Bug 17865

Summary: [i915] Bad texture indirect lookup counting
Product: Mesa Reporter: Eric Anholt <eric>
Component: Drivers/DRI/i915Assignee: Eric Anholt <eric>
Status: RESOLVED FIXED QA Contact:
Severity: normal    
Priority: medium    
Version: git   
Hardware: Other   
OS: All   
Whiteboard:
i915 platform: i915 features:
Bug Depends on:    
Bug Blocks: 11131    

Description Eric Anholt 2008-10-01 22:49:52 UTC 
The 915 driver is counting texture indirections incorrectly.  See ARB_fragment_program question (24) for details on texture indirection accounting -- they match our hardware quite well.  A simple summary of the failure would be a sample program that looks like:

---------------- phase 0
mul r0 t0 c0
mul r1 t1 c1
---------------- phase 1
texld r2 r0 s0
texld r3 r1 s1
mul oC r2 r3

Our driver would count this as

---------------- phase 0
mul r0 t0 c0
mul r1 t1 c1
---------------- phase 1
texld r2 r0 s0
---------------- phase 2
texld r3 r1 s1
mul oC r2 r3

We also fail to count indirections when the destination is write masked, and when the destination has already been read or written in the current phase.
Comment 1 Eric Anholt 2008-10-04 18:44:18 UTC 
Addded regression test to piglit

commit 94dac46a5c45e09c7163591435b3f4195b66175f
Author: Eric Anholt <eric@anholt.net>
Date:   Sat Oct 4 18:35:48 2008 -0700

    Add a test for ARB_fp texture indirection accounting.

and a fix for the testcase to mesa:

commit 91d0020eecb78ef2984fd0afafc5d555c0e957d8
Author: Eric Anholt <eric@anholt.net>
Date:   Sat Oct 4 18:20:35 2008 -0700

    i915: Refine the texture indirect lookup accounting.
    
    Without this, we would reject programs which sampled multiple times from
    registers defined in the same phase (block of instructions with the same
    texture indirection count), as each sample would count as a new phase
    beginning.  Instead, keep track of which phases registers were written in,
    and only bump phase when we're reading from one generated in this phase.
    
    On the other hand, we failed to count oC or oD texture samples as being new
    phases.
Comment 2 Adam Jackson 2009-08-24 12:30:57 UTC 
Mass version move, cvs -> git

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