* Redundant if clause in xdisp.c?
@ 2009-08-29 12:46 Eli Zaretskii
2009-08-29 14:16 ` Chong Yidong
2009-08-29 15:50 ` Stefan Monnier
0 siblings, 2 replies; 6+ messages in thread
From: Eli Zaretskii @ 2009-08-29 12:46 UTC (permalink / raw
To: emacs-devel
Unless I'm missing something, both branches of the if clause below
(from xdisp.c:redisplay_internal) are identical, except for the
comments:
if (Z - CHARPOS (tlendpos) == ZV)
{
/* This line ends at end of (accessible part of)
buffer. There is no newline to count. */
delta = (Z
- CHARPOS (tlendpos)
- MATRIX_ROW_START_CHARPOS (row));
delta_bytes = (Z_BYTE
- BYTEPOS (tlendpos)
- MATRIX_ROW_START_BYTEPOS (row));
}
else
{
/* This line ends in a newline. Must take
account of the newline and the rest of the
text that follows. */
delta = (Z
- CHARPOS (tlendpos)
- MATRIX_ROW_START_CHARPOS (row));
delta_bytes = (Z_BYTE
- BYTEPOS (tlendpos)
- MATRIX_ROW_START_BYTEPOS (row));
}
increment_matrix_positions (w->current_matrix,
this_line_vpos + 1,
w->current_matrix->nrows,
delta, delta_bytes);
Okay to remove the condition and to collapse both branches into a
single code fragment?
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: Redundant if clause in xdisp.c?
2009-08-29 12:46 Redundant if clause in xdisp.c? Eli Zaretskii
@ 2009-08-29 14:16 ` Chong Yidong
2009-08-29 15:50 ` Stefan Monnier
1 sibling, 0 replies; 6+ messages in thread
From: Chong Yidong @ 2009-08-29 14:16 UTC (permalink / raw
To: Eli Zaretskii; +Cc: emacs-devel
Eli Zaretskii <eliz@gnu.org> writes:
> Unless I'm missing something, both branches of the if clause below
> (from xdisp.c:redisplay_internal) are identical, except for the
> comments: ...
>
> Okay to remove the condition and to collapse both branches into a
> single code fragment?
Yes, please.
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: Redundant if clause in xdisp.c?
2009-08-29 12:46 Redundant if clause in xdisp.c? Eli Zaretskii
2009-08-29 14:16 ` Chong Yidong
@ 2009-08-29 15:50 ` Stefan Monnier
2009-08-29 17:40 ` Eli Zaretskii
1 sibling, 1 reply; 6+ messages in thread
From: Stefan Monnier @ 2009-08-29 15:50 UTC (permalink / raw
To: Eli Zaretskii; +Cc: emacs-devel
> Okay to remove the condition and to collapse both branches into a
> single code fragment?
Looks like a good idea, yes. BTW, before playing with the redisplay,
please just throw away keyboard.c's handling of self-insert-command,
forward-char and backward-char, as well as the corresponding
"direct-rendering fast-path" code.
These optimizations seem to be pointless nowadays: even when running
Emacs-23 on my cell-phone (FreeRunner) displaying on my desktop, they
don't make any noticeable difference.
I refrained from installing this change for Emacs-23.2, out of fear
bigfoot might come and bite me, but I'll definitely install it for
Emacs-24.
Stefan
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: Redundant if clause in xdisp.c?
2009-08-29 15:50 ` Stefan Monnier
@ 2009-08-29 17:40 ` Eli Zaretskii
2009-08-29 21:21 ` Stefan Monnier
0 siblings, 1 reply; 6+ messages in thread
From: Eli Zaretskii @ 2009-08-29 17:40 UTC (permalink / raw
To: Stefan Monnier; +Cc: emacs-devel
> From: Stefan Monnier <monnier@iro.umontreal.ca>
> Cc: emacs-devel@gnu.org
> Date: Sat, 29 Aug 2009 11:50:39 -0400
>
> > Okay to remove the condition and to collapse both branches into a
> > single code fragment?
>
> Looks like a good idea, yes.
Done.
> BTW, before playing with the redisplay, please just throw away
> keyboard.c's handling of self-insert-command, forward-char and
> backward-char, as well as the corresponding "direct-rendering
> fast-path" code.
These optimizations are disabled for bidi redisplay anyway, so they
don't bother me.
> These optimizations seem to be pointless nowadays: even when running
> Emacs-23 on my cell-phone (FreeRunner) displaying on my desktop, they
> don't make any noticeable difference.
How did you turn them off to measure their influence, and with what
kind of stuff in your buffer(s)?
> I refrained from installing this change for Emacs-23.2, out of fear
> bigfoot might come and bite me, but I'll definitely install it for
> Emacs-24.
OK, but for now I'd prefer not to do any changes in my bidi sandbox
that are not strictly related to bidirectional editing. Once we have
a way to commit these changes to CVS, fine with me, if we are sure
these optimizations don't matter anymore.
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: Redundant if clause in xdisp.c?
2009-08-29 17:40 ` Eli Zaretskii
@ 2009-08-29 21:21 ` Stefan Monnier
2009-08-30 18:06 ` Eli Zaretskii
0 siblings, 1 reply; 6+ messages in thread
From: Stefan Monnier @ 2009-08-29 21:21 UTC (permalink / raw
To: Eli Zaretskii; +Cc: emacs-devel
>> BTW, before playing with the redisplay, please just throw away
>> keyboard.c's handling of self-insert-command, forward-char and
>> backward-char, as well as the corresponding "direct-rendering
>> fast-path" code.
> These optimizations are disabled for bidi redisplay anyway, so they
> don't bother me.
Good.
>> These optimizations seem to be pointless nowadays: even when running
>> Emacs-23 on my cell-phone (FreeRunner) displaying on my desktop, they
>> don't make any noticeable difference.
> How did you turn them off to measure their influence,
I removed the corresponding code.
> and with what kind of stuff in your buffer(s)?
I tried it in *scratch* and in a Python-mode buffer (visiting
/usr/bin/zhone), doing random movement and typing (especially using the
auto-repeat to see when the redisplay keeps up and when it doesn't).
>> I refrained from installing this change for Emacs-23.2, out of fear
>> bigfoot might come and bite me, but I'll definitely install it for
>> Emacs-24.
> OK, but for now I'd prefer not to do any changes in my bidi sandbox
> that are not strictly related to bidirectional editing. Once we have
> a way to commit these changes to CVS, fine with me, if we are sure
> these optimizations don't matter anymore.
Sure, I just wanted to make sure you don't waste time in these parts of
the code.
Stefan
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: Redundant if clause in xdisp.c?
2009-08-29 21:21 ` Stefan Monnier
@ 2009-08-30 18:06 ` Eli Zaretskii
0 siblings, 0 replies; 6+ messages in thread
From: Eli Zaretskii @ 2009-08-30 18:06 UTC (permalink / raw
To: Stefan Monnier; +Cc: emacs-devel
> From: Stefan Monnier <monnier@iro.umontreal.ca>
> Date: Sat, 29 Aug 2009 17:21:42 -0400
> Cc: emacs-devel@gnu.org
>
> >> These optimizations seem to be pointless nowadays: even when running
> >> Emacs-23 on my cell-phone (FreeRunner) displaying on my desktop, they
> >> don't make any noticeable difference.
>
> > How did you turn them off to measure their influence,
>
> I removed the corresponding code.
I think it's enough to set direction-reversed non-nil.
> > and with what kind of stuff in your buffer(s)?
>
> I tried it in *scratch* and in a Python-mode buffer (visiting
> /usr/bin/zhone), doing random movement and typing (especially using the
> auto-repeat to see when the redisplay keeps up and when it doesn't).
GUI session or tty? The price of disabling these optimizations might
be more visible on a tty via a relatively slow link. I don't think we
should remove them before we try at least that.
> Sure, I just wanted to make sure you don't waste time in these parts of
> the code.
The first rule of optimization: don't do it. The second rule of
optimization: don't do it yet. I'm somewhere before the first and the
second one: I need to get the code work right before I make it faster
(if needed).
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2009-08-30 18:06 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2009-08-29 12:46 Redundant if clause in xdisp.c? Eli Zaretskii
2009-08-29 14:16 ` Chong Yidong
2009-08-29 15:50 ` Stefan Monnier
2009-08-29 17:40 ` Eli Zaretskii
2009-08-29 21:21 ` Stefan Monnier
2009-08-30 18:06 ` Eli Zaretskii
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