On Wed, Aug 12, 2015 at 1:58 PM, Matt Turner <matts...@gmail.com> wrote:
> If an immediate is written to multiple channels, we can load it in a
> single writemasked MOV.
>
> total instructions in shared programs: 6285144 -> 6261991 (-0.37%)
> instructions in affected programs: 718991 -> 695838 (-3.22%)
> helped: 5762
Nice catch!
Reviewed-by: Jason Ekstrand <jason.ekstr...@intel.com>
> ---
> The shader-db numbers are from a tree with the scalar_vs fixup.
>
> src/mesa/drivers/dri/i965/brw_vec4_nir.cpp | 21 ++++++++++++++++++---
> 1 file changed, 18 insertions(+), 3 deletions(-)
>
> diff --git a/src/mesa/drivers/dri/i965/brw_vec4_nir.cpp
> b/src/mesa/drivers/dri/i965/brw_vec4_nir.cpp
> index 923e2d3..632e409 100644
> --- a/src/mesa/drivers/dri/i965/brw_vec4_nir.cpp
> +++ b/src/mesa/drivers/dri/i965/brw_vec4_nir.cpp
> @@ -458,13 +458,28 @@ vec4_visitor::nir_emit_load_const(nir_load_const_instr
> *instr)
> dst_reg reg = dst_reg(GRF, alloc.allocate(1));
> reg.type = BRW_REGISTER_TYPE_F;
>
> + unsigned remaining = brw_writemask_for_size(instr->def.num_components);
> +
> /* @FIXME: consider emitting vector operations to save some MOVs in
> * cases where the components are representable in 8 bits.
> - * By now, we emit a MOV for each component.
> + * For now, we emit a MOV for each distinct value.
> */
> - for (unsigned i = 0; i < instr->def.num_components; ++i) {
> - reg.writemask = 1 << i;
> + for (unsigned i = 0; i < instr->def.num_components; i++) {
> + unsigned writemask = 1 << i;
> +
> + if ((remaining & writemask) == 0)
> + continue;
> +
> + for (unsigned j = i; j < instr->def.num_components; j++) {
> + if (instr->value.u[i] == instr->value.u[j]) {
> + writemask |= 1 << j;
> + }
> + }
> +
> + reg.writemask = writemask;
> emit(MOV(reg, src_reg(instr->value.f[i])));
> +
> + remaining &= ~writemask;
> }
>
> /* Set final writemask */
> --
> 2.4.6
>
> _______________________________________________
> mesa-dev mailing list
> mesa-dev@lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/mesa-dev
_______________________________________________
mesa-dev mailing list
mesa-dev@lists.freedesktop.org
http://lists.freedesktop.org/mailman/listinfo/mesa-dev
