llvm-6502/lib/ExecutionEngine/JIT/JITMemoryManager.cpp
Dan Gohman 5b78d50cad Initialize the PoisonMemory member before initializing
members that call methods that read the PoisonMemory member.
This fixes potential spurious (though probably otherwise
harmless) poising of unused memory, and fixes the
associated valgrind error.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@80192 91177308-0d34-0410-b5e6-96231b3b80d8
2009-08-27 01:25:57 +00:00

761 lines
28 KiB
C++

//===-- 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.
//
//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "jit"
#include "llvm/ExecutionEngine/JITMemoryManager.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/GlobalValue.h"
#include "llvm/Support/Allocator.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/System/Memory.h"
#include <map>
#include <vector>
#include <cassert>
#include <climits>
#include <cstdio>
#include <cstdlib>
#include <cstring>
using namespace llvm;
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 *(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, 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 = 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 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 JITSlabAllocator : public SlabAllocator {
DefaultJITMemoryManager &JMM;
public:
JITSlabAllocator(DefaultJITMemoryManager &jmm) : JMM(jmm) { }
virtual ~JITSlabAllocator() { }
virtual MemSlab *Allocate(size_t Size);
virtual void Deallocate(MemSlab *Slab);
};
/// 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 {
// 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 descibed above.
std::vector<sys::MemoryBlock> CodeSlabs;
JITSlabAllocator BumpSlabAllocator;
BumpPtrAllocator StubAllocator;
BumpPtrAllocator DataAllocator;
// Circular list of free blocks.
FreeRangeHeader *FreeMemoryList;
// When emitting code into a memory block, this is the block.
MemoryRangeHeader *CurBlock;
uint8_t *GOTBase; // Target Specific reserved memory
void *DlsymTable; // Stub external symbol information
std::map<const Function*, MemoryRangeHeader*> FunctionBlocks;
std::map<const Function*, MemoryRangeHeader*> TableBlocks;
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);
/// DefaultCodeSlabSize - When we have to go map more memory, we allocate at
/// least this much unless more is requested.
static const size_t DefaultCodeSlabSize;
/// DefaultSlabSize - Allocate data into slabs of this size unless we get
/// an allocation above SizeThreshold.
static const size_t DefaultSlabSize;
/// DefaultSizeThreshold - For any allocation larger than this threshold, we
/// should allocate a separate slab.
static const size_t DefaultSizeThreshold;
void AllocateGOT();
void SetDlsymTable(void *);
// Testing methods.
virtual bool CheckInvariants(std::string &ErrorStr);
size_t GetDefaultCodeSlabSize() { return DefaultCodeSlabSize; }
size_t GetDefaultDataSlabSize() { return DefaultSlabSize; }
size_t GetDefaultStubSlabSize() { return DefaultSlabSize; }
unsigned GetNumCodeSlabs() { return CodeSlabs.size(); }
unsigned GetNumDataSlabs() { return DataAllocator.GetNumSlabs(); }
unsigned GetNumStubSlabs() { 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) {
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(errs() << "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) {
assert(FunctionEnd > FunctionStart);
assert(FunctionStart == (uint8_t *)(CurBlock+1) &&
"Mismatched function start/end!");
uintptr_t BlockSize = FunctionEnd - (uint8_t *)CurBlock;
FunctionBlocks[F] = 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) {
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) {
return (uint8_t*)StubAllocator.Allocate(StubSize, Alignment);
}
/// allocateGlobal - Allocate memory for a global.
uint8_t *allocateGlobal(uintptr_t Size, unsigned Alignment) {
return (uint8_t*)DataAllocator.Allocate(Size, Alignment);
}
/// startExceptionTable - Use startFunctionBody to allocate memory for the
/// function's exception table.
uint8_t* startExceptionTable(const Function* F, uintptr_t &ActualSize) {
return startFunctionBody(F, ActualSize);
}
/// endExceptionTable - The exception table of F is now allocated,
/// and takes the memory in the range [TableStart,TableEnd).
void endExceptionTable(const Function *F, uint8_t *TableStart,
uint8_t *TableEnd, uint8_t* FrameRegister) {
assert(TableEnd > TableStart);
assert(TableStart == (uint8_t *)(CurBlock+1) &&
"Mismatched table start/end!");
uintptr_t BlockSize = TableEnd - (uint8_t *)CurBlock;
TableBlocks[F] = CurBlock;
// Release the memory at the end of this block that isn't needed.
FreeMemoryList =CurBlock->TrimAllocationToSize(FreeMemoryList, BlockSize);
}
uint8_t *getGOTBase() const {
return GOTBase;
}
void *getDlsymTable() const {
return DlsymTable;
}
/// 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!
if (PoisonMemory) {
memset(MemRange+1, 0xCD, MemRange->BlockSize-sizeof(*MemRange));
}
// Free the memory.
FreeMemoryList = MemRange->FreeBlock(FreeMemoryList);
// Finally, remove this entry from FunctionBlocks.
FunctionBlocks.erase(I);
I = TableBlocks.find(F);
if (I == TableBlocks.end()) return;
// Find the block that is allocated for this function.
MemRange = I->second;
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);
// Finally, remove this entry from TableBlocks.
TableBlocks.erase(I);
}
/// setMemoryWritable - When code generation is in progress,
/// the code pages may need permissions changed.
void setMemoryWritable()
{
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()
{
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) {
PoisonMemory = poison;
}
};
}
MemSlab *JITSlabAllocator::Allocate(size_t Size) {
sys::MemoryBlock B = JMM.allocateNewSlab(Size);
MemSlab *Slab = (MemSlab*)B.base();
Slab->Size = B.size();
Slab->NextPtr = 0;
return Slab;
}
void JITSlabAllocator::Deallocate(MemSlab *Slab) {
sys::MemoryBlock B(Slab, Slab->Size);
sys::Memory::ReleaseRWX(B);
}
DefaultJITMemoryManager::DefaultJITMemoryManager()
:
#ifdef NDEBUG
PoisonMemory(false),
#else
PoisonMemory(true),
#endif
LastSlab(0, 0),
BumpSlabAllocator(*this),
StubAllocator(DefaultSlabSize, DefaultSizeThreshold, BumpSlabAllocator),
DataAllocator(DefaultSlabSize, DefaultSizeThreshold, BumpSlabAllocator) {
// 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;
GOTBase = NULL;
DlsymTable = NULL;
}
void DefaultJITMemoryManager::AllocateGOT() {
assert(GOTBase == 0 && "Cannot allocate the got multiple times");
GOTBase = new uint8_t[sizeof(void*) * 8192];
HasGOT = true;
}
void DefaultJITMemoryManager::SetDlsymTable(void *ptr) {
DlsymTable = ptr;
}
DefaultJITMemoryManager::~DefaultJITMemoryManager() {
for (unsigned i = 0, e = CodeSlabs.size(); i != e; ++i)
sys::Memory::ReleaseRWX(CodeSlabs[i]);
delete[] GOTBase;
}
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 : 0;
sys::MemoryBlock B = sys::Memory::AllocateRWX(size, LastSlabPtr, &ErrMsg);
if (B.base() == 0) {
llvm_report_error("Allocation failed when allocating new memory in the"
" JIT\n" + 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 a 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 = NULL;
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;
}
JITMemoryManager *JITMemoryManager::CreateDefaultMemManager() {
return new DefaultJITMemoryManager();
}
// Allocate memory for code in 512K slabs.
const size_t DefaultJITMemoryManager::DefaultCodeSlabSize = 512 * 1024;
// Allocate globals and stubs in slabs of 64K. (probably 16 pages)
const size_t DefaultJITMemoryManager::DefaultSlabSize = 64 * 1024;
// Waste at most 16K at the end of each bump slab. (probably 4 pages)
const size_t DefaultJITMemoryManager::DefaultSizeThreshold = 16 * 1024;