Bug 1261988

Summary:	fragment and vertex shaders can't decrement variables by 1
Product:	Red Hat Enterprise Linux 7	Reporter:	Oded Gabbay <ogabbay>
Component:	mesa	Assignee:	Oded Gabbay <ogabbay>
Status:	CLOSED ERRATA	QA Contact:	Desktop QE <desktop-qa-list>
Severity:	medium	Docs Contact:
Priority:	unspecified
Version:	7.2	CC:	bugproxy, hannsj_uhl, kem, tlavigne, tpelka
Target Milestone:	rc
Target Release:	7.2
Hardware:	ppc64le
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	Bug Fix
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2015-11-19 09:08:02 UTC	Type:	Bug
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:
Bug Blocks:	1118366, 1252514

Description Oded Gabbay 2015-09-10 14:42:15 UTC

Description of problem:
On ppc64le and ppc64 machines that run with software rendering, the shader command to decrement a variable by 1 is never executed. This is because of a bug in the translation between tgsi and llvm ir for ppc64le and ppc64. 

Because this is such a basic command in shaders, it causes a lot of failures when running the piglit test suite

Version-Release number of selected component (if applicable):
mesa-10.6.5-1.20150824.el7

How reproducible:
By running various piglit tests. Around 350 tests fail because of this bug. It occurs 100% of the time

Steps to Reproduce:
1. Install piglit
2. Run bin/shader_runner tests/spec/glsl-1.30/execution/fs-decrement-int.shader_test -auto

Actual results:
The program returns "fail"

Expected results:
The program should return "success"

Comment 1 Oded Gabbay 2015-09-16 11:34:56 UTC

Fixed in mesa-10.6.5-2.20150824.el7

Comment 5 errata-xmlrpc 2015-11-19 09:08:02 UTC

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://rhn.redhat.com/errata/RHBA-2015-2250.html