[PATCH v11 1/6] elf: Refactor dl_new_hash so it can be tested / benchmarked

[Noah Goldstein]

On Thu, May 19, 2022 at 5:18 PM Noah Goldstein <goldstein.w.n@gmail.com> wrote:
>
> No change to the code other than moving the function to
> dl-new-hash.h. Changed name so its now in the reserved namespace.
> Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>

No changes v10 -> v11 so left reviewed by.
> ---
>  elf/dl-lookup.c   | 13 ++-----------
>  elf/dl-new-hash.h | 40 ++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 42 insertions(+), 11 deletions(-)
>  create mode 100644 elf/dl-new-hash.h
>
> diff --git a/elf/dl-lookup.c b/elf/dl-lookup.c
> index 989b073e4f..a42f6d5390 100644
> --- a/elf/dl-lookup.c
> +++ b/elf/dl-lookup.c
> @@ -24,6 +24,7 @@
>  #include <ldsodefs.h>
>  #include <dl-hash.h>
>  #include <dl-machine.h>
> +#include <dl-new-hash.h>
>  #include <dl-protected.h>
>  #include <sysdep-cancel.h>
>  #include <libc-lock.h>
> @@ -558,16 +559,6 @@ skip:
>  }
>
>
> -static uint32_t
> -dl_new_hash (const char *s)
> -{
> -  uint32_t h = 5381;
> -  for (unsigned char c = *s; c != '\0'; c = *++s)
> -    h = h * 33 + c;
> -  return h;
> -}
> -
> -
>  /* Add extra dependency on MAP to UNDEF_MAP.  */
>  static int
>  add_dependency (struct link_map *undef_map, struct link_map *map, int flags)
> @@ -816,7 +807,7 @@ _dl_lookup_symbol_x (const char *undef_name, struct link_map *undef_map,
>                      const struct r_found_version *version,
>                      int type_class, int flags, struct link_map *skip_map)
>  {
> -  const unsigned int new_hash = dl_new_hash (undef_name);
> +  const unsigned int new_hash = _dl_new_hash (undef_name);
>    unsigned long int old_hash = 0xffffffff;
>    struct sym_val current_value = { NULL, NULL };
>    struct r_scope_elem **scope = symbol_scope;
> diff --git a/elf/dl-new-hash.h b/elf/dl-new-hash.h
> new file mode 100644
> index 0000000000..8641bb4196
> --- /dev/null
> +++ b/elf/dl-new-hash.h
> @@ -0,0 +1,40 @@
> +/* _dl_new_hash for elf symbol lookup
> +   Copyright (C) 2022 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/>.  */
> +
> +#ifndef _DL_NEW_HASH_H
> +#define _DL_NEW_HASH_H 1
> +
> +#include <stdint.h>
> +/* For __always_inline.  */
> +#include <sys/cdefs.h>
> +
> +static __always_inline uint32_t
> +__attribute__ ((unused))
> +_dl_new_hash (const char *s)
> +{
> +  uint32_t h = 5381;
> +  for (unsigned char c = *s; c != '\0'; c = *++s)
> +    h = h * 33 + c;
> +  return h;
> +}
> +
> +/* For testing/benchmarking purposes.  */
> +#define __simple_dl_new_hash _dl_new_hash
> +
> +
> +#endif /* dl-new-hash.h */
> --
> 2.34.1
>