[Mesa-dev] [PATCH] ff_fragment_shader: Don't generate swizzles for scalar combiner inputs

[Eric Anholt]

On Mon, 02 Jan 2012 19:36:25 -0800, Ian Romanick <idr at freedesktop.org> wrote:
> On 12/23/2011 10:35 PM, Eric Anholt wrote:
> > On Thu, 22 Dec 2011 17:43:57 -0800, "Ian Romanick"<idr at freedesktop.org>  wrote:
> >> From: Ian Romanick<ian.d.romanick at intel.com>
> >>
> >> There are a couple scenarios where the source could be zero and the
> >> operand could be either SRC_ALPHA or ONE_MINUS_SRC_ALPHA.  For
> >> example, if the source was ZERO.  This would result in something like
> >> (0).w, and a later call to ir_validate would get angry.
> >>
> >> Signed-off-by: Ian Romanick<ian.d.romanick at intel.com>
> >> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=42517
> >
> > In other cases of handling this in the code, I was using the little
> > smear() helper function.  I'd tend towards using that here as well, but
> > no strong feeling.
> 
> smear replicates the X component to all four components of a vec4.
> 
> This code either extracts the W component from a vec4 and returns it as 
> a scalar, or it returns the scalar unmodified.
> 
> Do you think there should be a new helper function for this case?

Looks like I fail at reviewing on both counts.  Go ahead with your patch.
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