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Re: Building Emacs overflowed pure space
From: |
YAMAMOTO Mitsuharu |
Subject: |
Re: Building Emacs overflowed pure space |
Date: |
Tue, 25 Jul 2006 10:14:05 +0900 |
User-agent: |
Wanderlust/2.14.0 (Africa) SEMI/1.14.6 (Maruoka) FLIM/1.14.6 (Marutamachi) APEL/10.6 Emacs/22.0.50 (sparc-sun-solaris2.8) MULE/5.0 (SAKAKI) |
>>>>> On Sun, 23 Jul 2006 01:11:48 +0200, address@hidden (Kim F. Storm) said:
>>> If the string data in the pure storage can be assumed to be
>>> completely read-only (including the preloading stage), another
>>> hack could be considered. That is, sharing postfixes of string
>>> data among multiple pure strings. The following experimental
>>> patch shows another ~40KB reduction of the pure storage usage. (A
>>> slow and naive but reliable version not using Boyer-Moore also
>>> shows the same size of reduction.)
>>
> I tried the exact the same thing (using the naive version), but the
> dumped emacs crashed immediately after loadup, thinking that "nil"
> was a filename... So I didn't think it was safe to do this.
I'm not sure if this should be counted as an objection. If so, can I
have a look at the code just to make sure?
BTW, a condition was missing at the entrance of the function in my
previous patch. Below is a revised one:
YAMAMOTO Mitsuharu
address@hidden
Index: src/alloc.c
===================================================================
RCS file: /cvsroot/emacs/emacs/src/alloc.c,v
retrieving revision 1.397
diff -c -p -r1.397 alloc.c
*** src/alloc.c 20 Jul 2006 01:01:04 -0000 1.397
--- src/alloc.c 23 Jul 2006 04:21:49 -0000
*************** check_pure_size ()
*** 4767,4772 ****
--- 4767,4839 ----
}
+ /* Find the byte sequence {DATA[0], ..., DATA[NBYTES-1], '\0'} from
+ the non-Lisp data pool of the pure storage, and return its start
+ address. Return NULL if not found. */
+
+ static char *
+ find_string_data_in_pure (data, nbytes)
+ char *data;
+ int nbytes;
+ {
+ int i, skip, bm_skip[256], last_char_skip, infinity, start, start_max;
+ unsigned char *p;
+ char *non_lisp_beg;
+
+ if (pure_bytes_used_non_lisp < nbytes + 1)
+ return NULL;
+
+ /* Set up the Boyer-Moore table. */
+ skip = nbytes + 1;
+ for (i = 0; i < 256; i++)
+ bm_skip[i] = skip;
+
+ p = (unsigned char *) data;
+ while (--skip > 0)
+ bm_skip[*p++] = skip;
+
+ last_char_skip = bm_skip['\0'];
+
+ non_lisp_beg = purebeg + pure_size - pure_bytes_used_non_lisp;
+ start_max = pure_bytes_used_non_lisp - (nbytes + 1);
+
+ /* See the comments in the function `boyer_moore' (search.c) for the
+ use of `infinity'. */
+ infinity = pure_bytes_used_non_lisp + 1;
+ bm_skip['\0'] = infinity;
+
+ p = (unsigned char *) non_lisp_beg + nbytes;
+ start = 0;
+ do
+ {
+ /* Check the last character (== '\0'). */
+ do
+ {
+ start += bm_skip[*(p + start)];
+ }
+ while (start <= start_max);
+
+ if (start < infinity)
+ /* Couldn't find the last character. */
+ return NULL;
+
+ /* No less than `infinity' means we could find the last
+ character at `p[start - infinity]'. */
+ start -= infinity;
+
+ /* Check the remaining characters. */
+ if (memcmp (data, non_lisp_beg + start, nbytes) == 0)
+ /* Found. */
+ return non_lisp_beg + start;
+
+ start += last_char_skip;
+ }
+ while (start <= start_max);
+
+ return NULL;
+ }
+
+
/* Return a string allocated in pure space. DATA is a buffer holding
NCHARS characters, and NBYTES bytes of string data. MULTIBYTE
non-zero means make the result string multibyte.
*************** make_pure_string (data, nchars, nbytes,
*** 4785,4795 ****
struct Lisp_String *s;
s = (struct Lisp_String *) pure_alloc (sizeof *s, Lisp_String);
! s->data = (unsigned char *) pure_alloc (nbytes + 1, -1);
s->size = nchars;
s->size_byte = multibyte ? nbytes : -1;
- bcopy (data, s->data, nbytes);
- s->data[nbytes] = '\0';
s->intervals = NULL_INTERVAL;
XSETSTRING (string, s);
return string;
--- 4852,4866 ----
struct Lisp_String *s;
s = (struct Lisp_String *) pure_alloc (sizeof *s, Lisp_String);
! s->data = find_string_data_in_pure (data, nbytes);
! if (s->data == NULL)
! {
! s->data = (unsigned char *) pure_alloc (nbytes + 1, -1);
! bcopy (data, s->data, nbytes);
! s->data[nbytes] = '\0';
! }
s->size = nchars;
s->size_byte = multibyte ? nbytes : -1;
s->intervals = NULL_INTERVAL;
XSETSTRING (string, s);
return string;
- Re: Building Emacs overflowed pure space, (continued)
- Re: Building Emacs overflowed pure space, mituharu, 2006/07/19
- Re: Building Emacs overflowed pure space, Stefan Monnier, 2006/07/19
- Re: Building Emacs overflowed pure space, Richard Stallman, 2006/07/19
- Re: Building Emacs overflowed pure space, YAMAMOTO Mitsuharu, 2006/07/19
- Re: Building Emacs overflowed pure space, YAMAMOTO Mitsuharu, 2006/07/22
- Re: Building Emacs overflowed pure space, Stefan Monnier, 2006/07/22
- Re: Building Emacs overflowed pure space, Kim F. Storm, 2006/07/22
- Re: Building Emacs overflowed pure space, Stefan Monnier, 2006/07/22
- Re: Building Emacs overflowed pure space,
YAMAMOTO Mitsuharu <=
- Re: Building Emacs overflowed pure space, Richard Stallman, 2006/07/25
- Re: Building Emacs overflowed pure space, YAMAMOTO Mitsuharu, 2006/07/25
- Re: Building Emacs overflowed pure space, David Kastrup, 2006/07/25
- Re: Building Emacs overflowed pure space, Andreas Schwab, 2006/07/25
- Re: Building Emacs overflowed pure space, David Kastrup, 2006/07/25
- Message not available
- Re: Building Emacs overflowed pure space, Andreas Schwab, 2006/07/25
- Re: Building Emacs overflowed pure space, David Kastrup, 2006/07/25
- Re: Building Emacs overflowed pure space, Richard Stallman, 2006/07/23
- Re: Building Emacs overflowed pure space, Luc Teirlinck, 2006/07/18
- Re: Building Emacs overflowed pure space, Chong Yidong, 2006/07/18