[Mesa-dev] [PATCH 3/3 v5] i965/fs: Combine tex/fb_write operations (opt)

[Kenneth Graunke]

On Saturday, April 11, 2015 01:38:44 PM Ben Widawsky wrote:
> Certain platforms support the ability to sample from a texture, and write it out
> to the file RT - thus saving a costly send instructions (note that this is a
> potnential win if one wanted to backport to a tag that didn't have the patch
> from Topi which removed excess MOVs from LOAD_PAYLOAD - 97caf5fa04dbd2),
> 
> v2: Modify the algorithm. Instead of iterating in reverse through blocks and
> insts, since the last block/inst is the only thing which can benefit. Rebased
> on top of Ken's patching modifying is_last_send
> 
> v3: Rebased over almost 2 months, and Incorporated feedback from Matt:
> Some comment typo fixes and rewordings.
> Whitespace
> Move the optimization pass outside of the optimize loop
> 
> v4: Some cosmetic changes requested from Ken. These changes ensured that the
> optimization function always returned true when an optimization occurred, and
> false when one did not. This behavior did not exist with the original patch. As
> a result, having the separate helper function which Matt did not like no longer
> made sense, and so now I believe everyone should be happy.
> 
> Benchmark (n=20)   %diff
> *OglBatch5         -1.4
> *OglBatch7         -1.79
> OglFillTexMulti    5.57
> OglFillTexSingle   1.16
> OglShMapPcf        0.05
> OglTexFilterAniso  3.01
> OglTexFilterTri    1.94
> 
> No piglit regressions:
> (http://otc-gfxtest-01.jf.intel.com:8080/view/dev/job/bwidawsk/112/)
> 
> [*] I believe my measurements are incorrect for Batch5-7. If I add this new
> optimization, but never emit the new instruction I see similar results.
> 
> v5: Remove declaration of combine_tex_header since v4 dropped that function
> (Ben)
> Remove check for impossible case of an empty block (Matt)
> Set dest earlier to avoid extra special-casing in generate_tex (Matt)
> 
> Cc: Kenneth Graunke <kenneth at whitecape.org>
> Cc: Jason Ekstrand <jason at jlekstrand.net>
> Signed-off-by: Ben Widawsky <ben at bwidawsk.net>
> Reviewed-by: Matt Turner <mattst88 at gmail.com>

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