1 //===-- JITMemoryManager.cpp - Memory Allocator for JIT'd code ------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file defines the DefaultJITMemoryManager class.
12 //===----------------------------------------------------------------------===//
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/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"
33 #if defined(__linux__)
34 #if defined(HAVE_SYS_STAT_H)
43 STATISTIC(NumSlabs, "Number of slabs of memory allocated by the JIT");
45 JITMemoryManager::~JITMemoryManager() {}
47 //===----------------------------------------------------------------------===//
48 // Memory Block Implementation.
49 //===----------------------------------------------------------------------===//
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;
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;
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);
72 /// getBlockAfter - Return the memory block immediately after this one.
74 MemoryRangeHeader &getBlockAfter() const {
75 return *(MemoryRangeHeader*)((char*)this+BlockSize);
78 /// getFreeBlockBefore - If the block before this one is free, return it,
79 /// otherwise return null.
80 FreeRangeHeader *getFreeBlockBefore() const {
81 if (PrevAllocated) return 0;
82 intptr_t PrevSize = ((intptr_t *)this)[-1];
83 return (FreeRangeHeader*)((char*)this-PrevSize);
86 /// FreeBlock - Turn an allocated block into a free block, adjusting
87 /// bits in the object headers, and adding an end of region memory block.
88 FreeRangeHeader *FreeBlock(FreeRangeHeader *FreeList);
90 /// TrimAllocationToSize - If this allocated block is significantly larger
91 /// than NewSize, split it into two pieces (where the former is NewSize
92 /// bytes, including the header), and add the new block to the free list.
93 FreeRangeHeader *TrimAllocationToSize(FreeRangeHeader *FreeList,
97 /// FreeRangeHeader - For a memory block that isn't already allocated, this
98 /// keeps track of the current block and has a pointer to the next free block.
99 /// Free blocks are kept on a circularly linked list.
100 struct FreeRangeHeader : public MemoryRangeHeader {
101 FreeRangeHeader *Prev;
102 FreeRangeHeader *Next;
104 /// getMinBlockSize - Get the minimum size for a memory block. Blocks
105 /// smaller than this size cannot be created.
106 static unsigned getMinBlockSize() {
107 return sizeof(FreeRangeHeader)+sizeof(intptr_t);
110 /// SetEndOfBlockSizeMarker - The word at the end of every free block is
111 /// known to be the size of the free block. Set it for this block.
112 void SetEndOfBlockSizeMarker() {
113 void *EndOfBlock = (char*)this + BlockSize;
114 ((intptr_t *)EndOfBlock)[-1] = BlockSize;
117 FreeRangeHeader *RemoveFromFreeList() {
118 assert(Next->Prev == this && Prev->Next == this && "Freelist broken!");
120 return Prev->Next = Next;
123 void AddToFreeList(FreeRangeHeader *FreeList) {
125 Prev = FreeList->Prev;
130 /// GrowBlock - The block after this block just got deallocated. Merge it
131 /// into the current block.
132 void GrowBlock(uintptr_t NewSize);
134 /// AllocateBlock - Mark this entire block allocated, updating freelists
135 /// etc. This returns a pointer to the circular free-list.
136 FreeRangeHeader *AllocateBlock();
141 /// AllocateBlock - Mark this entire block allocated, updating freelists
142 /// etc. This returns a pointer to the circular free-list.
143 FreeRangeHeader *FreeRangeHeader::AllocateBlock() {
144 assert(!ThisAllocated && !getBlockAfter().PrevAllocated &&
145 "Cannot allocate an allocated block!");
146 // Mark this block allocated.
148 getBlockAfter().PrevAllocated = 1;
150 // Remove it from the free list.
151 return RemoveFromFreeList();
154 /// FreeBlock - Turn an allocated block into a free block, adjusting
155 /// bits in the object headers, and adding an end of region memory block.
156 /// If possible, coalesce this block with neighboring blocks. Return the
157 /// FreeRangeHeader to allocate from.
158 FreeRangeHeader *MemoryRangeHeader::FreeBlock(FreeRangeHeader *FreeList) {
159 MemoryRangeHeader *FollowingBlock = &getBlockAfter();
160 assert(ThisAllocated && "This block is already free!");
161 assert(FollowingBlock->PrevAllocated && "Flags out of sync!");
163 FreeRangeHeader *FreeListToReturn = FreeList;
165 // If the block after this one is free, merge it into this block.
166 if (!FollowingBlock->ThisAllocated) {
167 FreeRangeHeader &FollowingFreeBlock = *(FreeRangeHeader *)FollowingBlock;
168 // "FreeList" always needs to be a valid free block. If we're about to
169 // coalesce with it, update our notion of what the free list is.
170 if (&FollowingFreeBlock == FreeList) {
171 FreeList = FollowingFreeBlock.Next;
172 FreeListToReturn = 0;
173 assert(&FollowingFreeBlock != FreeList && "No tombstone block?");
175 FollowingFreeBlock.RemoveFromFreeList();
177 // Include the following block into this one.
178 BlockSize += FollowingFreeBlock.BlockSize;
179 FollowingBlock = &FollowingFreeBlock.getBlockAfter();
181 // Tell the block after the block we are coalescing that this block is
183 FollowingBlock->PrevAllocated = 1;
186 assert(FollowingBlock->ThisAllocated && "Missed coalescing?");
188 if (FreeRangeHeader *PrevFreeBlock = getFreeBlockBefore()) {
189 PrevFreeBlock->GrowBlock(PrevFreeBlock->BlockSize + BlockSize);
190 return FreeListToReturn ? FreeListToReturn : PrevFreeBlock;
193 // Otherwise, mark this block free.
194 FreeRangeHeader &FreeBlock = *(FreeRangeHeader*)this;
195 FollowingBlock->PrevAllocated = 0;
196 FreeBlock.ThisAllocated = 0;
198 // Link this into the linked list of free blocks.
199 FreeBlock.AddToFreeList(FreeList);
201 // Add a marker at the end of the block, indicating the size of this free
203 FreeBlock.SetEndOfBlockSizeMarker();
204 return FreeListToReturn ? FreeListToReturn : &FreeBlock;
207 /// GrowBlock - The block after this block just got deallocated. Merge it
208 /// into the current block.
209 void FreeRangeHeader::GrowBlock(uintptr_t NewSize) {
210 assert(NewSize > BlockSize && "Not growing block?");
212 SetEndOfBlockSizeMarker();
213 getBlockAfter().PrevAllocated = 0;
216 /// TrimAllocationToSize - If this allocated block is significantly larger
217 /// than NewSize, split it into two pieces (where the former is NewSize
218 /// bytes, including the header), and add the new block to the free list.
219 FreeRangeHeader *MemoryRangeHeader::
220 TrimAllocationToSize(FreeRangeHeader *FreeList, uint64_t NewSize) {
221 assert(ThisAllocated && getBlockAfter().PrevAllocated &&
222 "Cannot deallocate part of an allocated block!");
224 // Don't allow blocks to be trimmed below minimum required size
225 NewSize = std::max<uint64_t>(FreeRangeHeader::getMinBlockSize(), NewSize);
227 // Round up size for alignment of header.
228 unsigned HeaderAlign = __alignof(FreeRangeHeader);
229 NewSize = (NewSize+ (HeaderAlign-1)) & ~(HeaderAlign-1);
231 // Size is now the size of the block we will remove from the start of the
233 assert(NewSize <= BlockSize &&
234 "Allocating more space from this block than exists!");
236 // If splitting this block will cause the remainder to be too small, do not
238 if (BlockSize <= NewSize+FreeRangeHeader::getMinBlockSize())
241 // Otherwise, we splice the required number of bytes out of this block, form
242 // a new block immediately after it, then mark this block allocated.
243 MemoryRangeHeader &FormerNextBlock = getBlockAfter();
245 // Change the size of this block.
248 // Get the new block we just sliced out and turn it into a free block.
249 FreeRangeHeader &NewNextBlock = (FreeRangeHeader &)getBlockAfter();
250 NewNextBlock.BlockSize = (char*)&FormerNextBlock - (char*)&NewNextBlock;
251 NewNextBlock.ThisAllocated = 0;
252 NewNextBlock.PrevAllocated = 1;
253 NewNextBlock.SetEndOfBlockSizeMarker();
254 FormerNextBlock.PrevAllocated = 0;
255 NewNextBlock.AddToFreeList(FreeList);
256 return &NewNextBlock;
259 //===----------------------------------------------------------------------===//
260 // Memory Block Implementation.
261 //===----------------------------------------------------------------------===//
265 class DefaultJITMemoryManager;
267 class JITSlabAllocator : public SlabAllocator {
268 DefaultJITMemoryManager &JMM;
270 JITSlabAllocator(DefaultJITMemoryManager &jmm) : JMM(jmm) { }
271 virtual ~JITSlabAllocator() { }
272 virtual MemSlab *Allocate(size_t Size);
273 virtual void Deallocate(MemSlab *Slab);
276 /// DefaultJITMemoryManager - Manage memory for the JIT code generation.
277 /// This splits a large block of MAP_NORESERVE'd memory into two
278 /// sections, one for function stubs, one for the functions themselves. We
279 /// have to do this because we may need to emit a function stub while in the
280 /// middle of emitting a function, and we don't know how large the function we
282 class DefaultJITMemoryManager : public JITMemoryManager {
284 // Whether to poison freed memory.
287 /// LastSlab - This points to the last slab allocated and is used as the
288 /// NearBlock parameter to AllocateRWX so that we can attempt to lay out all
289 /// stubs, data, and code contiguously in memory. In general, however, this
290 /// is not possible because the NearBlock parameter is ignored on Windows
291 /// platforms and even on Unix it works on a best-effort pasis.
292 sys::MemoryBlock LastSlab;
294 // Memory slabs allocated by the JIT. We refer to them as slabs so we don't
295 // confuse them with the blocks of memory described above.
296 std::vector<sys::MemoryBlock> CodeSlabs;
297 JITSlabAllocator BumpSlabAllocator;
298 BumpPtrAllocator StubAllocator;
299 BumpPtrAllocator DataAllocator;
301 // Circular list of free blocks.
302 FreeRangeHeader *FreeMemoryList;
304 // When emitting code into a memory block, this is the block.
305 MemoryRangeHeader *CurBlock;
307 uint8_t *GOTBase; // Target Specific reserved memory
309 DefaultJITMemoryManager();
310 ~DefaultJITMemoryManager();
312 /// allocateNewSlab - Allocates a new MemoryBlock and remembers it as the
313 /// last slab it allocated, so that subsequent allocations follow it.
314 sys::MemoryBlock allocateNewSlab(size_t size);
316 /// DefaultCodeSlabSize - When we have to go map more memory, we allocate at
317 /// least this much unless more is requested.
318 static const size_t DefaultCodeSlabSize;
320 /// DefaultSlabSize - Allocate data into slabs of this size unless we get
321 /// an allocation above SizeThreshold.
322 static const size_t DefaultSlabSize;
324 /// DefaultSizeThreshold - For any allocation larger than this threshold, we
325 /// should allocate a separate slab.
326 static const size_t DefaultSizeThreshold;
328 /// getPointerToNamedFunction - This method returns the address of the
329 /// specified function by using the dlsym function call.
330 virtual void *getPointerToNamedFunction(const std::string &Name,
331 bool AbortOnFailure = true);
336 virtual bool CheckInvariants(std::string &ErrorStr);
337 size_t GetDefaultCodeSlabSize() { return DefaultCodeSlabSize; }
338 size_t GetDefaultDataSlabSize() { return DefaultSlabSize; }
339 size_t GetDefaultStubSlabSize() { return DefaultSlabSize; }
340 unsigned GetNumCodeSlabs() { return CodeSlabs.size(); }
341 unsigned GetNumDataSlabs() { return DataAllocator.GetNumSlabs(); }
342 unsigned GetNumStubSlabs() { return StubAllocator.GetNumSlabs(); }
344 /// startFunctionBody - When a function starts, allocate a block of free
345 /// executable memory, returning a pointer to it and its actual size.
346 uint8_t *startFunctionBody(const Function *F, uintptr_t &ActualSize) {
348 FreeRangeHeader* candidateBlock = FreeMemoryList;
349 FreeRangeHeader* head = FreeMemoryList;
350 FreeRangeHeader* iter = head->Next;
352 uintptr_t largest = candidateBlock->BlockSize;
354 // Search for the largest free block
355 while (iter != head) {
356 if (iter->BlockSize > largest) {
357 largest = iter->BlockSize;
358 candidateBlock = iter;
363 largest = largest - sizeof(MemoryRangeHeader);
365 // If this block isn't big enough for the allocation desired, allocate
366 // another block of memory and add it to the free list.
367 if (largest < ActualSize ||
368 largest <= FreeRangeHeader::getMinBlockSize()) {
369 DEBUG(dbgs() << "JIT: Allocating another slab of memory for function.");
370 candidateBlock = allocateNewCodeSlab((size_t)ActualSize);
373 // Select this candidate block for allocation
374 CurBlock = candidateBlock;
376 // Allocate the entire memory block.
377 FreeMemoryList = candidateBlock->AllocateBlock();
378 ActualSize = CurBlock->BlockSize - sizeof(MemoryRangeHeader);
379 return (uint8_t *)(CurBlock + 1);
382 /// allocateNewCodeSlab - Helper method to allocate a new slab of code
383 /// memory from the OS and add it to the free list. Returns the new
384 /// FreeRangeHeader at the base of the slab.
385 FreeRangeHeader *allocateNewCodeSlab(size_t MinSize) {
386 // If the user needs at least MinSize free memory, then we account for
387 // two MemoryRangeHeaders: the one in the user's block, and the one at the
389 size_t PaddedMin = MinSize + 2 * sizeof(MemoryRangeHeader);
390 size_t SlabSize = std::max(DefaultCodeSlabSize, PaddedMin);
391 sys::MemoryBlock B = allocateNewSlab(SlabSize);
392 CodeSlabs.push_back(B);
393 char *MemBase = (char*)(B.base());
395 // Put a tiny allocated block at the end of the memory chunk, so when
396 // FreeBlock calls getBlockAfter it doesn't fall off the end.
397 MemoryRangeHeader *EndBlock =
398 (MemoryRangeHeader*)(MemBase + B.size()) - 1;
399 EndBlock->ThisAllocated = 1;
400 EndBlock->PrevAllocated = 0;
401 EndBlock->BlockSize = sizeof(MemoryRangeHeader);
403 // Start out with a vast new block of free memory.
404 FreeRangeHeader *NewBlock = (FreeRangeHeader*)MemBase;
405 NewBlock->ThisAllocated = 0;
406 // Make sure getFreeBlockBefore doesn't look into unmapped memory.
407 NewBlock->PrevAllocated = 1;
408 NewBlock->BlockSize = (uintptr_t)EndBlock - (uintptr_t)NewBlock;
409 NewBlock->SetEndOfBlockSizeMarker();
410 NewBlock->AddToFreeList(FreeMemoryList);
412 assert(NewBlock->BlockSize - sizeof(MemoryRangeHeader) >= MinSize &&
413 "The block was too small!");
417 /// endFunctionBody - The function F is now allocated, and takes the memory
418 /// in the range [FunctionStart,FunctionEnd).
419 void endFunctionBody(const Function *F, uint8_t *FunctionStart,
420 uint8_t *FunctionEnd) {
421 assert(FunctionEnd > FunctionStart);
422 assert(FunctionStart == (uint8_t *)(CurBlock+1) &&
423 "Mismatched function start/end!");
425 uintptr_t BlockSize = FunctionEnd - (uint8_t *)CurBlock;
427 // Release the memory at the end of this block that isn't needed.
428 FreeMemoryList =CurBlock->TrimAllocationToSize(FreeMemoryList, BlockSize);
431 /// allocateSpace - Allocate a memory block of the given size. This method
432 /// cannot be called between calls to startFunctionBody and endFunctionBody.
433 uint8_t *allocateSpace(intptr_t Size, unsigned Alignment) {
434 CurBlock = FreeMemoryList;
435 FreeMemoryList = FreeMemoryList->AllocateBlock();
437 uint8_t *result = (uint8_t *)(CurBlock + 1);
439 if (Alignment == 0) Alignment = 1;
440 result = (uint8_t*)(((intptr_t)result+Alignment-1) &
441 ~(intptr_t)(Alignment-1));
443 uintptr_t BlockSize = result + Size - (uint8_t *)CurBlock;
444 FreeMemoryList =CurBlock->TrimAllocationToSize(FreeMemoryList, BlockSize);
449 /// allocateStub - Allocate memory for a function stub.
450 uint8_t *allocateStub(const GlobalValue* F, unsigned StubSize,
451 unsigned Alignment) {
452 return (uint8_t*)StubAllocator.Allocate(StubSize, Alignment);
455 /// allocateGlobal - Allocate memory for a global.
456 uint8_t *allocateGlobal(uintptr_t Size, unsigned Alignment) {
457 return (uint8_t*)DataAllocator.Allocate(Size, Alignment);
460 /// allocateCodeSection - Allocate memory for a code section.
461 uint8_t *allocateCodeSection(uintptr_t Size, unsigned Alignment,
462 unsigned SectionID) {
463 // Grow the required block size to account for the block header
464 Size += sizeof(*CurBlock);
466 // FIXME: Alignement handling.
467 FreeRangeHeader* candidateBlock = FreeMemoryList;
468 FreeRangeHeader* head = FreeMemoryList;
469 FreeRangeHeader* iter = head->Next;
471 uintptr_t largest = candidateBlock->BlockSize;
473 // Search for the largest free block.
474 while (iter != head) {
475 if (iter->BlockSize > largest) {
476 largest = iter->BlockSize;
477 candidateBlock = iter;
482 largest = largest - sizeof(MemoryRangeHeader);
484 // If this block isn't big enough for the allocation desired, allocate
485 // another block of memory and add it to the free list.
486 if (largest < Size || largest <= FreeRangeHeader::getMinBlockSize()) {
487 DEBUG(dbgs() << "JIT: Allocating another slab of memory for function.");
488 candidateBlock = allocateNewCodeSlab((size_t)Size);
491 // Select this candidate block for allocation
492 CurBlock = candidateBlock;
494 // Allocate the entire memory block.
495 FreeMemoryList = candidateBlock->AllocateBlock();
496 // Release the memory at the end of this block that isn't needed.
497 FreeMemoryList = CurBlock->TrimAllocationToSize(FreeMemoryList, Size);
498 return (uint8_t *)(CurBlock + 1);
501 /// allocateDataSection - Allocate memory for a data section.
502 uint8_t *allocateDataSection(uintptr_t Size, unsigned Alignment,
503 unsigned SectionID, bool IsReadOnly) {
504 return (uint8_t*)DataAllocator.Allocate(Size, Alignment);
507 bool applyPermissions(std::string *ErrMsg) {
511 /// startExceptionTable - Use startFunctionBody to allocate memory for the
512 /// function's exception table.
513 uint8_t* startExceptionTable(const Function* F, uintptr_t &ActualSize) {
514 return startFunctionBody(F, ActualSize);
517 /// endExceptionTable - The exception table of F is now allocated,
518 /// and takes the memory in the range [TableStart,TableEnd).
519 void endExceptionTable(const Function *F, uint8_t *TableStart,
520 uint8_t *TableEnd, uint8_t* FrameRegister) {
521 assert(TableEnd > TableStart);
522 assert(TableStart == (uint8_t *)(CurBlock+1) &&
523 "Mismatched table start/end!");
525 uintptr_t BlockSize = TableEnd - (uint8_t *)CurBlock;
527 // Release the memory at the end of this block that isn't needed.
528 FreeMemoryList =CurBlock->TrimAllocationToSize(FreeMemoryList, BlockSize);
531 uint8_t *getGOTBase() const {
535 void deallocateBlock(void *Block) {
536 // Find the block that is allocated for this function.
537 MemoryRangeHeader *MemRange = static_cast<MemoryRangeHeader*>(Block) - 1;
538 assert(MemRange->ThisAllocated && "Block isn't allocated!");
540 // Fill the buffer with garbage!
542 memset(MemRange+1, 0xCD, MemRange->BlockSize-sizeof(*MemRange));
546 FreeMemoryList = MemRange->FreeBlock(FreeMemoryList);
549 /// deallocateFunctionBody - Deallocate all memory for the specified
551 void deallocateFunctionBody(void *Body) {
552 if (Body) deallocateBlock(Body);
555 /// deallocateExceptionTable - Deallocate memory for the specified
557 void deallocateExceptionTable(void *ET) {
558 if (ET) deallocateBlock(ET);
561 /// setMemoryWritable - When code generation is in progress,
562 /// the code pages may need permissions changed.
563 void setMemoryWritable()
565 for (unsigned i = 0, e = CodeSlabs.size(); i != e; ++i)
566 sys::Memory::setWritable(CodeSlabs[i]);
568 /// setMemoryExecutable - When code generation is done and we're ready to
569 /// start execution, the code pages may need permissions changed.
570 void setMemoryExecutable()
572 for (unsigned i = 0, e = CodeSlabs.size(); i != e; ++i)
573 sys::Memory::setExecutable(CodeSlabs[i]);
576 /// setPoisonMemory - Controls whether we write garbage over freed memory.
578 void setPoisonMemory(bool poison) {
579 PoisonMemory = poison;
584 MemSlab *JITSlabAllocator::Allocate(size_t Size) {
585 sys::MemoryBlock B = JMM.allocateNewSlab(Size);
586 MemSlab *Slab = (MemSlab*)B.base();
587 Slab->Size = B.size();
592 void JITSlabAllocator::Deallocate(MemSlab *Slab) {
593 sys::MemoryBlock B(Slab, Slab->Size);
594 sys::Memory::ReleaseRWX(B);
597 DefaultJITMemoryManager::DefaultJITMemoryManager()
605 BumpSlabAllocator(*this),
606 StubAllocator(DefaultSlabSize, DefaultSizeThreshold, BumpSlabAllocator),
607 DataAllocator(DefaultSlabSize, DefaultSizeThreshold, BumpSlabAllocator) {
609 // Allocate space for code.
610 sys::MemoryBlock MemBlock = allocateNewSlab(DefaultCodeSlabSize);
611 CodeSlabs.push_back(MemBlock);
612 uint8_t *MemBase = (uint8_t*)MemBlock.base();
614 // We set up the memory chunk with 4 mem regions, like this:
616 // [ Free #0 ] -> Large space to allocate functions from.
617 // [ Allocated #1 ] -> Tiny space to separate regions.
618 // [ Free #2 ] -> Tiny space so there is always at least 1 free block.
619 // [ Allocated #3 ] -> Tiny space to prevent looking past end of block.
622 // The last three blocks are never deallocated or touched.
624 // Add MemoryRangeHeader to the end of the memory region, indicating that
625 // the space after the block of memory is allocated. This is block #3.
626 MemoryRangeHeader *Mem3 = (MemoryRangeHeader*)(MemBase+MemBlock.size())-1;
627 Mem3->ThisAllocated = 1;
628 Mem3->PrevAllocated = 0;
629 Mem3->BlockSize = sizeof(MemoryRangeHeader);
631 /// Add a tiny free region so that the free list always has one entry.
632 FreeRangeHeader *Mem2 =
633 (FreeRangeHeader *)(((char*)Mem3)-FreeRangeHeader::getMinBlockSize());
634 Mem2->ThisAllocated = 0;
635 Mem2->PrevAllocated = 1;
636 Mem2->BlockSize = FreeRangeHeader::getMinBlockSize();
637 Mem2->SetEndOfBlockSizeMarker();
638 Mem2->Prev = Mem2; // Mem2 *is* the free list for now.
641 /// Add a tiny allocated region so that Mem2 is never coalesced away.
642 MemoryRangeHeader *Mem1 = (MemoryRangeHeader*)Mem2-1;
643 Mem1->ThisAllocated = 1;
644 Mem1->PrevAllocated = 0;
645 Mem1->BlockSize = sizeof(MemoryRangeHeader);
647 // Add a FreeRangeHeader to the start of the function body region, indicating
648 // that the space is free. Mark the previous block allocated so we never look
650 FreeRangeHeader *Mem0 = (FreeRangeHeader*)MemBase;
651 Mem0->ThisAllocated = 0;
652 Mem0->PrevAllocated = 1;
653 Mem0->BlockSize = (char*)Mem1-(char*)Mem0;
654 Mem0->SetEndOfBlockSizeMarker();
655 Mem0->AddToFreeList(Mem2);
657 // Start out with the freelist pointing to Mem0.
658 FreeMemoryList = Mem0;
663 void DefaultJITMemoryManager::AllocateGOT() {
664 assert(GOTBase == 0 && "Cannot allocate the got multiple times");
665 GOTBase = new uint8_t[sizeof(void*) * 8192];
669 DefaultJITMemoryManager::~DefaultJITMemoryManager() {
670 for (unsigned i = 0, e = CodeSlabs.size(); i != e; ++i)
671 sys::Memory::ReleaseRWX(CodeSlabs[i]);
676 sys::MemoryBlock DefaultJITMemoryManager::allocateNewSlab(size_t size) {
677 // Allocate a new block close to the last one.
679 sys::MemoryBlock *LastSlabPtr = LastSlab.base() ? &LastSlab : 0;
680 sys::MemoryBlock B = sys::Memory::AllocateRWX(size, LastSlabPtr, &ErrMsg);
682 report_fatal_error("Allocation failed when allocating new memory in the"
683 " JIT\n" + Twine(ErrMsg));
687 // Initialize the slab to garbage when debugging.
689 memset(B.base(), 0xCD, B.size());
694 /// CheckInvariants - For testing only. Return "" if all internal invariants
695 /// are preserved, and a helpful error message otherwise. For free and
696 /// allocated blocks, make sure that adding BlockSize gives a valid block.
697 /// For free blocks, make sure they're in the free list and that their end of
698 /// block size marker is correct. This function should return an error before
699 /// accessing bad memory. This function is defined here instead of in
700 /// JITMemoryManagerTest.cpp so that we don't have to expose all of the
701 /// implementation details of DefaultJITMemoryManager.
702 bool DefaultJITMemoryManager::CheckInvariants(std::string &ErrorStr) {
703 raw_string_ostream Err(ErrorStr);
705 // Construct a the set of FreeRangeHeader pointers so we can query it
707 llvm::SmallPtrSet<MemoryRangeHeader*, 16> FreeHdrSet;
708 FreeRangeHeader* FreeHead = FreeMemoryList;
709 FreeRangeHeader* FreeRange = FreeHead;
712 // Check that the free range pointer is in the blocks we've allocated.
714 for (std::vector<sys::MemoryBlock>::iterator I = CodeSlabs.begin(),
715 E = CodeSlabs.end(); I != E && !Found; ++I) {
716 char *Start = (char*)I->base();
717 char *End = Start + I->size();
718 Found = (Start <= (char*)FreeRange && (char*)FreeRange < End);
721 Err << "Corrupt free list; points to " << FreeRange;
725 if (FreeRange->Next->Prev != FreeRange) {
726 Err << "Next and Prev pointers do not match.";
730 // Otherwise, add it to the set.
731 FreeHdrSet.insert(FreeRange);
732 FreeRange = FreeRange->Next;
733 } while (FreeRange != FreeHead);
735 // Go over each block, and look at each MemoryRangeHeader.
736 for (std::vector<sys::MemoryBlock>::iterator I = CodeSlabs.begin(),
737 E = CodeSlabs.end(); I != E; ++I) {
738 char *Start = (char*)I->base();
739 char *End = Start + I->size();
741 // Check each memory range.
742 for (MemoryRangeHeader *Hdr = (MemoryRangeHeader*)Start, *LastHdr = NULL;
743 Start <= (char*)Hdr && (char*)Hdr < End;
744 Hdr = &Hdr->getBlockAfter()) {
745 if (Hdr->ThisAllocated == 0) {
746 // Check that this range is in the free list.
747 if (!FreeHdrSet.count(Hdr)) {
748 Err << "Found free header at " << Hdr << " that is not in free list.";
752 // Now make sure the size marker at the end of the block is correct.
753 uintptr_t *Marker = ((uintptr_t*)&Hdr->getBlockAfter()) - 1;
754 if (!(Start <= (char*)Marker && (char*)Marker < End)) {
755 Err << "Block size in header points out of current MemoryBlock.";
758 if (Hdr->BlockSize != *Marker) {
759 Err << "End of block size marker (" << *Marker << ") "
760 << "and BlockSize (" << Hdr->BlockSize << ") don't match.";
765 if (LastHdr && LastHdr->ThisAllocated != Hdr->PrevAllocated) {
766 Err << "Hdr->PrevAllocated (" << Hdr->PrevAllocated << ") != "
767 << "LastHdr->ThisAllocated (" << LastHdr->ThisAllocated << ")";
769 } else if (!LastHdr && !Hdr->PrevAllocated) {
770 Err << "The first header should have PrevAllocated true.";
774 // Remember the last header.
779 // All invariants are preserved.
783 //===----------------------------------------------------------------------===//
784 // getPointerToNamedFunction() implementation.
785 //===----------------------------------------------------------------------===//
787 // AtExitHandlers - List of functions to call when the program exits,
788 // registered with the atexit() library function.
789 static std::vector<void (*)()> AtExitHandlers;
791 /// runAtExitHandlers - Run any functions registered by the program's
792 /// calls to atexit(3), which we intercept and store in
795 static void runAtExitHandlers() {
796 while (!AtExitHandlers.empty()) {
797 void (*Fn)() = AtExitHandlers.back();
798 AtExitHandlers.pop_back();
803 //===----------------------------------------------------------------------===//
804 // Function stubs that are invoked instead of certain library calls
806 // Force the following functions to be linked in to anything that uses the
807 // JIT. This is a hack designed to work around the all-too-clever Glibc
808 // strategy of making these functions work differently when inlined vs. when
809 // not inlined, and hiding their real definitions in a separate archive file
810 // that the dynamic linker can't see. For more info, search for
811 // 'libc_nonshared.a' on Google, or read http://llvm.org/PR274.
812 #if defined(__linux__)
813 /* stat functions are redirecting to __xstat with a version number. On x86-64
814 * linking with libc_nonshared.a and -Wl,--export-dynamic doesn't make 'stat'
815 * available as an exported symbol, so we have to add it explicitly.
821 sys::DynamicLibrary::AddSymbol("stat", (void*)(intptr_t)stat);
822 sys::DynamicLibrary::AddSymbol("fstat", (void*)(intptr_t)fstat);
823 sys::DynamicLibrary::AddSymbol("lstat", (void*)(intptr_t)lstat);
824 sys::DynamicLibrary::AddSymbol("stat64", (void*)(intptr_t)stat64);
825 sys::DynamicLibrary::AddSymbol("\x1stat64", (void*)(intptr_t)stat64);
826 sys::DynamicLibrary::AddSymbol("\x1open64", (void*)(intptr_t)open64);
827 sys::DynamicLibrary::AddSymbol("\x1lseek64", (void*)(intptr_t)lseek64);
828 sys::DynamicLibrary::AddSymbol("fstat64", (void*)(intptr_t)fstat64);
829 sys::DynamicLibrary::AddSymbol("lstat64", (void*)(intptr_t)lstat64);
830 sys::DynamicLibrary::AddSymbol("atexit", (void*)(intptr_t)atexit);
831 sys::DynamicLibrary::AddSymbol("mknod", (void*)(intptr_t)mknod);
835 static StatSymbols initStatSymbols;
838 // jit_exit - Used to intercept the "exit" library call.
839 static void jit_exit(int Status) {
840 runAtExitHandlers(); // Run atexit handlers...
844 // jit_atexit - Used to intercept the "atexit" library call.
845 static int jit_atexit(void (*Fn)()) {
846 AtExitHandlers.push_back(Fn); // Take note of atexit handler...
847 return 0; // Always successful
850 static int jit_noop() {
854 //===----------------------------------------------------------------------===//
856 /// getPointerToNamedFunction - This method returns the address of the specified
857 /// function by using the dynamic loader interface. As such it is only useful
858 /// for resolving library symbols, not code generated symbols.
860 void *DefaultJITMemoryManager::getPointerToNamedFunction(const std::string &Name,
861 bool AbortOnFailure) {
862 // Check to see if this is one of the functions we want to intercept. Note,
863 // we cast to intptr_t here to silence a -pedantic warning that complains
864 // about casting a function pointer to a normal pointer.
865 if (Name == "exit") return (void*)(intptr_t)&jit_exit;
866 if (Name == "atexit") return (void*)(intptr_t)&jit_atexit;
868 // We should not invoke parent's ctors/dtors from generated main()!
869 // On Mingw and Cygwin, the symbol __main is resolved to
870 // callee's(eg. tools/lli) one, to invoke wrong duplicated ctors
871 // (and register wrong callee's dtors with atexit(3)).
872 // We expect ExecutionEngine::runStaticConstructorsDestructors()
873 // is called before ExecutionEngine::runFunctionAsMain() is called.
874 if (Name == "__main") return (void*)(intptr_t)&jit_noop;
876 const char *NameStr = Name.c_str();
877 // If this is an asm specifier, skip the sentinal.
878 if (NameStr[0] == 1) ++NameStr;
880 // If it's an external function, look it up in the process image...
881 void *Ptr = sys::DynamicLibrary::SearchForAddressOfSymbol(NameStr);
884 // If it wasn't found and if it starts with an underscore ('_') character,
885 // try again without the underscore.
886 if (NameStr[0] == '_') {
887 Ptr = sys::DynamicLibrary::SearchForAddressOfSymbol(NameStr+1);
891 // Darwin/PPC adds $LDBLStub suffixes to various symbols like printf. These
892 // are references to hidden visibility symbols that dlsym cannot resolve.
893 // If we have one of these, strip off $LDBLStub and try again.
894 #if defined(__APPLE__) && defined(__ppc__)
895 if (Name.size() > 9 && Name[Name.size()-9] == '$' &&
896 memcmp(&Name[Name.size()-8], "LDBLStub", 8) == 0) {
897 // First try turning $LDBLStub into $LDBL128. If that fails, strip it off.
898 // This mirrors logic in libSystemStubs.a.
899 std::string Prefix = std::string(Name.begin(), Name.end()-9);
900 if (void *Ptr = getPointerToNamedFunction(Prefix+"$LDBL128", false))
902 if (void *Ptr = getPointerToNamedFunction(Prefix, false))
907 if (AbortOnFailure) {
908 report_fatal_error("Program used external function '"+Name+
909 "' which could not be resolved!");
916 JITMemoryManager *JITMemoryManager::CreateDefaultMemManager() {
917 return new DefaultJITMemoryManager();
920 // Allocate memory for code in 512K slabs.
921 const size_t DefaultJITMemoryManager::DefaultCodeSlabSize = 512 * 1024;
923 // Allocate globals and stubs in slabs of 64K. (probably 16 pages)
924 const size_t DefaultJITMemoryManager::DefaultSlabSize = 64 * 1024;
926 // Waste at most 16K at the end of each bump slab. (probably 4 pages)
927 const size_t DefaultJITMemoryManager::DefaultSizeThreshold = 16 * 1024;