[Mesa-dev] [Bug 90081] [llvmpipe] piglit ext_transform_feedback-immediate-reuse-uniform-buffer regression
https://bugs.freedesktop.org/show_bug.cgi?id=90081 GitLab Migration User changed: What|Removed |Added Resolution|--- |MOVED Status|NEW |RESOLVED --- Comment #2 from GitLab Migration User --- -- GitLab Migration Automatic Message -- This bug has been migrated to freedesktop.org's GitLab instance and has been closed from further activity. You can subscribe and participate further through the new bug through this link to our GitLab instance: https://gitlab.freedesktop.org/mesa/mesa/issues/234. -- You are receiving this mail because: You are the assignee for the bug. You are the QA Contact for the bug.___ mesa-dev mailing list mesa-dev@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/mesa-dev
[Mesa-dev] [Bug 90081] [llvmpipe] piglit ext_transform_feedback-immediate-reuse-uniform-buffer regression
https://bugs.freedesktop.org/show_bug.cgi?id=90081 Timothy Arceri changed: What|Removed |Added Component|Mesa core |Drivers/Gallium/llvmpipe -- You are receiving this mail because: You are the assignee for the bug. You are the QA Contact for the bug.___ mesa-dev mailing list mesa-dev@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/mesa-dev
[Mesa-dev] [Bug 90081] [llvmpipe] piglit ext_transform_feedback-immediate-reuse-uniform-buffer regression
https://bugs.freedesktop.org/show_bug.cgi?id=90081 Andrés Gómez García changed: What|Removed |Added See Also||https://bugs.freedesktop.or ||g/show_bug.cgi?id=103762 -- You are receiving this mail because: You are the QA Contact for the bug. You are the assignee for the bug.___ mesa-dev mailing list mesa-dev@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/mesa-dev
[Mesa-dev] [Bug 90081] [llvmpipe] piglit ext_transform_feedback-immediate-reuse-uniform-buffer regression
https://bugs.freedesktop.org/show_bug.cgi?id=90081 Vinson Lee changed: What|Removed |Added Version|git |10.6 -- You are receiving this mail because: You are the assignee for the bug. You are the QA Contact for the bug.___ mesa-dev mailing list mesa-dev@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/mesa-dev
[Mesa-dev] [Bug 90081] [llvmpipe] piglit ext_transform_feedback-immediate-reuse-uniform-buffer regression
https://bugs.freedesktop.org/show_bug.cgi?id=90081 Kenneth Graunke changed: What|Removed |Added Blocks|79706 | Referenced Bugs: https://bugs.freedesktop.org/show_bug.cgi?id=79706 [Bug 79706] [TRACKER] Mesa regression tracker -- You are receiving this mail because: You are the assignee for the bug. You are the QA Contact for the bug.___ mesa-dev mailing list mesa-dev@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/mesa-dev
[Mesa-dev] [Bug 90081] [llvmpipe] piglit ext_transform_feedback-immediate-reuse-uniform-buffer regression
https://bugs.freedesktop.org/show_bug.cgi?id=90081 Vinson Lee changed: What|Removed |Added Blocks||79706 -- You are receiving this mail because: You are the QA Contact for the bug. You are the assignee for the bug. ___ mesa-dev mailing list mesa-dev@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/mesa-dev
[Mesa-dev] [Bug 90081] [llvmpipe] piglit ext_transform_feedback-immediate-reuse-uniform-buffer regression
https://bugs.freedesktop.org/show_bug.cgi?id=90081 --- Comment #1 from Roland Scheidegger --- Ah yes I actually knew about that but didn't consider it all that important. The reason is that the code was already buggy and this change just exposed the bug. In short here's what happens: - the transform feedback buffer is only 4 bytes, which is later bound as constant buffer - constant buffers are expected to be in multiples of 16 bytes (as the contents are vec4 elements), thus the size is considered to be zero by (llvm) draw (and would be the same for llvmpipe fragment shaders as well). Before this change, this worked because we do not verify that an access to a buffer constant is within range of the buffer, IFF the access is done via an immediate (so, indirect access would always have returned zero even with the old code). This is in fact not very safe (I've got some quickly hacked up piglit test which tries to cause a crash but didn't manage really more than valgrind warnings). This did not change (though I think it probably will in the future), however for simplified shader code we now bind (1-element sized) fake buffers explicitly if the buffer size is zero (this was actually trivial to crash before just don't bind a constant buffer then any attempt at constant buffer lookup would have produced a nice clean null pointer dereference). I don't have time to fix these issues though for now. Well the one not verifying accesses outside of range ought to be easy but doesn't help this case, but the bug causing one I'm actually not quite sure HOW it should be fixed. Since it is not really ok to bind 4-byte sized buffers as a constant buffer which thus could be considered a state tracker bug but I'm not sure if it actually could do much about it. Of course could be easily hacked up in draw so the test passes again (could only use fake buffer if size is 0 before the divide by 16 for instance) but it wouldn't really serve much purpose, I'd rather have it fail so the issue doesn't get lost completely. -- You are receiving this mail because: You are the QA Contact for the bug. You are the assignee for the bug. ___ mesa-dev mailing list mesa-dev@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/mesa-dev
[Mesa-dev] [Bug 90081] [llvmpipe] piglit ext_transform_feedback-immediate-reuse-uniform-buffer regression
https://bugs.freedesktop.org/show_bug.cgi?id=90081
Bug ID: 90081
Summary: [llvmpipe] piglit
ext_transform_feedback-immediate-reuse-uniform-buffer
regression
Product: Mesa
Version: git
Hardware: x86-64 (AMD64)
OS: Linux (All)
Status: NEW
Keywords: bisected, regression
Severity: normal
Priority: medium
Component: Mesa core
Assignee: mesa-dev@lists.freedesktop.org
Reporter: v...@freedesktop.org
QA Contact: mesa-dev@lists.freedesktop.org
CC: jfons...@vmware.com, srol...@vmware.com
mesa: 1eac3ae1a6ebecf353054d937dd603a11ea33fb3 (master 10.6.0-devel)
$ ./bin/ext_transform_feedback-immediate-reuse-uniform-buffer -auto
Probe color at (16,0)
Expected: 0.062500 0.937500 0.062500
Observed: 0.00 0.00 0.00
Probe color at (32,0)
Expected: 0.125000 0.875000 0.125000
Observed: 0.00 0.00 0.00
Probe color at (48,0)
Expected: 0.187500 0.812500 0.187500
Observed: 0.00 0.00 0.00
Probe color at (64,0)
Expected: 0.25 0.75 0.25
Observed: 0.00 0.00 0.00
Probe color at (80,0)
Expected: 0.312500 0.687500 0.312500
Observed: 0.00 0.00 0.00
Probe color at (96,0)
Expected: 0.375000 0.625000 0.375000
Observed: 0.00 0.00 0.00
Probe color at (112,0)
Expected: 0.437500 0.562500 0.437500
Observed: 0.00 0.00 0.00
Probe color at (128,0)
Expected: 0.50 0.50 0.50
Observed: 0.00 0.00 0.00
Probe color at (144,0)
Expected: 0.562500 0.437500 0.562500
Observed: 0.00 0.00 0.00
Probe color at (160,0)
Expected: 0.625000 0.375000 0.625000
Observed: 0.00 0.00 0.00
Probe color at (176,0)
Expected: 0.687500 0.312500 0.687500
Observed: 0.00 0.00 0.00
Probe color at (192,0)
Expected: 0.75 0.25 0.75
Observed: 0.00 0.00 0.00
Probe color at (208,0)
Expected: 0.812500 0.187500 0.812500
Observed: 0.00 0.00 0.00
Probe color at (224,0)
Expected: 0.875000 0.125000 0.875000
Observed: 0.00 0.00 0.00
Probe color at (240,0)
Expected: 0.937500 0.062500 0.937500
Observed: 0.00 0.00 0.00
PIGLIT: {"result": "fail" }
586536a4e1c34725b3b38c3425db569fac0c91e9 is the first bad commit
commit 586536a4e1c34725b3b38c3425db569fac0c91e9
Author: Roland Scheidegger
Date: Thu Apr 9 00:49:11 2015 +0200
gallivm: don't use control flow when doing indirect constant buffer lookups
llvm goes crazy when doing that, using way more memory and time, though
there's
probably more to it - this points to a very much similar issue as fixed in
8a9f5ecdb116d0449d63f7b94efbfa8b205d826f. In any case I've seen a quite
plain looking vertex shader with just ~50 simple tgsi instructions (but
with a
dozen or so such indirect constant buffer lookups) go from a terribly high
~440ms compile time (consuming 25MB of memory in the process) down to a
still
awful ~230ms and 13MB with this fix (with llvm 3.3), so there's still
obvious
improvements possible (but I have no clue why it's so slow...).
The resulting shader is most likely also faster (certainly seemed so though
I don't have any hard numbers as it may have been influenced by compile
times)
since generally fetching constants outside the buffer range is most likely
an
app error (that is we expect all indices to be valid).
It is possible this fixes some mysterious vertex shader slowdowns we've
seen
ever since we are conforming to newer apis at least partially (the main
draw
loop also has similar looking conditionals which we probably could do
without -
if not for the fetch at least for the additional elts condition.)
v2: use static vars for the fake bufs, minor code cleanups
Reviewed-by: Jose Fonseca
:04 04 3d9c36f85b3f7cf81413a06ea0454a4c035ea447
9d2ff2be20f10d6f129bc3e1a9979d2a97a37a79 Msrc
bisect run success
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