[Mesa-dev] GLSL builtins constant constructor
Paul Berry
stereotype441 at gmail.com
Sun Sep 4 15:03:34 PDT 2011
On 4 September 2011 14:49, Ian Romanick <idr at freedesktop.org> wrote:
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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.
>
Yes, I did try it, and it worked just fine. Furthermore, the code in
ir_validate.cpp seems to indicate that multiplying a scalar by a vector is
allowed in GLSL IR:
case ir_binop_add:
case ir_binop_sub:
case ir_binop_mul:
case ir_binop_div:
case ir_binop_mod:
case ir_binop_min:
case ir_binop_max:
case ir_binop_pow:
if (ir->operands[0]->type->is_scalar())
assert(ir->operands[1]->type == ir->type);
else if (ir->operands[1]->type->is_scalar())
assert(ir->operands[0]->type == ir->type);
else if (ir->operands[0]->type->is_vector() &&
ir->operands[1]->type->is_vector()) {
assert(ir->operands[0]->type == ir->operands[1]->type);
assert(ir->operands[0]->type == ir->type);
}
break;
Also, as I noted in my previous email, this is what we do in several other
built-in functions, such as asin:
(signature vec2
(parameters
(declare (in) vec2 x))
((return (expression vec2 *
(expression vec2 sign (var_ref x))
(expression vec2 -
(constant float (1.5707964))
(expression vec2 *
(expression vec2 sqrt
(expression vec2 -
(constant float (1.0))
(expression vec2 abs (var_ref x))))
(expression vec2 +
(constant float (1.5707964))
(expression vec2 *
(expression vec2 abs (var_ref x))
(expression vec2 +
(constant float (-0.21460183))
(expression vec2 *
(expression vec2 abs (var_ref x))
(expression vec2 +
(constant float (0.086566724))
(expression vec2 *
(expression vec2 abs (var_ref x))
(constant float (-0.03102955))
))))))))))))
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