From: Torbjorn SVENSSON <torbjorn.svensson@foss.st.com>
To: Eli Zaretskii <eliz@gnu.org>, Simon Marchi <simark@simark.ca>
Cc: <cbiesinger@google.com>, <tom@tromey.com>,
<gdb-patches@sourceware.org>, <luis.machado@arm.com>
Subject: Re: Two observations using GDB 13 snapshot
Date: Thu, 5 Jan 2023 19:06:55 +0100 [thread overview]
Message-ID: <a8100d55-0c98-dba6-b783-5d614a96da39@foss.st.com> (raw)
In-Reply-To: <831qoayxuu.fsf@gnu.org>
On 2023-01-04 19:10, Eli Zaretskii via Gdb-patches wrote:
>> Date: Tue, 3 Jan 2023 16:34:53 -0500
>> Cc: tom@tromey.com, gdb-patches@sourceware.org, luis.machado@arm.com
>> From: Simon Marchi <simark@simark.ca>
>>
>>> In terms of the code, may be worth trying TOLOWER from
>>> include/safe-ctype.h instead of tolower()
>>
>> The tolower call is inside strcasecmp, we don't call tolower directly:
>>
>> #0 0x77c348d5 in msvcrt!__crtLCMapStringA ()
>> from C:\WINDOWS\system32\msvcrt.dll
>> #1 0x77c348cd in msvcrt!__crtLCMapStringA ()
>> from C:\WINDOWS\system32\msvcrt.dll
>> #2 0x77c30045 in wmktemp () from C:\WINDOWS\system32\msvcrt.dll
>> #3 0x77c1c992 in tolower () from C:\WINDOWS\system32\msvcrt.dll
>> #4 0x77c462a1 in stricmp () from C:\WINDOWS\system32\msvcrt.dll
>> #5 0x005107d3 in strcasecmp (__s2=<optimized out>, __s1=<optimized out>)
>> at d:/usr/include/strings.h:92
>> #6 cooked_index_entry::operator< (this=<optimized out>, other=...)
>> at ./dwarf2/cooked-index.h:150
>>
>> It would be interesting to change that strcasecmp call to strcmp, just
>> to see if it makes an impact on the performance. Whether or not that
>> would be correct is another thing, but it would help see if that
>> strcasecmp / tolower call is really at fault here.
>
> Looks like indeed strcasecmp is the culprit. With the patch below,
> which replaces strcasecmp with a simple case-insensitive comparison
> that only works with ASCII, the phase of reading symbols from gdb.exe
> goes down to just 6 seconds, which is basically the same time as with
> GDB 12.
>
> --- gdb/dwarf2/cooked-index.h~0 2022-12-17 03:47:12.000000000 +0200
> +++ gdb/dwarf2/cooked-index.h 2023-01-04 20:00:04.052250000 +0200
> @@ -35,6 +35,8 @@
> #include "dwarf2/tag.h"
> #include "gdbsupport/range-chain.h"
>
> +#define my_tolower(c) (('A' <= (c) && (c) <= 'Z') ? ((c) - 'A' + 'a') : (c))
> +
> struct dwarf2_per_cu_data;
>
> /* Flags that describe an entry in the index. */
> @@ -147,7 +149,20 @@ struct cooked_index_entry : public alloc
> entries. */
> bool operator< (const cooked_index_entry &other) const
> {
> +#if 0
> return strcasecmp (canonical, other.canonical) < 0;
> +#else
> + const unsigned char *s1 = (unsigned char *)canonical, *s2 = (unsigned char *)other.canonical;
> +
> + while (my_tolower(*s1) == my_tolower(*s2))
> + {
> + if (*s1 == 0)
> + return false;
Without any knowledge of the cooked_index_entry type or what it's
supposed to do, I think the return statement here is problematic in the
case where there are 2 cooked_index_entry instances contains the same
case insensitive canonical strings. I'm not sure if this can happen, but
it's just a thought.
It also appears that the old strcasecmp implementation would suffer the
same limitation. To avoid the issue, I guess the address of the 2
objects could be compared in order to get a stable result if there is no
other property that is guaranteed to be unique for the 2 instances.
Kind regards,
Torbjörn
> + s1++;
> + s2++;
> + }
> + return (int)my_tolower(*s1) < (int)my_tolower(*s2);
> +#endif
> }
>
> /* The name as it appears in DWARF. This always points into one of
next prev parent reply other threads:[~2023-01-05 18:07 UTC|newest]
Thread overview: 63+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-12-17 17:42 Eli Zaretskii
2022-12-19 10:07 ` Luis Machado
2022-12-19 12:48 ` Eli Zaretskii
2022-12-19 14:08 ` Luis Machado
2022-12-19 14:45 ` Eli Zaretskii
2022-12-19 21:18 ` Tom Tromey
2022-12-20 3:26 ` Eli Zaretskii
2022-12-23 3:34 ` Simon Marchi
2022-12-23 8:05 ` Eli Zaretskii
2022-12-24 17:57 ` Tom Tromey
2022-12-24 18:13 ` Eli Zaretskii
2022-12-27 17:19 ` Tom Tromey
2022-12-27 18:00 ` Eli Zaretskii
2022-12-28 12:35 ` Luis Machado
2022-12-28 16:35 ` Tom Tromey
2022-12-28 17:35 ` Eli Zaretskii
2022-12-28 22:47 ` Tom Tromey
2022-12-29 15:18 ` Eli Zaretskii
2022-12-29 18:17 ` Tom Tromey
2022-12-29 18:36 ` John Baldwin
2022-12-29 19:13 ` Eli Zaretskii
2022-12-29 20:22 ` Simon Marchi
2022-12-30 14:31 ` Eli Zaretskii
2023-01-03 19:44 ` Christian Biesinger
2023-01-03 20:18 ` Eli Zaretskii
2023-01-03 20:34 ` Christian Biesinger
2023-01-03 21:34 ` Simon Marchi
2023-01-03 21:43 ` Christian Biesinger
2023-01-04 1:03 ` Tom Tromey
2023-01-04 18:10 ` Eli Zaretskii
2023-01-04 22:33 ` Tom Tromey
2023-01-05 7:11 ` Eli Zaretskii
2023-01-05 14:49 ` Christian Biesinger
2023-01-05 15:12 ` Eli Zaretskii
2023-01-06 20:55 ` Tom Tromey
2023-01-05 18:06 ` Torbjorn SVENSSON [this message]
2023-01-07 6:30 ` Eli Zaretskii
2023-01-07 9:14 ` Andreas Schwab
2023-01-07 9:32 ` Eli Zaretskii
2023-01-07 10:00 ` Andreas Schwab
2023-01-07 10:51 ` Eli Zaretskii
2023-01-07 13:04 ` Andreas Schwab
2023-01-07 13:54 ` Eli Zaretskii
2023-01-07 13:59 ` Andreas Schwab
2023-01-07 14:12 ` Eli Zaretskii
2023-01-07 14:23 ` Andreas Schwab
2023-01-07 14:29 ` Eli Zaretskii
2023-01-07 14:40 ` Andreas Schwab
2023-01-07 15:07 ` Eli Zaretskii
2023-01-07 15:40 ` Andreas Schwab
2023-01-07 16:10 ` Eli Zaretskii
2023-01-07 16:15 ` Eli Zaretskii
2023-01-07 16:16 ` Hannes Domani
2023-01-07 16:22 ` Eli Zaretskii
2023-01-07 17:39 ` Andreas Schwab
2023-01-07 18:08 ` Eli Zaretskii
2023-01-07 18:26 ` Andreas Schwab
2023-01-07 18:38 ` Eli Zaretskii
2023-01-07 19:26 ` Andreas Schwab
2023-01-07 19:35 ` Eli Zaretskii
2023-01-07 18:28 ` Hannes Domani
2023-01-07 19:25 ` Andreas Schwab
2023-01-07 15:07 ` Eli Zaretskii
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=a8100d55-0c98-dba6-b783-5d614a96da39@foss.st.com \
--to=torbjorn.svensson@foss.st.com \
--cc=cbiesinger@google.com \
--cc=eliz@gnu.org \
--cc=gdb-patches@sourceware.org \
--cc=luis.machado@arm.com \
--cc=simark@simark.ca \
--cc=tom@tromey.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).