On Thursday, April 28, 2016 3:21:43 PM PDT Ian Romanick wrote: > On 04/28/2016 01:40 PM, Antia Puentes wrote: > > From: Alejandro Piñeiro <apinhe...@igalia.com> > > > > The HW has a restriction that only vertical stride may cross register > > boundaries. Until now this was only handled on VGRFs at > > rw_reg_from_fs_reg, but it is also needed for attributes. > > > > This can be seen as the equivalent of commit 552cfa9 but for > > attributes. Take a look to the git message on that commit for further > > info. > > --- > > src/mesa/drivers/dri/i965/brw_fs.cpp | 23 +++++++++++++++++++++-- > > 1 file changed, 21 insertions(+), 2 deletions(-) > > > > diff --git a/src/mesa/drivers/dri/i965/brw_fs.cpp b/src/mesa/drivers/dri/ i965/brw_fs.cpp > > index ce84d0a..98cbf9f 100644 > > --- a/src/mesa/drivers/dri/i965/brw_fs.cpp > > +++ b/src/mesa/drivers/dri/i965/brw_fs.cpp > > @@ -1844,11 +1844,30 @@ fs_visitor::convert_attr_sources_to_hw_regs(fs_inst *inst) > > inst->src[i].nr + > > inst->src[i].reg_offset; > > > > - unsigned width = inst->src[i].stride == 0 ? 1 : inst->exec_size; > > + unsigned exec_size; > > Blank line here. > > > + /* As explained at brw_reg_from_fs_reg, From the Haswell PRM: > > + * > > + * VertStride must be used to cross GRF register boundaries. This > > + * rule implies that elements within a 'Width' cannot cross GRF > > + * boundaries. > > + * > > + * So, for registers that are large enough, we have to split the exec > > + * size in two and trust the compression state to sort it out. > > + */ > > + unsigned total_size = inst->exec_size * > > + inst->src[i].stride * > > + type_sz(inst->src[i].type); > > const unsigned total_size = ... ; > > I think the code below is better as > > assert(total_size <= 64); > > const unsigned exec_size = (total_size <= 32) ? inst->exec_size : inst->exec_size / 2; > > I'll defer to one of the people who work more in the back end. >
I like Ian's suggestion. It might also be reasonable to use REG_SIZE:
assert(total_size <= 2 * REG_SIZE);
const unsigned exec_size =
(total_size <= REG_SIZE) ? inst->exec_size : inst->exec_size / 2;
Either way,
Reviewed-by: Kenneth Graunke <kenn...@whitecape.org>
> > + if (total_size <= 32) {
> > + exec_size = inst->exec_size;
> > + } else {
> > + assert(total_size / 2 <= 32);
> > + exec_size = inst->exec_size / 2;
> > + }
> > + unsigned width = inst->src[i].stride == 0 ? 1 : exec_size;
> > struct brw_reg reg =
> > stride(byte_offset(retype(brw_vec8_grf(grf, 0), inst-
>src[i].type),
> > inst->src[i].subreg_offset),
> > - inst->exec_size * inst->src[i].stride,
> > + exec_size * inst->src[i].stride,
> > width, inst->src[i].stride);
> > reg.abs = inst->src[i].abs;
> > reg.negate = inst->src[i].negate;
> >
>
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