[Mesa-dev] [PATCH] st/mesa: kill instruction if writemask=0 in eliminate_dead_code_advanced()

[Marek Olšák]

I think ARL is allowed to have no destination register, right? In that
case, there should be a special case not to eliminate ARLs.

Marek

On Fri, Oct 7, 2011 at 5:40 PM, Brian Paul <brian.e.paul at gmail.com> wrote:
> From: Brian Paul <brianp at vmware.com>
>
> This fixes a bug where we'd wind up emitting an invalid instruction like
> MOVE R[0]., R[1];  - note the empty/zero writemask.  If we don't write to
> any dest register channels, cull the instruction.
> ---
>  src/mesa/state_tracker/st_glsl_to_tgsi.cpp |    8 +++++++-
>  1 files changed, 7 insertions(+), 1 deletions(-)
>
> diff --git a/src/mesa/state_tracker/st_glsl_to_tgsi.cpp b/src/mesa/state_tracker/st_glsl_to_tgsi.cpp
> index d8ef8a3..44b1149 100644
> --- a/src/mesa/state_tracker/st_glsl_to_tgsi.cpp
> +++ b/src/mesa/state_tracker/st_glsl_to_tgsi.cpp
> @@ -3776,8 +3776,14 @@ glsl_to_tgsi_visitor::eliminate_dead_code_advanced(void)
>          iter.remove();
>          delete inst;
>          removed++;
> -      } else
> +      } else {
>          inst->dst.writemask &= ~(inst->dead_mask);
> +         if (inst->dst.writemask == 0) {
> +            iter.remove();
> +            delete inst;
> +            removed++;
> +         }
> +      }
>    }
>
>    ralloc_free(write_level);
> --
> 1.7.3.4
>
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