjectIdx+NumFixedObjects].isImmutable; 676 } 677 678 /// Marks the immutability of an object. setIsImmutableObjectIndex(int ObjectIdx,bool IsImmutable)679 void setIsImmutableObjectIndex(int ObjectIdx, bool IsImmutable) { 680 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() && 681 "Invalid Object Idx!"); 682 Objects[ObjectIdx+NumFixedObjects].isImmutable = IsImmutable; 683 } 684 685 /// Returns true if the specified index corresponds to a spill slot. isSpillSlotObjectIndex(int ObjectIdx)686 bool isSpillSlotObjectIndex(int ObjectIdx) const { 687 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() && 688 "Invalid Object Idx!"); 689 return Objects[ObjectIdx+NumFixedObjects].isSpillSlot; 690 } 691 isStatepointSpillSlotObjectIndex(int ObjectIdx)692 bool isStatepointSpillSlotObjectIndex(int ObjectIdx) const { 693 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() && 694 "Invalid Object Idx!"); 695 return Objects[ObjectIdx+NumFixedObjects].isStatepointSpillSlot; 696 } 697 698 /// \see StackID getStackID(int ObjectIdx)699 uint8_t getStackID(int ObjectIdx) const { 700 return Objects[ObjectIdx+NumFixedObjects].StackID; 701 } 702 703 /// \see StackID setStackID(int ObjectIdx,uint8_t ID)704 void setStackID(int ObjectIdx, uint8_t ID) { 705 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() && 706 "Invalid Object Idx!"); 707 Objects[ObjectIdx+NumFixedObjects].StackID = ID; 708 // If ID > 0, MaxAlignment may now be overly conservative. 709 // If ID == 0, MaxAlignment will need to be updated separately. 710 } 711 712 /// Returns true if the specified index corresponds to a dead object. isDeadObjectIndex(int ObjectIdx)713 bool isDeadObjectIndex(int ObjectIdx) const { 714 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() && 715 "Invalid Object Idx!"); 716 return Objects[ObjectIdx+NumFixedObjects].Size == ~0ULL; 717 } 718 719 /// Returns true if the specified index corresponds to a variable sized 720 /// object. isVariableSizedObjectIndex(int ObjectIdx)721 bool isVariableSizedObjectIndex(int ObjectIdx) const { 722 assert(unsigned(ObjectIdx + NumFixedObjects) < Objects.size() && 723 "Invalid Object Idx!"); 724 return Objects[ObjectIdx + NumFixedObjects].Size == 0; 725 } 726 markAsStatepointSpillSlotObjectIndex(int ObjectIdx)727 void markAsStatepointSpillSlotObjectIndex(int ObjectIdx) { 728 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() && 729 "Invalid Object Idx!"); 730 Objects[ObjectIdx+NumFixedObjects].isStatepointSpillSlot = true; 731 assert(isStatepointSpillSlotObjectIndex(ObjectIdx) && "inconsistent"); 732 } 733 734 /// Create a new statically sized stack object, returning 735 /// a nonnegative identifier to represent it. 736 int CreateStackObject(uint64_t Size, Align Alignment, bool isSpillSlot, 737 const AllocaInst *Alloca = nullptr, uint8_t ID = 0); 738 739 /// Create a new statically sized stack object that represents a spill slot, 740 /// returning a nonnegative identifier to represent it. 741 int CreateSpillStackObject(uint64_t Size, Align Alignment); 742 743 /// Remove or mark dead a statically sized stack object. RemoveStackObject(int ObjectIdx)744 void RemoveStackObject(int ObjectIdx) { 745 // Mark it dead. 746 Objects[ObjectIdx+NumFixedObjects].Size = ~0ULL; 747 } 748 749 /// Notify the MachineFrameInfo object that a variable sized object has been 750 /// created. This must be created whenever a variable sized object is 751 /// created, whether or not the index returned is actually used. 752 int CreateVariableSizedObject(Align Alignment, const AllocaInst *Alloca); 753 754 /// Returns a reference to call saved info vector for the current function. getCalleeSavedInfo()755 const std::vector<CalleeSavedInfo> &getCalleeSavedInfo() const { 756 return CSInfo; 757 } 758 /// \copydoc getCalleeSavedInfo() getCalleeSavedInfo()759 std::vector<CalleeSavedInfo> &getCalleeSavedInfo() { return CSInfo; } 760 761 /// Used by prolog/epilog inserter to set the function's callee saved 762 /// information. setCalleeSavedInfo(std::vector<CalleeSavedInfo> CSI)763 void setCalleeSavedInfo(std::vector<CalleeSavedInfo> CSI) { 764 CSInfo = std::move(CSI); 765 } 766 767 /// Has the callee saved info been calculated yet? isCalleeSavedInfoValid()768 bool isCalleeSavedInfoValid() const { return CSIValid; } 769 setCalleeSavedInfoValid(bool v)770 void setCalleeSavedInfoValid(bool v) { CSIValid = v; } 771 getSavePoint()772 MachineBasicBlock *getSavePoint() const { return Save; } setSavePoint(MachineBasicBlock * NewSave)773 void setSavePoint(MachineBasicBlock *NewSave) { Save = NewSave; } getRestorePoint()774 MachineBasicBlock *getRestorePoint() const { return Restore; } setRestorePoint(MachineBasicBlock * NewRestore)775 void setRestorePoint(MachineBasicBlock *NewRestore) { Restore = NewRestore; } 776 777 /// Return a set of physical registers that are pristine. 778 /// 779 /// Pristine registers hold a value that is useless to the current function, 780 /// but that must be preserved - they are callee saved registers that are not 781 /// saved. 782 /// 783 /// Before the PrologueEpilogueInserter has placed the CSR spill code, this 784 /// method always returns an empty set. 785 BitVector getPristineRegs(const MachineFunction &MF) const; 786 787 /// Used by the MachineFunction printer to print information about 788 /// stack objects. Implemented in MachineFunction.cpp. 789 void print(const MachineFunction &MF, raw_ostream &OS) const; 790 791 /// dump - Print the function to stderr. 792 void dump(const MachineFunction &MF) const; 793 }; 794 795 } // End llvm namespace 796 797 #endif 798