[Mesa-dev] [PATCH] nir: Copy-propagate vecN operations that are actually moves

[Connor Abbott]

I agree with Ken that the regressions are small enough, and it seems
they're mostly stuff we can prevent by being smarter when doing the
sel peephole, so it seems like the cleanup that will probably help
other passes is worth it.

Reviewed-by: Connor Abbott <cwabbott0 at gmail.com>

On Fri, Feb 20, 2015 at 1:03 AM, Jason Ekstrand <jason at jlekstrand.net> wrote:
> We were already do this for ALU operations but we haven't for non-ALU
> operations.  This changes that.
>
> total NIR instructions in shared programs: 2039883 -> 2022338 (-0.86%)
> NIR instructions in affected programs:     1768850 -> 1751305 (-0.99%)
> helped:                                    14244
> HURT:                                      124
>
> total FS instructions in shared programs: 4083960 -> 4084036 (0.00%)
> FS instructions in affected programs:     7302 -> 7378 (1.04%)
> helped:                                   12
> HURT:                                     51
>
> Signed-off-by: Jason Ekstrand <jason.ekstrand at intel.com>
> ---
>  src/glsl/nir/nir_opt_copy_propagate.c | 45 ++++++++++++++++++++++-------------
>  1 file changed, 29 insertions(+), 16 deletions(-)
>
> diff --git a/src/glsl/nir/nir_opt_copy_propagate.c b/src/glsl/nir/nir_opt_copy_propagate.c
> index dd0ec01..ee78e5a 100644
> --- a/src/glsl/nir/nir_opt_copy_propagate.c
> +++ b/src/glsl/nir/nir_opt_copy_propagate.c
> @@ -53,22 +53,6 @@ static bool is_move(nir_alu_instr *instr)
>
>  }
>
> -static bool
> -is_swizzleless_move(nir_alu_instr *instr)
> -{
> -   if (!is_move(instr))
> -      return false;
> -
> -   for (unsigned i = 0; i < 4; i++) {
> -      if (!((instr->dest.write_mask >> i) & 1))
> -         break;
> -      if (instr->src[0].swizzle[i] != i)
> -         return false;
> -   }
> -
> -   return true;
> -}
> -
>  static bool is_vec(nir_alu_instr *instr)
>  {
>     for (unsigned i = 0; i < nir_op_infos[instr->op].num_inputs; i++)
> @@ -80,6 +64,35 @@ static bool is_vec(nir_alu_instr *instr)
>            instr->op == nir_op_vec4;
>  }
>
> +static bool
> +is_swizzleless_move(nir_alu_instr *instr)
> +{
> +   if (is_move(instr)) {
> +      for (unsigned i = 0; i < 4; i++) {
> +         if (!((instr->dest.write_mask >> i) & 1))
> +            break;
> +         if (instr->src[0].swizzle[i] != i)
> +            return false;
> +      }
> +      return true;
> +   } else if (is_vec(instr)) {
> +      nir_ssa_def *def = NULL;
> +      for (unsigned i = 0; i < nir_op_infos[instr->op].num_inputs; i++) {
> +         if (instr->src[i].swizzle[0] != i)
> +            return false;
> +
> +         if (def == NULL) {
> +            def = instr->src[i].src.ssa;
> +         } else if (instr->src[i].src.ssa != def) {
> +            return false;
> +         }
> +      }
> +      return true;
> +   } else {
> +      return false;
> +   }
> +}
> +
>  typedef struct {
>     nir_ssa_def *def;
>     bool found;
> --
> 2.3.0
>
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