mesa/src/compiler/nir/nir_lower_sysvals_to_varyings.c
Faith Ekstrand 82280a7e86 nir: Support sysval intrinsics in lower_sysvals_to_varyings()
Since this is a downgrade path for drivers, it's useful to support both
forms of these common sysvals.

Reviewed-by: Alyssa Rosenzweig <alyssa.rosenzweig@intel.com>
Reviewed-by: Emma Anholt <emma@anholt.net>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/38562>
2025-11-29 00:50:32 +00:00

115 lines
4.1 KiB
C

/*
* Copyright © 2021 Collabora Ltd.
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice (including the next
* paragraph) shall be included in all copies or substantial portions of the
* Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
* IN THE SOFTWARE.
*/
#include "nir.h"
#include "nir_builder.h"
/*
* spirv_to_nir() creates system values for some builtin inputs, but
* backends might want to have those inputs exposed as varyings. This
* lowering pass allows backends to convert system values to input
* varyings and should be called just after spirv_to_nir() when needed.
*/
static bool
lower_sysvals_intrin(nir_builder *b, nir_intrinsic_instr *intrin, void * data)
{
const struct nir_lower_sysvals_to_varyings_options *options = data;
gl_varying_slot slot;
const struct glsl_type *type;
switch (intrin->intrinsic) {
#define SYSVAL_TO_VARYING(sysval, varying, typ) \
case nir_intrinsic_load_##sysval: \
if (!options->sysval) \
return false; \
slot = VARYING_SLOT_##varying; \
type = glsl_##typ##_type(); \
break;
SYSVAL_TO_VARYING(frag_coord, POS, vec4);
SYSVAL_TO_VARYING(point_coord, PNTC, vec2);
SYSVAL_TO_VARYING(front_face, FACE, bool);
SYSVAL_TO_VARYING(layer_id, LAYER, uint);
SYSVAL_TO_VARYING(view_index, VIEW_INDEX, uint);
#undef SYSVAL_TO_VARYING
default:
return false;
}
nir_variable *var =
nir_get_variable_with_location(b->shader, nir_var_shader_in,
slot, type);
if (b->shader->info.stage == MESA_SHADER_FRAGMENT &&
glsl_type_is_integer(type))
var->data.interpolation = INTERP_MODE_FLAT;
b->cursor = nir_before_instr(&intrin->instr);
nir_def *val = nir_load_var(b, var);
nir_def_replace(&intrin->def, val);
return true;
}
bool
nir_lower_sysvals_to_varyings(nir_shader *shader,
const struct nir_lower_sysvals_to_varyings_options *options)
{
bool progress = false;
nir_foreach_variable_with_modes(var, shader, nir_var_system_value) {
switch (var->data.location) {
#define SYSVAL_TO_VARYING(opt, sysval, varying) \
case SYSTEM_VALUE_##sysval: \
if (options->opt) { \
var->data.mode = nir_var_shader_in; \
var->data.location = VARYING_SLOT_##varying; \
progress = true; \
} \
break
SYSVAL_TO_VARYING(frag_coord, FRAG_COORD, POS);
SYSVAL_TO_VARYING(point_coord, POINT_COORD, PNTC);
SYSVAL_TO_VARYING(front_face, FRONT_FACE, FACE);
SYSVAL_TO_VARYING(layer_id, LAYER_ID, LAYER);
SYSVAL_TO_VARYING(view_index, VIEW_INDEX, VIEW_INDEX);
#undef SYSVAL_TO_VARYING
default:
break;
}
}
if (progress)
nir_fixup_deref_modes(shader);
progress |= nir_shader_intrinsics_pass(shader, lower_sysvals_intrin,
nir_metadata_control_flow |
nir_metadata_loop_analysis,
(void *)options);
return progress;
}