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Implement byte-tagging of memory

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Using a magic value for memory allocated but uninitialized and another one for memory about-to-be-released. Helps in debugging unitialized members, dangling pointerts, etc.

Disabled by default. Can be enabled for debug builds by defining `DEBUG_MEMORY_TAGGING`.
This commit is contained in:
Pedro J. Estébanez 2017-06-22 05:29:14 +02:00
parent 490a2ff0b9
commit 779693a79b
1 changed files with 26 additions and 2 deletions
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28
core/os/memory.cpp
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@ -47,6 +47,10 @@ void *operator new(size_t p_size, void *(*p_allocfunc)(size_t p_size)) {
#ifdef DEBUG_ENABLED #ifdef DEBUG_ENABLED
size_t Memory::mem_usage = 0; size_t Memory::mem_usage = 0;
size_t Memory::max_usage = 0; size_t Memory::max_usage = 0;
#ifdef DEBUG_MEMORY_TAGGING
#define MEM_UNINIT_TAG 0xEA
#define MEM_RELEASED_TAG 0xAE
#endif
#define PREPAD true #define PREPAD true
#else #else
#define PREPAD p_pad_align #define PREPAD p_pad_align
@ -73,8 +77,11 @@ void *Memory::alloc_static(size_t p_bytes, bool p_pad_align) {
uint64_t *s = (uint64_t *)mem; uint64_t *s = (uint64_t *)mem;
*s = p_bytes; *s = p_bytes;
uint8_t *s8 = (uint8_t *)mem; uint8_t *s8 = (uint8_t *)mem + PAD_ALIGN;
return s8 + PAD_ALIGN; #if defined DEBUG_ENABLED && defined DEBUG_MEMORY_TAGGING
memset(s8, MEM_UNINIT_TAG, p_bytes);
#endif
return s8;
} else { } else {
return mem; return mem;
} }
@ -95,10 +102,19 @@ void *Memory::realloc_static(void *p_memory, size_t p_bytes, bool p_pad_align) {
if (p_bytes == 0) { if (p_bytes == 0) {
#ifdef DEBUG_ENABLED #ifdef DEBUG_ENABLED
mem_usage -= *s; mem_usage -= *s;
#ifdef DEBUG_MEMORY_TAGGING
memset(mem, MEM_RELEASED_TAG, PAD_ALIGN + *s);
#endif
#endif #endif
free(mem); free(mem);
return NULL; return NULL;
} else { } else {
#if defined DEBUG_ENABLED && defined DEBUG_MEMORY_TAGGING
if (p_bytes < *s) {
memset(mem + PAD_ALIGN + p_bytes, MEM_RELEASED_TAG, *s - p_bytes);
}
#endif
mem = (uint8_t *)realloc(mem, p_bytes + PAD_ALIGN); mem = (uint8_t *)realloc(mem, p_bytes + PAD_ALIGN);
ERR_FAIL_COND_V(!mem, NULL); ERR_FAIL_COND_V(!mem, NULL);
@ -106,6 +122,11 @@ void *Memory::realloc_static(void *p_memory, size_t p_bytes, bool p_pad_align) {
#ifdef DEBUG_ENABLED #ifdef DEBUG_ENABLED
mem_usage -= *s; mem_usage -= *s;
mem_usage += p_bytes; mem_usage += p_bytes;
#ifdef DEBUG_MEMORY_TAGGING
if (p_bytes > *s) {
memset(mem + PAD_ALIGN + *s, MEM_UNINIT_TAG, p_bytes - *s);
}
#endif
#endif #endif
*s = p_bytes; *s = p_bytes;
@ -131,6 +152,9 @@ void Memory::free_static(void *p_ptr, bool p_pad_align) {
#ifdef DEBUG_ENABLED #ifdef DEBUG_ENABLED
const uint64_t s = *((uint64_t *)mem); const uint64_t s = *((uint64_t *)mem);
mem_usage -= s; mem_usage -= s;
#ifdef DEBUG_MEMORY_TAGGING
memset(mem, MEM_RELEASED_TAG, PAD_ALIGN + s);
#endif
#endif #endif
} }
atomic_decrement(&alloc_count); atomic_decrement(&alloc_count);