| Summary: | [ILK] GPU hang (and multiple fails) in piglit shader tests if spilling is forced in the vec4 backend | ||
|---|---|---|---|
| Product: | Mesa | Reporter: | Iago Toral <itoral> |
| Component: | Drivers/DRI/i965 | Assignee: | Intel 3D Bugs Mailing List <intel-3d-bugs> |
| Status: | RESOLVED MOVED | QA Contact: | Intel 3D Bugs Mailing List <intel-3d-bugs> |
| Severity: | normal | ||
| Priority: | medium | CC: | rhyskidd |
| Version: | git | ||
| Hardware: | Other | ||
| OS: | All | ||
| Whiteboard: | |||
| i915 platform: | i915 features: | ||
| Attachments: |
Native code producing the GPU hang
Minimal shader test program reproducing the problem Minimal native code reproducing the problem |
||
|
Description
Iago Toral
2015-09-24 08:52:04 UTC
Created attachment 118430 [details]
Native code producing the GPU hang
The test triggering the GPU hang is 'vs-loop-bounds-unrolled.shader_test'. The attachment includes the native VS code dump when spilling is forced. I'll try to look into it tomorrow.
Some additional information: The hang happens because scratch reads/writes are not working properly for some reason. In this particular test, the GPu hang is the result of an infinite loop because variables involved in the loop condition are always read a value of 0 when unspilled. I have been reviewing the ILK docs and the implementation but I have not found anything wrong with it yet. I'll attach a minimum shader_test program reproducing the problem soon. Created attachment 118701 [details]
Minimal shader test program reproducing the problem
Created attachment 118702 [details]
Minimal native code reproducing the problem
This is the native code for the minimal example I just attached, forcing spilling only for the the variable "sum". Since that variable is not part of the loop condition the program won't hang, but we still get an incorrect result (sum is 0). Notice that in this case the problem is limited to just one spill/unspill operation that does not work well for some reason.
I attempted to recreate this with spilling on ILK with a more recent Mesa. As Iago outlined with the minimal reproducer test, the shader_test didn't hang but it did fail with INTEL_DEBUG=spill_vec4.
$ INTEL_DEBUG=spill_vec4 mesa-debug bin/shader_runner vs-ilk-spill-fail.shader_test -auto
Probe color at (0,0)
Expected: 0 255 0 255
Observed: 0 0 0 255
PIGLIT: {"result": "fail" }
$ mesa-debug bin/shader_runner vs-ilk-spill-fail.shader_test -auto
PIGLIT: {"result": "pass" }
$ mesa-debug report-bug-info
Software versions:
4.4.0-22-generic
OpenGL version string: 2.1 Mesa 12.1.0-devel (git-f016e4b)
GPU hardware:
OpenGL renderer string: Mesa DRI Intel(R) Ironlake Mobile
00:02.0 VGA compatible controller [0300]: Intel Corporation Core Processor Integrated Graphics Controller [8086:0046] (rev 02)
CPU hardware:
x86_64
Intel(R) Core(TM) i5 CPU M 580 @ 2.67GHz
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