[Mesa-dev] [PATCH 07/23] ir_to_mesa: Add support for ir_triop_csel

[Juha-Pekka Heikkila]

Took a moment to understand how this works but I think it does.

Reviewed-by: Juha-Pekka Heikkila <juhapekka.heikkila at gmail.com>

/Juha-Pekka

On 20.03.2015 22:58, Ian Romanick wrote:
> From: Ian Romanick <ian.d.romanick at intel.com>
> 
> The only drivers that use this path are i915 and swrast.  Both of these
> support the CMP opcode.  This is untested, but it is similar to existing
> code in st_glsl_to_tgsi.cpp.
> 
> Without this change, a later commits "glsl: Distribute multiply over
> b2f" and "glsl: Optimize certain if-statements to ir_triop_csel" will
> cause assertion failures in ir_to_mesa.
> 
> Signed-off-by: Ian Romanick <ian.d.romanick at intel.com>
> Cc: Juha-Pekka Heikkila <juhapekka.heikkila at gmail.com>
> ---
>  src/mesa/program/ir_to_mesa.cpp | 9 ++++++++-
>  1 file changed, 8 insertions(+), 1 deletion(-)
> 
> diff --git a/src/mesa/program/ir_to_mesa.cpp b/src/mesa/program/ir_to_mesa.cpp
> index 39790ec..b7acbfa 100644
> --- a/src/mesa/program/ir_to_mesa.cpp
> +++ b/src/mesa/program/ir_to_mesa.cpp
> @@ -1426,6 +1426,14 @@ ir_to_mesa_visitor::visit(ir_expression *ir)
>        emit(ir, OPCODE_LRP, result_dst, op[2], op[1], op[0]);
>        break;
>  
> +   case ir_triop_csel:
> +      /* We assume that Boolean true and false are 1.0 and 0.0.  OPCODE_CMP
> +       * selects src1 if src0 is < 0, src2 otherwise.
> +       */
> +      op[0].negate = ~op[0].negate;
> +      emit(ir, OPCODE_CMP, result_dst, op[0], op[1], op[2]);
> +      break;
> +
>     case ir_binop_vector_extract:
>     case ir_binop_bfm:
>     case ir_triop_fma:
> @@ -1434,7 +1442,6 @@ ir_to_mesa_visitor::visit(ir_expression *ir)
>     case ir_triop_vector_insert:
>     case ir_quadop_bitfield_insert:
>     case ir_binop_ldexp:
> -   case ir_triop_csel:
>     case ir_binop_carry:
>     case ir_binop_borrow:
>     case ir_binop_imul_high:
>