[Mesa-dev] [PATCH 4/5] glsl: Fix conversions in array constructors

[Kenneth Graunke]

On 07/27/2011 10:55 PM, Chad Versace wrote:
> Array constructors obey narrower conversion rules than other constructors
> [1] --- they use the implicit conversion rules [2] instead of the scalar
> constructor conversions [3].  But process_array_constructor() was
> incorrectly applying the broader rules.
> 
> To fix this, first check (with glsl_type::can_be_implicitly_converted_to)
> if an implicit conversion is legal before performing the conversion.
> 
> [1] GLSL 1.50 spec, Section 5.4.4 Array Constructors, page 52 (58 of pdf)
> [2] GLSL 1.50 spec, Section 4.1.10 Implicit Conversions, page 25 (31 of pdf)
> [3] GLSL 1.50 spec, Section 5.4.1 Conversion, page 48 (54 of pdf)
> 
> Fixes Piglit tests:
>     spec/glsl-1.20/compiler/structure-and-array-operations/array-ctor-implicit-conversion-bool-float.vert
>     spec/glsl-1.20/compiler/structure-and-array-operations/array-ctor-implicit-conversion-bvec*-vec*.vert
> 
> Note: This is a candidate for the 7.10 and 7.11 branches.
> CC: Ian Romanick <ian.d.romanick at intel.com>
> CC: Kenneth Graunke <kenneth at whitecape.org>
> Signed-off-by: Chad Versace <chad at chad-versace.us>
> ---
>  src/glsl/ast_function.cpp |   12 ++++++++++--
>  1 files changed, 10 insertions(+), 2 deletions(-)
> 
> diff --git a/src/glsl/ast_function.cpp b/src/glsl/ast_function.cpp
> index bdb73f4..9bee3eb 100644
> --- a/src/glsl/ast_function.cpp
> +++ b/src/glsl/ast_function.cpp
> @@ -442,13 +442,21 @@ process_array_constructor(exec_list *instructions,
>        ir_rvalue *ir = (ir_rvalue *) n;
>        ir_rvalue *result = ir;
>  
> -      /* Apply implicit conversions (not the scalar constructor rules!) */
> +      /* Apply implicit conversions (not the scalar constructor rules!). See
> +       * the spec quote above. */
>        if (constructor_type->element_type()->is_float()) {
>  	 const glsl_type *desired_type =
>  	    glsl_type::get_instance(GLSL_TYPE_FLOAT,
>  				    ir->type->vector_elements,
>  				    ir->type->matrix_columns);
> -	 result = convert_component(ir, desired_type);
> +	 if (result->type->can_implicitly_convert_to(desired_type)) {
> +	    /* Even though convert_component() implements the scalar
> +	     * conversion rules, not the implicit conversion rules, its safe

* constructor rules (not the implicit conversion rules), it's safe

> +	     * to use it here because we already checked that the implicit
> +	     * conversion is legal.
> +	     */
> +	    result = convert_component(ir, desired_type);
> +	 }
>        }
>  
>        if (result->type != constructor_type->element_type()) {

Otherwise...
Reviewed-by: Kenneth Graunke <kenneth at whitecape.org>