bug#59530: 29.0.50; Fontification hangs with C header file

bug#59530: 29.0.50; Fontification hangs with C header file

[Sujith Manoharan]

Opening this header file with lots of macros makes Emacs
very slow.

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/gpu/drm/amd/include/asic_reg/dce/dce_12_0_sh_mask.h

Same behavior is seen with other header files inside asic_reg.
Fontification/scrolling hangs Emacs and it becomes unusable.

Bug #25706 suggested the workaround 'fast-but-imprecise-scrolling',
but enabling it doesn't seem to improve things now.


In GNU Emacs 29.0.50 (build 2, x86_64-pc-linux-gnu, X toolkit, cairo
 version 1.17.6, Xaw scroll bars) of 2022-11-24 built on comp-lnx
Repository revision: b37604c263e4813dc2a8b80e4e9131a3961c4f3e
Repository branch: master
Windowing system distributor 'The X.Org Foundation', version 11.0.12101004
System Description: Arch Linux

Configured using:
 'configure --prefix=/usr/local --enable-link-time-optimization
 --without-libsystemd --with-x-toolkit=lucid --without-dbus
 --without-gsettings --without-selinux --with-native-compilation
 --with-imagemagick 'CFLAGS=-O2 -march=native''

Configured features:
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bug#59530: 29.0.50; Fontification hangs with C header file

[Eli Zaretskii]

> From: Sujith Manoharan <sujith.wall@gmail.com>
> Date: Thu, 24 Nov 2022 09:32:03 +0530
> 
> Opening this header file with lots of macros makes Emacs
> very slow.
> 
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/gpu/drm/amd/include/asic_reg/dce/dce_12_0_sh_mask.h
> 
> Same behavior is seen with other header files inside asic_reg.
> Fontification/scrolling hangs Emacs and it becomes unusable.
> 
> Bug #25706 suggested the workaround 'fast-but-imprecise-scrolling',
> but enabling it doesn't seem to improve things now.

Alan, did you see this bug report?

bug#59530: 29.0.50; Fontification hangs with C header file

[Alan Mackenzie]

Hello, Eli.

On Sat, Nov 26, 2022 at 13:02:38 +0200, Eli Zaretskii wrote:
> > From: Sujith Manoharan <sujith.wall@gmail.com>
> > Date: Thu, 24 Nov 2022 09:32:03 +0530

> > Opening this header file with lots of macros makes Emacs
> > very slow.

> > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/gpu/drm/amd/include/asic_reg/dce/dce_12_0_sh_mask.h

> > Same behavior is seen with other header files inside asic_reg.
> > Fontification/scrolling hangs Emacs and it becomes unusable.

> > Bug #25706 suggested the workaround 'fast-but-imprecise-scrolling',
> > but enabling it doesn't seem to improve things now.

> Alan, did you see this bug report?

I hadn't, no, but I think it's already been fixed by the following
commit:

commit 3208a42c47c4f98cb03c4b15164ca83113244b40
Author: Alan Mackenzie <acm@muc.de>
Date:   Thu Nov 24 10:51:03 2022 +0000

    CC Mode: Make it scroll fast over buffers with only #define's

The OP's test file was around 6 MB big.  When I scrolled all the way
through it, it took around 32 seconds.

I'll look into this more carefully, and get in touch with the OP.

Thanks!

-- 
Alan Mackenzie (Nuremberg, Germany).

bug#59530: 29.0.50; Fontification hangs with C header file

[Alan Mackenzie]

Hello, Sujith.

On Thu, Nov 24, 2022 at 09:32:03 +0530, Sujith Manoharan wrote:
> Opening this header file with lots of macros makes Emacs
> very slow.

> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/gpu/drm/amd/include/asic_reg/dce/dce_12_0_sh_mask.h

> Same behavior is seen with other header files inside asic_reg.
> Fontification/scrolling hangs Emacs and it becomes unusable.

Thanks for taking the trouble to report this bug, and sorry for the
irritation it has caused.

> Bug #25706 suggested the workaround 'fast-but-imprecise-scrolling',
> but enabling it doesn't seem to improve things now.

I think the bug has already been fixed, coincidentally on Thursday, by
the following commit to master:

commit 3208a42c47c4f98cb03c4b15164ca83113244b40
Author: Alan Mackenzie <acm@muc.de>
Date:   Thu Nov 24 10:51:03 2022 +0000

    CC Mode: Make it scroll fast over buffers with only #define's

, committed just a few hours after you reported the bug.

I have a test script which scrolls all the way through a file, timing
how long it takes.  Before the above commit, it took ~1524 seconds on
dce_12-0_sh_mask.h, after the commit, it took ~31.4 seconds.

Would you please update your Emacs version, and see if this commit has
indeed resolved the problem, then let us know.

Thanks!

> In GNU Emacs 29.0.50 (build 2, x86_64-pc-linux-gnu, X toolkit, cairo
>  version 1.17.6, Xaw scroll bars) of 2022-11-24 built on comp-lnx
> Repository revision: b37604c263e4813dc2a8b80e4e9131a3961c4f3e
> Repository branch: master
> Windowing system distributor 'The X.Org Foundation', version 11.0.12101004
> System Description: Arch Linux

[ .... ]

-- 
Alan Mackenzie (Nuremberg, Germany).

bug#59530: 29.0.50; Fontification hangs with C header file

[Sujith Manoharan]

Alan Mackenzie <acm@muc.de> writes:
> I think the bug has already been fixed, coincidentally on Thursday, by
> the following commit to master:
>
> commit 3208a42c47c4f98cb03c4b15164ca83113244b40
> Author: Alan Mackenzie <acm@muc.de>
> Date:   Thu Nov 24 10:51:03 2022 +0000
>
>     CC Mode: Make it scroll fast over buffers with only #define's
>
> , committed just a few hours after you reported the bug.
>
> I have a test script which scrolls all the way through a file, timing
> how long it takes.  Before the above commit, it took ~1524 seconds on
> dce_12-0_sh_mask.h, after the commit, it took ~31.4 seconds.
>
> Would you please update your Emacs version, and see if this commit has
> indeed resolved the problem, then let us know.

This commit fixes the issue. It doesn't look like
fast-but-imprecise-scrolling is needed anymore at all.

Thanks !

Sujith

bug#59530: 29.0.50; Fontification hangs with C header file

[Alan Mackenzie]

Hello, Sujith.

On Sun, Nov 27, 2022 at 14:15:26 +0530, Sujith Manoharan wrote:
> Alan Mackenzie <acm@muc.de> writes:
> > I think the bug has already been fixed, coincidentally on Thursday, by
> > the following commit to master:

> > commit 3208a42c47c4f98cb03c4b15164ca83113244b40
> > Author: Alan Mackenzie <acm@muc.de>
> > Date:   Thu Nov 24 10:51:03 2022 +0000

> >     CC Mode: Make it scroll fast over buffers with only #define's

> > , committed just a few hours after you reported the bug.

> > I have a test script which scrolls all the way through a file, timing
> > how long it takes.  Before the above commit, it took ~1524 seconds on
> > dce_12-0_sh_mask.h, after the commit, it took ~31.4 seconds.

> > Would you please update your Emacs version, and see if this commit has
> > indeed resolved the problem, then let us know.

> This commit fixes the issue. It doesn't look like
> fast-but-imprecise-scrolling is needed anymore at all.

> Thanks !

Thank you for the testing, and I'm glad it works.  I'm closing the bug
with this post.

> Sujith

-- 
Alan Mackenzie (Nuremberg, Germany).