-//===----------------------------------------------------------------------===//
-// JITMemoryManager code.
-//
-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.
- intptr_t 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.
- intptr_t PrevAllocated : 1;
-
- /// BlockSize - This is the size in bytes of this memory block,
- /// including this header.
- uintptr_t BlockSize : (sizeof(intptr_t)*8 - 2);
-
-
- /// getBlockAfter - Return the memory block immediately after this one.
- ///
- MemoryRangeHeader &getBlockAfter() const {
- return *(MemoryRangeHeader*)((char*)this+BlockSize);
- }
-
- /// getFreeBlockBefore - If the block before this one is free, return it,
- /// otherwise return null.
- FreeRangeHeader *getFreeBlockBefore() const {
- if (PrevAllocated) return 0;
- intptr_t PrevSize = ((intptr_t *)this)[-1];
- return (FreeRangeHeader*)((char*)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, coallesce 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 allocated!");
- 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
- // coallesce with it, update our notion of what the free list is.
- if (&FollowingFreeBlock == FreeList) {
- FreeList = FollowingFreeBlock.Next;
- FreeListToReturn = 0;
- 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 coallescing that this block is
- // allocated.
- FollowingBlock->PrevAllocated = 1;
- }
-
- assert(FollowingBlock->ThisAllocated && "Missed coallescing?");
-
- 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!");
-
- // 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;
-}
-
-
-namespace {
- /// JITMemoryManager - Manage memory for the JIT code generation in a logical,
- /// sane way. 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. This never bothers to release the memory, because when
- /// we are ready to destroy the JIT, the program exits.
- class JITMemoryManager {
- std::vector<sys::MemoryBlock> Blocks; // Memory blocks allocated by the JIT
- FreeRangeHeader *FreeMemoryList; // Circular list of free blocks.
-
- // When emitting code into a memory block, this is the block.
- MemoryRangeHeader *CurBlock;
-
- unsigned char *CurStubPtr, *StubBase;
- unsigned char *GOTBase; // Target Specific reserved memory
-
- // Centralize memory block allocation.
- sys::MemoryBlock getNewMemoryBlock(unsigned size);
-
- std::map<const Function*, MemoryRangeHeader*> FunctionBlocks;
- public:
- JITMemoryManager(bool useGOT);
- ~JITMemoryManager();
-
- inline unsigned char *allocateStub(unsigned StubSize, unsigned Alignment);
-
- /// startFunctionBody - When a function starts, allocate a block of free
- /// executable memory, returning a pointer to it and its actual size.
- unsigned char *startFunctionBody(uintptr_t &ActualSize) {
- CurBlock = FreeMemoryList;
-
- // Allocate the entire memory block.
- FreeMemoryList = FreeMemoryList->AllocateBlock();
- ActualSize = CurBlock->BlockSize-sizeof(MemoryRangeHeader);
- return (unsigned char *)(CurBlock+1);
- }
-
- /// endFunctionBody - The function F is now allocated, and takes the memory
- /// in the range [FunctionStart,FunctionEnd).
- void endFunctionBody(const Function *F, unsigned char *FunctionStart,
- unsigned char *FunctionEnd) {
- assert(FunctionEnd > FunctionStart);
- assert(FunctionStart == (unsigned char *)(CurBlock+1) &&
- "Mismatched function start/end!");
-
- uintptr_t BlockSize = FunctionEnd - (unsigned char *)CurBlock;
- FunctionBlocks[F] = CurBlock;
-
- // Release the memory at the end of this block that isn't needed.
- FreeMemoryList =CurBlock->TrimAllocationToSize(FreeMemoryList, BlockSize);
- }
-
- unsigned char *getGOTBase() const {
- return GOTBase;
- }
- bool isManagingGOT() const {
- return GOTBase != NULL;
- }
-
- /// deallocateMemForFunction - Deallocate all memory for the specified
- /// function body.
- void deallocateMemForFunction(const Function *F) {
- std::map<const Function*, MemoryRangeHeader*>::iterator
- I = FunctionBlocks.find(F);
- if (I == FunctionBlocks.end()) return;
-
- // Find the block that is allocated for this function.
- MemoryRangeHeader *MemRange = I->second;
- assert(MemRange->ThisAllocated && "Block isn't allocated!");
-
- // Fill the buffer with garbage!
- DEBUG(memset(MemRange+1, 0xCD, MemRange->BlockSize-sizeof(*MemRange)));
-
- // Free the memory.
- FreeMemoryList = MemRange->FreeBlock(FreeMemoryList);
-
- // Finally, remove this entry from FunctionBlocks.
- FunctionBlocks.erase(I);
- }
- };
-}
-
-JITMemoryManager::JITMemoryManager(bool useGOT) {
- // Allocate a 16M block of memory for functions.
- sys::MemoryBlock MemBlock = getNewMemoryBlock(16 << 20);
-
- unsigned char *MemBase = reinterpret_cast<unsigned char*>(MemBlock.base());
-
- // Allocate stubs backwards from the base, allocate functions forward
- // from the base.
- StubBase = MemBase;
- CurStubPtr = MemBase + 512*1024; // Use 512k for stubs, working backwards.
-
- // 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 = 0;
-
- /// 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 coallesced away.
- MemoryRangeHeader *Mem1 = (MemoryRangeHeader*)Mem2-1;
- Mem1->ThisAllocated = 1;
- Mem1->PrevAllocated = 0;
- Mem1->BlockSize = (char*)Mem2 - (char*)Mem1;
-
- // 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*)CurStubPtr;
- 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;
-
- // Allocate the GOT.
- GOTBase = NULL;
- if (useGOT) GOTBase = new unsigned char[sizeof(void*) * 8192];
-}
-
-JITMemoryManager::~JITMemoryManager() {
- for (unsigned i = 0, e = Blocks.size(); i != e; ++i)
- sys::Memory::ReleaseRWX(Blocks[i]);
-
- delete[] GOTBase;
- Blocks.clear();
-}
-
-unsigned char *JITMemoryManager::allocateStub(unsigned StubSize,
- unsigned Alignment) {
- CurStubPtr -= StubSize;
- CurStubPtr = (unsigned char*)(((intptr_t)CurStubPtr) &
- ~(intptr_t)(Alignment-1));
- if (CurStubPtr < StubBase) {
- // FIXME: allocate a new block
- cerr << "JIT ran out of memory for function stubs!\n";
- abort();
- }
- return CurStubPtr;
-}
-
-sys::MemoryBlock JITMemoryManager::getNewMemoryBlock(unsigned size) {
- // Allocate a new block close to the last one.
- const sys::MemoryBlock *BOld = Blocks.empty() ? 0 : &Blocks.front();
- std::string ErrMsg;
- sys::MemoryBlock B = sys::Memory::AllocateRWX(size, BOld, &ErrMsg);
- if (B.base() == 0) {
- cerr << "Allocation failed when allocating new memory in the JIT\n";
- cerr << ErrMsg << "\n";
- abort();
- }
- Blocks.push_back(B);
- return B;
-}