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malloc: replace instances of __builtin_expect with __glibc_unlikely

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Replaced all instances of __builtin_expect to __glibc_unlikely
within malloc.c and malloc-debug.c.  This improves the portability
of glibc by avoiding calls to GNU C built-in functions.  Since all
the expected results from calls to __builtin_expect were 0,
__glibc_likely was never used as a replacement.  Multiple
calls to __builtin_expect within a single if statement have
been replaced with one call to __glibc_unlikely, which wraps
every condition.

Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>
Reviewed-by: Wilco Dijkstra  <Wilco.Dijkstra@arm.com>
This commit is contained in:
William Hunt
2025-06-26 15:07:14 +00:00
committed by Wilco Dijkstra
parent d1ad959b00
commit 9a5a7613ac
2 changed files with 25 additions and 26 deletions
Download Patch File Download Diff File Expand all files Collapse all files

10
malloc/malloc-debug.c
View File

@ -169,7 +169,7 @@ static void *
__debug_malloc (size_t bytes)
{
void *(*hook) (size_t, const void *) = atomic_forced_read (__malloc_hook);
if (__builtin_expect (hook != NULL, 0))
if (__glibc_unlikely (hook != NULL))
return (*hook)(bytes, RETURN_ADDRESS (0));
void *victim = NULL;
@ -193,7 +193,7 @@ static void
__debug_free (void *mem)
{
void (*hook) (void *, const void *) = atomic_forced_read (__free_hook);
if (__builtin_expect (hook != NULL, 0))
if (__glibc_unlikely (hook != NULL))
{
(*hook)(mem, RETURN_ADDRESS (0));
return;
@ -218,7 +218,7 @@ __debug_realloc (void *oldmem, size_t bytes)
{
void *(*hook) (void *, size_t, const void *) =
atomic_forced_read (__realloc_hook);
if (__builtin_expect (hook != NULL, 0))
if (__glibc_unlikely (hook != NULL))
return (*hook)(oldmem, bytes, RETURN_ADDRESS (0));
size_t orig_bytes = bytes, oldsize = 0;
@ -272,7 +272,7 @@ _debug_mid_memalign (size_t alignment, size_t bytes, const void *address)
{
void *(*hook) (size_t, size_t, const void *) =
atomic_forced_read (__memalign_hook);
if (__builtin_expect (hook != NULL, 0))
if (__glibc_unlikely (hook != NULL))
return (*hook)(alignment, bytes, address);
void *victim = NULL;
@ -371,7 +371,7 @@ __debug_calloc (size_t nmemb, size_t size)
}
void *(*hook) (size_t, const void *) = atomic_forced_read (__malloc_hook);
if (__builtin_expect (hook != NULL, 0))
if (__glibc_unlikely (hook != NULL))
{
void *mem = (*hook)(bytes, RETURN_ADDRESS (0));

41
malloc/malloc.c
View File

@ -1621,7 +1621,7 @@ unlink_chunk (mstate av, mchunkptr p)
mchunkptr fd = p->fd;
mchunkptr bk = p->bk;
if (__builtin_expect (fd->bk != p || bk->fd != p, 0))
if (__glibc_unlikely (fd->bk != p || bk->fd != p))
malloc_printerr ("corrupted double-linked list");
fd->bk = bk;
@ -3628,8 +3628,8 @@ __libc_realloc (void *oldmem, size_t bytes)
never wraps around at the end of the address space. Therefore
we can exclude some size values which might appear here by
accident or by "design" from some intruder. */
if ((__builtin_expect ((uintptr_t) oldp > (uintptr_t) -oldsize, 0)
|| __builtin_expect (misaligned_chunk (oldp), 0)))
if (__glibc_unlikely ((uintptr_t) oldp > (uintptr_t) -oldsize
|| misaligned_chunk (oldp)))
malloc_printerr ("realloc(): invalid pointer");
nb = checked_request2size (bytes);
@ -3899,7 +3899,7 @@ __libc_calloc2 (size_t sz)
/* Two optional cases in which clearing not necessary */
if (chunk_is_mmapped (p))
{
if (__builtin_expect (perturb_byte, 0))
if (__glibc_unlikely (perturb_byte))
return memset (mem, 0, sz);
return mem;
@ -4064,7 +4064,7 @@ _int_malloc (mstate av, size_t bytes)
if (__glibc_likely (victim != NULL))
{
size_t victim_idx = fastbin_index (chunksize (victim));
if (__builtin_expect (victim_idx != idx, 0))
if (__glibc_unlikely (victim_idx != idx))
malloc_printerr ("malloc(): memory corruption (fast)");
check_remalloced_chunk (av, victim, nb);
#if USE_TCACHE
@ -4653,10 +4653,9 @@ _int_free_chunk (mstate av, mchunkptr p, INTERNAL_SIZE_T size, int have_lock)
#endif
) {
if (__builtin_expect (chunksize_nomask (chunk_at_offset (p, size))
<= CHUNK_HDR_SZ, 0)
|| __builtin_expect (chunksize (chunk_at_offset (p, size))
>= av->system_mem, 0))
if (__glibc_unlikely (
chunksize_nomask (chunk_at_offset(p, size)) <= CHUNK_HDR_SZ
|| chunksize (chunk_at_offset(p, size)) >= av->system_mem))
{
bool fail = true;
/* We might not have a lock at this point and concurrent modifications
@ -4687,7 +4686,7 @@ _int_free_chunk (mstate av, mchunkptr p, INTERNAL_SIZE_T size, int have_lock)
{
/* Check that the top of the bin is not the record we are going to
add (i.e., double free). */
if (__builtin_expect (old == p, 0))
if (__glibc_unlikely (old == p))
malloc_printerr ("double free or corruption (fasttop)");
p->fd = PROTECT_PTR (&p->fd, old);
*fb = p;
@ -4697,7 +4696,7 @@ _int_free_chunk (mstate av, mchunkptr p, INTERNAL_SIZE_T size, int have_lock)
{
/* Check that the top of the bin is not the record we are going to
add (i.e., double free). */
if (__builtin_expect (old == p, 0))
if (__glibc_unlikely (old == p))
malloc_printerr ("double free or corruption (fasttop)");
old2 = old;
p->fd = PROTECT_PTR (&p->fd, old);
@ -4710,7 +4709,7 @@ _int_free_chunk (mstate av, mchunkptr p, INTERNAL_SIZE_T size, int have_lock)
only if we have the lock, otherwise it might have already been
allocated again. */
if (have_lock && old != NULL
&& __builtin_expect (fastbin_index (chunksize (old)) != idx, 0))
&& __glibc_unlikely (fastbin_index (chunksize (old)) != idx))
malloc_printerr ("invalid fastbin entry (free)");
}
@ -4777,17 +4776,17 @@ _int_free_merge_chunk (mstate av, mchunkptr p, INTERNAL_SIZE_T size)
if (__glibc_unlikely (p == av->top))
malloc_printerr ("double free or corruption (top)");
/* Or whether the next chunk is beyond the boundaries of the arena. */
if (__builtin_expect (contiguous (av)
if (__glibc_unlikely (contiguous (av)
&& (char *) nextchunk
>= ((char *) av->top + chunksize(av->top)), 0))
>= ((char *) av->top + chunksize(av->top))))
malloc_printerr ("double free or corruption (out)");
/* Or whether the block is actually not marked used. */
if (__glibc_unlikely (!prev_inuse(nextchunk)))
malloc_printerr ("double free or corruption (!prev)");
INTERNAL_SIZE_T nextsize = chunksize(nextchunk);
if (__builtin_expect (chunksize_nomask (nextchunk) <= CHUNK_HDR_SZ, 0)
|| __builtin_expect (nextsize >= av->system_mem, 0))
if (__glibc_unlikely (chunksize_nomask (nextchunk) <= CHUNK_HDR_SZ
|| nextsize >= av->system_mem))
malloc_printerr ("free(): invalid next size (normal)");
free_perturb (chunk2mem(p), size - CHUNK_HDR_SZ);
@ -5044,9 +5043,9 @@ _int_realloc (mstate av, mchunkptr oldp, INTERNAL_SIZE_T oldsize,
unsigned long remainder_size; /* its size */
/* oldmem size */
if (__builtin_expect (chunksize_nomask (oldp) <= CHUNK_HDR_SZ, 0)
|| __builtin_expect (oldsize >= av->system_mem, 0)
|| __builtin_expect (oldsize != chunksize (oldp), 0))
if (__glibc_unlikely (chunksize_nomask (oldp) <= CHUNK_HDR_SZ
|| oldsize >= av->system_mem
|| oldsize != chunksize (oldp)))
malloc_printerr ("realloc(): invalid old size");
check_inuse_chunk (av, oldp);
@ -5056,8 +5055,8 @@ _int_realloc (mstate av, mchunkptr oldp, INTERNAL_SIZE_T oldsize,
next = chunk_at_offset (oldp, oldsize);
INTERNAL_SIZE_T nextsize = chunksize (next);
if (__builtin_expect (chunksize_nomask (next) <= CHUNK_HDR_SZ, 0)
|| __builtin_expect (nextsize >= av->system_mem, 0))
if (__glibc_unlikely (chunksize_nomask (next) <= CHUNK_HDR_SZ
|| nextsize >= av->system_mem))
malloc_printerr ("realloc(): invalid next size");
if ((unsigned long) (oldsize) >= (unsigned long) (nb))