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 zero-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 /// Return true if there are any stack objects in this function. hasStackObjects()346 bool hasStackObjects() const { return !Objects.empty(); } 347 348 /// This method may be called any time after instruction 349 /// selection is complete to determine if the stack frame for this function 350 /// contains any variable sized objects. hasVarSizedObjects()351 bool hasVarSizedObjects() const { return HasVarSizedObjects; } 352 353 /// Return the index for the stack protector object. getStackProtectorIndex()354 int getStackProtectorIndex() const { return StackProtectorIdx; } setStackProtectorIndex(int I)355 void setStackProtectorIndex(int I) { StackProtectorIdx = I; } hasStackProtectorIndex()356 bool hasStackProtectorIndex() const { return StackProtectorIdx != -1; } 357 358 /// Return the index for the function context object. 359 /// This object is used for SjLj exceptions. getFunctionContextIndex()360 int getFunctionContextIndex() const { return FunctionContextIdx; } setFunctionContextIndex(int I)361 void setFunctionContextIndex(int I) { FunctionContextIdx = I; } 362 363 /// This method may be called any time after instruction 364 /// selection is complete to determine if there is a call to 365 /// \@llvm.frameaddress in this function. isFrameAddressTaken()366 bool isFrameAddressTaken() const { return FrameAddressTaken; } setFrameAddressIsTaken(bool T)367 void setFrameAddressIsTaken(bool T) { FrameAddressTaken = T; } 368 369 /// This method may be called any time after 370 /// instruction selection is complete to determine if there is a call to 371 /// \@llvm.returnaddress in this function. isReturnAddressTaken()372 bool isReturnAddressTaken() const { return ReturnAddressTaken; } setReturnAddressIsTaken(bool s)373 void setReturnAddressIsTaken(bool s) { ReturnAddressTaken = s; } 374 375 /// This method may be called any time after instruction 376 /// selection is complete to determine if there is a call to builtin 377 /// \@llvm.experimental.stackmap. hasStackMap()378 bool hasStackMap() const { return HasStackMap; } 379 void setHasStackMap(bool s = true) { HasStackMap = s; } 380 381 /// This method may be called any time after instruction 382 /// selection is complete to determine if there is a call to builtin 383 /// \@llvm.experimental.patchpoint. hasPatchPoint()384 bool hasPatchPoint() const { return HasPatchPoint; } 385 void setHasPatchPoint(bool s = true) { HasPatchPoint = s; } 386 387 /// Return the minimum frame object index. getObjectIndexBegin()388 int getObjectIndexBegin() const { return -NumFixedObjects; } 389 390 /// Return one past the maximum frame object index. getObjectIndexEnd()391 int getObjectIndexEnd() const { return (int)Objects.size()-NumFixedObjects; } 392 393 /// Return the number of fixed objects. getNumFixedObjects()394 unsigned getNumFixedObjects() const { return NumFixedObjects; } 395 396 /// Return the number of objects. getNumObjects()397 unsigned getNumObjects() const { return Objects.size(); } 398 399 /// Map a frame index into the local object block mapLocalFrameObject(int ObjectIndex,int64_t Offset)400 void mapLocalFrameObject(int ObjectIndex, int64_t Offset) { 401 LocalFrameObjects.push_back(std::pair<int, int64_t>(ObjectIndex, Offset)); 402 Objects[ObjectIndex + NumFixedObjects].PreAllocated = true; 403 } 404 405 /// Get the local offset mapping for a for an object. getLocalFrameObjectMap(int i)406 std::pair<int, int64_t> getLocalFrameObjectMap(int i) const { 407 assert (i >= 0 && (unsigned)i < LocalFrameObjects.size() && 408 "Invalid local object reference!"); 409 return LocalFrameObjects[i]; 410 } 411 412 /// Return the number of objects allocated into the local object block. getLocalFrameObjectCount()413 int64_t getLocalFrameObjectCount() const { return LocalFrameObjects.size(); } 414 415 /// Set the size of the local object blob. setLocalFrameSize(int64_t sz)416 void setLocalFrameSize(int64_t sz) { LocalFrameSize = sz; } 417 418 /// Get the size of the local object blob. getLocalFrameSize()419 int64_t getLocalFrameSize() const { return LocalFrameSize; } 420 421 /// Required alignment of the local object blob, 422 /// which is the strictest alignment of any object in it. setLocalFrameMaxAlign(Align Alignment)423 void setLocalFrameMaxAlign(Align Alignment) { 424 LocalFrameMaxAlign = Alignment; 425 } 426 427 /// Return the required alignment of the local object blob. getLocalFrameMaxAlign()428 Align getLocalFrameMaxAlign() const { return LocalFrameMaxAlign; } 429 430 /// Get whether the local allocation blob should be allocated together or 431 /// let PEI allocate the locals in it directly. getUseLocalStackAllocationBlock()432 bool getUseLocalStackAllocationBlock() const { 433 return UseLocalStackAllocationBlock; 434 } 435 436 /// setUseLocalStackAllocationBlock - Set whether the local allocation blob 437 /// should be allocated together or let PEI allocate the locals in it 438 /// directly. setUseLocalStackAllocationBlock(bool v)439 void setUseLocalStackAllocationBlock(bool v) { 440 UseLocalStackAllocationBlock = v; 441 } 442 443 /// Return true if the object was pre-allocated into the local block. isObjectPreAllocated(int ObjectIdx)444 bool isObjectPreAllocated(int ObjectIdx) const { 445 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() && 446 "Invalid Object Idx!"); 447 return Objects[ObjectIdx+NumFixedObjects].PreAllocated; 448 } 449 450 /// Return the size of the specified object. getObjectSize(int ObjectIdx)451 int64_t getObjectSize(int ObjectIdx) const { 452 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() && 453 "Invalid Object Idx!"); 454 return Objects[ObjectIdx+NumFixedObjects].Size; 455 } 456 457 /// Change the size of the specified stack object. setObjectSize(int ObjectIdx,int64_t Size)458 void setObjectSize(int ObjectIdx, int64_t Size) { 459 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() && 460 "Invalid Object Idx!"); 461 Objects[ObjectIdx+NumFixedObjects].Size = Size; 462 } 463 464 /// Return the alignment of the specified stack object. getObjectAlign(int ObjectIdx)465 Align getObjectAlign(int ObjectIdx) const { 466 assert(unsigned(ObjectIdx + NumFixedObjects) < Objects.size() && 467 "Invalid Object Idx!"); 468 return Objects[ObjectIdx + NumFixedObjects].Alignment; 469 } 470 471 /// setObjectAlignment - Change the alignment of the specified stack object. setObjectAlignment(int ObjectIdx,Align Alignment)472 void setObjectAlignment(int ObjectIdx, Align Alignment) { 473 assert(unsigned(ObjectIdx + NumFixedObjects) < Objects.size() && 474 "Invalid Object Idx!"); 475 Objects[ObjectIdx + NumFixedObjects].Alignment = Alignment; 476 477 // Only ensure max alignment for the default stack. 478 if (getStackID(ObjectIdx) == 0) 479 ensureMaxAlignment(Alignment); 480 } 481 482 /// Return the underlying Alloca of the specified 483 /// stack object if it exists. Returns 0 if none exists. getObjectAllocation(int ObjectIdx)484 const AllocaInst* getObjectAllocation(int ObjectIdx) const { 485 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() && 486 "Invalid Object Idx!"); 487 return Objects[ObjectIdx+NumFixedObjects].Alloca; 488 } 489 490 /// Return the assigned stack offset of the specified object 491 /// from the incoming stack pointer. getObjectOffset(int ObjectIdx)492 int64_t getObjectOffset(int ObjectIdx) const { 493 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() && 494 "Invalid Object Idx!"); 495 assert(!isDeadObjectIndex(ObjectIdx) && 496 "Getting frame offset for a dead object?"); 497 return Objects[ObjectIdx+NumFixedObjects].SPOffset; 498 } 499 isObjectZExt(int ObjectIdx)500 bool isObjectZExt(int ObjectIdx) const { 501 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() && 502 "Invalid Object Idx!"); 503 return Objects[ObjectIdx+NumFixedObjects].isZExt; 504 } 505 setObjectZExt(int ObjectIdx,bool IsZExt)506 void setObjectZExt(int ObjectIdx, bool IsZExt) { 507 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() && 508 "Invalid Object Idx!"); 509 Objects[ObjectIdx+NumFixedObjects].isZExt = IsZExt; 510 } 511 isObjectSExt(int ObjectIdx)512 bool isObjectSExt(int ObjectIdx) const { 513 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() && 514 "Invalid Object Idx!"); 515 return Objects[ObjectIdx+NumFixedObjects].isSExt; 516 } 517 setObjectSExt(int ObjectIdx,bool IsSExt)518 void setObjectSExt(int ObjectIdx, bool IsSExt) { 519 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() && 520 "Invalid Object Idx!"); 521 Objects[ObjectIdx+NumFixedObjects].isSExt = IsSExt; 522 } 523 524 /// Set the stack frame offset of the specified object. The 525 /// offset is relative to the stack pointer on entry to the function. setObjectOffset(int ObjectIdx,int64_t SPOffset)526 void setObjectOffset(int ObjectIdx, int64_t SPOffset) { 527 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() && 528 "Invalid Object Idx!"); 529 assert(!isDeadObjectIndex(ObjectIdx) && 530 "Setting frame offset for a dead object?"); 531 Objects[ObjectIdx+NumFixedObjects].SPOffset = SPOffset; 532 } 533 getObjectSSPLayout(int ObjectIdx)534 SSPLayoutKind getObjectSSPLayout(int ObjectIdx) const { 535 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() && 536 "Invalid Object Idx!"); 537 return (SSPLayoutKind)Objects[ObjectIdx+NumFixedObjects].SSPLayout; 538 } 539 setObjectSSPLayout(int ObjectIdx,SSPLayoutKind Kind)540 void setObjectSSPLayout(int ObjectIdx, SSPLayoutKind Kind) { 541 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() && 542 "Invalid Object Idx!"); 543 assert(!isDeadObjectIndex(ObjectIdx) && 544 "Setting SSP layout for a dead object?"); 545 Objects[ObjectIdx+NumFixedObjects].SSPLayout = Kind; 546 } 547 548 /// Return the number of bytes that must be allocated to hold 549 /// all of the fixed size frame objects. This is only valid after 550 /// Prolog/Epilog code insertion has finalized the stack frame layout. getStackSize()551 uint64_t getStackSize() const { return StackSize; } 552 553 /// Set the size of the stack. setStackSize(uint64_t Size)554 void setStackSize(uint64_t Size) { StackSize = Size; } 555 556 /// Estimate and return the size of the stack frame. 557 uint64_t estimateStackSize(const MachineFunction &MF) const; 558 559 /// Return the correction for frame offsets. getOffsetAdjustment()560 int getOffsetAdjustment() const { return OffsetAdjustment; } 561 562 /// Set the correction for frame offsets. setOffsetAdjustment(int Adj)563 void setOffsetAdjustment(int Adj) { OffsetAdjustment = Adj; } 564 565 /// Return the alignment in bytes that this function must be aligned to, 566 /// which is greater than the default stack alignment provided by the target. getMaxAlign()567 Align getMaxAlign() const { return MaxAlignment; } 568 569 /// Make sure the function is at least Align bytes aligned. 570 void ensureMaxAlignment(Align Alignment); 571 572 /// Return true if this function adjusts the stack -- e.g., 573 /// when calling another function. This is only valid during and after 574 /// prolog/epilog code insertion. adjustsStack()575 bool adjustsStack() const { return AdjustsStack; } setAdjustsStack(bool V)576 void setAdjustsStack(bool V) { AdjustsStack = V; } 577 578 /// Return true if the current function has any function calls. hasCalls()579 bool hasCalls() const { return HasCalls; } setHasCalls(bool V)580 void setHasCalls(bool V) { HasCalls = V; } 581 582 /// Returns true if the function contains opaque dynamic stack adjustments. hasOpaqueSPAdjustment()583 bool hasOpaqueSPAdjustment() const { return HasOpaqueSPAdjustment; } setHasOpaqueSPAdjustment(bool B)584 void setHasOpaqueSPAdjustment(bool B) { HasOpaqueSPAdjustment = B; } 585 586 /// Returns true if the function contains operations which will lower down to 587 /// instructions which manipulate the stack pointer. hasCopyImplyingStackAdjustment()588 bool hasCopyImplyingStackAdjustment() const { 589 return HasCopyImplyingStackAdjustment; 590 } setHasCopyImplyingStackAdjustment(bool B)591 void setHasCopyImplyingStackAdjustment(bool B) { 592 HasCopyImplyingStackAdjustment = B; 593 } 594 595 /// Returns true if the function calls the llvm.va_start intrinsic. hasVAStart()596 bool hasVAStart() const { return HasVAStart; } setHasVAStart(bool B)597 void setHasVAStart(bool B) { HasVAStart = B; } 598 599 /// Returns true if the function is variadic and contains a musttail call. hasMustTailInVarArgFunc()600 bool hasMustTailInVarArgFunc() const { return HasMustTailInVarArgFunc; } setHasMustTailInVarArgFunc(bool B)601 void setHasMustTailInVarArgFunc(bool B) { HasMustTailInVarArgFunc = B; } 602 603 /// Returns true if the function contains a tail call. hasTailCall()604 bool hasTailCall() const { return HasTailCall; } 605 void setHasTailCall(bool V = true) { HasTailCall = V; } 606 607 /// Computes the maximum size of a callframe and the AdjustsStack property. 608 /// This only works for targets defining 609 /// TargetInstrInfo::getCallFrameSetupOpcode(), getCallFrameDestroyOpcode(), 610 /// and getFrameSize(). 611 /// This is usually computed by the prologue epilogue inserter but some 612 /// targets may call this to compute it earlier. 613 void computeMaxCallFrameSize(const MachineFunction &MF); 614 615 /// Return the maximum size of a call frame that must be 616 /// allocated for an outgoing function call. This is only available if 617 /// CallFrameSetup/Destroy pseudo instructions are used by the target, and 618 /// then only during or after prolog/epilog code insertion. 619 /// getMaxCallFrameSize()620 unsigned getMaxCallFrameSize() const { 621 // TODO: Enable this assert when targets are fixed. 622 //assert(isMaxCallFrameSizeComputed() && "MaxCallFrameSize not computed yet"); 623 if (!isMaxCallFrameSizeComputed()) 624 return 0; 625 return MaxCallFrameSize; 626 } isMaxCallFrameSizeComputed()627 bool isMaxCallFrameSizeComputed() const { 628 return MaxCallFrameSize != ~0u; 629 } setMaxCallFrameSize(unsigned S)630 void setMaxCallFrameSize(unsigned S) { MaxCallFrameSize = S; } 631 632 /// Returns how many bytes of callee-saved registers the target pushed in the 633 /// prologue. Only used for debug info. getCVBytesOfCalleeSavedRegisters()634 unsigned getCVBytesOfCalleeSavedRegisters() const { 635 return CVBytesOfCalleeSavedRegisters; 636 } setCVBytesOfCalleeSavedRegisters(unsigned S)637 void setCVBytesOfCalleeSavedRegisters(unsigned S) { 638 CVBytesOfCalleeSavedRegisters = S; 639 } 640 641 /// Create a new object at a fixed location on the stack. 642 /// All fixed objects should be created before other objects are created for 643 /// efficiency. By default, fixed objects are not pointed to by LLVM IR 644 /// values. This returns an index with a negative value. 645 int CreateFixedObject(uint64_t Size, int64_t SPOffset, bool IsImmutable, 646 bool isAliased = false); 647 648 /// Create a spill slot at a fixed location on the stack. 649 /// Returns an index with a negative value. 650 int CreateFixedSpillStackObject(uint64_t Size, int64_t SPOffset, 651 bool IsImmutable = false); 652 653 /// Returns true if the specified index corresponds to a fixed stack object. isFixedObjectIndex(int ObjectIdx)654 bool isFixedObjectIndex(int ObjectIdx) const { 655 return ObjectIdx < 0 && (ObjectIdx >= -(int)NumFixedObjects); 656 } 657 658 /// Returns true if the specified index corresponds 659 /// to an object that might be pointed to by an LLVM IR value. isAliasedObjectIndex(int ObjectIdx)660 bool isAliasedObjectIndex(int ObjectIdx) const { 661 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() && 662 "Invalid Object Idx!"); 663 return Objects[ObjectIdx+NumFixedObjects].isAliased; 664 } 665 666 /// Returns true if the specified index corresponds to an immutable object. isImmutableObjectIndex(int ObjectIdx)667 bool isImmutableObjectIndex(int ObjectIdx) const { 668 // Tail calling functions can clobber their function arguments. 669 if (HasTailCall) 670 return false; 671 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() && 672 "Invalid Object Idx!"); 673 return Objects[ObjectIdx+NumFixedObjects].isImmutable; 674 } 675 676 /// Marks the immutability of an object. setIsImmutableObjectIndex(int ObjectIdx,bool IsImmutable)677 void setIsImmutableObjectIndex(int ObjectIdx, bool IsImmutable) { 678 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() && 679 "Invalid Object Idx!"); 680 Objects[ObjectIdx+NumFixedObjects].isImmutable = IsImmutable; 681 } 682 683 /// Returns true if the specified index corresponds to a spill slot. isSpillSlotObjectIndex(int ObjectIdx)684 bool isSpillSlotObjectIndex(int ObjectIdx) const { 685 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() && 686 "Invalid Object Idx!"); 687 return Objects[ObjectIdx+NumFixedObjects].isSpillSlot; 688 } 689 isStatepointSpillSlotObjectIndex(int ObjectIdx)690 bool isStatepointSpillSlotObjectIndex(int ObjectIdx) const { 691 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() && 692 "Invalid Object Idx!"); 693 return Objects[ObjectIdx+NumFixedObjects].isStatepointSpillSlot; 694 } 695 696 /// \see StackID getStackID(int ObjectIdx)697 uint8_t getStackID(int ObjectIdx) const { 698 return Objects[ObjectIdx+NumFixedObjects].StackID; 699 } 700 701 /// \see StackID setStackID(int ObjectIdx,uint8_t ID)702 void setStackID(int ObjectIdx, uint8_t ID) { 703 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() && 704 "Invalid Object Idx!"); 705 Objects[ObjectIdx+NumFixedObjects].StackID = ID; 706 // If ID > 0, MaxAlignment may now be overly conservative. 707 // If ID == 0, MaxAlignment will need to be updated separately. 708 } 709 710 /// Returns true if the specified index corresponds to a dead object. isDeadObjectIndex(int ObjectIdx)711 bool isDeadObjectIndex(int ObjectIdx) const { 712 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() && 713 "Invalid Object Idx!"); 714 return Objects[ObjectIdx+NumFixedObjects].Size == ~0ULL; 715 } 716 717 /// Returns true if the specified index corresponds to a variable sized 718 /// object. isVariableSizedObjectIndex(int ObjectIdx)719 bool isVariableSizedObjectIndex(int ObjectIdx) const { 720 assert(unsigned(ObjectIdx + NumFixedObjects) < Objects.size() && 721 "Invalid Object Idx!"); 722 return Objects[ObjectIdx + NumFixedObjects].Size == 0; 723 } 724 markAsStatepointSpillSlotObjectIndex(int ObjectIdx)725 void markAsStatepointSpillSlotObjectIndex(int ObjectIdx) { 726 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() && 727 "Invalid Object Idx!"); 728 Objects[ObjectIdx+NumFixedObjects].isStatepointSpillSlot = true; 729 assert(isStatepointSpillSlotObjectIndex(ObjectIdx) && "inconsistent"); 730 } 731 732 /// Create a new statically sized stack object, returning 733 /// a nonnegative identifier to represent it. 734 int CreateStackObject(uint64_t Size, Align Alignment, bool isSpillSlot, 735 const AllocaInst *Alloca = nullptr, uint8_t ID = 0); 736 737 /// Create a new statically sized stack object that represents a spill slot, 738 /// returning a nonnegative identifier to represent it. 739 int CreateSpillStackObject(uint64_t Size, Align Alignment); 740 741 /// Remove or mark dead a statically sized stack object. RemoveStackObject(int ObjectIdx)742 void RemoveStackObject(int ObjectIdx) { 743 // Mark it dead. 744 Objects[ObjectIdx+NumFixedObjects].Size = ~0ULL; 745 } 746 747 /// Notify the MachineFrameInfo object that a variable sized object has been 748 /// created. This must be created whenever a variable sized object is 749 /// created, whether or not the index returned is actually used. 750 int CreateVariableSizedObject(Align Alignment, const AllocaInst *Alloca); 751 752 /// Returns a reference to call saved info vector for the current function. getCalleeSavedInfo()753 const std::vector<CalleeSavedInfo> &getCalleeSavedInfo() const { 754 return CSInfo; 755 } 756 /// \copydoc getCalleeSavedInfo() getCalleeSavedInfo()757 std::vector<CalleeSavedInfo> &getCalleeSavedInfo() { return CSInfo; } 758 759 /// Used by prolog/epilog inserter to set the function's callee saved 760 /// information. setCalleeSavedInfo(std::vector<CalleeSavedInfo> CSI)761 void setCalleeSavedInfo(std::vector<CalleeSavedInfo> CSI) { 762 CSInfo = std::move(CSI); 763 } 764 765 /// Has the callee saved info been calculated yet? isCalleeSavedInfoValid()766 bool isCalleeSavedInfoValid() const { return CSIValid; } 767 setCalleeSavedInfoValid(bool v)768 void setCalleeSavedInfoValid(bool v) { CSIValid = v; } 769 getSavePoint()770 MachineBasicBlock *getSavePoint() const { return Save; } setSavePoint(MachineBasicBlock * NewSave)771 void setSavePoint(MachineBasicBlock *NewSave) { Save = NewSave; } getRestorePoint()772 MachineBasicBlock *getRestorePoint() const { return Restore; } setRestorePoint(MachineBasicBlock * NewRestore)773 void setRestorePoint(MachineBasicBlock *NewRestore) { Restore = NewRestore; } 774 775 /// Return a set of physical registers that are pristine. 776 /// 777 /// Pristine registers hold a value that is useless to the current function, 778 /// but that must be preserved - they are callee saved registers that are not 779 /// saved. 780 /// 781 /// Before the PrologueEpilogueInserter has placed the CSR spill code, this 782 /// method always returns an empty set. 783 BitVector getPristineRegs(const MachineFunction &MF) const; 784 785 /// Used by the MachineFunction printer to print information about 786 /// stack objects. Implemented in MachineFunction.cpp. 787 void print(const MachineFunction &MF, raw_ostream &OS) const; 788 789 /// dump - Print the function to stderr. 790 void dump(const MachineFunction &MF) const; 791 }; 792 793 } // End llvm namespace 794 795 #endif 796