[glibc] elf: Refactor dl_new_hash so it can be tested / benchmarked

[glibc] elf: Refactor dl_new_hash so it can be tested / benchmarked

[Noah Goldstein]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=c4bd509d477373b79b2becb625634d3441193005

commit c4bd509d477373b79b2becb625634d3441193005
Author: Noah Goldstein <goldstein.w.n@gmail.com>
Date:   Thu May 19 17:17:58 2022 -0500

    elf: Refactor dl_new_hash so it can be tested / benchmarked
    
    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>

Diff:
---
 elf/dl-lookup.c   | 13 ++-----------
 elf/dl-new-hash.h | 40 ++++++++++++++++++++++++++++++++++++++++
 2 files changed, 42 insertions(+), 11 deletions(-)

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 */