JITMemoryManager.cpp revision 36b56886974eae4f9c5ebc96befd3e7bfe5de338
1//===-- JITMemoryManager.cpp - Memory Allocator for JIT'd code ------------===// 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// This file defines the DefaultJITMemoryManager class. 11// 12//===----------------------------------------------------------------------===// 13 14#define DEBUG_TYPE "jit" 15#include "llvm/ExecutionEngine/JITMemoryManager.h" 16#include "llvm/ADT/SmallPtrSet.h" 17#include "llvm/ADT/Statistic.h" 18#include "llvm/ADT/Twine.h" 19#include "llvm/Config/config.h" 20#include "llvm/IR/GlobalValue.h" 21#include "llvm/Support/Allocator.h" 22#include "llvm/Support/Compiler.h" 23#include "llvm/Support/Debug.h" 24#include "llvm/Support/DynamicLibrary.h" 25#include "llvm/Support/ErrorHandling.h" 26#include "llvm/Support/Memory.h" 27#include "llvm/Support/raw_ostream.h" 28#include <cassert> 29#include <climits> 30#include <cstring> 31#include <vector> 32 33#if defined(__linux__) 34#if defined(HAVE_SYS_STAT_H) 35#include <sys/stat.h> 36#endif 37#include <fcntl.h> 38#include <unistd.h> 39#endif 40 41using namespace llvm; 42 43STATISTIC(NumSlabs, "Number of slabs of memory allocated by the JIT"); 44 45JITMemoryManager::~JITMemoryManager() {} 46 47//===----------------------------------------------------------------------===// 48// Memory Block Implementation. 49//===----------------------------------------------------------------------===// 50 51namespace { 52 /// MemoryRangeHeader - For a range of memory, this is the header that we put 53 /// on the block of memory. It is carefully crafted to be one word of memory. 54 /// Allocated blocks have just this header, free'd blocks have FreeRangeHeader 55 /// which starts with this. 56 struct FreeRangeHeader; 57 struct MemoryRangeHeader { 58 /// ThisAllocated - This is true if this block is currently allocated. If 59 /// not, this can be converted to a FreeRangeHeader. 60 unsigned ThisAllocated : 1; 61 62 /// PrevAllocated - Keep track of whether the block immediately before us is 63 /// allocated. If not, the word immediately before this header is the size 64 /// of the previous block. 65 unsigned PrevAllocated : 1; 66 67 /// BlockSize - This is the size in bytes of this memory block, 68 /// including this header. 69 uintptr_t BlockSize : (sizeof(intptr_t)*CHAR_BIT - 2); 70 71 72 /// getBlockAfter - Return the memory block immediately after this one. 73 /// 74 MemoryRangeHeader &getBlockAfter() const { 75 return *reinterpret_cast<MemoryRangeHeader *>( 76 reinterpret_cast<char*>( 77 const_cast<MemoryRangeHeader *>(this))+BlockSize); 78 } 79 80 /// getFreeBlockBefore - If the block before this one is free, return it, 81 /// otherwise return null. 82 FreeRangeHeader *getFreeBlockBefore() const { 83 if (PrevAllocated) return 0; 84 intptr_t PrevSize = reinterpret_cast<intptr_t *>( 85 const_cast<MemoryRangeHeader *>(this))[-1]; 86 return reinterpret_cast<FreeRangeHeader *>( 87 reinterpret_cast<char*>( 88 const_cast<MemoryRangeHeader *>(this))-PrevSize); 89 } 90 91 /// FreeBlock - Turn an allocated block into a free block, adjusting 92 /// bits in the object headers, and adding an end of region memory block. 93 FreeRangeHeader *FreeBlock(FreeRangeHeader *FreeList); 94 95 /// TrimAllocationToSize - If this allocated block is significantly larger 96 /// than NewSize, split it into two pieces (where the former is NewSize 97 /// bytes, including the header), and add the new block to the free list. 98 FreeRangeHeader *TrimAllocationToSize(FreeRangeHeader *FreeList, 99 uint64_t NewSize); 100 }; 101 102 /// FreeRangeHeader - For a memory block that isn't already allocated, this 103 /// keeps track of the current block and has a pointer to the next free block. 104 /// Free blocks are kept on a circularly linked list. 105 struct FreeRangeHeader : public MemoryRangeHeader { 106 FreeRangeHeader *Prev; 107 FreeRangeHeader *Next; 108 109 /// getMinBlockSize - Get the minimum size for a memory block. Blocks 110 /// smaller than this size cannot be created. 111 static unsigned getMinBlockSize() { 112 return sizeof(FreeRangeHeader)+sizeof(intptr_t); 113 } 114 115 /// SetEndOfBlockSizeMarker - The word at the end of every free block is 116 /// known to be the size of the free block. Set it for this block. 117 void SetEndOfBlockSizeMarker() { 118 void *EndOfBlock = (char*)this + BlockSize; 119 ((intptr_t *)EndOfBlock)[-1] = BlockSize; 120 } 121 122 FreeRangeHeader *RemoveFromFreeList() { 123 assert(Next->Prev == this && Prev->Next == this && "Freelist broken!"); 124 Next->Prev = Prev; 125 return Prev->Next = Next; 126 } 127 128 void AddToFreeList(FreeRangeHeader *FreeList) { 129 Next = FreeList; 130 Prev = FreeList->Prev; 131 Prev->Next = this; 132 Next->Prev = this; 133 } 134 135 /// GrowBlock - The block after this block just got deallocated. Merge it 136 /// into the current block. 137 void GrowBlock(uintptr_t NewSize); 138 139 /// AllocateBlock - Mark this entire block allocated, updating freelists 140 /// etc. This returns a pointer to the circular free-list. 141 FreeRangeHeader *AllocateBlock(); 142 }; 143} 144 145 146/// AllocateBlock - Mark this entire block allocated, updating freelists 147/// etc. This returns a pointer to the circular free-list. 148FreeRangeHeader *FreeRangeHeader::AllocateBlock() { 149 assert(!ThisAllocated && !getBlockAfter().PrevAllocated && 150 "Cannot allocate an allocated block!"); 151 // Mark this block allocated. 152 ThisAllocated = 1; 153 getBlockAfter().PrevAllocated = 1; 154 155 // Remove it from the free list. 156 return RemoveFromFreeList(); 157} 158 159/// FreeBlock - Turn an allocated block into a free block, adjusting 160/// bits in the object headers, and adding an end of region memory block. 161/// If possible, coalesce this block with neighboring blocks. Return the 162/// FreeRangeHeader to allocate from. 163FreeRangeHeader *MemoryRangeHeader::FreeBlock(FreeRangeHeader *FreeList) { 164 MemoryRangeHeader *FollowingBlock = &getBlockAfter(); 165 assert(ThisAllocated && "This block is already free!"); 166 assert(FollowingBlock->PrevAllocated && "Flags out of sync!"); 167 168 FreeRangeHeader *FreeListToReturn = FreeList; 169 170 // If the block after this one is free, merge it into this block. 171 if (!FollowingBlock->ThisAllocated) { 172 FreeRangeHeader &FollowingFreeBlock = *(FreeRangeHeader *)FollowingBlock; 173 // "FreeList" always needs to be a valid free block. If we're about to 174 // coalesce with it, update our notion of what the free list is. 175 if (&FollowingFreeBlock == FreeList) { 176 FreeList = FollowingFreeBlock.Next; 177 FreeListToReturn = 0; 178 assert(&FollowingFreeBlock != FreeList && "No tombstone block?"); 179 } 180 FollowingFreeBlock.RemoveFromFreeList(); 181 182 // Include the following block into this one. 183 BlockSize += FollowingFreeBlock.BlockSize; 184 FollowingBlock = &FollowingFreeBlock.getBlockAfter(); 185 186 // Tell the block after the block we are coalescing that this block is 187 // allocated. 188 FollowingBlock->PrevAllocated = 1; 189 } 190 191 assert(FollowingBlock->ThisAllocated && "Missed coalescing?"); 192 193 if (FreeRangeHeader *PrevFreeBlock = getFreeBlockBefore()) { 194 PrevFreeBlock->GrowBlock(PrevFreeBlock->BlockSize + BlockSize); 195 return FreeListToReturn ? FreeListToReturn : PrevFreeBlock; 196 } 197 198 // Otherwise, mark this block free. 199 FreeRangeHeader &FreeBlock = *(FreeRangeHeader*)this; 200 FollowingBlock->PrevAllocated = 0; 201 FreeBlock.ThisAllocated = 0; 202 203 // Link this into the linked list of free blocks. 204 FreeBlock.AddToFreeList(FreeList); 205 206 // Add a marker at the end of the block, indicating the size of this free 207 // block. 208 FreeBlock.SetEndOfBlockSizeMarker(); 209 return FreeListToReturn ? FreeListToReturn : &FreeBlock; 210} 211 212/// GrowBlock - The block after this block just got deallocated. Merge it 213/// into the current block. 214void FreeRangeHeader::GrowBlock(uintptr_t NewSize) { 215 assert(NewSize > BlockSize && "Not growing block?"); 216 BlockSize = NewSize; 217 SetEndOfBlockSizeMarker(); 218 getBlockAfter().PrevAllocated = 0; 219} 220 221/// TrimAllocationToSize - If this allocated block is significantly larger 222/// than NewSize, split it into two pieces (where the former is NewSize 223/// bytes, including the header), and add the new block to the free list. 224FreeRangeHeader *MemoryRangeHeader:: 225TrimAllocationToSize(FreeRangeHeader *FreeList, uint64_t NewSize) { 226 assert(ThisAllocated && getBlockAfter().PrevAllocated && 227 "Cannot deallocate part of an allocated block!"); 228 229 // Don't allow blocks to be trimmed below minimum required size 230 NewSize = std::max<uint64_t>(FreeRangeHeader::getMinBlockSize(), NewSize); 231 232 // Round up size for alignment of header. 233 unsigned HeaderAlign = __alignof(FreeRangeHeader); 234 NewSize = (NewSize+ (HeaderAlign-1)) & ~(HeaderAlign-1); 235 236 // Size is now the size of the block we will remove from the start of the 237 // current block. 238 assert(NewSize <= BlockSize && 239 "Allocating more space from this block than exists!"); 240 241 // If splitting this block will cause the remainder to be too small, do not 242 // split the block. 243 if (BlockSize <= NewSize+FreeRangeHeader::getMinBlockSize()) 244 return FreeList; 245 246 // Otherwise, we splice the required number of bytes out of this block, form 247 // a new block immediately after it, then mark this block allocated. 248 MemoryRangeHeader &FormerNextBlock = getBlockAfter(); 249 250 // Change the size of this block. 251 BlockSize = NewSize; 252 253 // Get the new block we just sliced out and turn it into a free block. 254 FreeRangeHeader &NewNextBlock = (FreeRangeHeader &)getBlockAfter(); 255 NewNextBlock.BlockSize = (char*)&FormerNextBlock - (char*)&NewNextBlock; 256 NewNextBlock.ThisAllocated = 0; 257 NewNextBlock.PrevAllocated = 1; 258 NewNextBlock.SetEndOfBlockSizeMarker(); 259 FormerNextBlock.PrevAllocated = 0; 260 NewNextBlock.AddToFreeList(FreeList); 261 return &NewNextBlock; 262} 263 264//===----------------------------------------------------------------------===// 265// Memory Block Implementation. 266//===----------------------------------------------------------------------===// 267 268namespace { 269 270 class DefaultJITMemoryManager; 271 272 class JITSlabAllocator : public SlabAllocator { 273 DefaultJITMemoryManager &JMM; 274 public: 275 JITSlabAllocator(DefaultJITMemoryManager &jmm) : JMM(jmm) { } 276 virtual ~JITSlabAllocator() { } 277 MemSlab *Allocate(size_t Size) override; 278 void Deallocate(MemSlab *Slab) override; 279 }; 280 281 /// DefaultJITMemoryManager - Manage memory for the JIT code generation. 282 /// This splits a large block of MAP_NORESERVE'd memory into two 283 /// sections, one for function stubs, one for the functions themselves. We 284 /// have to do this because we may need to emit a function stub while in the 285 /// middle of emitting a function, and we don't know how large the function we 286 /// are emitting is. 287 class DefaultJITMemoryManager : public JITMemoryManager { 288 public: 289 /// DefaultCodeSlabSize - When we have to go map more memory, we allocate at 290 /// least this much unless more is requested. Currently, in 512k slabs. 291 static const size_t DefaultCodeSlabSize = 512 * 1024; 292 293 /// DefaultSlabSize - Allocate globals and stubs into slabs of 64K (probably 294 /// 16 pages) unless we get an allocation above SizeThreshold. 295 static const size_t DefaultSlabSize = 64 * 1024; 296 297 /// DefaultSizeThreshold - For any allocation larger than 16K (probably 298 /// 4 pages), we should allocate a separate slab to avoid wasted space at 299 /// the end of a normal slab. 300 static const size_t DefaultSizeThreshold = 16 * 1024; 301 302 private: 303 // Whether to poison freed memory. 304 bool PoisonMemory; 305 306 /// LastSlab - This points to the last slab allocated and is used as the 307 /// NearBlock parameter to AllocateRWX so that we can attempt to lay out all 308 /// stubs, data, and code contiguously in memory. In general, however, this 309 /// is not possible because the NearBlock parameter is ignored on Windows 310 /// platforms and even on Unix it works on a best-effort pasis. 311 sys::MemoryBlock LastSlab; 312 313 // Memory slabs allocated by the JIT. We refer to them as slabs so we don't 314 // confuse them with the blocks of memory described above. 315 std::vector<sys::MemoryBlock> CodeSlabs; 316 JITSlabAllocator BumpSlabAllocator; 317 BumpPtrAllocatorImpl<DefaultSlabSize, DefaultSizeThreshold> StubAllocator; 318 BumpPtrAllocatorImpl<DefaultSlabSize, DefaultSizeThreshold> DataAllocator; 319 320 // Circular list of free blocks. 321 FreeRangeHeader *FreeMemoryList; 322 323 // When emitting code into a memory block, this is the block. 324 MemoryRangeHeader *CurBlock; 325 326 uint8_t *GOTBase; // Target Specific reserved memory 327 public: 328 DefaultJITMemoryManager(); 329 ~DefaultJITMemoryManager(); 330 331 /// allocateNewSlab - Allocates a new MemoryBlock and remembers it as the 332 /// last slab it allocated, so that subsequent allocations follow it. 333 sys::MemoryBlock allocateNewSlab(size_t size); 334 335 /// getPointerToNamedFunction - This method returns the address of the 336 /// specified function by using the dlsym function call. 337 void *getPointerToNamedFunction(const std::string &Name, 338 bool AbortOnFailure = true) override; 339 340 void AllocateGOT() override; 341 342 // Testing methods. 343 bool CheckInvariants(std::string &ErrorStr) override; 344 size_t GetDefaultCodeSlabSize() override { return DefaultCodeSlabSize; } 345 size_t GetDefaultDataSlabSize() override { return DefaultSlabSize; } 346 size_t GetDefaultStubSlabSize() override { return DefaultSlabSize; } 347 unsigned GetNumCodeSlabs() override { return CodeSlabs.size(); } 348 unsigned GetNumDataSlabs() override { return DataAllocator.GetNumSlabs(); } 349 unsigned GetNumStubSlabs() override { return StubAllocator.GetNumSlabs(); } 350 351 /// startFunctionBody - When a function starts, allocate a block of free 352 /// executable memory, returning a pointer to it and its actual size. 353 uint8_t *startFunctionBody(const Function *F, 354 uintptr_t &ActualSize) override { 355 356 FreeRangeHeader* candidateBlock = FreeMemoryList; 357 FreeRangeHeader* head = FreeMemoryList; 358 FreeRangeHeader* iter = head->Next; 359 360 uintptr_t largest = candidateBlock->BlockSize; 361 362 // Search for the largest free block 363 while (iter != head) { 364 if (iter->BlockSize > largest) { 365 largest = iter->BlockSize; 366 candidateBlock = iter; 367 } 368 iter = iter->Next; 369 } 370 371 largest = largest - sizeof(MemoryRangeHeader); 372 373 // If this block isn't big enough for the allocation desired, allocate 374 // another block of memory and add it to the free list. 375 if (largest < ActualSize || 376 largest <= FreeRangeHeader::getMinBlockSize()) { 377 DEBUG(dbgs() << "JIT: Allocating another slab of memory for function."); 378 candidateBlock = allocateNewCodeSlab((size_t)ActualSize); 379 } 380 381 // Select this candidate block for allocation 382 CurBlock = candidateBlock; 383 384 // Allocate the entire memory block. 385 FreeMemoryList = candidateBlock->AllocateBlock(); 386 ActualSize = CurBlock->BlockSize - sizeof(MemoryRangeHeader); 387 return (uint8_t *)(CurBlock + 1); 388 } 389 390 /// allocateNewCodeSlab - Helper method to allocate a new slab of code 391 /// memory from the OS and add it to the free list. Returns the new 392 /// FreeRangeHeader at the base of the slab. 393 FreeRangeHeader *allocateNewCodeSlab(size_t MinSize) { 394 // If the user needs at least MinSize free memory, then we account for 395 // two MemoryRangeHeaders: the one in the user's block, and the one at the 396 // end of the slab. 397 size_t PaddedMin = MinSize + 2 * sizeof(MemoryRangeHeader); 398 size_t SlabSize = std::max(DefaultCodeSlabSize, PaddedMin); 399 sys::MemoryBlock B = allocateNewSlab(SlabSize); 400 CodeSlabs.push_back(B); 401 char *MemBase = (char*)(B.base()); 402 403 // Put a tiny allocated block at the end of the memory chunk, so when 404 // FreeBlock calls getBlockAfter it doesn't fall off the end. 405 MemoryRangeHeader *EndBlock = 406 (MemoryRangeHeader*)(MemBase + B.size()) - 1; 407 EndBlock->ThisAllocated = 1; 408 EndBlock->PrevAllocated = 0; 409 EndBlock->BlockSize = sizeof(MemoryRangeHeader); 410 411 // Start out with a vast new block of free memory. 412 FreeRangeHeader *NewBlock = (FreeRangeHeader*)MemBase; 413 NewBlock->ThisAllocated = 0; 414 // Make sure getFreeBlockBefore doesn't look into unmapped memory. 415 NewBlock->PrevAllocated = 1; 416 NewBlock->BlockSize = (uintptr_t)EndBlock - (uintptr_t)NewBlock; 417 NewBlock->SetEndOfBlockSizeMarker(); 418 NewBlock->AddToFreeList(FreeMemoryList); 419 420 assert(NewBlock->BlockSize - sizeof(MemoryRangeHeader) >= MinSize && 421 "The block was too small!"); 422 return NewBlock; 423 } 424 425 /// endFunctionBody - The function F is now allocated, and takes the memory 426 /// in the range [FunctionStart,FunctionEnd). 427 void endFunctionBody(const Function *F, uint8_t *FunctionStart, 428 uint8_t *FunctionEnd) override { 429 assert(FunctionEnd > FunctionStart); 430 assert(FunctionStart == (uint8_t *)(CurBlock+1) && 431 "Mismatched function start/end!"); 432 433 uintptr_t BlockSize = FunctionEnd - (uint8_t *)CurBlock; 434 435 // Release the memory at the end of this block that isn't needed. 436 FreeMemoryList =CurBlock->TrimAllocationToSize(FreeMemoryList, BlockSize); 437 } 438 439 /// allocateSpace - Allocate a memory block of the given size. This method 440 /// cannot be called between calls to startFunctionBody and endFunctionBody. 441 uint8_t *allocateSpace(intptr_t Size, unsigned Alignment) override { 442 CurBlock = FreeMemoryList; 443 FreeMemoryList = FreeMemoryList->AllocateBlock(); 444 445 uint8_t *result = (uint8_t *)(CurBlock + 1); 446 447 if (Alignment == 0) Alignment = 1; 448 result = (uint8_t*)(((intptr_t)result+Alignment-1) & 449 ~(intptr_t)(Alignment-1)); 450 451 uintptr_t BlockSize = result + Size - (uint8_t *)CurBlock; 452 FreeMemoryList =CurBlock->TrimAllocationToSize(FreeMemoryList, BlockSize); 453 454 return result; 455 } 456 457 /// allocateStub - Allocate memory for a function stub. 458 uint8_t *allocateStub(const GlobalValue* F, unsigned StubSize, 459 unsigned Alignment) override { 460 return (uint8_t*)StubAllocator.Allocate(StubSize, Alignment); 461 } 462 463 /// allocateGlobal - Allocate memory for a global. 464 uint8_t *allocateGlobal(uintptr_t Size, unsigned Alignment) override { 465 return (uint8_t*)DataAllocator.Allocate(Size, Alignment); 466 } 467 468 /// allocateCodeSection - Allocate memory for a code section. 469 uint8_t *allocateCodeSection(uintptr_t Size, unsigned Alignment, 470 unsigned SectionID, 471 StringRef SectionName) override { 472 // Grow the required block size to account for the block header 473 Size += sizeof(*CurBlock); 474 475 // Alignment handling. 476 if (!Alignment) 477 Alignment = 16; 478 Size += Alignment - 1; 479 480 FreeRangeHeader* candidateBlock = FreeMemoryList; 481 FreeRangeHeader* head = FreeMemoryList; 482 FreeRangeHeader* iter = head->Next; 483 484 uintptr_t largest = candidateBlock->BlockSize; 485 486 // Search for the largest free block. 487 while (iter != head) { 488 if (iter->BlockSize > largest) { 489 largest = iter->BlockSize; 490 candidateBlock = iter; 491 } 492 iter = iter->Next; 493 } 494 495 largest = largest - sizeof(MemoryRangeHeader); 496 497 // If this block isn't big enough for the allocation desired, allocate 498 // another block of memory and add it to the free list. 499 if (largest < Size || largest <= FreeRangeHeader::getMinBlockSize()) { 500 DEBUG(dbgs() << "JIT: Allocating another slab of memory for function."); 501 candidateBlock = allocateNewCodeSlab((size_t)Size); 502 } 503 504 // Select this candidate block for allocation 505 CurBlock = candidateBlock; 506 507 // Allocate the entire memory block. 508 FreeMemoryList = candidateBlock->AllocateBlock(); 509 // Release the memory at the end of this block that isn't needed. 510 FreeMemoryList = CurBlock->TrimAllocationToSize(FreeMemoryList, Size); 511 uintptr_t unalignedAddr = (uintptr_t)CurBlock + sizeof(*CurBlock); 512 return (uint8_t*)RoundUpToAlignment((uint64_t)unalignedAddr, Alignment); 513 } 514 515 /// allocateDataSection - Allocate memory for a data section. 516 uint8_t *allocateDataSection(uintptr_t Size, unsigned Alignment, 517 unsigned SectionID, StringRef SectionName, 518 bool IsReadOnly) override { 519 return (uint8_t*)DataAllocator.Allocate(Size, Alignment); 520 } 521 522 bool finalizeMemory(std::string *ErrMsg) override { 523 return false; 524 } 525 526 uint8_t *getGOTBase() const override { 527 return GOTBase; 528 } 529 530 void deallocateBlock(void *Block) { 531 // Find the block that is allocated for this function. 532 MemoryRangeHeader *MemRange = static_cast<MemoryRangeHeader*>(Block) - 1; 533 assert(MemRange->ThisAllocated && "Block isn't allocated!"); 534 535 // Fill the buffer with garbage! 536 if (PoisonMemory) { 537 memset(MemRange+1, 0xCD, MemRange->BlockSize-sizeof(*MemRange)); 538 } 539 540 // Free the memory. 541 FreeMemoryList = MemRange->FreeBlock(FreeMemoryList); 542 } 543 544 /// deallocateFunctionBody - Deallocate all memory for the specified 545 /// function body. 546 void deallocateFunctionBody(void *Body) override { 547 if (Body) deallocateBlock(Body); 548 } 549 550 /// setMemoryWritable - When code generation is in progress, 551 /// the code pages may need permissions changed. 552 void setMemoryWritable() override { 553 for (unsigned i = 0, e = CodeSlabs.size(); i != e; ++i) 554 sys::Memory::setWritable(CodeSlabs[i]); 555 } 556 /// setMemoryExecutable - When code generation is done and we're ready to 557 /// start execution, the code pages may need permissions changed. 558 void setMemoryExecutable() override { 559 for (unsigned i = 0, e = CodeSlabs.size(); i != e; ++i) 560 sys::Memory::setExecutable(CodeSlabs[i]); 561 } 562 563 /// setPoisonMemory - Controls whether we write garbage over freed memory. 564 /// 565 void setPoisonMemory(bool poison) override { 566 PoisonMemory = poison; 567 } 568 }; 569} 570 571MemSlab *JITSlabAllocator::Allocate(size_t Size) { 572 sys::MemoryBlock B = JMM.allocateNewSlab(Size); 573 MemSlab *Slab = (MemSlab*)B.base(); 574 Slab->Size = B.size(); 575 Slab->NextPtr = 0; 576 return Slab; 577} 578 579void JITSlabAllocator::Deallocate(MemSlab *Slab) { 580 sys::MemoryBlock B(Slab, Slab->Size); 581 sys::Memory::ReleaseRWX(B); 582} 583 584DefaultJITMemoryManager::DefaultJITMemoryManager() 585 : 586#ifdef NDEBUG 587 PoisonMemory(false), 588#else 589 PoisonMemory(true), 590#endif 591 LastSlab(0, 0), 592 BumpSlabAllocator(*this), 593 StubAllocator(BumpSlabAllocator), 594 DataAllocator(BumpSlabAllocator) { 595 596 // Allocate space for code. 597 sys::MemoryBlock MemBlock = allocateNewSlab(DefaultCodeSlabSize); 598 CodeSlabs.push_back(MemBlock); 599 uint8_t *MemBase = (uint8_t*)MemBlock.base(); 600 601 // We set up the memory chunk with 4 mem regions, like this: 602 // [ START 603 // [ Free #0 ] -> Large space to allocate functions from. 604 // [ Allocated #1 ] -> Tiny space to separate regions. 605 // [ Free #2 ] -> Tiny space so there is always at least 1 free block. 606 // [ Allocated #3 ] -> Tiny space to prevent looking past end of block. 607 // END ] 608 // 609 // The last three blocks are never deallocated or touched. 610 611 // Add MemoryRangeHeader to the end of the memory region, indicating that 612 // the space after the block of memory is allocated. This is block #3. 613 MemoryRangeHeader *Mem3 = (MemoryRangeHeader*)(MemBase+MemBlock.size())-1; 614 Mem3->ThisAllocated = 1; 615 Mem3->PrevAllocated = 0; 616 Mem3->BlockSize = sizeof(MemoryRangeHeader); 617 618 /// Add a tiny free region so that the free list always has one entry. 619 FreeRangeHeader *Mem2 = 620 (FreeRangeHeader *)(((char*)Mem3)-FreeRangeHeader::getMinBlockSize()); 621 Mem2->ThisAllocated = 0; 622 Mem2->PrevAllocated = 1; 623 Mem2->BlockSize = FreeRangeHeader::getMinBlockSize(); 624 Mem2->SetEndOfBlockSizeMarker(); 625 Mem2->Prev = Mem2; // Mem2 *is* the free list for now. 626 Mem2->Next = Mem2; 627 628 /// Add a tiny allocated region so that Mem2 is never coalesced away. 629 MemoryRangeHeader *Mem1 = (MemoryRangeHeader*)Mem2-1; 630 Mem1->ThisAllocated = 1; 631 Mem1->PrevAllocated = 0; 632 Mem1->BlockSize = sizeof(MemoryRangeHeader); 633 634 // Add a FreeRangeHeader to the start of the function body region, indicating 635 // that the space is free. Mark the previous block allocated so we never look 636 // at it. 637 FreeRangeHeader *Mem0 = (FreeRangeHeader*)MemBase; 638 Mem0->ThisAllocated = 0; 639 Mem0->PrevAllocated = 1; 640 Mem0->BlockSize = (char*)Mem1-(char*)Mem0; 641 Mem0->SetEndOfBlockSizeMarker(); 642 Mem0->AddToFreeList(Mem2); 643 644 // Start out with the freelist pointing to Mem0. 645 FreeMemoryList = Mem0; 646 647 GOTBase = NULL; 648} 649 650void DefaultJITMemoryManager::AllocateGOT() { 651 assert(GOTBase == 0 && "Cannot allocate the got multiple times"); 652 GOTBase = new uint8_t[sizeof(void*) * 8192]; 653 HasGOT = true; 654} 655 656DefaultJITMemoryManager::~DefaultJITMemoryManager() { 657 for (unsigned i = 0, e = CodeSlabs.size(); i != e; ++i) 658 sys::Memory::ReleaseRWX(CodeSlabs[i]); 659 660 delete[] GOTBase; 661} 662 663sys::MemoryBlock DefaultJITMemoryManager::allocateNewSlab(size_t size) { 664 // Allocate a new block close to the last one. 665 std::string ErrMsg; 666 sys::MemoryBlock *LastSlabPtr = LastSlab.base() ? &LastSlab : 0; 667 sys::MemoryBlock B = sys::Memory::AllocateRWX(size, LastSlabPtr, &ErrMsg); 668 if (B.base() == 0) { 669 report_fatal_error("Allocation failed when allocating new memory in the" 670 " JIT\n" + Twine(ErrMsg)); 671 } 672 LastSlab = B; 673 ++NumSlabs; 674 // Initialize the slab to garbage when debugging. 675 if (PoisonMemory) { 676 memset(B.base(), 0xCD, B.size()); 677 } 678 return B; 679} 680 681/// CheckInvariants - For testing only. Return "" if all internal invariants 682/// are preserved, and a helpful error message otherwise. For free and 683/// allocated blocks, make sure that adding BlockSize gives a valid block. 684/// For free blocks, make sure they're in the free list and that their end of 685/// block size marker is correct. This function should return an error before 686/// accessing bad memory. This function is defined here instead of in 687/// JITMemoryManagerTest.cpp so that we don't have to expose all of the 688/// implementation details of DefaultJITMemoryManager. 689bool DefaultJITMemoryManager::CheckInvariants(std::string &ErrorStr) { 690 raw_string_ostream Err(ErrorStr); 691 692 // Construct a the set of FreeRangeHeader pointers so we can query it 693 // efficiently. 694 llvm::SmallPtrSet<MemoryRangeHeader*, 16> FreeHdrSet; 695 FreeRangeHeader* FreeHead = FreeMemoryList; 696 FreeRangeHeader* FreeRange = FreeHead; 697 698 do { 699 // Check that the free range pointer is in the blocks we've allocated. 700 bool Found = false; 701 for (std::vector<sys::MemoryBlock>::iterator I = CodeSlabs.begin(), 702 E = CodeSlabs.end(); I != E && !Found; ++I) { 703 char *Start = (char*)I->base(); 704 char *End = Start + I->size(); 705 Found = (Start <= (char*)FreeRange && (char*)FreeRange < End); 706 } 707 if (!Found) { 708 Err << "Corrupt free list; points to " << FreeRange; 709 return false; 710 } 711 712 if (FreeRange->Next->Prev != FreeRange) { 713 Err << "Next and Prev pointers do not match."; 714 return false; 715 } 716 717 // Otherwise, add it to the set. 718 FreeHdrSet.insert(FreeRange); 719 FreeRange = FreeRange->Next; 720 } while (FreeRange != FreeHead); 721 722 // Go over each block, and look at each MemoryRangeHeader. 723 for (std::vector<sys::MemoryBlock>::iterator I = CodeSlabs.begin(), 724 E = CodeSlabs.end(); I != E; ++I) { 725 char *Start = (char*)I->base(); 726 char *End = Start + I->size(); 727 728 // Check each memory range. 729 for (MemoryRangeHeader *Hdr = (MemoryRangeHeader*)Start, *LastHdr = NULL; 730 Start <= (char*)Hdr && (char*)Hdr < End; 731 Hdr = &Hdr->getBlockAfter()) { 732 if (Hdr->ThisAllocated == 0) { 733 // Check that this range is in the free list. 734 if (!FreeHdrSet.count(Hdr)) { 735 Err << "Found free header at " << Hdr << " that is not in free list."; 736 return false; 737 } 738 739 // Now make sure the size marker at the end of the block is correct. 740 uintptr_t *Marker = ((uintptr_t*)&Hdr->getBlockAfter()) - 1; 741 if (!(Start <= (char*)Marker && (char*)Marker < End)) { 742 Err << "Block size in header points out of current MemoryBlock."; 743 return false; 744 } 745 if (Hdr->BlockSize != *Marker) { 746 Err << "End of block size marker (" << *Marker << ") " 747 << "and BlockSize (" << Hdr->BlockSize << ") don't match."; 748 return false; 749 } 750 } 751 752 if (LastHdr && LastHdr->ThisAllocated != Hdr->PrevAllocated) { 753 Err << "Hdr->PrevAllocated (" << Hdr->PrevAllocated << ") != " 754 << "LastHdr->ThisAllocated (" << LastHdr->ThisAllocated << ")"; 755 return false; 756 } else if (!LastHdr && !Hdr->PrevAllocated) { 757 Err << "The first header should have PrevAllocated true."; 758 return false; 759 } 760 761 // Remember the last header. 762 LastHdr = Hdr; 763 } 764 } 765 766 // All invariants are preserved. 767 return true; 768} 769 770//===----------------------------------------------------------------------===// 771// getPointerToNamedFunction() implementation. 772//===----------------------------------------------------------------------===// 773 774// AtExitHandlers - List of functions to call when the program exits, 775// registered with the atexit() library function. 776static std::vector<void (*)()> AtExitHandlers; 777 778/// runAtExitHandlers - Run any functions registered by the program's 779/// calls to atexit(3), which we intercept and store in 780/// AtExitHandlers. 781/// 782static void runAtExitHandlers() { 783 while (!AtExitHandlers.empty()) { 784 void (*Fn)() = AtExitHandlers.back(); 785 AtExitHandlers.pop_back(); 786 Fn(); 787 } 788} 789 790//===----------------------------------------------------------------------===// 791// Function stubs that are invoked instead of certain library calls 792// 793// Force the following functions to be linked in to anything that uses the 794// JIT. This is a hack designed to work around the all-too-clever Glibc 795// strategy of making these functions work differently when inlined vs. when 796// not inlined, and hiding their real definitions in a separate archive file 797// that the dynamic linker can't see. For more info, search for 798// 'libc_nonshared.a' on Google, or read http://llvm.org/PR274. 799#if defined(__linux__) && defined(__GLIBC__) 800/* stat functions are redirecting to __xstat with a version number. On x86-64 801 * linking with libc_nonshared.a and -Wl,--export-dynamic doesn't make 'stat' 802 * available as an exported symbol, so we have to add it explicitly. 803 */ 804namespace { 805class StatSymbols { 806public: 807 StatSymbols() { 808 sys::DynamicLibrary::AddSymbol("stat", (void*)(intptr_t)stat); 809 sys::DynamicLibrary::AddSymbol("fstat", (void*)(intptr_t)fstat); 810 sys::DynamicLibrary::AddSymbol("lstat", (void*)(intptr_t)lstat); 811 sys::DynamicLibrary::AddSymbol("stat64", (void*)(intptr_t)stat64); 812 sys::DynamicLibrary::AddSymbol("\x1stat64", (void*)(intptr_t)stat64); 813 sys::DynamicLibrary::AddSymbol("\x1open64", (void*)(intptr_t)open64); 814 sys::DynamicLibrary::AddSymbol("\x1lseek64", (void*)(intptr_t)lseek64); 815 sys::DynamicLibrary::AddSymbol("fstat64", (void*)(intptr_t)fstat64); 816 sys::DynamicLibrary::AddSymbol("lstat64", (void*)(intptr_t)lstat64); 817 sys::DynamicLibrary::AddSymbol("atexit", (void*)(intptr_t)atexit); 818 sys::DynamicLibrary::AddSymbol("mknod", (void*)(intptr_t)mknod); 819 } 820}; 821} 822static StatSymbols initStatSymbols; 823#endif // __linux__ 824 825// jit_exit - Used to intercept the "exit" library call. 826static void jit_exit(int Status) { 827 runAtExitHandlers(); // Run atexit handlers... 828 exit(Status); 829} 830 831// jit_atexit - Used to intercept the "atexit" library call. 832static int jit_atexit(void (*Fn)()) { 833 AtExitHandlers.push_back(Fn); // Take note of atexit handler... 834 return 0; // Always successful 835} 836 837static int jit_noop() { 838 return 0; 839} 840 841//===----------------------------------------------------------------------===// 842// 843/// getPointerToNamedFunction - This method returns the address of the specified 844/// function by using the dynamic loader interface. As such it is only useful 845/// for resolving library symbols, not code generated symbols. 846/// 847void *DefaultJITMemoryManager::getPointerToNamedFunction(const std::string &Name, 848 bool AbortOnFailure) { 849 // Check to see if this is one of the functions we want to intercept. Note, 850 // we cast to intptr_t here to silence a -pedantic warning that complains 851 // about casting a function pointer to a normal pointer. 852 if (Name == "exit") return (void*)(intptr_t)&jit_exit; 853 if (Name == "atexit") return (void*)(intptr_t)&jit_atexit; 854 855 // We should not invoke parent's ctors/dtors from generated main()! 856 // On Mingw and Cygwin, the symbol __main is resolved to 857 // callee's(eg. tools/lli) one, to invoke wrong duplicated ctors 858 // (and register wrong callee's dtors with atexit(3)). 859 // We expect ExecutionEngine::runStaticConstructorsDestructors() 860 // is called before ExecutionEngine::runFunctionAsMain() is called. 861 if (Name == "__main") return (void*)(intptr_t)&jit_noop; 862 863 const char *NameStr = Name.c_str(); 864 // If this is an asm specifier, skip the sentinal. 865 if (NameStr[0] == 1) ++NameStr; 866 867 // If it's an external function, look it up in the process image... 868 void *Ptr = sys::DynamicLibrary::SearchForAddressOfSymbol(NameStr); 869 if (Ptr) return Ptr; 870 871 // If it wasn't found and if it starts with an underscore ('_') character, 872 // try again without the underscore. 873 if (NameStr[0] == '_') { 874 Ptr = sys::DynamicLibrary::SearchForAddressOfSymbol(NameStr+1); 875 if (Ptr) return Ptr; 876 } 877 878 // Darwin/PPC adds $LDBLStub suffixes to various symbols like printf. These 879 // are references to hidden visibility symbols that dlsym cannot resolve. 880 // If we have one of these, strip off $LDBLStub and try again. 881#if defined(__APPLE__) && defined(__ppc__) 882 if (Name.size() > 9 && Name[Name.size()-9] == '$' && 883 memcmp(&Name[Name.size()-8], "LDBLStub", 8) == 0) { 884 // First try turning $LDBLStub into $LDBL128. If that fails, strip it off. 885 // This mirrors logic in libSystemStubs.a. 886 std::string Prefix = std::string(Name.begin(), Name.end()-9); 887 if (void *Ptr = getPointerToNamedFunction(Prefix+"$LDBL128", false)) 888 return Ptr; 889 if (void *Ptr = getPointerToNamedFunction(Prefix, false)) 890 return Ptr; 891 } 892#endif 893 894 if (AbortOnFailure) { 895 report_fatal_error("Program used external function '"+Name+ 896 "' which could not be resolved!"); 897 } 898 return 0; 899} 900 901 902 903JITMemoryManager *JITMemoryManager::CreateDefaultMemManager() { 904 return new DefaultJITMemoryManager(); 905} 906 907const size_t DefaultJITMemoryManager::DefaultCodeSlabSize; 908const size_t DefaultJITMemoryManager::DefaultSlabSize; 909const size_t DefaultJITMemoryManager::DefaultSizeThreshold; 910