[Mesa-dev] [PATCH 27/59] i965/fs: add a stride helper

[Iago Toral]

On Mon, 2016-05-02 at 10:30 +0300, Pohjolainen, Topi wrote:
> On Fri, Apr 29, 2016 at 01:29:24PM +0200, Samuel Iglesias Gons?lvez wrote:
> > From: Connor Abbott <connor.w.abbott at intel.com>
> > 
> > Similar to retype() and offset().
> > ---
> >  src/mesa/drivers/dri/i965/brw_ir_fs.h | 8 ++++++++
> >  1 file changed, 8 insertions(+)
> > 
> > diff --git a/src/mesa/drivers/dri/i965/brw_ir_fs.h b/src/mesa/drivers/dri/i965/brw_ir_fs.h
> > index e4f20f4..abda2c3 100644
> > --- a/src/mesa/drivers/dri/i965/brw_ir_fs.h
> > +++ b/src/mesa/drivers/dri/i965/brw_ir_fs.h
> > @@ -78,6 +78,14 @@ retype(fs_reg reg, enum brw_reg_type type)
> >  }
> >  
> >  static inline fs_reg
> > +stride(fs_reg reg, unsigned stride)
> > +{
> > +   if (reg.stride != 0)
> > +      reg.stride = stride;
> 
> Do we have cases where we should silently ignore the given stride? Stride
> zero is reserved for uniforms and immediates, right? Or should we have:

If the register is a uniform the stride operation is a no-op and we
should just ignore it. I am not sure right now if we can end up here
with a uniform/immediate but I think that might be possible for example
when copy-propagating from a uniform register, and in that case, this
does exactly what we want it to do.

>       /* Cannot change stride for uniforms or immediates (stride zero). */
>       assert(reg.stride);
>       reg.stride = stride;
> 
> > +   return reg;
> > +}
> > +
> > +static inline fs_reg
> >  byte_offset(fs_reg reg, unsigned delta)
> >  {
> >     switch (reg.file) {
> > -- 
> > 2.5.0
> > 
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