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/*
* Copyright © 2015 Red Hat
*
* 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.
*
* Authors:
* Rob Clark <robclark@freedesktop.org>
*/
#include "nir.h"
#include "nir_builder.h"
#define MAX_COLORS 2 /* VARYING_SLOT_COL0/COL1 */
typedef struct {
nir_builder b;
nir_shader *shader;
struct {
nir_variable *front; /* COLn */
nir_variable *back; /* BFCn */
} colors[MAX_COLORS];
int colors_count;
} lower_2side_state;
/* Lowering pass for fragment shaders to emulated two-sided-color. For
* each COLOR input, a corresponding BCOLOR input is created, and bcsel
* instruction used to select front or back color based on FACE.
*/
static nir_variable *
create_input(nir_shader *shader, unsigned drvloc, gl_varying_slot slot)
{
nir_variable *var = rzalloc(shader, nir_variable);
var->data.driver_location = drvloc;
var->type = glsl_vec4_type();
var->data.mode = nir_var_shader_in;
var->name = ralloc_asprintf(var, "in_%d", drvloc);
var->data.index = 0;
var->data.location = slot;
exec_list_push_tail(&shader->inputs, &var->node);
shader->num_inputs++; /* TODO use type_size() */
return var;
}
static nir_ssa_def *
load_input(nir_builder *b, nir_variable *in)
{
nir_intrinsic_instr *load;
load = nir_intrinsic_instr_create(b->shader, nir_intrinsic_load_input);
load->num_components = 4;
nir_intrinsic_set_base(load, in->data.driver_location);
load->src[0] = nir_src_for_ssa(nir_imm_int(b, 0));
nir_ssa_dest_init(&load->instr, &load->dest, 4, 32, NULL);
nir_builder_instr_insert(b, &load->instr);
return &load->dest.ssa;
}
static int
setup_inputs(lower_2side_state *state)
{
int maxloc = -1;
/* find color inputs: */
nir_foreach_variable(var, &state->shader->inputs) {
int loc = var->data.driver_location;
/* keep track of last used driver-location.. we'll be
* appending BCLr after last existing input:
*/
maxloc = MAX2(maxloc, loc);
switch (var->data.location) {
case VARYING_SLOT_COL0:
case VARYING_SLOT_COL1:
assert(state->colors_count < ARRAY_SIZE(state->colors));
state->colors[state->colors_count].front = var;
state->colors_count++;
break;
}
}
/* if we don't have any color inputs, nothing to do: */
if (state->colors_count == 0)
return -1;
/* add required back-face color inputs: */
for (int i = 0; i < state->colors_count; i++) {
gl_varying_slot slot;
if (state->colors[i].front->data.location == VARYING_SLOT_COL0)
slot = VARYING_SLOT_BFC0;
else
slot = VARYING_SLOT_BFC1;
state->colors[i].back = create_input(state->shader, ++maxloc, slot);
}
return 0;
}
static bool
nir_lower_two_sided_color_block(nir_block *block,
lower_2side_state *state)
{
nir_builder *b = &state->b;
nir_foreach_instr_safe(instr, block) {
if (instr->type != nir_instr_type_intrinsic)
continue;
nir_intrinsic_instr *intr = nir_instr_as_intrinsic(instr);
if (intr->intrinsic != nir_intrinsic_load_input)
continue;
int idx;
for (idx = 0; idx < state->colors_count; idx++) {
unsigned drvloc =
state->colors[idx].front->data.driver_location;
if (nir_intrinsic_base(intr) == drvloc) {
assert(nir_src_as_const_value(intr->src[0]));
break;
}
}
if (idx == state->colors_count)
continue;
/* replace load_input(COLn) with
* bcsel(load_system_value(FACE), load_input(COLn), load_input(BFCn))
*/
b->cursor = nir_before_instr(&intr->instr);
nir_ssa_def *face = nir_load_front_face(b);
nir_ssa_def *front = load_input(b, state->colors[idx].front);
nir_ssa_def *back = load_input(b, state->colors[idx].back);
nir_ssa_def *color = nir_bcsel(b, face, front, back);
assert(intr->dest.is_ssa);
nir_ssa_def_rewrite_uses(&intr->dest.ssa, nir_src_for_ssa(color));
}
return true;
}
static void
nir_lower_two_sided_color_impl(nir_function_impl *impl,
lower_2side_state *state)
{
nir_builder *b = &state->b;
nir_builder_init(b, impl);
nir_foreach_block(block, impl) {
nir_lower_two_sided_color_block(block, state);
}
nir_metadata_preserve(impl, nir_metadata_block_index |
nir_metadata_dominance);
}
void
nir_lower_two_sided_color(nir_shader *shader)
{
lower_2side_state state = {
.shader = shader,
};
if (shader->stage != MESA_SHADER_FRAGMENT)
return;
if (setup_inputs(&state) != 0)
return;
nir_foreach_function(function, shader) {
if (function->impl)
nir_lower_two_sided_color_impl(function->impl, &state);
}
}
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