[Mesa-dev] [PATCH 2/2] mesa/program: Don't copy propagate from swizzles.

[Ian Romanick]

On 04/24/2013 04:30 PM, Fabian Bieler wrote:
> Do not propagate a copy if source and destination are identical.
>
> Otherwise code like
>
> MOV TEMP[0].xyzw, TEMP[0].wzyx
> MOV TEMP[1].xyzw, TEMP[0].xyzw
>
> is changed to
>
> MOV TEMP[0].xyzw, TEMP[0].wzyx
> MOV TEMP[1].xyzw, TEMP[0].wzyx
>
> This fixes Piglit test shaders/glsl-copy-propagation-self-2 for drivers that
> use Mesa IR.

D'oh.  Good catch.  Please add

NOTE: This is a candidate for stable branches.

to the commit message.

Reviewed-by: Ian Romanick <ian.d.romanick at intel.com>

> ---
>   src/mesa/program/ir_to_mesa.cpp | 2 ++
>   1 file changed, 2 insertions(+)
>
> diff --git a/src/mesa/program/ir_to_mesa.cpp b/src/mesa/program/ir_to_mesa.cpp
> index 14cf5ba..dff1762 100644
> --- a/src/mesa/program/ir_to_mesa.cpp
> +++ b/src/mesa/program/ir_to_mesa.cpp
> @@ -2757,6 +2757,8 @@ ir_to_mesa_visitor::copy_propagate(void)
>         /* If this is a copy, add it to the ACP. */
>         if (inst->op == OPCODE_MOV &&
>   	  inst->dst.file == PROGRAM_TEMPORARY &&
> +	  !(inst->dst.file == inst->src[0].file &&
> +	    inst->dst.index == inst->src[0].index) &&
>   	  !inst->dst.reladdr &&
>   	  !inst->saturate &&
>   	  !inst->src[0].reladdr &&
>