MachineFrameInfo.h revision 344779
1//===-- CodeGen/MachineFrameInfo.h - Abstract Stack Frame Rep. --*- C++ -*-===// 2// 3// The LLVM Compiler Infrastructure 4// 5// This file is distributed under the University of Illinois Open Source 6// License. See LICENSE.TXT for details. 7// 8//===----------------------------------------------------------------------===// 9// 10// The file defines the MachineFrameInfo class. 11// 12//===----------------------------------------------------------------------===// 13 14#ifndef LLVM_CODEGEN_MACHINEFRAMEINFO_H 15#define LLVM_CODEGEN_MACHINEFRAMEINFO_H 16 17#include "llvm/ADT/SmallVector.h" 18#include "llvm/Support/DataTypes.h" 19#include <cassert> 20#include <vector> 21 22namespace llvm { 23class raw_ostream; 24class MachineFunction; 25class MachineBasicBlock; 26class BitVector; 27class 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. 33class 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 56public: 57 explicit CalleeSavedInfo(unsigned R, int FI = 0) 58 : Reg(R), FrameIdx(FI), Restored(true), SpilledToReg(false) {} 59 60 // Accessors. 61 unsigned getReg() const { return Reg; } 62 int getFrameIdx() const { return FrameIdx; } 63 unsigned getDstReg() const { return DstReg; } 64 void setFrameIdx(int FI) { 65 FrameIdx = FI; 66 SpilledToReg = false; 67 } 68 void setDstReg(unsigned SpillReg) { 69 DstReg = SpillReg; 70 SpilledToReg = true; 71 } 72 bool isRestored() const { return Restored; } 73 void setRestored(bool R) { Restored = R; } 74 bool isSpilledToReg() const { return SpilledToReg; } 75}; 76 77/// The MachineFrameInfo class represents an abstract stack frame until 78/// prolog/epilog code is inserted. This class is key to allowing stack frame 79/// representation optimizations, such as frame pointer elimination. It also 80/// allows more mundane (but still important) optimizations, such as reordering 81/// of abstract objects on the stack frame. 82/// 83/// To support this, the class assigns unique integer identifiers to stack 84/// objects requested clients. These identifiers are negative integers for 85/// fixed stack objects (such as arguments passed on the stack) or nonnegative 86/// for objects that may be reordered. Instructions which refer to stack 87/// objects use a special MO_FrameIndex operand to represent these frame 88/// indexes. 89/// 90/// Because this class keeps track of all references to the stack frame, it 91/// knows when a variable sized object is allocated on the stack. This is the 92/// sole condition which prevents frame pointer elimination, which is an 93/// important optimization on register-poor architectures. Because original 94/// variable sized alloca's in the source program are the only source of 95/// variable sized stack objects, it is safe to decide whether there will be 96/// any variable sized objects before all stack objects are known (for 97/// example, register allocator spill code never needs variable sized 98/// objects). 99/// 100/// When prolog/epilog code emission is performed, the final stack frame is 101/// built and the machine instructions are modified to refer to the actual 102/// stack offsets of the object, eliminating all MO_FrameIndex operands from 103/// the program. 104/// 105/// Abstract Stack Frame Information 106class MachineFrameInfo { 107public: 108 /// Stack Smashing Protection (SSP) rules require that vulnerable stack 109 /// allocations are located close the stack protector. 110 enum SSPLayoutKind { 111 SSPLK_None, ///< Did not trigger a stack protector. No effect on data 112 ///< layout. 113 SSPLK_LargeArray, ///< Array or nested array >= SSP-buffer-size. Closest 114 ///< to the stack protector. 115 SSPLK_SmallArray, ///< Array or nested array < SSP-buffer-size. 2nd closest 116 ///< to the stack protector. 117 SSPLK_AddrOf ///< The address of this allocation is exposed and 118 ///< triggered protection. 3rd closest to the protector. 119 }; 120 121private: 122 // Represent a single object allocated on the stack. 123 struct StackObject { 124 // The offset of this object from the stack pointer on entry to 125 // the function. This field has no meaning for a variable sized element. 126 int64_t SPOffset; 127 128 // The size of this object on the stack. 0 means a variable sized object, 129 // ~0ULL means a dead object. 130 uint64_t Size; 131 132 // The required alignment of this stack slot. 133 unsigned 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, unsigned Alignment, int64_t SPOffset, 185 bool IsImmutable, bool IsSpillSlot, const AllocaInst *Alloca, 186 bool IsAliased, uint8_t StackID = 0) 187 : SPOffset(SPOffset), Size(Size), Alignment(Alignment), 188 isImmutable(IsImmutable), isSpillSlot(IsSpillSlot), 189 StackID(StackID), Alloca(Alloca), isAliased(IsAliased), 190 SSPLayout(SSPLK_None) {} 191 }; 192 193 /// The alignment of the stack. 194 unsigned 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 unsigned MaxAlignment = 0; 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 unsigned LocalFrameMaxAlign = 0; 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 339public: 340 explicit MachineFrameInfo(unsigned StackAlignment, bool StackRealignable, 341 bool ForcedRealign) 342 : StackAlignment(StackAlignment), StackRealignable(StackRealignable), 343 ForcedRealign(ForcedRealign) {} 344 345 /// Return true if there are any stack objects in this function. 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. 351 bool hasVarSizedObjects() const { return HasVarSizedObjects; } 352 353 /// Return the index for the stack protector object. 354 int getStackProtectorIndex() const { return StackProtectorIdx; } 355 void setStackProtectorIndex(int I) { StackProtectorIdx = I; } 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. 360 int getFunctionContextIndex() const { return FunctionContextIdx; } 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. 366 bool isFrameAddressTaken() const { return FrameAddressTaken; } 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. 372 bool isReturnAddressTaken() const { return ReturnAddressTaken; } 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. 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. 384 bool hasPatchPoint() const { return HasPatchPoint; } 385 void setHasPatchPoint(bool s = true) { HasPatchPoint = s; } 386 387 /// Return the minimum frame object index. 388 int getObjectIndexBegin() const { return -NumFixedObjects; } 389 390 /// Return one past the maximum frame object index. 391 int getObjectIndexEnd() const { return (int)Objects.size()-NumFixedObjects; } 392 393 /// Return the number of fixed objects. 394 unsigned getNumFixedObjects() const { return NumFixedObjects; } 395 396 /// Return the number of objects. 397 unsigned getNumObjects() const { return Objects.size(); } 398 399 /// Map a frame index into the local object block 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. 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. 413 int64_t getLocalFrameObjectCount() const { return LocalFrameObjects.size(); } 414 415 /// Set the size of the local object blob. 416 void setLocalFrameSize(int64_t sz) { LocalFrameSize = sz; } 417 418 /// Get the size of the local object blob. 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. 423 void setLocalFrameMaxAlign(unsigned Align) { LocalFrameMaxAlign = Align; } 424 425 /// Return the required alignment of the local object blob. 426 unsigned getLocalFrameMaxAlign() const { return LocalFrameMaxAlign; } 427 428 /// Get whether the local allocation blob should be allocated together or 429 /// let PEI allocate the locals in it directly. 430 bool getUseLocalStackAllocationBlock() const { 431 return UseLocalStackAllocationBlock; 432 } 433 434 /// setUseLocalStackAllocationBlock - Set whether the local allocation blob 435 /// should be allocated together or let PEI allocate the locals in it 436 /// directly. 437 void setUseLocalStackAllocationBlock(bool v) { 438 UseLocalStackAllocationBlock = v; 439 } 440 441 /// Return true if the object was pre-allocated into the local block. 442 bool isObjectPreAllocated(int ObjectIdx) const { 443 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() && 444 "Invalid Object Idx!"); 445 return Objects[ObjectIdx+NumFixedObjects].PreAllocated; 446 } 447 448 /// Return the size of the specified object. 449 int64_t getObjectSize(int ObjectIdx) const { 450 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() && 451 "Invalid Object Idx!"); 452 return Objects[ObjectIdx+NumFixedObjects].Size; 453 } 454 455 /// Change the size of the specified stack object. 456 void setObjectSize(int ObjectIdx, int64_t Size) { 457 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() && 458 "Invalid Object Idx!"); 459 Objects[ObjectIdx+NumFixedObjects].Size = Size; 460 } 461 462 /// Return the alignment of the specified stack object. 463 unsigned getObjectAlignment(int ObjectIdx) const { 464 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() && 465 "Invalid Object Idx!"); 466 return Objects[ObjectIdx+NumFixedObjects].Alignment; 467 } 468 469 /// setObjectAlignment - Change the alignment of the specified stack object. 470 void setObjectAlignment(int ObjectIdx, unsigned Align) { 471 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() && 472 "Invalid Object Idx!"); 473 Objects[ObjectIdx+NumFixedObjects].Alignment = Align; 474 ensureMaxAlignment(Align); 475 } 476 477 /// Return the underlying Alloca of the specified 478 /// stack object if it exists. Returns 0 if none exists. 479 const AllocaInst* getObjectAllocation(int ObjectIdx) const { 480 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() && 481 "Invalid Object Idx!"); 482 return Objects[ObjectIdx+NumFixedObjects].Alloca; 483 } 484 485 /// Return the assigned stack offset of the specified object 486 /// from the incoming stack pointer. 487 int64_t getObjectOffset(int ObjectIdx) const { 488 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() && 489 "Invalid Object Idx!"); 490 assert(!isDeadObjectIndex(ObjectIdx) && 491 "Getting frame offset for a dead object?"); 492 return Objects[ObjectIdx+NumFixedObjects].SPOffset; 493 } 494 495 bool isObjectZExt(int ObjectIdx) const { 496 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() && 497 "Invalid Object Idx!"); 498 return Objects[ObjectIdx+NumFixedObjects].isZExt; 499 } 500 501 void setObjectZExt(int ObjectIdx, bool IsZExt) { 502 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() && 503 "Invalid Object Idx!"); 504 Objects[ObjectIdx+NumFixedObjects].isZExt = IsZExt; 505 } 506 507 bool isObjectSExt(int ObjectIdx) const { 508 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() && 509 "Invalid Object Idx!"); 510 return Objects[ObjectIdx+NumFixedObjects].isSExt; 511 } 512 513 void setObjectSExt(int ObjectIdx, bool IsSExt) { 514 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() && 515 "Invalid Object Idx!"); 516 Objects[ObjectIdx+NumFixedObjects].isSExt = IsSExt; 517 } 518 519 /// Set the stack frame offset of the specified object. The 520 /// offset is relative to the stack pointer on entry to the function. 521 void setObjectOffset(int ObjectIdx, int64_t SPOffset) { 522 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() && 523 "Invalid Object Idx!"); 524 assert(!isDeadObjectIndex(ObjectIdx) && 525 "Setting frame offset for a dead object?"); 526 Objects[ObjectIdx+NumFixedObjects].SPOffset = SPOffset; 527 } 528 529 SSPLayoutKind getObjectSSPLayout(int ObjectIdx) const { 530 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() && 531 "Invalid Object Idx!"); 532 return (SSPLayoutKind)Objects[ObjectIdx+NumFixedObjects].SSPLayout; 533 } 534 535 void setObjectSSPLayout(int ObjectIdx, SSPLayoutKind Kind) { 536 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() && 537 "Invalid Object Idx!"); 538 assert(!isDeadObjectIndex(ObjectIdx) && 539 "Setting SSP layout for a dead object?"); 540 Objects[ObjectIdx+NumFixedObjects].SSPLayout = Kind; 541 } 542 543 /// Return the number of bytes that must be allocated to hold 544 /// all of the fixed size frame objects. This is only valid after 545 /// Prolog/Epilog code insertion has finalized the stack frame layout. 546 uint64_t getStackSize() const { return StackSize; } 547 548 /// Set the size of the stack. 549 void setStackSize(uint64_t Size) { StackSize = Size; } 550 551 /// Estimate and return the size of the stack frame. 552 unsigned estimateStackSize(const MachineFunction &MF) const; 553 554 /// Return the correction for frame offsets. 555 int getOffsetAdjustment() const { return OffsetAdjustment; } 556 557 /// Set the correction for frame offsets. 558 void setOffsetAdjustment(int Adj) { OffsetAdjustment = Adj; } 559 560 /// Return the alignment in bytes that this function must be aligned to, 561 /// which is greater than the default stack alignment provided by the target. 562 unsigned getMaxAlignment() const { return MaxAlignment; } 563 564 /// Make sure the function is at least Align bytes aligned. 565 void ensureMaxAlignment(unsigned Align); 566 567 /// Return true if this function adjusts the stack -- e.g., 568 /// when calling another function. This is only valid during and after 569 /// prolog/epilog code insertion. 570 bool adjustsStack() const { return AdjustsStack; } 571 void setAdjustsStack(bool V) { AdjustsStack = V; } 572 573 /// Return true if the current function has any function calls. 574 bool hasCalls() const { return HasCalls; } 575 void setHasCalls(bool V) { HasCalls = V; } 576 577 /// Returns true if the function contains opaque dynamic stack adjustments. 578 bool hasOpaqueSPAdjustment() const { return HasOpaqueSPAdjustment; } 579 void setHasOpaqueSPAdjustment(bool B) { HasOpaqueSPAdjustment = B; } 580 581 /// Returns true if the function contains operations which will lower down to 582 /// instructions which manipulate the stack pointer. 583 bool hasCopyImplyingStackAdjustment() const { 584 return HasCopyImplyingStackAdjustment; 585 } 586 void setHasCopyImplyingStackAdjustment(bool B) { 587 HasCopyImplyingStackAdjustment = B; 588 } 589 590 /// Returns true if the function calls the llvm.va_start intrinsic. 591 bool hasVAStart() const { return HasVAStart; } 592 void setHasVAStart(bool B) { HasVAStart = B; } 593 594 /// Returns true if the function is variadic and contains a musttail call. 595 bool hasMustTailInVarArgFunc() const { return HasMustTailInVarArgFunc; } 596 void setHasMustTailInVarArgFunc(bool B) { HasMustTailInVarArgFunc = B; } 597 598 /// Returns true if the function contains a tail call. 599 bool hasTailCall() const { return HasTailCall; } 600 void setHasTailCall() { HasTailCall = true; } 601 602 /// Computes the maximum size of a callframe and the AdjustsStack property. 603 /// This only works for targets defining 604 /// TargetInstrInfo::getCallFrameSetupOpcode(), getCallFrameDestroyOpcode(), 605 /// and getFrameSize(). 606 /// This is usually computed by the prologue epilogue inserter but some 607 /// targets may call this to compute it earlier. 608 void computeMaxCallFrameSize(const MachineFunction &MF); 609 610 /// Return the maximum size of a call frame that must be 611 /// allocated for an outgoing function call. This is only available if 612 /// CallFrameSetup/Destroy pseudo instructions are used by the target, and 613 /// then only during or after prolog/epilog code insertion. 614 /// 615 unsigned getMaxCallFrameSize() const { 616 // TODO: Enable this assert when targets are fixed. 617 //assert(isMaxCallFrameSizeComputed() && "MaxCallFrameSize not computed yet"); 618 if (!isMaxCallFrameSizeComputed()) 619 return 0; 620 return MaxCallFrameSize; 621 } 622 bool isMaxCallFrameSizeComputed() const { 623 return MaxCallFrameSize != ~0u; 624 } 625 void setMaxCallFrameSize(unsigned S) { MaxCallFrameSize = S; } 626 627 /// Returns how many bytes of callee-saved registers the target pushed in the 628 /// prologue. Only used for debug info. 629 unsigned getCVBytesOfCalleeSavedRegisters() const { 630 return CVBytesOfCalleeSavedRegisters; 631 } 632 void setCVBytesOfCalleeSavedRegisters(unsigned S) { 633 CVBytesOfCalleeSavedRegisters = S; 634 } 635 636 /// Create a new object at a fixed location on the stack. 637 /// All fixed objects should be created before other objects are created for 638 /// efficiency. By default, fixed objects are not pointed to by LLVM IR 639 /// values. This returns an index with a negative value. 640 int CreateFixedObject(uint64_t Size, int64_t SPOffset, bool IsImmutable, 641 bool isAliased = false); 642 643 /// Create a spill slot at a fixed location on the stack. 644 /// Returns an index with a negative value. 645 int CreateFixedSpillStackObject(uint64_t Size, int64_t SPOffset, 646 bool IsImmutable = false); 647 648 /// Returns true if the specified index corresponds to a fixed stack object. 649 bool isFixedObjectIndex(int ObjectIdx) const { 650 return ObjectIdx < 0 && (ObjectIdx >= -(int)NumFixedObjects); 651 } 652 653 /// Returns true if the specified index corresponds 654 /// to an object that might be pointed to by an LLVM IR value. 655 bool isAliasedObjectIndex(int ObjectIdx) const { 656 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() && 657 "Invalid Object Idx!"); 658 return Objects[ObjectIdx+NumFixedObjects].isAliased; 659 } 660 661 /// Returns true if the specified index corresponds to an immutable object. 662 bool isImmutableObjectIndex(int ObjectIdx) const { 663 // Tail calling functions can clobber their function arguments. 664 if (HasTailCall) 665 return false; 666 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() && 667 "Invalid Object Idx!"); 668 return Objects[ObjectIdx+NumFixedObjects].isImmutable; 669 } 670 671 /// Marks the immutability of an object. 672 void setIsImmutableObjectIndex(int ObjectIdx, bool IsImmutable) { 673 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() && 674 "Invalid Object Idx!"); 675 Objects[ObjectIdx+NumFixedObjects].isImmutable = IsImmutable; 676 } 677 678 /// Returns true if the specified index corresponds to a spill slot. 679 bool isSpillSlotObjectIndex(int ObjectIdx) const { 680 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() && 681 "Invalid Object Idx!"); 682 return Objects[ObjectIdx+NumFixedObjects].isSpillSlot; 683 } 684 685 bool isStatepointSpillSlotObjectIndex(int ObjectIdx) const { 686 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() && 687 "Invalid Object Idx!"); 688 return Objects[ObjectIdx+NumFixedObjects].isStatepointSpillSlot; 689 } 690 691 /// \see StackID 692 uint8_t getStackID(int ObjectIdx) const { 693 return Objects[ObjectIdx+NumFixedObjects].StackID; 694 } 695 696 /// \see StackID 697 void setStackID(int ObjectIdx, uint8_t ID) { 698 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() && 699 "Invalid Object Idx!"); 700 Objects[ObjectIdx+NumFixedObjects].StackID = ID; 701 } 702 703 /// Returns true if the specified index corresponds to a dead object. 704 bool isDeadObjectIndex(int ObjectIdx) const { 705 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() && 706 "Invalid Object Idx!"); 707 return Objects[ObjectIdx+NumFixedObjects].Size == ~0ULL; 708 } 709 710 /// Returns true if the specified index corresponds to a variable sized 711 /// object. 712 bool isVariableSizedObjectIndex(int ObjectIdx) const { 713 assert(unsigned(ObjectIdx + NumFixedObjects) < Objects.size() && 714 "Invalid Object Idx!"); 715 return Objects[ObjectIdx + NumFixedObjects].Size == 0; 716 } 717 718 void markAsStatepointSpillSlotObjectIndex(int ObjectIdx) { 719 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() && 720 "Invalid Object Idx!"); 721 Objects[ObjectIdx+NumFixedObjects].isStatepointSpillSlot = true; 722 assert(isStatepointSpillSlotObjectIndex(ObjectIdx) && "inconsistent"); 723 } 724 725 /// Create a new statically sized stack object, returning 726 /// a nonnegative identifier to represent it. 727 int CreateStackObject(uint64_t Size, unsigned Alignment, bool isSpillSlot, 728 const AllocaInst *Alloca = nullptr, uint8_t ID = 0); 729 730 /// Create a new statically sized stack object that represents a spill slot, 731 /// returning a nonnegative identifier to represent it. 732 int CreateSpillStackObject(uint64_t Size, unsigned Alignment); 733 734 /// Remove or mark dead a statically sized stack object. 735 void RemoveStackObject(int ObjectIdx) { 736 // Mark it dead. 737 Objects[ObjectIdx+NumFixedObjects].Size = ~0ULL; 738 } 739 740 /// Notify the MachineFrameInfo object that a variable sized object has been 741 /// created. This must be created whenever a variable sized object is 742 /// created, whether or not the index returned is actually used. 743 int CreateVariableSizedObject(unsigned Alignment, const AllocaInst *Alloca); 744 745 /// Returns a reference to call saved info vector for the current function. 746 const std::vector<CalleeSavedInfo> &getCalleeSavedInfo() const { 747 return CSInfo; 748 } 749 /// \copydoc getCalleeSavedInfo() 750 std::vector<CalleeSavedInfo> &getCalleeSavedInfo() { return CSInfo; } 751 752 /// Used by prolog/epilog inserter to set the function's callee saved 753 /// information. 754 void setCalleeSavedInfo(const std::vector<CalleeSavedInfo> &CSI) { 755 CSInfo = CSI; 756 } 757 758 /// Has the callee saved info been calculated yet? 759 bool isCalleeSavedInfoValid() const { return CSIValid; } 760 761 void setCalleeSavedInfoValid(bool v) { CSIValid = v; } 762 763 MachineBasicBlock *getSavePoint() const { return Save; } 764 void setSavePoint(MachineBasicBlock *NewSave) { Save = NewSave; } 765 MachineBasicBlock *getRestorePoint() const { return Restore; } 766 void setRestorePoint(MachineBasicBlock *NewRestore) { Restore = NewRestore; } 767 768 /// Return a set of physical registers that are pristine. 769 /// 770 /// Pristine registers hold a value that is useless to the current function, 771 /// but that must be preserved - they are callee saved registers that are not 772 /// saved. 773 /// 774 /// Before the PrologueEpilogueInserter has placed the CSR spill code, this 775 /// method always returns an empty set. 776 BitVector getPristineRegs(const MachineFunction &MF) const; 777 778 /// Used by the MachineFunction printer to print information about 779 /// stack objects. Implemented in MachineFunction.cpp. 780 void print(const MachineFunction &MF, raw_ostream &OS) const; 781 782 /// dump - Print the function to stderr. 783 void dump(const MachineFunction &MF) const; 784}; 785 786} // End llvm namespace 787 788#endif 789