MachineFrameInfo.h revision 212904
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/ADT/IndexedMap.h" 19#include "llvm/System/DataTypes.h" 20#include <cassert> 21#include <vector> 22 23namespace llvm { 24class raw_ostream; 25class TargetData; 26class TargetRegisterClass; 27class Type; 28class MachineFunction; 29class MachineBasicBlock; 30class TargetFrameInfo; 31class BitVector; 32 33/// The CalleeSavedInfo class tracks the information need to locate where a 34/// callee saved register is in the current frame. 35class CalleeSavedInfo { 36 unsigned Reg; 37 int FrameIdx; 38 39public: 40 explicit CalleeSavedInfo(unsigned R, int FI = 0) 41 : Reg(R), FrameIdx(FI) {} 42 43 // Accessors. 44 unsigned getReg() const { return Reg; } 45 int getFrameIdx() const { return FrameIdx; } 46 void setFrameIdx(int FI) { FrameIdx = FI; } 47}; 48 49/// The MachineFrameInfo class represents an abstract stack frame until 50/// prolog/epilog code is inserted. This class is key to allowing stack frame 51/// representation optimizations, such as frame pointer elimination. It also 52/// allows more mundane (but still important) optimizations, such as reordering 53/// of abstract objects on the stack frame. 54/// 55/// To support this, the class assigns unique integer identifiers to stack 56/// objects requested clients. These identifiers are negative integers for 57/// fixed stack objects (such as arguments passed on the stack) or nonnegative 58/// for objects that may be reordered. Instructions which refer to stack 59/// objects use a special MO_FrameIndex operand to represent these frame 60/// indexes. 61/// 62/// Because this class keeps track of all references to the stack frame, it 63/// knows when a variable sized object is allocated on the stack. This is the 64/// sole condition which prevents frame pointer elimination, which is an 65/// important optimization on register-poor architectures. Because original 66/// variable sized alloca's in the source program are the only source of 67/// variable sized stack objects, it is safe to decide whether there will be 68/// any variable sized objects before all stack objects are known (for 69/// example, register allocator spill code never needs variable sized 70/// objects). 71/// 72/// When prolog/epilog code emission is performed, the final stack frame is 73/// built and the machine instructions are modified to refer to the actual 74/// stack offsets of the object, eliminating all MO_FrameIndex operands from 75/// the program. 76/// 77/// @brief Abstract Stack Frame Information 78class MachineFrameInfo { 79 80 // StackObject - Represent a single object allocated on the stack. 81 struct StackObject { 82 // SPOffset - The offset of this object from the stack pointer on entry to 83 // the function. This field has no meaning for a variable sized element. 84 int64_t SPOffset; 85 86 // The size of this object on the stack. 0 means a variable sized object, 87 // ~0ULL means a dead object. 88 uint64_t Size; 89 90 // Alignment - The required alignment of this stack slot. 91 unsigned Alignment; 92 93 // isImmutable - If true, the value of the stack object is set before 94 // entering the function and is not modified inside the function. By 95 // default, fixed objects are immutable unless marked otherwise. 96 bool isImmutable; 97 98 // isSpillSlot - If true the stack object is used as spill slot. It 99 // cannot alias any other memory objects. 100 bool isSpillSlot; 101 102 // MayNeedSP - If true the stack object triggered the creation of the stack 103 // protector. We should allocate this object right after the stack 104 // protector. 105 bool MayNeedSP; 106 107 // PreAllocated - If true, the object was mapped into the local frame 108 // block and doesn't need additional handling for allocation beyond that. 109 bool PreAllocated; 110 111 StackObject(uint64_t Sz, unsigned Al, int64_t SP, bool IM, 112 bool isSS, bool NSP) 113 : SPOffset(SP), Size(Sz), Alignment(Al), isImmutable(IM), 114 isSpillSlot(isSS), MayNeedSP(NSP), PreAllocated(false) {} 115 }; 116 117 /// Objects - The list of stack objects allocated... 118 /// 119 std::vector<StackObject> Objects; 120 121 /// NumFixedObjects - This contains the number of fixed objects contained on 122 /// the stack. Because fixed objects are stored at a negative index in the 123 /// Objects list, this is also the index to the 0th object in the list. 124 /// 125 unsigned NumFixedObjects; 126 127 /// HasVarSizedObjects - This boolean keeps track of whether any variable 128 /// sized objects have been allocated yet. 129 /// 130 bool HasVarSizedObjects; 131 132 /// FrameAddressTaken - This boolean keeps track of whether there is a call 133 /// to builtin \@llvm.frameaddress. 134 bool FrameAddressTaken; 135 136 /// ReturnAddressTaken - This boolean keeps track of whether there is a call 137 /// to builtin \@llvm.returnaddress. 138 bool ReturnAddressTaken; 139 140 /// StackSize - The prolog/epilog code inserter calculates the final stack 141 /// offsets for all of the fixed size objects, updating the Objects list 142 /// above. It then updates StackSize to contain the number of bytes that need 143 /// to be allocated on entry to the function. 144 /// 145 uint64_t StackSize; 146 147 /// OffsetAdjustment - The amount that a frame offset needs to be adjusted to 148 /// have the actual offset from the stack/frame pointer. The exact usage of 149 /// this is target-dependent, but it is typically used to adjust between 150 /// SP-relative and FP-relative offsets. E.G., if objects are accessed via 151 /// SP then OffsetAdjustment is zero; if FP is used, OffsetAdjustment is set 152 /// to the distance between the initial SP and the value in FP. For many 153 /// targets, this value is only used when generating debug info (via 154 /// TargetRegisterInfo::getFrameIndexOffset); when generating code, the 155 /// corresponding adjustments are performed directly. 156 int OffsetAdjustment; 157 158 /// MaxAlignment - The prolog/epilog code inserter may process objects 159 /// that require greater alignment than the default alignment the target 160 /// provides. To handle this, MaxAlignment is set to the maximum alignment 161 /// needed by the objects on the current frame. If this is greater than the 162 /// native alignment maintained by the compiler, dynamic alignment code will 163 /// be needed. 164 /// 165 unsigned MaxAlignment; 166 167 /// AdjustsStack - Set to true if this function adjusts the stack -- e.g., 168 /// when calling another function. This is only valid during and after 169 /// prolog/epilog code insertion. 170 bool AdjustsStack; 171 172 /// HasCalls - Set to true if this function has any function calls. 173 bool HasCalls; 174 175 /// StackProtectorIdx - The frame index for the stack protector. 176 int StackProtectorIdx; 177 178 /// MaxCallFrameSize - This contains the size of the largest call frame if the 179 /// target uses frame setup/destroy pseudo instructions (as defined in the 180 /// TargetFrameInfo class). This information is important for frame pointer 181 /// elimination. If is only valid during and after prolog/epilog code 182 /// insertion. 183 /// 184 unsigned MaxCallFrameSize; 185 186 /// CSInfo - The prolog/epilog code inserter fills in this vector with each 187 /// callee saved register saved in the frame. Beyond its use by the prolog/ 188 /// epilog code inserter, this data used for debug info and exception 189 /// handling. 190 std::vector<CalleeSavedInfo> CSInfo; 191 192 /// CSIValid - Has CSInfo been set yet? 193 bool CSIValid; 194 195 /// SpillObjects - A vector indicating which frame indices refer to 196 /// spill slots. 197 SmallVector<bool, 8> SpillObjects; 198 199 /// TargetFrameInfo - Target information about frame layout. 200 /// 201 const TargetFrameInfo &TFI; 202 203 /// LocalFrameObjects - References to frame indices which are mapped 204 /// into the local frame allocation block. <FrameIdx, LocalOffset> 205 SmallVector<std::pair<int, int64_t>, 32> LocalFrameObjects; 206 207 /// LocalFrameSize - Size of the pre-allocated local frame block. 208 int64_t LocalFrameSize; 209 210 /// Required alignment of the local object blob, which is the strictest 211 /// alignment of any object in it. 212 unsigned LocalFrameMaxAlign; 213 214 /// Whether the local object blob needs to be allocated together. If not, 215 /// PEI should ignore the isPreAllocated flags on the stack objects and 216 /// just allocate them normally. 217 bool UseLocalStackAllocationBlock; 218 219public: 220 explicit MachineFrameInfo(const TargetFrameInfo &tfi) : TFI(tfi) { 221 StackSize = NumFixedObjects = OffsetAdjustment = MaxAlignment = 0; 222 HasVarSizedObjects = false; 223 FrameAddressTaken = false; 224 ReturnAddressTaken = false; 225 AdjustsStack = false; 226 HasCalls = false; 227 StackProtectorIdx = -1; 228 MaxCallFrameSize = 0; 229 CSIValid = false; 230 LocalFrameSize = 0; 231 LocalFrameMaxAlign = 0; 232 UseLocalStackAllocationBlock = false; 233 } 234 235 /// hasStackObjects - Return true if there are any stack objects in this 236 /// function. 237 /// 238 bool hasStackObjects() const { return !Objects.empty(); } 239 240 /// hasVarSizedObjects - This method may be called any time after instruction 241 /// selection is complete to determine if the stack frame for this function 242 /// contains any variable sized objects. 243 /// 244 bool hasVarSizedObjects() const { return HasVarSizedObjects; } 245 246 /// getStackProtectorIndex/setStackProtectorIndex - Return the index for the 247 /// stack protector object. 248 /// 249 int getStackProtectorIndex() const { return StackProtectorIdx; } 250 void setStackProtectorIndex(int I) { StackProtectorIdx = I; } 251 252 /// isFrameAddressTaken - This method may be called any time after instruction 253 /// selection is complete to determine if there is a call to 254 /// \@llvm.frameaddress in this function. 255 bool isFrameAddressTaken() const { return FrameAddressTaken; } 256 void setFrameAddressIsTaken(bool T) { FrameAddressTaken = T; } 257 258 /// isReturnAddressTaken - This method may be called any time after 259 /// instruction selection is complete to determine if there is a call to 260 /// \@llvm.returnaddress in this function. 261 bool isReturnAddressTaken() const { return ReturnAddressTaken; } 262 void setReturnAddressIsTaken(bool s) { ReturnAddressTaken = s; } 263 264 /// getObjectIndexBegin - Return the minimum frame object index. 265 /// 266 int getObjectIndexBegin() const { return -NumFixedObjects; } 267 268 /// getObjectIndexEnd - Return one past the maximum frame object index. 269 /// 270 int getObjectIndexEnd() const { return (int)Objects.size()-NumFixedObjects; } 271 272 /// getNumFixedObjects - Return the number of fixed objects. 273 unsigned getNumFixedObjects() const { return NumFixedObjects; } 274 275 /// getNumObjects - Return the number of objects. 276 /// 277 unsigned getNumObjects() const { return Objects.size(); } 278 279 /// mapLocalFrameObject - Map a frame index into the local object block 280 void mapLocalFrameObject(int ObjectIndex, int64_t Offset) { 281 LocalFrameObjects.push_back(std::pair<int, int64_t>(ObjectIndex, Offset)); 282 Objects[ObjectIndex + NumFixedObjects].PreAllocated = true; 283 } 284 285 /// getLocalFrameObjectMap - Get the local offset mapping for a for an object 286 std::pair<int, int64_t> getLocalFrameObjectMap(int i) { 287 assert (i >= 0 && (unsigned)i < LocalFrameObjects.size() && 288 "Invalid local object reference!"); 289 return LocalFrameObjects[i]; 290 } 291 292 /// getLocalFrameObjectCount - Return the number of objects allocated into 293 /// the local object block. 294 int64_t getLocalFrameObjectCount() { return LocalFrameObjects.size(); } 295 296 /// setLocalFrameSize - Set the size of the local object blob. 297 void setLocalFrameSize(int64_t sz) { LocalFrameSize = sz; } 298 299 /// getLocalFrameSize - Get the size of the local object blob. 300 int64_t getLocalFrameSize() const { return LocalFrameSize; } 301 302 /// setLocalFrameMaxAlign - Required alignment of the local object blob, 303 /// which is the strictest alignment of any object in it. 304 void setLocalFrameMaxAlign(unsigned Align) { LocalFrameMaxAlign = Align; } 305 306 /// getLocalFrameMaxAlign - Return the required alignment of the local 307 /// object blob. 308 unsigned getLocalFrameMaxAlign() const { return LocalFrameMaxAlign; } 309 310 /// getUseLocalStackAllocationBlock - Get whether the local allocation blob 311 /// should be allocated together or let PEI allocate the locals in it 312 /// directly. 313 bool getUseLocalStackAllocationBlock() {return UseLocalStackAllocationBlock;} 314 315 /// setUseLocalStackAllocationBlock - Set whether the local allocation blob 316 /// should be allocated together or let PEI allocate the locals in it 317 /// directly. 318 void setUseLocalStackAllocationBlock(bool v) { 319 UseLocalStackAllocationBlock = v; 320 } 321 322 /// isObjectPreAllocated - Return true if the object was pre-allocated into 323 /// the local block. 324 bool isObjectPreAllocated(int ObjectIdx) const { 325 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() && 326 "Invalid Object Idx!"); 327 return Objects[ObjectIdx+NumFixedObjects].PreAllocated; 328 } 329 330 /// getObjectSize - Return the size of the specified object. 331 /// 332 int64_t getObjectSize(int ObjectIdx) const { 333 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() && 334 "Invalid Object Idx!"); 335 return Objects[ObjectIdx+NumFixedObjects].Size; 336 } 337 338 /// setObjectSize - Change the size of the specified stack object. 339 void setObjectSize(int ObjectIdx, int64_t Size) { 340 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() && 341 "Invalid Object Idx!"); 342 Objects[ObjectIdx+NumFixedObjects].Size = Size; 343 } 344 345 /// getObjectAlignment - Return the alignment of the specified stack object. 346 unsigned getObjectAlignment(int ObjectIdx) const { 347 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() && 348 "Invalid Object Idx!"); 349 return Objects[ObjectIdx+NumFixedObjects].Alignment; 350 } 351 352 /// setObjectAlignment - Change the alignment of the specified stack object. 353 void setObjectAlignment(int ObjectIdx, unsigned Align) { 354 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() && 355 "Invalid Object Idx!"); 356 Objects[ObjectIdx+NumFixedObjects].Alignment = Align; 357 MaxAlignment = std::max(MaxAlignment, Align); 358 } 359 360 /// NeedsStackProtector - Returns true if the object may need stack 361 /// protectors. 362 bool MayNeedStackProtector(int ObjectIdx) const { 363 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() && 364 "Invalid Object Idx!"); 365 return Objects[ObjectIdx+NumFixedObjects].MayNeedSP; 366 } 367 368 /// getObjectOffset - Return the assigned stack offset of the specified object 369 /// from the incoming stack pointer. 370 /// 371 int64_t getObjectOffset(int ObjectIdx) const { 372 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() && 373 "Invalid Object Idx!"); 374 assert(!isDeadObjectIndex(ObjectIdx) && 375 "Getting frame offset for a dead object?"); 376 return Objects[ObjectIdx+NumFixedObjects].SPOffset; 377 } 378 379 /// setObjectOffset - Set the stack frame offset of the specified object. The 380 /// offset is relative to the stack pointer on entry to the function. 381 /// 382 void setObjectOffset(int ObjectIdx, int64_t SPOffset) { 383 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() && 384 "Invalid Object Idx!"); 385 assert(!isDeadObjectIndex(ObjectIdx) && 386 "Setting frame offset for a dead object?"); 387 Objects[ObjectIdx+NumFixedObjects].SPOffset = SPOffset; 388 } 389 390 /// getStackSize - Return the number of bytes that must be allocated to hold 391 /// all of the fixed size frame objects. This is only valid after 392 /// Prolog/Epilog code insertion has finalized the stack frame layout. 393 /// 394 uint64_t getStackSize() const { return StackSize; } 395 396 /// setStackSize - Set the size of the stack... 397 /// 398 void setStackSize(uint64_t Size) { StackSize = Size; } 399 400 /// getOffsetAdjustment - Return the correction for frame offsets. 401 /// 402 int getOffsetAdjustment() const { return OffsetAdjustment; } 403 404 /// setOffsetAdjustment - Set the correction for frame offsets. 405 /// 406 void setOffsetAdjustment(int Adj) { OffsetAdjustment = Adj; } 407 408 /// getMaxAlignment - Return the alignment in bytes that this function must be 409 /// aligned to, which is greater than the default stack alignment provided by 410 /// the target. 411 /// 412 unsigned getMaxAlignment() const { return MaxAlignment; } 413 414 /// setMaxAlignment - Set the preferred alignment. 415 /// 416 void setMaxAlignment(unsigned Align) { MaxAlignment = Align; } 417 418 /// AdjustsStack - Return true if this function adjusts the stack -- e.g., 419 /// when calling another function. This is only valid during and after 420 /// prolog/epilog code insertion. 421 bool adjustsStack() const { return AdjustsStack; } 422 void setAdjustsStack(bool V) { AdjustsStack = V; } 423 424 /// hasCalls - Return true if the current function has any function calls. 425 bool hasCalls() const { return HasCalls; } 426 void setHasCalls(bool V) { HasCalls = V; } 427 428 /// getMaxCallFrameSize - Return the maximum size of a call frame that must be 429 /// allocated for an outgoing function call. This is only available if 430 /// CallFrameSetup/Destroy pseudo instructions are used by the target, and 431 /// then only during or after prolog/epilog code insertion. 432 /// 433 unsigned getMaxCallFrameSize() const { return MaxCallFrameSize; } 434 void setMaxCallFrameSize(unsigned S) { MaxCallFrameSize = S; } 435 436 /// CreateFixedObject - Create a new object at a fixed location on the stack. 437 /// All fixed objects should be created before other objects are created for 438 /// efficiency. By default, fixed objects are immutable. This returns an 439 /// index with a negative value. 440 /// 441 int CreateFixedObject(uint64_t Size, int64_t SPOffset, bool Immutable); 442 443 444 /// isFixedObjectIndex - Returns true if the specified index corresponds to a 445 /// fixed stack object. 446 bool isFixedObjectIndex(int ObjectIdx) const { 447 return ObjectIdx < 0 && (ObjectIdx >= -(int)NumFixedObjects); 448 } 449 450 /// isImmutableObjectIndex - Returns true if the specified index corresponds 451 /// to an immutable object. 452 bool isImmutableObjectIndex(int ObjectIdx) const { 453 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() && 454 "Invalid Object Idx!"); 455 return Objects[ObjectIdx+NumFixedObjects].isImmutable; 456 } 457 458 /// isSpillSlotObjectIndex - Returns true if the specified index corresponds 459 /// to a spill slot.. 460 bool isSpillSlotObjectIndex(int ObjectIdx) const { 461 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() && 462 "Invalid Object Idx!"); 463 return Objects[ObjectIdx+NumFixedObjects].isSpillSlot;; 464 } 465 466 /// isDeadObjectIndex - Returns true if the specified index corresponds to 467 /// a dead object. 468 bool isDeadObjectIndex(int ObjectIdx) const { 469 assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() && 470 "Invalid Object Idx!"); 471 return Objects[ObjectIdx+NumFixedObjects].Size == ~0ULL; 472 } 473 474 /// CreateStackObject - Create a new statically sized stack object, returning 475 /// a nonnegative identifier to represent it. 476 /// 477 int CreateStackObject(uint64_t Size, unsigned Alignment, bool isSS, 478 bool MayNeedSP = false) { 479 assert(Size != 0 && "Cannot allocate zero size stack objects!"); 480 Objects.push_back(StackObject(Size, Alignment, 0, false, isSS, MayNeedSP)); 481 int Index = (int)Objects.size() - NumFixedObjects - 1; 482 assert(Index >= 0 && "Bad frame index!"); 483 MaxAlignment = std::max(MaxAlignment, Alignment); 484 return Index; 485 } 486 487 /// CreateSpillStackObject - Create a new statically sized stack object that 488 /// represents a spill slot, returning a nonnegative identifier to represent 489 /// it. 490 /// 491 int CreateSpillStackObject(uint64_t Size, unsigned Alignment) { 492 CreateStackObject(Size, Alignment, true, false); 493 int Index = (int)Objects.size() - NumFixedObjects - 1; 494 MaxAlignment = std::max(MaxAlignment, Alignment); 495 return Index; 496 } 497 498 /// RemoveStackObject - Remove or mark dead a statically sized stack object. 499 /// 500 void RemoveStackObject(int ObjectIdx) { 501 // Mark it dead. 502 Objects[ObjectIdx+NumFixedObjects].Size = ~0ULL; 503 } 504 505 /// CreateVariableSizedObject - Notify the MachineFrameInfo object that a 506 /// variable sized object has been created. This must be created whenever a 507 /// variable sized object is created, whether or not the index returned is 508 /// actually used. 509 /// 510 int CreateVariableSizedObject(unsigned Alignment) { 511 HasVarSizedObjects = true; 512 Objects.push_back(StackObject(0, Alignment, 0, false, false, true)); 513 MaxAlignment = std::max(MaxAlignment, Alignment); 514 return (int)Objects.size()-NumFixedObjects-1; 515 } 516 517 /// getCalleeSavedInfo - Returns a reference to call saved info vector for the 518 /// current function. 519 const std::vector<CalleeSavedInfo> &getCalleeSavedInfo() const { 520 return CSInfo; 521 } 522 523 /// setCalleeSavedInfo - Used by prolog/epilog inserter to set the function's 524 /// callee saved information. 525 void setCalleeSavedInfo(const std::vector<CalleeSavedInfo> &CSI) { 526 CSInfo = CSI; 527 } 528 529 /// isCalleeSavedInfoValid - Has the callee saved info been calculated yet? 530 bool isCalleeSavedInfoValid() const { return CSIValid; } 531 532 void setCalleeSavedInfoValid(bool v) { CSIValid = v; } 533 534 /// getPristineRegs - Return a set of physical registers that are pristine on 535 /// entry to the MBB. 536 /// 537 /// Pristine registers hold a value that is useless to the current function, 538 /// but that must be preserved - they are callee saved registers that have not 539 /// been saved yet. 540 /// 541 /// Before the PrologueEpilogueInserter has placed the CSR spill code, this 542 /// method always returns an empty set. 543 BitVector getPristineRegs(const MachineBasicBlock *MBB) const; 544 545 /// print - Used by the MachineFunction printer to print information about 546 /// stack objects. Implemented in MachineFunction.cpp 547 /// 548 void print(const MachineFunction &MF, raw_ostream &OS) const; 549 550 /// dump - Print the function to stderr. 551 void dump(const MachineFunction &MF) const; 552}; 553 554} // End llvm namespace 555 556#endif 557