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#include <stdafx.h>
#include "BufferAllocator.h"
#include <immintrin.h>
#include <ammintrin.h>
using namespace CpuCompute;
HRESULT BufferAllocator::create( size_t cb )
{
CHECK( buffer.allocate( cb ) );
head = 0;
size = cb;
dbgMarkUninitializedMemory( buffer.pointer(), cb );
return S_OK;
}
namespace
{
// Round up the integer by 32 bytes
__forceinline size_t roundUpAlloc( size_t cb )
{
const size_t mask = 31;
cb += mask;
// We require AVX1+FMA3 support, might as well use BMI1
return _andn_u64( mask, cb );
}
}
void* BufferAllocator::allocate( size_t cb, size_t align ) noexcept
{
assert( align <= 32 );
cb = roundUpAlloc( cb );
uint8_t* pointer = buffer.pointer();
if( head + cb > size || nullptr == pointer )
{
logError( u8"BufferAllocator.allocate, not enough capacity" );
return nullptr;
}
void* const res = pointer + head;
head += cb;
assert( head <= size );
dbgMarkUninitializedMemory( res, cb );
return res;
}
namespace
{
// 2 MB of memory, we hope the OS kernel will then be smart enough to give us large pages.
constexpr size_t virtualAllocGranularityExp2 = 21;
constexpr size_t virtualAllocGranularityMask = ( ( (size_t)1 ) << virtualAllocGranularityExp2 ) - 1;
// Round up the integer by 2 megabytes
__forceinline size_t roundUpVirtualAlloc( size_t cb )
{
const size_t mask = virtualAllocGranularityMask;
cb += mask;
return _andn_u64( mask, cb );
}
}
HRESULT VirtualAllocator::create( size_t cb )
{
if( nullptr != pointer )
return HRESULT_FROM_WIN32( ERROR_ALREADY_INITIALIZED );
cb = roundUpVirtualAlloc( cb );
pointer = (uint8_t*)VirtualAlloc( NULL, cb, MEM_RESERVE, PAGE_READWRITE );
if( nullptr != pointer )
{
head = 0;
sizeAllocated = 0;
sizeVirtual = cb;
return S_OK;
}
const HRESULT hr = getLastHr();
logErrorHr( hr, u8"VirtualAlloc failed" );
return hr;
}
void* VirtualAllocator::allocate( size_t cb, size_t align ) noexcept
{
assert( align <= 32 );
cb = roundUpAlloc( cb );
const size_t newHead = head + cb;
if( newHead <= sizeAllocated )
{
void* const res = pointer + head;
head = newHead;
dbgMarkUninitializedMemory( res, cb );
return res;
}
if( newHead <= sizeVirtual )
{
uint8_t* const ptrCommit = pointer + sizeAllocated;
const size_t cbCommit = roundUpVirtualAlloc( newHead ) - sizeAllocated;
void* const res = VirtualAlloc( ptrCommit, cbCommit, MEM_COMMIT, PAGE_READWRITE );
if( nullptr != res )
{
sizeAllocated += cbCommit;
assert( sizeAllocated <= sizeVirtual );
void* const res = pointer + head;
head = newHead;
dbgMarkUninitializedMemory( res, cb );
return res;
}
const HRESULT hr = getLastHr();
logErrorHr( hr, u8"VirtualAllocator.allocate, VirtualAlloc failed" );
return nullptr;
}
logError( u8"VirtualAllocator.allocate, not enough arena capacity" );
return nullptr;
}
VirtualAllocator::~VirtualAllocator()
{
if( nullptr == pointer )
return;
if( VirtualFree( pointer, 0, MEM_RELEASE ) )
{
pointer = nullptr;
return;
}
const HRESULT hr = getLastHr();
logErrorHr( hr, u8"VirtualFree failed" );
}
#ifndef NDEBUG
// Reusing Microsoft's magic numbers: https://asawicki.info/news_1292_magic_numbers_in_visual_c
void CpuCompute::dbgMarkUninitializedMemory( void* pv, size_t cb )
{
__stosb( (uint8_t*)pv, 0xCD, cb );
}
void CpuCompute::dbgMarkFreedMemory( void* pv, size_t cb )
{
__stosd( (DWORD*)pv, 0xFEEEFEEEu, cb / 4 );
}
#endif
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