On Tue, Jun 5, 2018 at 10:38 AM, Philipp Zabel <p.za...@pengutronix.de> wrote:
> The temporary input/output register 0 is reserved for position in the
> fragment shader. Hardwire it to 0 and start other input/output variables
> at 1. The intrinsic input load and output store base corresponds to the
> temporary register number.
I didn't look at this very closely, but at RA time you can pre-color
(pre-assign) specific registers, see ra_set_node_reg().. not sure if
this would be a better approach. I do this for a few frag shader
registers, mostly because at the time I hadn't found the cmdstream
register/bitfield to configure it to something other than r0.x..
BR,
-R
>
> Signed-off-by: Philipp Zabel <p.za...@pengutronix.de>
> Signed-off-by: Michael Tretter <m.tret...@pengutronix.de>
> ---
> src/gallium/drivers/etnaviv/etnaviv_nir.c | 76 +++++++++++++++++++++++
> 1 file changed, 76 insertions(+)
>
> diff --git a/src/gallium/drivers/etnaviv/etnaviv_nir.c
> b/src/gallium/drivers/etnaviv/etnaviv_nir.c
> index 1ddfbb818922..3b29ea9a0e76 100644
> --- a/src/gallium/drivers/etnaviv/etnaviv_nir.c
> +++ b/src/gallium/drivers/etnaviv/etnaviv_nir.c
> @@ -81,6 +81,81 @@ etna_optimize_loop(nir_shader *s)
> } while (progress);
> }
>
> +/* The temporary PS input/output register 0 is reserved for the position */
> +static void
> +etna_hardwire_io_position(nir_shader *shader)
> +{
> + bool fixup_needed = false;
> + int pos_in = -1, pos_out = -1;
> + int max_in = 0, max_out = 0;
> +
> + if (shader->info.stage != MESA_SHADER_FRAGMENT)
> + return;
> +
> + nir_foreach_variable(var, &shader->inputs) {
> + if (var->data.location == VARYING_SLOT_POS) {
> + pos_in = var->data.driver_location;
> + } else {
> + max_in = MAX2(max_in, var->data.driver_location);
> + if (var->data.driver_location == 0)
> + fixup_needed = true;
> + }
> + }
> + nir_foreach_variable(var, &shader->outputs) {
> + if (var->data.location == FRAG_RESULT_DEPTH) {
> + pos_out = var->data.driver_location;
> + } else {
> + max_out = MAX2(max_out, var->data.driver_location);
> + if (var->data.driver_location == 0)
> + fixup_needed = true;
> + }
> + }
> +
> + fixup_needed |= (pos_in > 0) || (pos_out > 0);
> + if (!fixup_needed)
> + return;
> +
> + if (pos_in == -1)
> + pos_in = max_in + 1;
> + if (pos_out == -1)
> + pos_out = max_out + 1;
> +
> + nir_foreach_variable(var, &shader->inputs) {
> + if (var->data.location == VARYING_SLOT_POS)
> + var->data.driver_location = 0;
> + else if (var->data.driver_location < pos_in)
> + var->data.driver_location++;
> + }
> + nir_foreach_variable(var, &shader->outputs) {
> + if (var->data.location == FRAG_RESULT_DEPTH)
> + var->data.driver_location = 0;
> + else if (var->data.driver_location < pos_out)
> + var->data.driver_location++;
> + }
> +
> + nir_foreach_function(function, shader) {
> + nir_foreach_block(block, function->impl) {
> + nir_foreach_instr(instr, block) {
> + if (instr->type != nir_instr_type_intrinsic)
> + continue;
> + nir_intrinsic_instr *intr = nir_instr_as_intrinsic(instr);
> + unsigned pos;
> + if (intr->intrinsic == nir_intrinsic_load_input)
> + pos = pos_in;
> + else if (intr->intrinsic == nir_intrinsic_store_output)
> + pos = pos_out;
> + else
> + continue;
> + unsigned base = nir_intrinsic_base(intr);
> + if (base <= pos)
> + nir_intrinsic_set_base(intr, (base == pos) ? 0 : (base + 1));
> + }
> + }
> + nir_metadata_preserve(function->impl,
> + nir_metadata_block_index |
> nir_metadata_dominance);
> + }
> +}
> +
> /* Move const loads, input load intrinsics, and uniform load intrinsics to
> the
> * beginning of the function implementation.
> *
> @@ -545,6 +620,7 @@ etna_optimize_nir(struct etna_shader *shader,
> NIR_PASS_V(s, nir_opt_global_to_local);
> NIR_PASS_V(s, nir_lower_regs_to_ssa);
> NIR_PASS_V(s, etna_move_load_intrinsics);
> + NIR_PASS_V(s, etna_hardwire_io_position);
>
> etna_optimize_loop(s);
>
> --
> 2.17.1
>
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