On Sun, 03 Jun 2012 18:12:05 -0400, Matt Turner <matts...@gmail.com> wrote:
> On Sun, 2012-06-03 at 14:30 -0700, Kenneth Graunke wrote:
> > On 06/03/2012 10:15 AM, Matt Turner wrote:
> > > It seems that we already do this.
> > > ---
> > > src/glsl/TODO | 3 ---
> > > 1 files changed, 0 insertions(+), 3 deletions(-)
> > >
> > > diff --git a/src/glsl/TODO b/src/glsl/TODO
> > > index eb73fc2..bd077a8 100644
> > > --- a/src/glsl/TODO
> > > +++ b/src/glsl/TODO
> > > @@ -6,9 +6,6 @@
> > > constant index values. For others it is more complicated. Perhaps
> > > these
> > > cases should be silently converted to uniforms?
> > >
> > > -- Implement support for ir_binop_dot in opt_algebraic.cpp. Perform
> > > - transformations such as "dot(v, vec3(0.0, 1.0, 0.0))" -> v.y.
> > > -
> > > - Track source locations throughout the IR. There are currently several
> > > places where we cannot emit line numbers for errors (and currently
> > > emit 0:0)
> > > because we've "lost" the line number information. This is particularly
> >
> > We do? Considering there's no instance of ir_binop_dot in
> > opt_algebraic.cpp, I'm a bit skeptical :)
>
> I could of course be mistaken, but consider the following fragment
> shader:
>
> varying vec3 light;
> void main() {
> const vec4 DiffuseColor = vec4(0.9, 0.9, 0.9, 1.0);
> float DiffuseTerm = dot(vec3(0.0, 1.0, 0.0), light);
> gl_FragColor = DiffuseColor * DiffuseTerm;
> }
>
> From this, we generate this GLSL IR:
>
> (
> (declare (temporary ) float light_y)
> (declare (out ) vec4 gl_FragColor)
> (function main
> (signature void
> (parameters
> )
> (
> (assign (x) (var_ref gl_FragColor) (expression float * (constant
> float (0.900000)) (var_ref light_y) ) )
> (assign (y) (var_ref gl_FragColor) (expression float * (constant
> float (0.900000)) (var_ref light_y) ) )
> (assign (z) (var_ref gl_FragColor) (expression float * (constant
> float (0.900000)) (var_ref light_y) ) )
> (assign (w) (var_ref gl_FragColor) (var_ref light_y) )
> ))
>
> )
> )
>
> I don't claim to understand how (obviously there's no ir_binop_dot in
> opt_algebraic.cpp, so) but it looks like we're already getting the
> result of the TODO.
>
> The other part that I thought opt_algebraic.cpp's ir_binop_dot case
> should handle was zero vectors, but they're already handled as well. I
> presume because dot is lowered into mul/madd which already handle zero
> vectors.
>
> Does this sound right, or did I miss some piece?The i965 fragment shader breaks everything down to scalar operations, at which point the dot to swizzle thing falls out. The TODO I think meant doing it in the general vec4 IR case.
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