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avoid atomic read on aligned allocation on Linux

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This commit is contained in:
daan 2019-08-11 08:00:10 -07:00
parent dbe010f2d4
commit a1384bff72
1 changed files with 10 additions and 8 deletions
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18
src/os.c
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@ -240,12 +240,14 @@ static void* mi_wasm_heap_grow(size_t size, size_t try_alignment) {
static void* mi_unix_mmapx(size_t size, size_t try_alignment, int protect_flags, int flags, int fd) {
void* p = NULL;
#if (MI_INTPTR_SIZE >= 8) && !defined(MAP_ALIGNED)
// on 64-bit systems, use a special area for 4MiB aligned allocations
// on 64-bit systems, use the virtual address area after 4TiB for 4MiB aligned allocations
static volatile intptr_t aligned_base = ((intptr_t)1 << 42); // starting at 4TiB
if (try_alignment <= MI_SEGMENT_SIZE && (size%MI_SEGMENT_SIZE)==0 && (aligned_base%try_alignment)==0) {
if (try_alignment <= MI_SEGMENT_SIZE && (size%MI_SEGMENT_SIZE)==0) {
intptr_t hint = mi_atomic_add(&aligned_base,size) - size;
p = mmap((void*)hint,size,protect_flags,flags,fd,0);
if (p==MAP_FAILED) p = NULL; // fall back to regular mmap
if (hint%try_alignment == 0) {
p = mmap((void*)hint,size,protect_flags,flags,fd,0);
if (p==MAP_FAILED) p = NULL; // fall back to regular mmap
}
}
#endif
if (p==NULL) {
@ -273,10 +275,10 @@ static void* mi_unix_mmap(size_t size, size_t try_alignment, int protect_flags)
protect_flags |= PROT_MAX(PROT_READ | PROT_WRITE); // BSD
#endif
#if defined(VM_MAKE_TAG)
// darwin: tracking anonymous page with a specific ID all up to 98 are taken officially but LLVM sanitizers had taken 99
// macOS: tracking anonymous page with a specific ID. (All up to 98 are taken officially but LLVM sanitizers had taken 99)
fd = VM_MAKE_TAG(100);
#endif
if (large_os_page_size > 0 && use_large_os_page(size, try_alignment)) {
if (use_large_os_page(size, try_alignment)) {
int lflags = flags;
int lfd = fd;
#ifdef MAP_ALIGNED_SUPER
@ -308,7 +310,7 @@ static void* mi_unix_mmap(size_t size, size_t try_alignment, int protect_flags)
#endif
// Primitive allocation from the OS.
// Note: the `alignment` is just a hint and the returned pointer is not guaranteed to be aligned.
// Note: the `try_alignment` is just a hint and the returned pointer is not guaranteed to be aligned.
static void* mi_os_mem_alloc(size_t size, size_t try_alignment, bool commit, mi_stats_t* stats) {
mi_assert_internal(size > 0 && (size % _mi_os_page_size()) == 0);
if (size == 0) return NULL;
@ -319,7 +321,7 @@ static void* mi_os_mem_alloc(size_t size, size_t try_alignment, bool commit, mi_
if (commit) flags |= MEM_COMMIT;
p = mi_win_virtual_alloc(NULL, size, try_alignment, flags);
#elif defined(__wasi__)
p = mi_wasm_heap_grow(size, try_alignment);
p = mi_wasm_herap_grow(size, try_alignment);
#else
int protect_flags = (commit ? (PROT_WRITE | PROT_READ) : PROT_NONE);
p = mi_unix_mmap(size, try_alignment, protect_flags);