1 // 2 // free.cpp 3 // 4 // Copyright (c) Microsoft Corporation. All rights reserved. 5 // 6 // Implementation of free(). 7 // 8 #include <corecrt_internal.h> 9 #include <malloc.h> 10 11 // Frees a block in the heap. The 'block' pointer must either be a null pointer 12 // or must point to a valid block in the heap. 13 // 14 // This function supports patching and therefore must be marked noinline. 15 // Both _free_dbg and _free_base must also be marked noinline 16 // to prevent identical COMDAT folding from substituting calls to free 17 // with either other function or vice versa. 18 extern "C" _CRT_HYBRIDPATCHABLE __declspec(noinline) void __cdecl free(void* const block) 19 { 20 // Some libraries that hook memory allocation routines (such as libtcmalloc) 21 // look for an appropriate place inside free to place a patch to its version 22 // of free. Without these extra instructions padding the call to _free_base, 23 // some libraries may choose to insert this patch in _free_base instead. 24 volatile int extra_instructions_for_patching_libraries = 0; 25 (void) extra_instructions_for_patching_libraries; 26 27 #ifdef _DEBUG 28 _free_dbg(block, _NORMAL_BLOCK); 29 #else 30 _free_base(block); 31 #endif 32 } 33