diff options
| -rw-r--r-- | malloc/malloc-internal.h | 1 | ||||
| -rw-r--r-- | malloc/malloc.c | 36 | ||||
| -rw-r--r-- | sysdeps/generic/calloc-clear-memory.h | 49 |
3 files changed, 51 insertions, 35 deletions
diff --git a/malloc/malloc-internal.h b/malloc/malloc-internal.h index cba0343..3349e2d 100644 --- a/malloc/malloc-internal.h +++ b/malloc/malloc-internal.h @@ -23,6 +23,7 @@ #include <malloc-sysdep.h> #include <malloc-size.h> #include <malloc-hugepages.h> +#include <calloc-clear-memory.h> /* Called in the parent process before a fork. */ void __malloc_fork_lock_parent (void) attribute_hidden; diff --git a/malloc/malloc.c b/malloc/malloc.c index 287fa09..ac3901b 100644 --- a/malloc/malloc.c +++ b/malloc/malloc.c @@ -3755,8 +3755,6 @@ __libc_calloc (size_t n, size_t elem_size) INTERNAL_SIZE_T sz, oldtopsize; void *mem; unsigned long clearsize; - unsigned long nclears; - INTERNAL_SIZE_T *d; ptrdiff_t bytes; if (__glibc_unlikely (__builtin_mul_overflow (n, elem_size, &bytes))) @@ -3853,40 +3851,8 @@ __libc_calloc (size_t n, size_t elem_size) } #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; + return clear_memory ((INTERNAL_SIZE_T *) mem, clearsize); } #endif /* IS_IN (libc) */ diff --git a/sysdeps/generic/calloc-clear-memory.h b/sysdeps/generic/calloc-clear-memory.h new file mode 100644 index 0000000..1f9d70d --- /dev/null +++ b/sysdeps/generic/calloc-clear-memory.h @@ -0,0 +1,49 @@ +/* Clear a block of memory for calloc. Generic version. + Copyright (C) 2024 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + <https://www.gnu.org/licenses/>. */ + +static __always_inline void * +clear_memory (INTERNAL_SIZE_T *d, unsigned long clearsize) +{ + /* Unroll clear memory size up to 9 * INTERNAL_SIZE_T bytes. We know + that contents have an odd number of INTERNAL_SIZE_T-sized words; + minimally 3 words. */ + unsigned long nclears = clearsize / sizeof (INTERNAL_SIZE_T); + + if (nclears > 9) + return memset (d, 0, clearsize); + + /* NB: The VRP pass in GCC 14.2 will optimize it out. */ + if (nclears < 3) + __builtin_unreachable (); + + /* Use repeated stores with 1 branch, instead of up to 3. */ + *(d + 0) = 0; + *(d + 1) = 0; + *(d + 2) = 0; + *(d + nclears - 2) = 0; + *(d + nclears - 2 + 1) = 0; + if (nclears > 5) + { + *(d + 3) = 0; + *(d + 3 + 1) = 0; + *(d + nclears - 4) = 0; + *(d + nclears - 4 + 1) = 0; + } + + return d; +} |