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Theodosius/Examples/Theodosius-Usermode/asmjit/core/zone.cpp

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4 years ago
// AsmJit - Machine code generation for C++
//
// * Official AsmJit Home Page: https://asmjit.com
// * Official Github Repository: https://github.com/asmjit/asmjit
//
// Copyright (c) 2008-2020 The AsmJit Authors
//
// This software is provided 'as-is', without any express or implied
// warranty. In no event will the authors be held liable for any damages
// arising from the use of this software.
//
// Permission is granted to anyone to use this software for any purpose,
// including commercial applications, and to alter it and redistribute it
// freely, subject to the following restrictions:
//
// 1. The origin of this software must not be misrepresented; you must not
// claim that you wrote the original software. If you use this software
// in a product, an acknowledgment in the product documentation would be
// appreciated but is not required.
// 2. Altered source versions must be plainly marked as such, and must not be
// misrepresented as being the original software.
// 3. This notice may not be removed or altered from any source distribution.
#include "../core/api-build_p.h"
#include "../core/support.h"
#include "../core/zone.h"
ASMJIT_BEGIN_NAMESPACE
// ============================================================================
// [asmjit::Zone - Statics]
// ============================================================================
// Zero size block used by `Zone` that doesn't have any memory allocated.
// Should be allocated in read-only memory and should never be modified.
const Zone::Block Zone::_zeroBlock = { nullptr, nullptr, 0 };
// ============================================================================
// [asmjit::Zone - Init / Reset]
// ============================================================================
void Zone::_init(size_t blockSize, size_t blockAlignment, const Support::Temporary* temporary) noexcept {
ASMJIT_ASSERT(blockSize >= kMinBlockSize);
ASMJIT_ASSERT(blockSize <= kMaxBlockSize);
ASMJIT_ASSERT(blockAlignment <= 64);
// Just to make the compiler happy...
constexpr size_t kBlockSizeMask = (Support::allOnes<size_t>() >> 4);
constexpr size_t kBlockAlignmentShiftMask = 0x7u;
_assignZeroBlock();
_blockSize = blockSize & kBlockSizeMask;
_isTemporary = temporary != nullptr;
_blockAlignmentShift = Support::ctz(blockAlignment) & kBlockAlignmentShiftMask;
// Setup the first [temporary] block, if necessary.
if (temporary) {
Block* block = temporary->data<Block>();
block->prev = nullptr;
block->next = nullptr;
ASMJIT_ASSERT(temporary->size() >= kBlockSize);
block->size = temporary->size() - kBlockSize;
_assignBlock(block);
}
}
void Zone::reset(uint32_t resetPolicy) noexcept {
Block* cur = _block;
// Can't be altered.
if (cur == &_zeroBlock)
return;
if (resetPolicy == Globals::kResetHard) {
Block* initial = const_cast<Zone::Block*>(&_zeroBlock);
_ptr = initial->data();
_end = initial->data();
_block = initial;
// Since cur can be in the middle of the double-linked list, we have to
// traverse both directions (`prev` and `next`) separately to visit all.
Block* next = cur->next;
do {
Block* prev = cur->prev;
// If this is the first block and this ZoneTmp is temporary then the
// first block is statically allocated. We cannot free it and it makes
// sense to keep it even when this is hard reset.
if (prev == nullptr && _isTemporary) {
cur->prev = nullptr;
cur->next = nullptr;
_assignBlock(cur);
break;
}
::free(cur);
cur = prev;
} while (cur);
cur = next;
while (cur) {
next = cur->next;
::free(cur);
cur = next;
}
}
else {
while (cur->prev)
cur = cur->prev;
_assignBlock(cur);
}
}
// ============================================================================
// [asmjit::Zone - Alloc]
// ============================================================================
void* Zone::_alloc(size_t size, size_t alignment) noexcept {
Block* curBlock = _block;
Block* next = curBlock->next;
size_t rawBlockAlignment = blockAlignment();
size_t minimumAlignment = Support::max<size_t>(alignment, rawBlockAlignment);
// If the `Zone` has been cleared the current block doesn't have to be the
// last one. Check if there is a block that can be used instead of allocating
// a new one. If there is a `next` block it's completely unused, we don't have
// to check for remaining bytes in that case.
if (next) {
uint8_t* ptr = Support::alignUp(next->data(), minimumAlignment);
uint8_t* end = Support::alignDown(next->data() + next->size, rawBlockAlignment);
if (size <= (size_t)(end - ptr)) {
_block = next;
_ptr = ptr + size;
_end = Support::alignDown(next->data() + next->size, rawBlockAlignment);
return static_cast<void*>(ptr);
}
}
size_t blockAlignmentOverhead = alignment - Support::min<size_t>(alignment, Globals::kAllocAlignment);
size_t newSize = Support::max(blockSize(), size);
// Prevent arithmetic overflow.
if (ASMJIT_UNLIKELY(newSize > SIZE_MAX - kBlockSize - blockAlignmentOverhead))
return nullptr;
// Allocate new block - we add alignment overhead to `newSize`, which becomes the
// new block size, and we also add `kBlockOverhead` to the allocator as it includes
// members of `Zone::Block` structure.
newSize += blockAlignmentOverhead;
Block* newBlock = static_cast<Block*>(::malloc(newSize + kBlockSize));
if (ASMJIT_UNLIKELY(!newBlock))
return nullptr;
// Align the pointer to `minimumAlignment` and adjust the size of this block
// accordingly. It's the same as using `minimumAlignment - Support::alignUpDiff()`,
// just written differently.
{
newBlock->prev = nullptr;
newBlock->next = nullptr;
newBlock->size = newSize;
if (curBlock != &_zeroBlock) {
newBlock->prev = curBlock;
curBlock->next = newBlock;
// Does only happen if there is a next block, but the requested memory
// can't fit into it. In this case a new buffer is allocated and inserted
// between the current block and the next one.
if (next) {
newBlock->next = next;
next->prev = newBlock;
}
}
uint8_t* ptr = Support::alignUp(newBlock->data(), minimumAlignment);
uint8_t* end = Support::alignDown(newBlock->data() + newSize, rawBlockAlignment);
_ptr = ptr + size;
_end = end;
_block = newBlock;
ASMJIT_ASSERT(_ptr <= _end);
return static_cast<void*>(ptr);
}
}
void* Zone::allocZeroed(size_t size, size_t alignment) noexcept {
void* p = alloc(size, alignment);
if (ASMJIT_UNLIKELY(!p))
return p;
return memset(p, 0, size);
}
void* Zone::dup(const void* data, size_t size, bool nullTerminate) noexcept {
if (ASMJIT_UNLIKELY(!data || !size))
return nullptr;
ASMJIT_ASSERT(size != SIZE_MAX);
uint8_t* m = allocT<uint8_t>(size + nullTerminate);
if (ASMJIT_UNLIKELY(!m)) return nullptr;
memcpy(m, data, size);
if (nullTerminate) m[size] = '\0';
return static_cast<void*>(m);
}
char* Zone::sformat(const char* fmt, ...) noexcept {
if (ASMJIT_UNLIKELY(!fmt))
return nullptr;
char buf[512];
size_t size;
va_list ap;
va_start(ap, fmt);
size = unsigned(vsnprintf(buf, ASMJIT_ARRAY_SIZE(buf) - 1, fmt, ap));
va_end(ap);
buf[size++] = 0;
return static_cast<char*>(dup(buf, size));
}
// ============================================================================
// [asmjit::ZoneAllocator - Helpers]
// ============================================================================
#if defined(ASMJIT_BUILD_DEBUG)
static bool ZoneAllocator_hasDynamicBlock(ZoneAllocator* self, ZoneAllocator::DynamicBlock* block) noexcept {
ZoneAllocator::DynamicBlock* cur = self->_dynamicBlocks;
while (cur) {
if (cur == block)
return true;
cur = cur->next;
}
return false;
}
#endif
// ============================================================================
// [asmjit::ZoneAllocator - Init / Reset]
// ============================================================================
void ZoneAllocator::reset(Zone* zone) noexcept {
// Free dynamic blocks.
DynamicBlock* block = _dynamicBlocks;
while (block) {
DynamicBlock* next = block->next;
::free(block);
block = next;
}
// Zero the entire class and initialize to the given `zone`.
memset(this, 0, sizeof(*this));
_zone = zone;
}
// ============================================================================
// [asmjit::ZoneAllocator - Alloc / Release]
// ============================================================================
void* ZoneAllocator::_alloc(size_t size, size_t& allocatedSize) noexcept {
ASMJIT_ASSERT(isInitialized());
// Use the memory pool only if the requested block has a reasonable size.
uint32_t slot;
if (_getSlotIndex(size, slot, allocatedSize)) {
// Slot reuse.
uint8_t* p = reinterpret_cast<uint8_t*>(_slots[slot]);
size = allocatedSize;
if (p) {
_slots[slot] = reinterpret_cast<Slot*>(p)->next;
return p;
}
_zone->align(kBlockAlignment);
p = _zone->ptr();
size_t remain = (size_t)(_zone->end() - p);
if (ASMJIT_LIKELY(remain >= size)) {
_zone->setPtr(p + size);
return p;
}
else {
// Distribute the remaining memory to suitable slots, if possible.
if (remain >= kLoGranularity) {
do {
size_t distSize = Support::min<size_t>(remain, kLoMaxSize);
uint32_t distSlot = uint32_t((distSize - kLoGranularity) / kLoGranularity);
ASMJIT_ASSERT(distSlot < kLoCount);
reinterpret_cast<Slot*>(p)->next = _slots[distSlot];
_slots[distSlot] = reinterpret_cast<Slot*>(p);
p += distSize;
remain -= distSize;
} while (remain >= kLoGranularity);
_zone->setPtr(p);
}
p = static_cast<uint8_t*>(_zone->_alloc(size, kBlockAlignment));
if (ASMJIT_UNLIKELY(!p)) {
allocatedSize = 0;
return nullptr;
}
return p;
}
}
else {
// Allocate a dynamic block.
size_t kBlockOverhead = sizeof(DynamicBlock) + sizeof(DynamicBlock*) + kBlockAlignment;
// Handle a possible overflow.
if (ASMJIT_UNLIKELY(kBlockOverhead >= SIZE_MAX - size))
return nullptr;
void* p = ::malloc(size + kBlockOverhead);
if (ASMJIT_UNLIKELY(!p)) {
allocatedSize = 0;
return nullptr;
}
// Link as first in `_dynamicBlocks` double-linked list.
DynamicBlock* block = static_cast<DynamicBlock*>(p);
DynamicBlock* next = _dynamicBlocks;
if (next)
next->prev = block;
block->prev = nullptr;
block->next = next;
_dynamicBlocks = block;
// Align the pointer to the guaranteed alignment and store `DynamicBlock`
// at the beginning of the memory block, so `_releaseDynamic()` can find it.
p = Support::alignUp(static_cast<uint8_t*>(p) + sizeof(DynamicBlock) + sizeof(DynamicBlock*), kBlockAlignment);
reinterpret_cast<DynamicBlock**>(p)[-1] = block;
allocatedSize = size;
return p;
}
}
void* ZoneAllocator::_allocZeroed(size_t size, size_t& allocatedSize) noexcept {
ASMJIT_ASSERT(isInitialized());
void* p = _alloc(size, allocatedSize);
if (ASMJIT_UNLIKELY(!p)) return p;
return memset(p, 0, allocatedSize);
}
void ZoneAllocator::_releaseDynamic(void* p, size_t size) noexcept {
DebugUtils::unused(size);
ASMJIT_ASSERT(isInitialized());
// Pointer to `DynamicBlock` is stored at [-1].
DynamicBlock* block = reinterpret_cast<DynamicBlock**>(p)[-1];
ASMJIT_ASSERT(ZoneAllocator_hasDynamicBlock(this, block));
// Unlink and free.
DynamicBlock* prev = block->prev;
DynamicBlock* next = block->next;
if (prev)
prev->next = next;
else
_dynamicBlocks = next;
if (next)
next->prev = prev;
::free(block);
}
ASMJIT_END_NAMESPACE