[Mesa-dev] [PATCH v2 0/1] Do not require all components to apply opt_vector_float()

Juan A. Suarez Romero jasuarez at igalia.com
Wed Dec 2 07:43:08 PST 2015

This patch, based on Matt suggestion, replaces the former two ones, as it gets
better results.

Basically, so far opt_vector_float() is only applied when the 4 components of
the register are written with MOV. This patch changes the behaviour so it
doesn't require to write the 4 components to apply it.

Results obtained with shader-db tests are:

    total instructions in shared programs: 6819484 -> 6811698 (-0.11%)
    instructions in affected programs:     387245 -> 379459 (-2.01%)
    total loops in shared programs:        1971 -> 1971 (0.00%)
    helped:                                3980
    HURT:                                  0
    GAINED:                                3
    LOST:                                  0

Which are better than the ones obtained in the first version.

Couple of final comments:

* In the original version Matt commented about a bug in
  opt_dead_code_eliminate(). As he already wrote a patch, I'm just waiting for
  him to send it.

* Matt commented also about a possible improvement in an example that allows
  evaluating at compile-time. As it is a different optimization, I'm not
  covering it on this patch, and rather letting it for a future improvement.

* I commented about a wrong application of opt_vector_float() in an example Matt
  found. He told that probably it lacks resetting last_reg to -1. This patch is
  covering that error.

Juan A. Suarez Romero (1):
  i965: add opportunistic behaviour to opt_vector_float()

 src/mesa/drivers/dri/i965/brw_vec4.cpp | 60 +++++++++++++++++++++-------------
 src/mesa/drivers/dri/i965/brw_vec4.h   |  3 ++
 2 files changed, 41 insertions(+), 22 deletions(-)


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