|Summary:||dEQP ldexp precision tests fail|
|Product:||Mesa||Reporter:||Kenneth Graunke <kenneth>|
|Component:||Drivers/DRI/i965||Assignee:||Jason Ekstrand <jason>|
|Status:||RESOLVED FIXED||QA Contact:||Intel 3D Bugs Mailing List <intel-3d-bugs>|
|i915 platform:||i915 features:|
|Bug Depends on:|
Description Kenneth Graunke 2016-03-26 09:29:16 UTC
24 of the dEQP-GLES31.functional.shaders.builtin_functions.precision.ldexp.* tests fail, at least on Broadwell. (These tests also exist in the Vulkan conformance suite.) It seems that our current lowering breaks for certain values.
Comment 1 Jason Ekstrand 2016-03-26 14:42:45 UTC
Among the patches I posted to the list yesterday is a new lowering for ldexp that I think is better than both the spec stupidity and what we have today. The spec'd f*2.0^exp is sufficient for deqp but has range problems. What we have today misses some edge cases when denormals get involved.
Comment 2 Kenneth Graunke 2016-04-14 05:57:23 UTC
Fixed in master by Jason: commit 505a8fbdf8f2b6d2aaab5a04244cd3329f9dbe97 Author: Kenneth Graunke <firstname.lastname@example.org> Date: Tue Apr 12 02:30:25 2016 -0700 i965: Switch to NIR for ldexp lowering. The old GLSL IR based lowering doesn't quite work right in all cases, and fails several dEQP-GLES31 and Vulkan CTS tests. Jason's new approach in NIR passes all the tests. There's not likely to be a ton of advantage to lowering early in GLSL IR anyway, so...switch. Signed-off-by: Kenneth Graunke <email@example.com> Reviewed-by: Jason Ekstrand <firstname.lastname@example.org> Reviewed-by: Matt Turner <email@example.com> commit 4455bfa9a0cc53a3c7e3c171b022cbe6d6dcdff8 Author: Jason Ekstrand <firstname.lastname@example.org> Date: Fri Mar 25 12:12:38 2016 -0700 nir/algebraic: Add lowering for ldexp The algorithm used is different from both the naive suggestion from the GLSL spec and the one used in GLSL IR today. Unfortunately, the GLSL IR implementation that we have today doesn't handle denormals (for those that care) or the case where the float source is +-inf. Reviewed-by: Matt Turner <email@example.com> Thanks Jason and Matt!