7342c5ed8c
Address sanitizer can detect underflows so we don't really need the custom allocator. Additionally, custom allocator can return memory that is not pointer-aligned; this causes undefined behavior sanitizer to complain.
163 lines
3.4 KiB
C++
163 lines
3.4 KiB
C++
#include "allocator.hpp"
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#include <string.h>
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#include <assert.h>
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#include <stdlib.h>
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// Low-level allocation functions
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#if defined(_WIN32) || defined(_WIN64)
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# ifdef __MWERKS__
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# pragma ANSI_strict off // disable ANSI strictness to include windows.h
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# pragma cpp_extensions on // enable some extensions to include windows.h
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# endif
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# if defined(_MSC_VER)
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# pragma warning(disable: 4201) // nonstandard extension used: nameless struct/union
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# endif
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# ifdef _XBOX_VER
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# define NOD3D
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# include <xtl.h>
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# else
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# include <windows.h>
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# endif
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namespace
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{
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const size_t page_size = 4096;
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size_t align_to_page(size_t value)
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{
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return (value + page_size - 1) & ~(page_size - 1);
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}
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void* allocate_page_aligned(size_t size)
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{
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// We can't use VirtualAlloc because it has 64Kb granularity so we run out of address space quickly
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// We can't use malloc because of occasional problems with CW on CRT termination
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static HANDLE heap = HeapCreate(0, 0, 0);
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void* result = HeapAlloc(heap, 0, size + page_size);
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return reinterpret_cast<void*>(align_to_page(reinterpret_cast<size_t>(result)));
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}
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void* allocate(size_t size)
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{
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size_t aligned_size = align_to_page(size);
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void* ptr = allocate_page_aligned(aligned_size + page_size);
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if (!ptr) return 0;
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char* end = static_cast<char*>(ptr) + aligned_size;
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DWORD old_flags;
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VirtualProtect(end, page_size, PAGE_NOACCESS, &old_flags);
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return end - size;
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}
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void deallocate(void* ptr, size_t size)
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{
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size_t aligned_size = align_to_page(size);
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void* rptr = static_cast<char*>(ptr) + size - aligned_size;
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DWORD old_flags;
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VirtualProtect(rptr, aligned_size + page_size, PAGE_NOACCESS, &old_flags);
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}
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}
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#elif (defined(__APPLE__) || defined(__linux__)) && !((defined(__has_feature) && __has_feature(address_sanitizer)) || defined(__SANITIZE_ADDRESS__))
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# include <sys/mman.h>
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namespace
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{
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const size_t page_size = 4096;
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size_t align_to_page(size_t value)
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{
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return (value + page_size - 1) & ~(page_size - 1);
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}
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void* allocate_page_aligned(size_t size)
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{
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void* result = malloc(size + page_size);
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return reinterpret_cast<void*>(align_to_page(reinterpret_cast<size_t>(result)));
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}
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void* allocate(size_t size)
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{
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size_t aligned_size = align_to_page(size);
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void* ptr = allocate_page_aligned(aligned_size + page_size);
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if (!ptr) return 0;
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char* end = static_cast<char*>(ptr) + aligned_size;
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int res = mprotect(end, page_size, PROT_NONE);
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assert(res == 0);
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(void)!res;
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return end - size;
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}
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void deallocate(void* ptr, size_t size)
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{
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size_t aligned_size = align_to_page(size);
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void* rptr = static_cast<char*>(ptr) + size - aligned_size;
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int res = mprotect(rptr, aligned_size + page_size, PROT_NONE);
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assert(res == 0);
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(void)!res;
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}
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}
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#else
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namespace
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{
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void* allocate(size_t size)
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{
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return malloc(size);
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}
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void deallocate(void* ptr, size_t size)
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{
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(void)size;
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free(ptr);
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}
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}
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#endif
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// High-level allocation functions
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void* memory_allocate(size_t size)
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{
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void* result = allocate(size + sizeof(size_t));
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if (!result) return 0;
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memcpy(result, &size, sizeof(size_t));
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return static_cast<size_t*>(result) + 1;
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}
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size_t memory_size(void* ptr)
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{
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assert(ptr);
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size_t result;
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memcpy(&result, static_cast<size_t*>(ptr) - 1, sizeof(size_t));
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return result;
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}
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void memory_deallocate(void* ptr)
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{
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if (!ptr) return;
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size_t size = memory_size(ptr);
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deallocate(static_cast<size_t*>(ptr) - 1, size + sizeof(size_t));
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}
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