That looks like a regression in glamor, possibly commit be334f4 ?

https://cgit.freedesktop.org/xorg/xserver/commit/?id=be334f4

Can you try to reproduce without that commit?

(In reply to Olivier Fourdan from comment #1)
> Can you try to reproduce without that commit?

As you asked I reverted line 199 of glamor_composite_glyphs.c to
---
                "varying vec2 glyph_pos;\n"),
    .vs_exec = (GLAMOR_POS(gl_Position, primitive)
                "       glyph_pos = source.xy * ATLAS_DIM_INV;\n"),
---
and recompiled xserver.

Still getting the same fatal error.

(In reply to Olivier Fourdan from comment #1)
> That looks like a regression in glamor, possibly commit be334f4 ?
> 
> https://cgit.freedesktop.org/xorg/xserver/commit/?id=be334f4
> 
> Can you try to reproduce without that commit?

Sorry for my previous message, I first only logged out and in.

After rebooting this error doesn't reproduce anymore!
Reverting commit be334f4 fixes this issue.
Thanks!

(In reply to Olivier Fourdan from comment #1)
> That looks like a regression in glamor, possibly commit be334f4 ?
> 
> https://cgit.freedesktop.org/xorg/xserver/commit/?id=be334f4
> 
> Can you try to reproduce without that commit?

I feel very sorry, I messed up the xserver versions I was using.
I now first double checked the used version!

Reverting commit be334f4 doesn't fix the issue,
but it no longer occurs when reverting all glamor to the one
used in xserver version 1.19.1
So the regression seems to be in another glamor file.

I did some more research.
Using /git/xserver/glamor and only reverting glamor_dash.c to the version
in xserver-1.19.1 fixes the issue.

This means reverting
static const char dash_vs_exec[] =
    "       dash_offset = primitive.z / dash_length;\n"
    "       vec2_pos = vec2(0,0);\n"
    GLAMOR_POS(gl_Position, primitive.xy);
to
static const char dash_vs_exec[] =
    "       dash_offset = primitive.z / dash_length;\n"
    GLAMOR_POS(gl_Position, primitive.xy);

*** Bug 100039 has been marked as a duplicate of this bug. ***

Thanks for the report, fixed in Git master:

commit 0c1574d9882a91b2c1a046bf4ac5a9b138a37965
Author: Michel Dänzer <michel.daenzer@amd.com>
Date:   Thu Mar 9 18:13:31 2017 +0900

    glamor: Fix typo: "vec2_pos" -> "vec2 pos"

(In reply to Michel Dänzer from comment #7)
 
>     glamor: Fix typo: "vec2_pos" -> "vec2 pos"

No more fatal server error, thanks!