Bug 86811 - [BDW/BSW Bisected]Piglit spec_arb_shading_language_packing_execution_built-in-functions_vs-unpackSnorm4x8 fails
Summary: [BDW/BSW Bisected]Piglit spec_arb_shading_language_packing_execution_built-in...
Alias: None
Product: Mesa
Classification: Unclassified
Component: Drivers/DRI/i965 (show other bugs)
Version: unspecified
Hardware: All Linux (All)
: medium major
Assignee: Matt Turner
QA Contact: Intel 3D Bugs Mailing List
URL: http://lists.freedesktop.org/archives...
Depends on:
Reported: 2014-11-28 06:31 UTC by lu hua
Modified: 2015-03-02 07:35 UTC (History)
1 user (show)

See Also:
i915 platform:
i915 features:


Description lu hua 2014-11-28 06:31:33 UTC
System Environment:
Platform: BDW
Libdrm:		(master)libdrm-2.4.58-13-gfb4177046de19730a784c3c16e4b73aab0ec6e41
Mesa:		(master)91a827624c01d40613e97322632aaffe319540f1
Xserver:	(master)xorg-server-
Libva:		(master)c095cc6cf08523cd0dffcfe5ac4bce9122527f22
Kernel:   (drm-intel-nightly)904b8529cd69f98b98d33b533a211003f99fb1cd

Bug detailed description:
It fails on BDW with mesa master branch, works well on 10.4 branch.
spec_arb_shading_language_packing_execution_built-in-functions_vs-unpackUnorm4x8 also fails.

Bisect shows: 94a30bbd4fe5f3eda167819e307f736268fd33f6 is the first bad commit.
commit 94a30bbd4fe5f3eda167819e307f736268fd33f6
Author:     Matt Turner <mattst88@gmail.com>
AuthorDate: Sun Mar 9 20:22:23 2014 -0700
Commit:     Matt Turner <mattst88@gmail.com>
CommitDate: Tue Nov 25 17:29:02 2014 -0800

    i965/vec4: Optimize unpackSnorm4x8().

    Reduces the number of instructions needed to implement unpackSnorm4x8()
    from 16 -> 6.

    Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>

Probe color at (0,0)
  Expected: 0.000000 1.000000 0.000000 1.000000
  Observed: 1.000000 0.000000 0.000000 1.000000
PIGLIT: {"result": "fail" }

Reproduce steps:
1. xinit
2. ./bin/shader_runner generated_tests/spec/arb_shading_language_packing/execution/built-in-functions/vs-unpackSnorm4x8.shader_test -auto
Comment 1 lu hua 2014-12-03 07:40:43 UTC
It also fails on BSW.
Comment 2 Matt Turner 2015-02-06 21:05:48 UTC
Note that this will only be reproducible with the vec4 backend, which you can force-enable with INTEL_DEBUG=vec4vs.
Comment 3 Matt Turner 2015-02-12 02:18:41 UTC
Patch on the list.
Comment 4 Matt Turner 2015-02-20 06:10:26 UTC
Fixed by

commit e0137fd6f720e4977466b1760ac02a72c5abceb8
Author: Matt Turner <mattst88@gmail.com>
Date:   Thu Feb 12 01:42:43 2015 +0000

    i965/vec4: Add and use byte-MOV instruction for unpack 4x8.
    Previously we were using a B/UB source in an Align16 instruction, which
    is illegal. It for some reason works on all platforms, except Broadwell.
    Cc: "10.5" <mesa-stable@lists.freedesktop.org>
    Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=86811
    Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
Comment 5 lu hua 2015-03-02 07:35:04 UTC

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