[Mesa-dev] [PATCH 1/2] i965/gs: Add dummy source to prepare_channel_masks instruction.

[Kenneth Graunke]

On 04/04/2014 03:28 PM, Matt Turner wrote:
> The generator uses its destination as a source implicitly, which breaks
> some assumptions in dead code elimination. Giving the instruction a
> source allows us to reason about it better.
> ---
>  src/mesa/drivers/dri/i965/brw_vec4_gs_visitor.cpp | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/src/mesa/drivers/dri/i965/brw_vec4_gs_visitor.cpp b/src/mesa/drivers/dri/i965/brw_vec4_gs_visitor.cpp
> index 13d6d38..1321a94 100644
> --- a/src/mesa/drivers/dri/i965/brw_vec4_gs_visitor.cpp
> +++ b/src/mesa/drivers/dri/i965/brw_vec4_gs_visitor.cpp
> @@ -408,7 +408,8 @@ vec4_gs_visitor::emit_control_data_bits()
>           src_reg channel_mask(this, glsl_type::uint_type);
>           inst = emit(SHL(dst_reg(channel_mask), one, channel));
>           inst->force_writemask_all = true;
> -         emit(GS_OPCODE_PREPARE_CHANNEL_MASKS, dst_reg(channel_mask));
> +         emit(GS_OPCODE_PREPARE_CHANNEL_MASKS, dst_reg(channel_mask),
> +                                               channel_mask);
>           emit(GS_OPCODE_SET_CHANNEL_MASKS, mrf_reg, channel_mask);
>        }
>  
> 

This seems reasonable, though I'd like to see generator changes to
match.  Either use the source register, or at least:

   assert(src[0] == dst);

in both generators.

-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 836 bytes
Desc: OpenPGP digital signature
URL: <http://lists.freedesktop.org/archives/mesa-dev/attachments/20140405/32db9460/attachment.sig>