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

[Bryan Cain]

On 04/20/2013 12:40 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
> ---
>  src/mesa/state_tracker/st_glsl_to_tgsi.cpp |    2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/src/mesa/state_tracker/st_glsl_to_tgsi.cpp b/src/mesa/state_tracker/st_glsl_to_tgsi.cpp
> index f2eb3e7..b5d0534 100644
> --- a/src/mesa/state_tracker/st_glsl_to_tgsi.cpp
> +++ b/src/mesa/state_tracker/st_glsl_to_tgsi.cpp
> @@ -3544,6 +3544,8 @@ glsl_to_tgsi_visitor::copy_propagate(void)
>        /* If this is a copy, add it to the ACP. */
>        if (inst->op == TGSI_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 &&

Nice catch.  FYI, it seems that the almost identical copy_progagate
function in ir_to_mesa also needs this fix.

Bryan