[Mesa-dev] GLSL builtins constant constructor

[Ian Romanick]

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On 09/04/2011 08:35 AM, Paul Berry wrote:
> On 4 September 2011 06:20, Christoph Bumiller
> <e0425955 at student.tuwien.ac.at <mailto:e0425955 at student.tuwien.ac.at>>
> wrote:
> 
>     I encountered some failures in piglit's tests of builtins because a
>     vector constructor that is given only 1 single argument does not
>     replicate the argument into the yzw components, for example:
> 
>     diff --git a/src/glsl/builtins/ir/cosh b/src/glsl/builtins/ir/cosh
>     index 45e0ae4..8bf3ad2 100644
>     --- a/src/glsl/builtins/ir/cosh
>     +++ b/src/glsl/builtins/ir/cosh
>     @@ -9,21 +9,21 @@
>        (signature vec2
>          (parameters
>            (declare (in) vec2 x))
>     -     ((return (expression vec2 * (constant vec2 (0.5))
>     +     ((return (expression vec2 * (constant vec2 (0.5, 0.5))
>                     (expression vec2 +
>                      (expression vec2 exp (var_ref x))
>                      (expression vec2 exp (expression vec2 neg (var_ref
>     x))))))))
>        (signature vec3
>          (parameters
>            (declare (in) vec3 x))
> 
>     Should the constructors or should all the builtin files be fixed ?
> 
> 
> Thanks for noticing this, Christoph.  I wrote the tests for hyperbolic
> trig functions a few weeks ago, and I've been waiting for some i965
> churn to settle down before looping back to fix the bugs.
> 
> Personally, I'd prefer to fix this bug by making the constant a scalar,
> like this:

I don't recall for sure, but, while that is valid GLSL, I don't think
that's valid in the IR.  Did you try it?  I think you may have to wrap
it in a swizzle, at which point it's probably better to use the correct
vec# constructor.

> diff --git a/src/glsl/builtins/ir/cosh b/src/glsl/builtins/ir/cosh
> index 45e0ae4..9457431 100644
> --- a/src/glsl/builtins/ir/cosh
> +++ b/src/glsl/builtins/ir/cosh
> @@ -9,21 +9,21 @@
>     (signature vec2
>       (parameters
>         (declare (in) vec2 x))
> -     ((return (expression vec2 * (constant vec2 (0.5))
> +     ((return (expression vec2 * (constant float (0.5))
>                  (expression vec2 +
>                   (expression vec2 exp (var_ref x))
>                   (expression vec2 exp (expression vec2 neg (var_ref
> x))))))))
>     (signature vec3
>       (parameters
>         (declare (in) vec3 x))
> 
> That would be consistent with what we do in other builtin functions that
> require constants (e.g. see "asin").
> 
> 
> 
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