[Mesa-dev] [PATCH 8/8] i965/vec4: Do copy before constant propagation after opt_vector_float().

[Ian Romanick]

On 12/21/2014 03:24 PM, Matt Turner wrote:
> total instructions in shared programs: 5877012 -> 5876617 (-0.01%)
> instructions in affected programs:     33140 -> 32745 (-1.19%)
> 
> From before the commit that allows VF constant propagation (which hurt
> some programs) to here, the results are:
> 
> total instructions in shared programs: 5877951 -> 5876617 (-0.02%)
> instructions in affected programs:     123444 -> 122110 (-1.08%)
> 
> with no programs hurt.
> ---
>  src/mesa/drivers/dri/i965/brw_vec4.cpp | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/src/mesa/drivers/dri/i965/brw_vec4.cpp b/src/mesa/drivers/dri/i965/brw_vec4.cpp
> index d36a735..c9ba338 100644
> --- a/src/mesa/drivers/dri/i965/brw_vec4.cpp
> +++ b/src/mesa/drivers/dri/i965/brw_vec4.cpp
> @@ -1800,6 +1800,7 @@ vec4_visitor::run()
>  
>     if (opt_vector_float()) {
>        opt_cse();
> +      opt_copy_propagation(false);

The commit messages suggest the above line should go before the
opt_cse() call.

>        opt_copy_propagation();

Seeing these two lines together makes the default parameter to
opt_copy_propagation feel a little icky... but I guess the
OPT(opt_copy_propagation()) in vec4_visitor::run won't really work
otherwise.

Maybe pass an explicit true here anyway?

>        dead_code_eliminate();
>     }
>