+++ /dev/null
-//===-- JITMemoryManager.cpp - Memory Allocator for JIT'd code ------------===//
-//
-// The LLVM Compiler Infrastructure
-//
-// This file is distributed under the University of Illinois Open Source
-// License. See LICENSE.TXT for details.
-//
-//===----------------------------------------------------------------------===//
-//
-// This file defines the DefaultJITMemoryManager class.
-//
-//===----------------------------------------------------------------------===//
-
-#include "llvm/ExecutionEngine/JITMemoryManager.h"
-#include "llvm/ADT/SmallPtrSet.h"
-#include "llvm/ADT/Statistic.h"
-#include "llvm/ADT/Twine.h"
-#include "llvm/Config/config.h"
-#include "llvm/IR/GlobalValue.h"
-#include "llvm/Support/Allocator.h"
-#include "llvm/Support/Compiler.h"
-#include "llvm/Support/Debug.h"
-#include "llvm/Support/DynamicLibrary.h"
-#include "llvm/Support/ErrorHandling.h"
-#include "llvm/Support/Memory.h"
-#include "llvm/Support/raw_ostream.h"
-#include <cassert>
-#include <climits>
-#include <cstring>
-#include <vector>
-
-#if defined(__linux__)
-#if defined(HAVE_SYS_STAT_H)
-#include <sys/stat.h>
-#endif
-#include <fcntl.h>
-#include <unistd.h>
-#endif
-
-using namespace llvm;
-
-#define DEBUG_TYPE "jit"
-
-STATISTIC(NumSlabs, "Number of slabs of memory allocated by the JIT");
-
-JITMemoryManager::~JITMemoryManager() {}
-
-//===----------------------------------------------------------------------===//
-// Memory Block Implementation.
-//===----------------------------------------------------------------------===//
-
-namespace {
- /// MemoryRangeHeader - For a range of memory, this is the header that we put
- /// on the block of memory. It is carefully crafted to be one word of memory.
- /// Allocated blocks have just this header, free'd blocks have FreeRangeHeader
- /// which starts with this.
- struct FreeRangeHeader;
- struct MemoryRangeHeader {
- /// ThisAllocated - This is true if this block is currently allocated. If
- /// not, this can be converted to a FreeRangeHeader.
- unsigned ThisAllocated : 1;
-
- /// PrevAllocated - Keep track of whether the block immediately before us is
- /// allocated. If not, the word immediately before this header is the size
- /// of the previous block.
- unsigned PrevAllocated : 1;
-
- /// BlockSize - This is the size in bytes of this memory block,
- /// including this header.
- uintptr_t BlockSize : (sizeof(intptr_t)*CHAR_BIT - 2);
-
-
- /// getBlockAfter - Return the memory block immediately after this one.
- ///
- MemoryRangeHeader &getBlockAfter() const {
- return *reinterpret_cast<MemoryRangeHeader *>(
- reinterpret_cast<char*>(
- const_cast<MemoryRangeHeader *>(this))+BlockSize);
- }
-
- /// getFreeBlockBefore - If the block before this one is free, return it,
- /// otherwise return null.
- FreeRangeHeader *getFreeBlockBefore() const {
- if (PrevAllocated) return nullptr;
- intptr_t PrevSize = reinterpret_cast<intptr_t *>(
- const_cast<MemoryRangeHeader *>(this))[-1];
- return reinterpret_cast<FreeRangeHeader *>(
- reinterpret_cast<char*>(
- const_cast<MemoryRangeHeader *>(this))-PrevSize);
- }
-
- /// FreeBlock - Turn an allocated block into a free block, adjusting
- /// bits in the object headers, and adding an end of region memory block.
- FreeRangeHeader *FreeBlock(FreeRangeHeader *FreeList);
-
- /// TrimAllocationToSize - If this allocated block is significantly larger
- /// than NewSize, split it into two pieces (where the former is NewSize
- /// bytes, including the header), and add the new block to the free list.
- FreeRangeHeader *TrimAllocationToSize(FreeRangeHeader *FreeList,
- uint64_t NewSize);
- };
-
- /// FreeRangeHeader - For a memory block that isn't already allocated, this
- /// keeps track of the current block and has a pointer to the next free block.
- /// Free blocks are kept on a circularly linked list.
- struct FreeRangeHeader : public MemoryRangeHeader {
- FreeRangeHeader *Prev;
- FreeRangeHeader *Next;
-
- /// getMinBlockSize - Get the minimum size for a memory block. Blocks
- /// smaller than this size cannot be created.
- static unsigned getMinBlockSize() {
- return sizeof(FreeRangeHeader)+sizeof(intptr_t);
- }
-
- /// SetEndOfBlockSizeMarker - The word at the end of every free block is
- /// known to be the size of the free block. Set it for this block.
- void SetEndOfBlockSizeMarker() {
- void *EndOfBlock = (char*)this + BlockSize;
- ((intptr_t *)EndOfBlock)[-1] = BlockSize;
- }
-
- FreeRangeHeader *RemoveFromFreeList() {
- assert(Next->Prev == this && Prev->Next == this && "Freelist broken!");
- Next->Prev = Prev;
- return Prev->Next = Next;
- }
-
- void AddToFreeList(FreeRangeHeader *FreeList) {
- Next = FreeList;
- Prev = FreeList->Prev;
- Prev->Next = this;
- Next->Prev = this;
- }
-
- /// GrowBlock - The block after this block just got deallocated. Merge it
- /// into the current block.
- void GrowBlock(uintptr_t NewSize);
-
- /// AllocateBlock - Mark this entire block allocated, updating freelists
- /// etc. This returns a pointer to the circular free-list.
- FreeRangeHeader *AllocateBlock();
- };
-}
-
-
-/// AllocateBlock - Mark this entire block allocated, updating freelists
-/// etc. This returns a pointer to the circular free-list.
-FreeRangeHeader *FreeRangeHeader::AllocateBlock() {
- assert(!ThisAllocated && !getBlockAfter().PrevAllocated &&
- "Cannot allocate an allocated block!");
- // Mark this block allocated.
- ThisAllocated = 1;
- getBlockAfter().PrevAllocated = 1;
-
- // Remove it from the free list.
- return RemoveFromFreeList();
-}
-
-/// FreeBlock - Turn an allocated block into a free block, adjusting
-/// bits in the object headers, and adding an end of region memory block.
-/// If possible, coalesce this block with neighboring blocks. Return the
-/// FreeRangeHeader to allocate from.
-FreeRangeHeader *MemoryRangeHeader::FreeBlock(FreeRangeHeader *FreeList) {
- MemoryRangeHeader *FollowingBlock = &getBlockAfter();
- assert(ThisAllocated && "This block is already free!");
- assert(FollowingBlock->PrevAllocated && "Flags out of sync!");
-
- FreeRangeHeader *FreeListToReturn = FreeList;
-
- // If the block after this one is free, merge it into this block.
- if (!FollowingBlock->ThisAllocated) {
- FreeRangeHeader &FollowingFreeBlock = *(FreeRangeHeader *)FollowingBlock;
- // "FreeList" always needs to be a valid free block. If we're about to
- // coalesce with it, update our notion of what the free list is.
- if (&FollowingFreeBlock == FreeList) {
- FreeList = FollowingFreeBlock.Next;
- FreeListToReturn = nullptr;
- assert(&FollowingFreeBlock != FreeList && "No tombstone block?");
- }
- FollowingFreeBlock.RemoveFromFreeList();
-
- // Include the following block into this one.
- BlockSize += FollowingFreeBlock.BlockSize;
- FollowingBlock = &FollowingFreeBlock.getBlockAfter();
-
- // Tell the block after the block we are coalescing that this block is
- // allocated.
- FollowingBlock->PrevAllocated = 1;
- }
-
- assert(FollowingBlock->ThisAllocated && "Missed coalescing?");
-
- if (FreeRangeHeader *PrevFreeBlock = getFreeBlockBefore()) {
- PrevFreeBlock->GrowBlock(PrevFreeBlock->BlockSize + BlockSize);
- return FreeListToReturn ? FreeListToReturn : PrevFreeBlock;
- }
-
- // Otherwise, mark this block free.
- FreeRangeHeader &FreeBlock = *(FreeRangeHeader*)this;
- FollowingBlock->PrevAllocated = 0;
- FreeBlock.ThisAllocated = 0;
-
- // Link this into the linked list of free blocks.
- FreeBlock.AddToFreeList(FreeList);
-
- // Add a marker at the end of the block, indicating the size of this free
- // block.
- FreeBlock.SetEndOfBlockSizeMarker();
- return FreeListToReturn ? FreeListToReturn : &FreeBlock;
-}
-
-/// GrowBlock - The block after this block just got deallocated. Merge it
-/// into the current block.
-void FreeRangeHeader::GrowBlock(uintptr_t NewSize) {
- assert(NewSize > BlockSize && "Not growing block?");
- BlockSize = NewSize;
- SetEndOfBlockSizeMarker();
- getBlockAfter().PrevAllocated = 0;
-}
-
-/// TrimAllocationToSize - If this allocated block is significantly larger
-/// than NewSize, split it into two pieces (where the former is NewSize
-/// bytes, including the header), and add the new block to the free list.
-FreeRangeHeader *MemoryRangeHeader::
-TrimAllocationToSize(FreeRangeHeader *FreeList, uint64_t NewSize) {
- assert(ThisAllocated && getBlockAfter().PrevAllocated &&
- "Cannot deallocate part of an allocated block!");
-
- // Don't allow blocks to be trimmed below minimum required size
- NewSize = std::max<uint64_t>(FreeRangeHeader::getMinBlockSize(), NewSize);
-
- // Round up size for alignment of header.
- unsigned HeaderAlign = __alignof(FreeRangeHeader);
- NewSize = (NewSize+ (HeaderAlign-1)) & ~(HeaderAlign-1);
-
- // Size is now the size of the block we will remove from the start of the
- // current block.
- assert(NewSize <= BlockSize &&
- "Allocating more space from this block than exists!");
-
- // If splitting this block will cause the remainder to be too small, do not
- // split the block.
- if (BlockSize <= NewSize+FreeRangeHeader::getMinBlockSize())
- return FreeList;
-
- // Otherwise, we splice the required number of bytes out of this block, form
- // a new block immediately after it, then mark this block allocated.
- MemoryRangeHeader &FormerNextBlock = getBlockAfter();
-
- // Change the size of this block.
- BlockSize = NewSize;
-
- // Get the new block we just sliced out and turn it into a free block.
- FreeRangeHeader &NewNextBlock = (FreeRangeHeader &)getBlockAfter();
- NewNextBlock.BlockSize = (char*)&FormerNextBlock - (char*)&NewNextBlock;
- NewNextBlock.ThisAllocated = 0;
- NewNextBlock.PrevAllocated = 1;
- NewNextBlock.SetEndOfBlockSizeMarker();
- FormerNextBlock.PrevAllocated = 0;
- NewNextBlock.AddToFreeList(FreeList);
- return &NewNextBlock;
-}
-
-//===----------------------------------------------------------------------===//
-// Memory Block Implementation.
-//===----------------------------------------------------------------------===//
-
-namespace {
-
- class DefaultJITMemoryManager;
-
- class JITAllocator {
- DefaultJITMemoryManager &JMM;
- public:
- JITAllocator(DefaultJITMemoryManager &jmm) : JMM(jmm) { }
- void *Allocate(size_t Size, size_t /*Alignment*/);
- void Deallocate(void *Slab, size_t Size);
- };
-
- /// DefaultJITMemoryManager - Manage memory for the JIT code generation.
- /// This splits a large block of MAP_NORESERVE'd memory into two
- /// sections, one for function stubs, one for the functions themselves. We
- /// have to do this because we may need to emit a function stub while in the
- /// middle of emitting a function, and we don't know how large the function we
- /// are emitting is.
- class DefaultJITMemoryManager : public JITMemoryManager {
- public:
- /// DefaultCodeSlabSize - When we have to go map more memory, we allocate at
- /// least this much unless more is requested. Currently, in 512k slabs.
- static const size_t DefaultCodeSlabSize = 512 * 1024;
-
- /// DefaultSlabSize - Allocate globals and stubs into slabs of 64K (probably
- /// 16 pages) unless we get an allocation above SizeThreshold.
- static const size_t DefaultSlabSize = 64 * 1024;
-
- /// DefaultSizeThreshold - For any allocation larger than 16K (probably
- /// 4 pages), we should allocate a separate slab to avoid wasted space at
- /// the end of a normal slab.
- static const size_t DefaultSizeThreshold = 16 * 1024;
-
- private:
- // Whether to poison freed memory.
- bool PoisonMemory;
-
- /// LastSlab - This points to the last slab allocated and is used as the
- /// NearBlock parameter to AllocateRWX so that we can attempt to lay out all
- /// stubs, data, and code contiguously in memory. In general, however, this
- /// is not possible because the NearBlock parameter is ignored on Windows
- /// platforms and even on Unix it works on a best-effort pasis.
- sys::MemoryBlock LastSlab;
-
- // Memory slabs allocated by the JIT. We refer to them as slabs so we don't
- // confuse them with the blocks of memory described above.
- std::vector<sys::MemoryBlock> CodeSlabs;
- BumpPtrAllocatorImpl<JITAllocator, DefaultSlabSize,
- DefaultSizeThreshold> StubAllocator;
- BumpPtrAllocatorImpl<JITAllocator, DefaultSlabSize,
- DefaultSizeThreshold> DataAllocator;
-
- // Circular list of free blocks.
- FreeRangeHeader *FreeMemoryList;
-
- // When emitting code into a memory block, this is the block.
- MemoryRangeHeader *CurBlock;
-
- std::unique_ptr<uint8_t[]> GOTBase; // Target Specific reserved memory
- public:
- DefaultJITMemoryManager();
- ~DefaultJITMemoryManager();
-
- /// allocateNewSlab - Allocates a new MemoryBlock and remembers it as the
- /// last slab it allocated, so that subsequent allocations follow it.
- sys::MemoryBlock allocateNewSlab(size_t size);
-
- /// getPointerToNamedFunction - This method returns the address of the
- /// specified function by using the dlsym function call.
- void *getPointerToNamedFunction(const std::string &Name,
- bool AbortOnFailure = true) override;
-
- void AllocateGOT() override;
-
- // Testing methods.
- bool CheckInvariants(std::string &ErrorStr) override;
- size_t GetDefaultCodeSlabSize() override { return DefaultCodeSlabSize; }
- size_t GetDefaultDataSlabSize() override { return DefaultSlabSize; }
- size_t GetDefaultStubSlabSize() override { return DefaultSlabSize; }
- unsigned GetNumCodeSlabs() override { return CodeSlabs.size(); }
- unsigned GetNumDataSlabs() override { return DataAllocator.GetNumSlabs(); }
- unsigned GetNumStubSlabs() override { return StubAllocator.GetNumSlabs(); }
-
- /// startFunctionBody - When a function starts, allocate a block of free
- /// executable memory, returning a pointer to it and its actual size.
- uint8_t *startFunctionBody(const Function *F,
- uintptr_t &ActualSize) override {
-
- FreeRangeHeader* candidateBlock = FreeMemoryList;
- FreeRangeHeader* head = FreeMemoryList;
- FreeRangeHeader* iter = head->Next;
-
- uintptr_t largest = candidateBlock->BlockSize;
-
- // Search for the largest free block
- while (iter != head) {
- if (iter->BlockSize > largest) {
- largest = iter->BlockSize;
- candidateBlock = iter;
- }
- iter = iter->Next;
- }
-
- largest = largest - sizeof(MemoryRangeHeader);
-
- // If this block isn't big enough for the allocation desired, allocate
- // another block of memory and add it to the free list.
- if (largest < ActualSize ||
- largest <= FreeRangeHeader::getMinBlockSize()) {
- DEBUG(dbgs() << "JIT: Allocating another slab of memory for function.");
- candidateBlock = allocateNewCodeSlab((size_t)ActualSize);
- }
-
- // Select this candidate block for allocation
- CurBlock = candidateBlock;
-
- // Allocate the entire memory block.
- FreeMemoryList = candidateBlock->AllocateBlock();
- ActualSize = CurBlock->BlockSize - sizeof(MemoryRangeHeader);
- return (uint8_t *)(CurBlock + 1);
- }
-
- /// allocateNewCodeSlab - Helper method to allocate a new slab of code
- /// memory from the OS and add it to the free list. Returns the new
- /// FreeRangeHeader at the base of the slab.
- FreeRangeHeader *allocateNewCodeSlab(size_t MinSize) {
- // If the user needs at least MinSize free memory, then we account for
- // two MemoryRangeHeaders: the one in the user's block, and the one at the
- // end of the slab.
- size_t PaddedMin = MinSize + 2 * sizeof(MemoryRangeHeader);
- size_t SlabSize = std::max(DefaultCodeSlabSize, PaddedMin);
- sys::MemoryBlock B = allocateNewSlab(SlabSize);
- CodeSlabs.push_back(B);
- char *MemBase = (char*)(B.base());
-
- // Put a tiny allocated block at the end of the memory chunk, so when
- // FreeBlock calls getBlockAfter it doesn't fall off the end.
- MemoryRangeHeader *EndBlock =
- (MemoryRangeHeader*)(MemBase + B.size()) - 1;
- EndBlock->ThisAllocated = 1;
- EndBlock->PrevAllocated = 0;
- EndBlock->BlockSize = sizeof(MemoryRangeHeader);
-
- // Start out with a vast new block of free memory.
- FreeRangeHeader *NewBlock = (FreeRangeHeader*)MemBase;
- NewBlock->ThisAllocated = 0;
- // Make sure getFreeBlockBefore doesn't look into unmapped memory.
- NewBlock->PrevAllocated = 1;
- NewBlock->BlockSize = (uintptr_t)EndBlock - (uintptr_t)NewBlock;
- NewBlock->SetEndOfBlockSizeMarker();
- NewBlock->AddToFreeList(FreeMemoryList);
-
- assert(NewBlock->BlockSize - sizeof(MemoryRangeHeader) >= MinSize &&
- "The block was too small!");
- return NewBlock;
- }
-
- /// endFunctionBody - The function F is now allocated, and takes the memory
- /// in the range [FunctionStart,FunctionEnd).
- void endFunctionBody(const Function *F, uint8_t *FunctionStart,
- uint8_t *FunctionEnd) override {
- assert(FunctionEnd > FunctionStart);
- assert(FunctionStart == (uint8_t *)(CurBlock+1) &&
- "Mismatched function start/end!");
-
- uintptr_t BlockSize = FunctionEnd - (uint8_t *)CurBlock;
-
- // Release the memory at the end of this block that isn't needed.
- FreeMemoryList =CurBlock->TrimAllocationToSize(FreeMemoryList, BlockSize);
- }
-
- /// allocateSpace - Allocate a memory block of the given size. This method
- /// cannot be called between calls to startFunctionBody and endFunctionBody.
- uint8_t *allocateSpace(intptr_t Size, unsigned Alignment) override {
- CurBlock = FreeMemoryList;
- FreeMemoryList = FreeMemoryList->AllocateBlock();
-
- uint8_t *result = (uint8_t *)(CurBlock + 1);
-
- if (Alignment == 0) Alignment = 1;
- result = (uint8_t*)(((intptr_t)result+Alignment-1) &
- ~(intptr_t)(Alignment-1));
-
- uintptr_t BlockSize = result + Size - (uint8_t *)CurBlock;
- FreeMemoryList =CurBlock->TrimAllocationToSize(FreeMemoryList, BlockSize);
-
- return result;
- }
-
- /// allocateStub - Allocate memory for a function stub.
- uint8_t *allocateStub(const GlobalValue* F, unsigned StubSize,
- unsigned Alignment) override {
- return (uint8_t*)StubAllocator.Allocate(StubSize, Alignment);
- }
-
- /// allocateGlobal - Allocate memory for a global.
- uint8_t *allocateGlobal(uintptr_t Size, unsigned Alignment) override {
- return (uint8_t*)DataAllocator.Allocate(Size, Alignment);
- }
-
- /// allocateCodeSection - Allocate memory for a code section.
- uint8_t *allocateCodeSection(uintptr_t Size, unsigned Alignment,
- unsigned SectionID,
- StringRef SectionName) override {
- // Grow the required block size to account for the block header
- Size += sizeof(*CurBlock);
-
- // Alignment handling.
- if (!Alignment)
- Alignment = 16;
- Size += Alignment - 1;
-
- FreeRangeHeader* candidateBlock = FreeMemoryList;
- FreeRangeHeader* head = FreeMemoryList;
- FreeRangeHeader* iter = head->Next;
-
- uintptr_t largest = candidateBlock->BlockSize;
-
- // Search for the largest free block.
- while (iter != head) {
- if (iter->BlockSize > largest) {
- largest = iter->BlockSize;
- candidateBlock = iter;
- }
- iter = iter->Next;
- }
-
- largest = largest - sizeof(MemoryRangeHeader);
-
- // If this block isn't big enough for the allocation desired, allocate
- // another block of memory and add it to the free list.
- if (largest < Size || largest <= FreeRangeHeader::getMinBlockSize()) {
- DEBUG(dbgs() << "JIT: Allocating another slab of memory for function.");
- candidateBlock = allocateNewCodeSlab((size_t)Size);
- }
-
- // Select this candidate block for allocation
- CurBlock = candidateBlock;
-
- // Allocate the entire memory block.
- FreeMemoryList = candidateBlock->AllocateBlock();
- // Release the memory at the end of this block that isn't needed.
- FreeMemoryList = CurBlock->TrimAllocationToSize(FreeMemoryList, Size);
- uintptr_t unalignedAddr = (uintptr_t)CurBlock + sizeof(*CurBlock);
- return (uint8_t*)RoundUpToAlignment((uint64_t)unalignedAddr, Alignment);
- }
-
- /// allocateDataSection - Allocate memory for a data section.
- uint8_t *allocateDataSection(uintptr_t Size, unsigned Alignment,
- unsigned SectionID, StringRef SectionName,
- bool IsReadOnly) override {
- return (uint8_t*)DataAllocator.Allocate(Size, Alignment);
- }
-
- bool finalizeMemory(std::string *ErrMsg) override {
- return false;
- }
-
- uint8_t *getGOTBase() const override {
- return GOTBase.get();
- }
-
- void deallocateBlock(void *Block) {
- // Find the block that is allocated for this function.
- MemoryRangeHeader *MemRange = static_cast<MemoryRangeHeader*>(Block) - 1;
- assert(MemRange->ThisAllocated && "Block isn't allocated!");
-
- // Fill the buffer with garbage!
- if (PoisonMemory) {
- memset(MemRange+1, 0xCD, MemRange->BlockSize-sizeof(*MemRange));
- }
-
- // Free the memory.
- FreeMemoryList = MemRange->FreeBlock(FreeMemoryList);
- }
-
- /// deallocateFunctionBody - Deallocate all memory for the specified
- /// function body.
- void deallocateFunctionBody(void *Body) override {
- if (Body) deallocateBlock(Body);
- }
-
- /// setMemoryWritable - When code generation is in progress,
- /// the code pages may need permissions changed.
- void setMemoryWritable() override {
- for (unsigned i = 0, e = CodeSlabs.size(); i != e; ++i)
- sys::Memory::setWritable(CodeSlabs[i]);
- }
- /// setMemoryExecutable - When code generation is done and we're ready to
- /// start execution, the code pages may need permissions changed.
- void setMemoryExecutable() override {
- for (unsigned i = 0, e = CodeSlabs.size(); i != e; ++i)
- sys::Memory::setExecutable(CodeSlabs[i]);
- }
-
- /// setPoisonMemory - Controls whether we write garbage over freed memory.
- ///
- void setPoisonMemory(bool poison) override {
- PoisonMemory = poison;
- }
- };
-}
-
-void *JITAllocator::Allocate(size_t Size, size_t /*Alignment*/) {
- sys::MemoryBlock B = JMM.allocateNewSlab(Size);
- return B.base();
-}
-
-void JITAllocator::Deallocate(void *Slab, size_t Size) {
- sys::MemoryBlock B(Slab, Size);
- sys::Memory::ReleaseRWX(B);
-}
-
-DefaultJITMemoryManager::DefaultJITMemoryManager()
- :
-#ifdef NDEBUG
- PoisonMemory(false),
-#else
- PoisonMemory(true),
-#endif
- LastSlab(nullptr, 0), StubAllocator(*this), DataAllocator(*this) {
-
- // Allocate space for code.
- sys::MemoryBlock MemBlock = allocateNewSlab(DefaultCodeSlabSize);
- CodeSlabs.push_back(MemBlock);
- uint8_t *MemBase = (uint8_t*)MemBlock.base();
-
- // We set up the memory chunk with 4 mem regions, like this:
- // [ START
- // [ Free #0 ] -> Large space to allocate functions from.
- // [ Allocated #1 ] -> Tiny space to separate regions.
- // [ Free #2 ] -> Tiny space so there is always at least 1 free block.
- // [ Allocated #3 ] -> Tiny space to prevent looking past end of block.
- // END ]
- //
- // The last three blocks are never deallocated or touched.
-
- // Add MemoryRangeHeader to the end of the memory region, indicating that
- // the space after the block of memory is allocated. This is block #3.
- MemoryRangeHeader *Mem3 = (MemoryRangeHeader*)(MemBase+MemBlock.size())-1;
- Mem3->ThisAllocated = 1;
- Mem3->PrevAllocated = 0;
- Mem3->BlockSize = sizeof(MemoryRangeHeader);
-
- /// Add a tiny free region so that the free list always has one entry.
- FreeRangeHeader *Mem2 =
- (FreeRangeHeader *)(((char*)Mem3)-FreeRangeHeader::getMinBlockSize());
- Mem2->ThisAllocated = 0;
- Mem2->PrevAllocated = 1;
- Mem2->BlockSize = FreeRangeHeader::getMinBlockSize();
- Mem2->SetEndOfBlockSizeMarker();
- Mem2->Prev = Mem2; // Mem2 *is* the free list for now.
- Mem2->Next = Mem2;
-
- /// Add a tiny allocated region so that Mem2 is never coalesced away.
- MemoryRangeHeader *Mem1 = (MemoryRangeHeader*)Mem2-1;
- Mem1->ThisAllocated = 1;
- Mem1->PrevAllocated = 0;
- Mem1->BlockSize = sizeof(MemoryRangeHeader);
-
- // Add a FreeRangeHeader to the start of the function body region, indicating
- // that the space is free. Mark the previous block allocated so we never look
- // at it.
- FreeRangeHeader *Mem0 = (FreeRangeHeader*)MemBase;
- Mem0->ThisAllocated = 0;
- Mem0->PrevAllocated = 1;
- Mem0->BlockSize = (char*)Mem1-(char*)Mem0;
- Mem0->SetEndOfBlockSizeMarker();
- Mem0->AddToFreeList(Mem2);
-
- // Start out with the freelist pointing to Mem0.
- FreeMemoryList = Mem0;
-}
-
-void DefaultJITMemoryManager::AllocateGOT() {
- assert(!GOTBase && "Cannot allocate the got multiple times");
- GOTBase = make_unique<uint8_t[]>(sizeof(void*) * 8192);
- HasGOT = true;
-}
-
-DefaultJITMemoryManager::~DefaultJITMemoryManager() {
- for (unsigned i = 0, e = CodeSlabs.size(); i != e; ++i)
- sys::Memory::ReleaseRWX(CodeSlabs[i]);
-}
-
-sys::MemoryBlock DefaultJITMemoryManager::allocateNewSlab(size_t size) {
- // Allocate a new block close to the last one.
- std::string ErrMsg;
- sys::MemoryBlock *LastSlabPtr = LastSlab.base() ? &LastSlab : nullptr;
- sys::MemoryBlock B = sys::Memory::AllocateRWX(size, LastSlabPtr, &ErrMsg);
- if (!B.base()) {
- report_fatal_error("Allocation failed when allocating new memory in the"
- " JIT\n" + Twine(ErrMsg));
- }
- LastSlab = B;
- ++NumSlabs;
- // Initialize the slab to garbage when debugging.
- if (PoisonMemory) {
- memset(B.base(), 0xCD, B.size());
- }
- return B;
-}
-
-/// CheckInvariants - For testing only. Return "" if all internal invariants
-/// are preserved, and a helpful error message otherwise. For free and
-/// allocated blocks, make sure that adding BlockSize gives a valid block.
-/// For free blocks, make sure they're in the free list and that their end of
-/// block size marker is correct. This function should return an error before
-/// accessing bad memory. This function is defined here instead of in
-/// JITMemoryManagerTest.cpp so that we don't have to expose all of the
-/// implementation details of DefaultJITMemoryManager.
-bool DefaultJITMemoryManager::CheckInvariants(std::string &ErrorStr) {
- raw_string_ostream Err(ErrorStr);
-
- // Construct the set of FreeRangeHeader pointers so we can query it
- // efficiently.
- llvm::SmallPtrSet<MemoryRangeHeader*, 16> FreeHdrSet;
- FreeRangeHeader* FreeHead = FreeMemoryList;
- FreeRangeHeader* FreeRange = FreeHead;
-
- do {
- // Check that the free range pointer is in the blocks we've allocated.
- bool Found = false;
- for (std::vector<sys::MemoryBlock>::iterator I = CodeSlabs.begin(),
- E = CodeSlabs.end(); I != E && !Found; ++I) {
- char *Start = (char*)I->base();
- char *End = Start + I->size();
- Found = (Start <= (char*)FreeRange && (char*)FreeRange < End);
- }
- if (!Found) {
- Err << "Corrupt free list; points to " << FreeRange;
- return false;
- }
-
- if (FreeRange->Next->Prev != FreeRange) {
- Err << "Next and Prev pointers do not match.";
- return false;
- }
-
- // Otherwise, add it to the set.
- FreeHdrSet.insert(FreeRange);
- FreeRange = FreeRange->Next;
- } while (FreeRange != FreeHead);
-
- // Go over each block, and look at each MemoryRangeHeader.
- for (std::vector<sys::MemoryBlock>::iterator I = CodeSlabs.begin(),
- E = CodeSlabs.end(); I != E; ++I) {
- char *Start = (char*)I->base();
- char *End = Start + I->size();
-
- // Check each memory range.
- for (MemoryRangeHeader *Hdr = (MemoryRangeHeader*)Start, *LastHdr = nullptr;
- Start <= (char*)Hdr && (char*)Hdr < End;
- Hdr = &Hdr->getBlockAfter()) {
- if (Hdr->ThisAllocated == 0) {
- // Check that this range is in the free list.
- if (!FreeHdrSet.count(Hdr)) {
- Err << "Found free header at " << Hdr << " that is not in free list.";
- return false;
- }
-
- // Now make sure the size marker at the end of the block is correct.
- uintptr_t *Marker = ((uintptr_t*)&Hdr->getBlockAfter()) - 1;
- if (!(Start <= (char*)Marker && (char*)Marker < End)) {
- Err << "Block size in header points out of current MemoryBlock.";
- return false;
- }
- if (Hdr->BlockSize != *Marker) {
- Err << "End of block size marker (" << *Marker << ") "
- << "and BlockSize (" << Hdr->BlockSize << ") don't match.";
- return false;
- }
- }
-
- if (LastHdr && LastHdr->ThisAllocated != Hdr->PrevAllocated) {
- Err << "Hdr->PrevAllocated (" << Hdr->PrevAllocated << ") != "
- << "LastHdr->ThisAllocated (" << LastHdr->ThisAllocated << ")";
- return false;
- } else if (!LastHdr && !Hdr->PrevAllocated) {
- Err << "The first header should have PrevAllocated true.";
- return false;
- }
-
- // Remember the last header.
- LastHdr = Hdr;
- }
- }
-
- // All invariants are preserved.
- return true;
-}
-
-//===----------------------------------------------------------------------===//
-// getPointerToNamedFunction() implementation.
-//===----------------------------------------------------------------------===//
-
-// AtExitHandlers - List of functions to call when the program exits,
-// registered with the atexit() library function.
-static std::vector<void (*)()> AtExitHandlers;
-
-/// runAtExitHandlers - Run any functions registered by the program's
-/// calls to atexit(3), which we intercept and store in
-/// AtExitHandlers.
-///
-static void runAtExitHandlers() {
- while (!AtExitHandlers.empty()) {
- void (*Fn)() = AtExitHandlers.back();
- AtExitHandlers.pop_back();
- Fn();
- }
-}
-
-//===----------------------------------------------------------------------===//
-// Function stubs that are invoked instead of certain library calls
-//
-// Force the following functions to be linked in to anything that uses the
-// JIT. This is a hack designed to work around the all-too-clever Glibc
-// strategy of making these functions work differently when inlined vs. when
-// not inlined, and hiding their real definitions in a separate archive file
-// that the dynamic linker can't see. For more info, search for
-// 'libc_nonshared.a' on Google, or read http://llvm.org/PR274.
-#if defined(__linux__) && defined(__GLIBC__)
-/* stat functions are redirecting to __xstat with a version number. On x86-64
- * linking with libc_nonshared.a and -Wl,--export-dynamic doesn't make 'stat'
- * available as an exported symbol, so we have to add it explicitly.
- */
-namespace {
-class StatSymbols {
-public:
- StatSymbols() {
- sys::DynamicLibrary::AddSymbol("stat", (void*)(intptr_t)stat);
- sys::DynamicLibrary::AddSymbol("fstat", (void*)(intptr_t)fstat);
- sys::DynamicLibrary::AddSymbol("lstat", (void*)(intptr_t)lstat);
- sys::DynamicLibrary::AddSymbol("stat64", (void*)(intptr_t)stat64);
- sys::DynamicLibrary::AddSymbol("\x1stat64", (void*)(intptr_t)stat64);
- sys::DynamicLibrary::AddSymbol("\x1open64", (void*)(intptr_t)open64);
- sys::DynamicLibrary::AddSymbol("\x1lseek64", (void*)(intptr_t)lseek64);
- sys::DynamicLibrary::AddSymbol("fstat64", (void*)(intptr_t)fstat64);
- sys::DynamicLibrary::AddSymbol("lstat64", (void*)(intptr_t)lstat64);
- sys::DynamicLibrary::AddSymbol("atexit", (void*)(intptr_t)atexit);
- sys::DynamicLibrary::AddSymbol("mknod", (void*)(intptr_t)mknod);
- }
-};
-}
-static StatSymbols initStatSymbols;
-#endif // __linux__
-
-// jit_exit - Used to intercept the "exit" library call.
-static void jit_exit(int Status) {
- runAtExitHandlers(); // Run atexit handlers...
- exit(Status);
-}
-
-// jit_atexit - Used to intercept the "atexit" library call.
-static int jit_atexit(void (*Fn)()) {
- AtExitHandlers.push_back(Fn); // Take note of atexit handler...
- return 0; // Always successful
-}
-
-static int jit_noop() {
- return 0;
-}
-
-//===----------------------------------------------------------------------===//
-//
-/// getPointerToNamedFunction - This method returns the address of the specified
-/// function by using the dynamic loader interface. As such it is only useful
-/// for resolving library symbols, not code generated symbols.
-///
-void *DefaultJITMemoryManager::getPointerToNamedFunction(const std::string &Name,
- bool AbortOnFailure) {
- // Check to see if this is one of the functions we want to intercept. Note,
- // we cast to intptr_t here to silence a -pedantic warning that complains
- // about casting a function pointer to a normal pointer.
- if (Name == "exit") return (void*)(intptr_t)&jit_exit;
- if (Name == "atexit") return (void*)(intptr_t)&jit_atexit;
-
- // We should not invoke parent's ctors/dtors from generated main()!
- // On Mingw and Cygwin, the symbol __main is resolved to
- // callee's(eg. tools/lli) one, to invoke wrong duplicated ctors
- // (and register wrong callee's dtors with atexit(3)).
- // We expect ExecutionEngine::runStaticConstructorsDestructors()
- // is called before ExecutionEngine::runFunctionAsMain() is called.
- if (Name == "__main") return (void*)(intptr_t)&jit_noop;
-
- const char *NameStr = Name.c_str();
- // If this is an asm specifier, skip the sentinal.
- if (NameStr[0] == 1) ++NameStr;
-
- // If it's an external function, look it up in the process image...
- void *Ptr = sys::DynamicLibrary::SearchForAddressOfSymbol(NameStr);
- if (Ptr) return Ptr;
-
- // If it wasn't found and if it starts with an underscore ('_') character,
- // try again without the underscore.
- if (NameStr[0] == '_') {
- Ptr = sys::DynamicLibrary::SearchForAddressOfSymbol(NameStr+1);
- if (Ptr) return Ptr;
- }
-
- // Darwin/PPC adds $LDBLStub suffixes to various symbols like printf. These
- // are references to hidden visibility symbols that dlsym cannot resolve.
- // If we have one of these, strip off $LDBLStub and try again.
-#if defined(__APPLE__) && defined(__ppc__)
- if (Name.size() > 9 && Name[Name.size()-9] == '$' &&
- memcmp(&Name[Name.size()-8], "LDBLStub", 8) == 0) {
- // First try turning $LDBLStub into $LDBL128. If that fails, strip it off.
- // This mirrors logic in libSystemStubs.a.
- std::string Prefix = std::string(Name.begin(), Name.end()-9);
- if (void *Ptr = getPointerToNamedFunction(Prefix+"$LDBL128", false))
- return Ptr;
- if (void *Ptr = getPointerToNamedFunction(Prefix, false))
- return Ptr;
- }
-#endif
-
- if (AbortOnFailure) {
- report_fatal_error("Program used external function '"+Name+
- "' which could not be resolved!");
- }
- return nullptr;
-}
-
-
-
-JITMemoryManager *JITMemoryManager::CreateDefaultMemManager() {
- return new DefaultJITMemoryManager();
-}
-
-const size_t DefaultJITMemoryManager::DefaultCodeSlabSize;
-const size_t DefaultJITMemoryManager::DefaultSlabSize;
-const size_t DefaultJITMemoryManager::DefaultSizeThreshold;
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