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Simplify calloc implementation.

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To make future improvements of allocator simpler we could for now calloc
just call malloc and memset. With that we could omit a changes that
would duplicate malloc changes anyway.
This commit is contained in:
Ondřej Bílka 2014-02-26 13:13:09 +01:00
parent ade40b10ff
commit 4248f0da6f
2 changed files with 10 additions and 109 deletions
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4
ChangeLog
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@ -1,3 +1,7 @@
2014-02-26 Ondřej Bílka <neleai@seznam.cz>
* malloc/malloc.c (__libc_calloc): Simplify implementation.
2014-02-25 Carlos O'Donell <carlos@redhat.com> 2014-02-25 Carlos O'Donell <carlos@redhat.com>
[BZ #16632] [BZ #16632]

115
malloc/malloc.c
View File

@ -3141,13 +3141,8 @@ __libc_pvalloc (size_t bytes)
void * void *
__libc_calloc (size_t n, size_t elem_size) __libc_calloc (size_t n, size_t elem_size)
{ {
mstate av; INTERNAL_SIZE_T bytes;
mchunkptr oldtop, p;
INTERNAL_SIZE_T bytes, sz, csz, oldtopsize;
void *mem; void *mem;
unsigned long clearsize;
unsigned long nclears;
INTERNAL_SIZE_T *d;
/* size_t is unsigned so the behavior on overflow is defined. */ /* size_t is unsigned so the behavior on overflow is defined. */
bytes = n * elem_size; bytes = n * elem_size;
@ -3166,113 +3161,15 @@ __libc_calloc (size_t n, size_t elem_size)
atomic_forced_read (__malloc_hook); atomic_forced_read (__malloc_hook);
if (__builtin_expect (hook != NULL, 0)) if (__builtin_expect (hook != NULL, 0))
{ {
sz = bytes; mem = (*hook)(bytes, RETURN_ADDRESS (0));
mem = (*hook)(sz, RETURN_ADDRESS (0));
if (mem == 0)
return 0;
return memset (mem, 0, sz);
} }
else
sz = bytes; mem = __libc_malloc (bytes);
arena_get (av, sz);
if (!av)
return 0;
/* Check if we hand out the top chunk, in which case there may be no
need to clear. */
#if MORECORE_CLEARS
oldtop = top (av);
oldtopsize = chunksize (top (av));
# if MORECORE_CLEARS < 2
/* Only newly allocated memory is guaranteed to be cleared. */
if (av == &main_arena &&
oldtopsize < mp_.sbrk_base + av->max_system_mem - (char *) oldtop)
oldtopsize = (mp_.sbrk_base + av->max_system_mem - (char *) oldtop);
# endif
if (av != &main_arena)
{
heap_info *heap = heap_for_ptr (oldtop);
if (oldtopsize < (char *) heap + heap->mprotect_size - (char *) oldtop)
oldtopsize = (char *) heap + heap->mprotect_size - (char *) oldtop;
}
#endif
mem = _int_malloc (av, sz);
assert (!mem || chunk_is_mmapped (mem2chunk (mem)) ||
av == arena_for_chunk (mem2chunk (mem)));
if (mem == 0) if (mem == 0)
{ return 0;
LIBC_PROBE (memory_calloc_retry, 1, sz);
av = arena_get_retry (av, sz);
if (__builtin_expect (av != NULL, 1))
{
mem = _int_malloc (av, sz);
(void) mutex_unlock (&av->mutex);
}
if (mem == 0)
return 0;
}
else
(void) mutex_unlock (&av->mutex);
p = mem2chunk (mem);
/* Two optional cases in which clearing not necessary */ return memset (mem, 0, bytes);
if (chunk_is_mmapped (p))
{
if (__builtin_expect (perturb_byte, 0))
return memset (mem, 0, sz);
return mem;
}
csz = chunksize (p);
#if MORECORE_CLEARS
if (perturb_byte == 0 && (p == oldtop && csz > oldtopsize))
{
/* clear only the bytes from non-freshly-sbrked memory */
csz = oldtopsize;
}
#endif
/* Unroll clear of <= 36 bytes (72 if 8byte sizes). We know that
contents have an odd number of INTERNAL_SIZE_T-sized words;
minimally 3. */
d = (INTERNAL_SIZE_T *) mem;
clearsize = csz - SIZE_SZ;
nclears = clearsize / sizeof (INTERNAL_SIZE_T);
assert (nclears >= 3);
if (nclears > 9)
return memset (d, 0, clearsize);
else
{
*(d + 0) = 0;
*(d + 1) = 0;
*(d + 2) = 0;
if (nclears > 4)
{
*(d + 3) = 0;
*(d + 4) = 0;
if (nclears > 6)
{
*(d + 5) = 0;
*(d + 6) = 0;
if (nclears > 8)
{
*(d + 7) = 0;
*(d + 8) = 0;
}
}
}
}
return mem;
} }
/* /*