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Optimize __get_tls_addr a bit 

Rearrange code to avoid creation of a stack frame.  At least on x86-64
the code for the fast path should be down to the bare minimum.
This commit is contained in:
Ulrich Drepper 2012-01-30 22:32:05 -05:00
parent 96bc5b45a6
commit 27a25b6e63
2 changed files with 36 additions and 16 deletions
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8
ChangeLog
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@ -1,3 +1,11 @@
2012-01-30 Ulrich Drepper <drepper@gmail.com>
* elf/dl-tls.c (__tls_get_addr): Optimize by transforming all calls
into tail calls.
(update_get_addr): New function.
(tls_get_addr_tail): Take GET_ADDR_ARGS parameter, remove
GET_ADDR_MODULE parameter.
2012-01-28 Ulrich Drepper <drepper@gmail.com>
* sysdeps/x86_64/fpu/bits/mathinline.h (__signbitl): Optimize a bit.

44
elf/dl-tls.c
View File

@ -1,5 +1,5 @@
/* Thread-local storage handling in the ELF dynamic linker. Generic version.
Copyright (C) 2002-2006,2008,2011 Free Software Foundation, Inc.
Copyright (C) 2002-2006,2008,2011,2012 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
@ -509,6 +509,7 @@ rtld_hidden_def (_dl_deallocate_tls)
of the following macros. */
# ifndef GET_ADDR_ARGS
# define GET_ADDR_ARGS tls_index *ti
# define GET_ADDR_PARAM ti
# endif
# ifndef GET_ADDR_MODULE
# define GET_ADDR_MODULE ti->ti_module
@ -690,13 +691,13 @@ _dl_update_slotinfo (unsigned long int req_modid)
static void *
__attribute_noinline__
tls_get_addr_tail (dtv_t *dtv, struct link_map *the_map, size_t module)
tls_get_addr_tail (GET_ADDR_ARGS, dtv_t *dtv, struct link_map *the_map)
{
/* The allocation was deferred. Do it now. */
if (the_map == NULL)
{
/* Find the link map for this module. */
size_t idx = module;
size_t idx = GET_ADDR_MODULE;
struct dtv_slotinfo_list *listp = GL(dl_tls_dtv_slotinfo_list);
while (idx >= listp->len)
@ -728,18 +729,34 @@ tls_get_addr_tail (dtv_t *dtv, struct link_map *the_map, size_t module)
if (__builtin_expect (the_map->l_tls_offset
!= FORCED_DYNAMIC_TLS_OFFSET, 1))
{
void *p = dtv[module].pointer.val;
void *p = dtv[GET_ADDR_MODULE].pointer.val;
if (__builtin_expect (p == TLS_DTV_UNALLOCATED, 0))
goto again;
return p;
return (char *) p + GET_ADDR_OFFSET;
}
}
}
void *p = dtv[module].pointer.val = allocate_and_init (the_map);
dtv[module].pointer.is_static = false;
void *p = dtv[GET_ADDR_MODULE].pointer.val = allocate_and_init (the_map);
dtv[GET_ADDR_MODULE].pointer.is_static = false;
return p;
return (char *) p + GET_ADDR_OFFSET;
}
static struct link_map *
__attribute_noinline__
update_get_addr (GET_ADDR_ARGS)
{
struct link_map *the_map = _dl_update_slotinfo (GET_ADDR_MODULE);
dtv_t *dtv = THREAD_DTV ();
void *p = dtv[GET_ADDR_MODULE].pointer.val;
if (__builtin_expect (p == TLS_DTV_UNALLOCATED, 0))
return tls_get_addr_tail (GET_ADDR_PARAM, dtv, the_map);
return (char *) p + GET_ADDR_OFFSET;
}
@ -749,19 +766,14 @@ void *
__tls_get_addr (GET_ADDR_ARGS)
{
dtv_t *dtv = THREAD_DTV ();
struct link_map *the_map = NULL;
void *p;
if (__builtin_expect (dtv[0].counter != GL(dl_tls_generation), 0))
{
the_map = _dl_update_slotinfo (GET_ADDR_MODULE);
dtv = THREAD_DTV ();
}
return update_get_addr (GET_ADDR_PARAM);
p = dtv[GET_ADDR_MODULE].pointer.val;
void *p = dtv[GET_ADDR_MODULE].pointer.val;
if (__builtin_expect (p == TLS_DTV_UNALLOCATED, 0))
p = tls_get_addr_tail (dtv, the_map, GET_ADDR_MODULE);
return tls_get_addr_tail (GET_ADDR_PARAM, dtv, NULL);
return (char *) p + GET_ADDR_OFFSET;
}