libbb: auto_string() for efficient handling of temporary malloced stirngs

Use it in libiproute: get rid of one static string buffer.

function                                             old     new   delta
auto_string                                            -      51     +51
ll_index_to_name                                      10      49     +39
buffer_fill_and_print                                169     178      +9
scan_recursive                                       378     380      +2
decode_one_format                                    732     734      +2
cmdputs                                              334     332      -2
static.cur_saved                                       4       1      -3
static.nbuf                                           16       -     -16
printable_string                                      94      57     -37
ll_idx_n2a                                            53       -     -53
------------------------------------------------------------------------------
(add/remove: 2/2 grow/shrink: 4/3 up/down: 103/-111)           Total: -8 bytes
   text	   data	    bss	    dec	    hex	filename
 939880	    992	  17496	 958368	  e9fa0	busybox_old
 939880	    992	  17480	 958352	  e9f90	busybox_unstripped

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko 2015-10-09 17:59:56 +02:00
parent 550bf5b4a4
commit e52da5570e
5 changed files with 33 additions and 16 deletions

View File

@ -692,6 +692,7 @@ int bb_putchar(int ch) FAST_FUNC;
/* Note: does not use stdio, writes to fd 2 directly */ /* Note: does not use stdio, writes to fd 2 directly */
int bb_putchar_stderr(char ch) FAST_FUNC; int bb_putchar_stderr(char ch) FAST_FUNC;
char *xasprintf(const char *format, ...) __attribute__ ((format(printf, 1, 2))) FAST_FUNC RETURNS_MALLOC; char *xasprintf(const char *format, ...) __attribute__ ((format(printf, 1, 2))) FAST_FUNC RETURNS_MALLOC;
char *auto_string(char *str) FAST_FUNC;
// gcc-4.1.1 still isn't good enough at optimizing it // gcc-4.1.1 still isn't good enough at optimizing it
// (+200 bytes compared to macro) // (+200 bytes compared to macro)
//static ALWAYS_INLINE //static ALWAYS_INLINE

23
libbb/auto_string.c Normal file
View File

@ -0,0 +1,23 @@
/* vi: set sw=4 ts=4: */
/*
* Utility routines.
*
* Copyright (C) 2015 Denys Vlasenko
*
* Licensed under GPLv2, see file LICENSE in this source tree.
*/
//kbuild:lib-y += auto_string.o
#include "libbb.h"
char* FAST_FUNC auto_string(char *str)
{
static char *saved[4];
static uint8_t cur_saved; /* = 0 */
free(saved[cur_saved]);
saved[cur_saved] = str;
cur_saved = (cur_saved + 1) & (ARRAY_SIZE(saved)-1);
return str;
}

View File

@ -11,9 +11,6 @@
const char* FAST_FUNC printable_string(uni_stat_t *stats, const char *str) const char* FAST_FUNC printable_string(uni_stat_t *stats, const char *str)
{ {
static char *saved[4];
static unsigned cur_saved; /* = 0 */
char *dst; char *dst;
const char *s; const char *s;
@ -56,10 +53,5 @@ const char* FAST_FUNC printable_string(uni_stat_t *stats, const char *str)
} }
} }
#endif #endif
return auto_string(dst);
free(saved[cur_saved]);
saved[cur_saved] = dst;
cur_saved = (cur_saved + 1) & (ARRAY_SIZE(saved)-1);
return dst;
} }

View File

@ -86,7 +86,8 @@ int FAST_FUNC ll_remember_index(const struct sockaddr_nl *who UNUSED_PARAM,
return 0; return 0;
} }
const char FAST_FUNC *ll_idx_n2a(int idx, char *buf) static
const char FAST_FUNC *ll_idx_n2a(int idx/*, char *buf*/)
{ {
struct idxmap *im; struct idxmap *im;
@ -95,15 +96,15 @@ const char FAST_FUNC *ll_idx_n2a(int idx, char *buf)
im = find_by_index(idx); im = find_by_index(idx);
if (im) if (im)
return im->name; return im->name;
snprintf(buf, 16, "if%d", idx); //snprintf(buf, 16, "if%d", idx);
return buf; //return buf;
return auto_string(xasprintf("if%d", idx));
} }
const char FAST_FUNC *ll_index_to_name(int idx) const char FAST_FUNC *ll_index_to_name(int idx)
{ {
static char nbuf[16]; //static char nbuf[16];
return ll_idx_n2a(idx/*, nbuf*/);
return ll_idx_n2a(idx, nbuf);
} }
#ifdef UNUSED #ifdef UNUSED

View File

@ -7,8 +7,8 @@ PUSH_AND_SET_FUNCTION_VISIBILITY_TO_HIDDEN
int ll_remember_index(const struct sockaddr_nl *who, struct nlmsghdr *n, void *arg) FAST_FUNC; int ll_remember_index(const struct sockaddr_nl *who, struct nlmsghdr *n, void *arg) FAST_FUNC;
int ll_init_map(struct rtnl_handle *rth) FAST_FUNC; int ll_init_map(struct rtnl_handle *rth) FAST_FUNC;
int xll_name_to_index(const char *name) FAST_FUNC; int xll_name_to_index(const char *name) FAST_FUNC;
//static: const char *ll_idx_n2a(int idx, char *buf) FAST_FUNC;
const char *ll_index_to_name(int idx) FAST_FUNC; const char *ll_index_to_name(int idx) FAST_FUNC;
const char *ll_idx_n2a(int idx, char *buf) FAST_FUNC;
/* int ll_index_to_type(int idx); */ /* int ll_index_to_type(int idx); */
unsigned ll_index_to_flags(int idx) FAST_FUNC; unsigned ll_index_to_flags(int idx) FAST_FUNC;