On Mon, 2016-05-02 at 15:11 -0400, Connor Abbott wrote:
> On Fri, Apr 29, 2016 at 7:29 AM, Samuel Iglesias Gonsálvez
> <sigles...@igalia.com> wrote:
> > From: Iago Toral Quiroga <ito...@igalia.com>
> >
> > When we are actually creating a double using values obtained from a
> > previous unpack operation we can bypass the unpack and source from
> > the original double value directly.
> > ---
> > src/mesa/drivers/dri/i965/brw_fs_nir.cpp | 23 +++++++++++++++++++++++
> > 1 file changed, 23 insertions(+)
> >
> > diff --git a/src/mesa/drivers/dri/i965/brw_fs_nir.cpp
> > b/src/mesa/drivers/dri/i965/brw_fs_nir.cpp
> > index ca1f24f..4332575 100644
> > --- a/src/mesa/drivers/dri/i965/brw_fs_nir.cpp
> > +++ b/src/mesa/drivers/dri/i965/brw_fs_nir.cpp
> > @@ -1091,6 +1091,29 @@ fs_visitor::nir_emit_alu(const fs_builder &bld,
> > nir_alu_instr *instr)
> > break;
> >
> > case nir_op_pack_double_2x32_split:
> > + /* Optimize the common case where we are re-packing a double with
> > + * the result of a previous double unpack. In this case we can take
> > the
> > + * 32-bit value to use in the re-pack from the original double and
> > bypass
> > + * the unpack operation.
> > + */
> > + for (int i = 0; i < 2; i++) {
> > + if (instr->src[i].src.is_ssa) {
> > + nir_instr *parent_instr = instr->src[i].src.ssa->parent_instr;
> > + if (parent_instr->type == nir_instr_type_alu) {
> > + nir_alu_instr *alu_parent = nir_instr_as_alu(parent_instr);
> > + if (alu_parent->op == nir_op_unpack_double_2x32_split_x ||
> > + alu_parent->op == nir_op_unpack_double_2x32_split_y) {
> > + op[i] = get_nir_src(alu_parent->src[0].src);
>
> The source could be a register here (say, if it was part of a phi web
> that got collapsed) in which case we should bail since something else
> might've overwritten it in the meantime. Implementing Topi's
> suggestion to use early exits instead will prevent this from getting
> even more unwieldy when fixing this up.
Oh right, good catch! I'll fix that and implement's Topi's changes too.
Thanks!
> > + op[i] = offset(retype(op[i], BRW_REGISTER_TYPE_DF), bld,
> > + alu_parent->src[0].swizzle[channel]);
> > + op[i] = retype(op[i], BRW_REGISTER_TYPE_UD);
> > + if (alu_parent->op == nir_op_unpack_double_2x32_split_y)
> > + op[i] = horiz_offset(op[i], 1);
> > + op[i] = stride(op[i], 2);
> > + }
> > + }
> > + }
> > + }
> > bld.emit(FS_OPCODE_PACK, result, op[0], op[1]);
> > break;
> >
> > --
> > 2.5.0
> >
> > _______________________________________________
> > mesa-dev mailing list
> > mesa-dev@lists.freedesktop.org
> > https://lists.freedesktop.org/mailman/listinfo/mesa-dev
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