[Mesa-dev] [PATCH 4/4] glsl: Generated masked write instead of vector array index for UBO lowering

[Kenneth Graunke]

On 03/27/2013 09:30 AM, Ian Romanick wrote:
> From: Ian Romanick <ian.d.romanick at intel.com>
>
> When reading a column from a row-major matrix, we would slot the single
> value read into the vector using an ir_dereference_array of the vector
> with a constant index.  This will (eventually) get optimized to a
> masked-write, so just generate the masked write in the first place.
>
> Signed-off-by: Ian Romanick <ian.d.romanick at intel.com>
> Cc: Eric Anholt <eric at anholt.net>
> ---
>   src/glsl/lower_ubo_reference.cpp | 9 +++------
>   1 file changed, 3 insertions(+), 6 deletions(-)
>
> diff --git a/src/glsl/lower_ubo_reference.cpp b/src/glsl/lower_ubo_reference.cpp
> index 026197d..9e5e951 100644
> --- a/src/glsl/lower_ubo_reference.cpp
> +++ b/src/glsl/lower_ubo_reference.cpp
> @@ -357,17 +357,14 @@ lower_ubo_reference_visitor::emit_ubo_loads(ir_dereference *deref,
>
>         for (unsigned i = 0; i < deref->type->vector_elements; i++) {
>   	 ir_rvalue *chan = new(mem_ctx) ir_constant((int)i);

lower_ubo_reference.cpp:359:14: warning: unused variable 'chan' 
[-Wunused-variable]

You should delete this too.  Otherwise,

For the series:
Reviewed-by: Kenneth Graunke <kenneth at whitecape.org>

> -	 ir_dereference *deref_chan =
> -	    new(mem_ctx) ir_dereference_array(deref->clone(mem_ctx, NULL),
> -					      chan);
> -
>   	 ir_rvalue *chan_offset =
>   	    add(base_offset,
>   		new(mem_ctx) ir_constant(deref_offset + i * matrix_stride));
>
> -	 base_ir->insert_before(assign(deref_chan,
> +	 base_ir->insert_before(assign(deref->clone(mem_ctx, NULL),
>   				       ubo_load(glsl_type::float_type,
> -						chan_offset)));
> +						chan_offset),
> +				       (1U << i)));
>         }
>      }
>   }
>