/*
* Copyright © 2015 Broadcom
*
* 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.
*/
/**
* Implements most of the fixed function fragment pipeline in shader code.
*
* VC4 doesn't have any hardware support for blending, alpha test, logic ops,
* or color mask. Instead, you read the current contents of the destination
* from the tile buffer after having waited for the scoreboard (which is
* handled by vc4_qpu_emit.c), then do math using your output color and that
* destination value, and update the output color appropriately.
*
* Once this pass is done, the color write will either have one component (for
* single sample) with packed argb8888, or 4 components with the per-sample
* argb8888 result.
*/
/**
* Lowers fixed-function blending to a load of the destination color and a
* series of ALU operations before the store of the output.
*/
#include "util/u_format.h"
#include "vc4_qir.h"
#include "compiler/nir/nir_builder.h"
#include "vc4_context.h"
static bool
blend_depends_on_dst_color(struct vc4_compile *c)
{
return (c->fs_key->blend.blend_enable ||
c->fs_key->blend.colormask != 0xf ||
c->fs_key->logicop_func != PIPE_LOGICOP_COPY);
}
/** Emits a load of the previous fragment color from the tile buffer. */
static nir_ssa_def *
vc4_nir_get_dst_color(nir_builder *b, int sample)
{
nir_intrinsic_instr *load =
nir_intrinsic_instr_create(b->shader,
nir_intrinsic_load_input);
load->num_components = 1;
nir_intrinsic_set_base(load, VC4_NIR_TLB_COLOR_READ_INPUT + sample);
load->src[0] = nir_src_for_ssa(nir_imm_int(b, 0));
nir_ssa_dest_init(&load->instr, &load->dest, 1, 32, NULL);
nir_builder_instr_insert(b, &load->instr);
return &load->dest.ssa;
}
static nir_ssa_def *
vc4_nir_srgb_decode(nir_builder *b, nir_ssa_def *srgb)
{
nir_ssa_def *is_low = nir_flt(b, srgb, nir_imm_float(b, 0.04045));
nir_ssa_def *low = nir_fmul(b, srgb, nir_imm_float(b, 1.0 / 12.92));
nir_ssa_def *high = nir_fpow(b,
nir_fmul(b,
nir_fadd(b, srgb,
nir_imm_float(b, 0.055)),
nir_imm_float(b, 1.0 / 1.055)),
nir_imm_float(b, 2.4));
return nir_bcsel(b, is_low, low, high);
}
static nir_ssa_def *
vc4_nir_srgb_encode(nir_builder *b, nir_ssa_def *linear)
{
nir_ssa_def *is_low = nir_flt(b, linear, nir_imm_float(b, 0.0031308));
nir_ssa_def *low = nir_fmul(b, linear, nir_imm_float(b, 12.92));
nir_ssa_def *high = nir_fsub(b,
nir_fmul(b,
nir_imm_float(b, 1.055),
nir_fpow(b,
linear,
nir_imm_float(b, 0.41666))),
nir_imm_float(b, 0.055));
return nir_bcsel(b, is_low, low, high);
}
static nir_ssa_def *
vc4_blend_channel_f(nir_builder *b,
nir_ssa_def **src,
nir_ssa_def **dst,
unsigned factor,
int channel)
{
switch(factor) {
case PIPE_BLENDFACTOR_ONE:
return nir_imm_float(b, 1.0);
case PIPE_BLENDFACTOR_SRC_COLOR:
return src[channel];
case PIPE_BLENDFACTOR_SRC_ALPHA:
return src[3];
case PIPE_BLENDFACTOR_DST_ALPHA:
return dst[3];
case PIPE_BLENDFACTOR_DST_COLOR:
return dst[channel];
case PIPE_BLENDFACTOR_SRC_ALPHA_SATURATE:
if (channel != 3) {
return nir_fmin(b,
src[3],
nir_fsub(b,
nir_imm_float(b, 1.0),
dst[3]));
} else {
return nir_imm_float(b, 1.0);
}
case PIPE_BLENDFACTOR_CONST_COLOR:
return nir_load_system_value(b,
nir_intrinsic_load_blend_const_color_r_float +
channel,
0);
case PIPE_BLENDFACTOR_CONST_ALPHA:
return nir_load_blend_const_color_a_float(b);
case PIPE_BLENDFACTOR_ZERO:
return nir_imm_float(b, 0.0);
case PIPE_BLENDFACTOR_INV_SRC_COLOR:
return nir_fsub(b, nir_imm_float(b, 1.0), src[channel]);
case PIPE_BLENDFACTOR_INV_SRC_ALPHA:
return nir_fsub(b, nir_imm_float(b, 1.0), src[3]);
case PIPE_BLENDFACTOR_INV_DST_ALPHA:
return nir_fsub(b, nir_imm_float(b, 1.0), dst[3]);
case PIPE_BLENDFACTOR_INV_DST_COLOR:
return nir_fsub(b, nir_imm_float(b, 1.0), dst[channel]);
case PIPE_BLENDFACTOR_INV_CONST_COLOR:
return nir_fsub(b, nir_imm_float(b, 1.0),
nir_load_system_value(b,
nir_intrinsic_load_blend_const_color_r_float +
channel,
0));
case PIPE_BLENDFACTOR_INV_CONST_ALPHA:
return nir_fsub(b, nir_imm_float(b, 1.0),
nir_load_blend_const_color_a_float(b));
default:
case PIPE_BLENDFACTOR_SRC1_COLOR:
case PIPE_BLENDFACTOR_SRC1_ALPHA:
case PIPE_BLENDFACTOR_INV_SRC1_COLOR:
case PIPE_BLENDFACTOR_INV_SRC1_ALPHA:
/* Unsupported. */
fprintf(stderr, "Unknown blend factor %d\n", factor);
return nir_imm_float(b, 1.0);
}
}
static nir_ssa_def *
vc4_nir_set_packed_chan(nir_builder *b, nir_ssa_def *src0, nir_ssa_def *src1,
int chan)
{
unsigned chan_mask = 0xff << (chan * 8);
return nir_ior(b,
nir_iand(b, src0, nir_imm_int(b, ~chan_mask)),
nir_iand(b, src1, nir_imm_int(b, chan_mask)));
}
static nir_ssa_def *
vc4_blend_channel_i(nir_builder *b,
nir_ssa_def *src,
nir_ssa_def *dst,
nir_ssa_def *src_a,
nir_ssa_def *dst_a,
unsigned factor,
int a_chan)
{
switch (factor) {
case PIPE_BLENDFACTOR_ONE:
return nir_imm_int(b, ~0);
case PIPE_BLENDFACTOR_SRC_COLOR:
return src;
case PIPE_BLENDFACTOR_SRC_ALPHA:
return src_a;
case PIPE_BLENDFACTOR_DST_ALPHA:
return dst_a;
case PIPE_BLENDFACTOR_DST_COLOR:
return dst;
case PIPE_BLENDFACTOR_SRC_ALPHA_SATURATE:
return vc4_nir_set_packed_chan(b,
nir_umin_4x8(b,
src_a,
nir_inot(b, dst_a)),
nir_imm_int(b, ~0),
a_chan);
case PIPE_BLENDFACTOR_CONST_COLOR:
return nir_load_blend_const_color_rgba8888_unorm(b);
case PIPE_BLENDFACTOR_CONST_ALPHA:
return nir_load_blend_const_color_aaaa8888_unorm(b);
case PIPE_BLENDFACTOR_ZERO:
return nir_imm_int(b, 0);
case PIPE_BLENDFACTOR_INV_SRC_COLOR:
return nir_inot(b, src);
case PIPE_BLENDFACTOR_INV_SRC_ALPHA:
return nir_inot(b, src_a);
case PIPE_BLENDFACTOR_INV_DST_ALPHA:
return nir_inot(b, dst_a);
case PIPE_BLENDFACTOR_INV_DST_COLOR:
return nir_inot(b, dst);
case PIPE_BLENDFACTOR_INV_CONST_COLOR:
return nir_inot(b,
nir_load_blend_const_color_rgba8888_unorm(b));
case PIPE_BLENDFACTOR_INV_CONST_ALPHA:
return nir_inot(b,
nir_load_blend_const_color_aaaa8888_unorm(b));
default:
case PIPE_BLENDFACTOR_SRC1_COLOR:
case PIPE_BLENDFACTOR_SRC1_ALPHA:
case PIPE_BLENDFACTOR_INV_SRC1_COLOR:
case PIPE_BLENDFACTOR_INV_SRC1_ALPHA:
/* Unsupported. */
fprintf(stderr, "Unknown blend factor %d\n", factor);
return nir_imm_int(b, ~0);
}
}
static nir_ssa_def *
vc4_blend_func_f(nir_builder *b, nir_ssa_def *src, nir_ssa_def *dst,
unsigned func)
{
switch (func) {
case PIPE_BLEND_ADD:
return nir_fadd(b, src, dst);
case PIPE_BLEND_SUBTRACT:
return nir_fsub(b, src, dst);
case PIPE_BLEND_REVERSE_SUBTRACT:
return nir_fsub(b, dst, src);
case PIPE_BLEND_MIN:
return nir_fmin(b, src, dst);
case PIPE_BLEND_MAX:
return nir_fmax(b, src, dst);
default:
/* Unsupported. */
fprintf(stderr, "Unknown blend func %d\n", func);
return src;
}
}
static nir_ssa_def *
vc4_blend_func_i(nir_builder *b, nir_ssa_def *src, nir_ssa_def *dst,
unsigned func)
{
switch (func) {
case PIPE_BLEND_ADD:
return nir_usadd_4x8(b, src, dst);
case PIPE_BLEND_SUBTRACT:
return nir_ussub_4x8(b, src, dst);
case PIPE_BLEND_REVERSE_SUBTRACT:
return nir_ussub_4x8(b, dst, src);
case PIPE_BLEND_MIN:
return nir_umin_4x8(b, src, dst);
case PIPE_BLEND_MAX:
return nir_umax_4x8(b, src, dst);
default:
/* Unsupported. */
fprintf(stderr, "Unknown blend func %d\n", func);
return src;
}
}
static void
vc4_do_blending_f(struct vc4_compile *c, nir_builder *b, nir_ssa_def **result,
nir_ssa_def **src_color, nir_ssa_def **dst_color)
{
struct pipe_rt_blend_state *blend = &c->fs_key->blend;
if (!blend->blend_enable) {
for (int i = 0; i < 4; i++)
result[i] = src_color[i];
return;
}
/* Clamp the src color to [0, 1]. Dest is already clamped. */
for (int i = 0; i < 4; i++)
src_color[i] = nir_fsat(b, src_color[i]);
nir_ssa_def *src_blend[4], *dst_blend[4];
for (int i = 0; i < 4; i++) {
int src_factor = ((i != 3) ? blend->rgb_src_factor :
blend->alpha_src_factor);
int dst_factor = ((i != 3) ? blend->rgb_dst_factor :
blend->alpha_dst_factor);
src_blend[i] = nir_fmul(b, src_color[i],
vc4_blend_channel_f(b,
src_color, dst_color,
src_factor, i));
dst_blend[i] = nir_fmul(b, dst_color[i],
vc4_blend_channel_f(b,
src_color, dst_color,
dst_factor, i));
}
for (int i = 0; i < 4; i++) {
result[i] = vc4_blend_func_f(b, src_blend[i], dst_blend[i],
((i != 3) ? blend->rgb_func :
blend->alpha_func));
}
}
static nir_ssa_def *
vc4_nir_splat(nir_builder *b, nir_ssa_def *src)
{
nir_ssa_def *or1 = nir_ior(b, src, nir_ishl(b, src, nir_imm_int(b, 8)));
return nir_ior(b, or1, nir_ishl(b, or1, nir_imm_int(b, 16)));
}
static nir_ssa_def *
vc4_do_blending_i(struct vc4_compile *c, nir_builder *b,
nir_ssa_def *src_color, nir_ssa_def *dst_color,
nir_ssa_def *src_float_a)
{
struct pipe_rt_blend_state *blend = &c->fs_key->blend;
if (!blend->blend_enable)
return src_color;
enum pipe_format color_format = c->fs_key->color_format;
const uint8_t *format_swiz = vc4_get_format_swizzle(color_format);
nir_ssa_def *imm_0xff = nir_imm_int(b, 0xff);
nir_ssa_def *src_a = nir_pack_unorm_4x8(b, src_float_a);
nir_ssa_def *dst_a;
int alpha_chan;
for (alpha_chan = 0; alpha_chan < 4; alpha_chan++) {
if (format_swiz[alpha_chan] == 3)
break;
}
if (alpha_chan != 4) {
nir_ssa_def *shift = nir_imm_int(b, alpha_chan * 8);
dst_a = vc4_nir_splat(b, nir_iand(b, nir_ushr(b, dst_color,
shift), imm_0xff));
} else {
dst_a = nir_imm_int(b, ~0);
}
nir_ssa_def *src_factor = vc4_blend_channel_i(b,
src_color, dst_color,
src_a, dst_a,
blend->rgb_src_factor,
alpha_chan);
nir_ssa_def *dst_factor = vc4_blend_channel_i(b,
src_color, dst_color,
src_a, dst_a,
blend->rgb_dst_factor,
alpha_chan);
if (alpha_chan != 4 &&
blend->alpha_src_factor != blend->rgb_src_factor) {
nir_ssa_def *src_alpha_factor =
vc4_blend_channel_i(b,
src_color, dst_color,
src_a, dst_a,
blend->alpha_src_factor,
alpha_chan);
src_factor = vc4_nir_set_packed_chan(b, src_factor,
src_alpha_factor,
alpha_chan);
}
if (alpha_chan != 4 &&
blend->alpha_dst_factor != blend->rgb_dst_factor) {
nir_ssa_def *dst_alpha_factor =
vc4_blend_channel_i(b,
src_color, dst_color,
src_a, dst_a,
blend->alpha_dst_factor,
alpha_chan);
dst_factor = vc4_nir_set_packed_chan(b, dst_factor,
dst_alpha_factor,
alpha_chan);
}
nir_ssa_def *src_blend = nir_umul_unorm_4x8(b, src_color, src_factor);
nir_ssa_def *dst_blend = nir_umul_unorm_4x8(b, dst_color, dst_factor);
nir_ssa_def *result =
vc4_blend_func_i(b, src_blend, dst_blend, blend->rgb_func);
if (alpha_chan != 4 && blend->alpha_func != blend->rgb_func) {
nir_ssa_def *result_a = vc4_blend_func_i(b,
src_blend,
dst_blend,
blend->alpha_func);
result = vc4_nir_set_packed_chan(b, result, result_a,
alpha_chan);
}
return result;
}
static nir_ssa_def *
vc4_logicop(nir_builder *b, int logicop_func,
nir_ssa_def *src, nir_ssa_def *dst)
{
switch (logicop_func) {
case PIPE_LOGICOP_CLEAR:
return nir_imm_int(b, 0);
case PIPE_LOGICOP_NOR:
return nir_inot(b, nir_ior(b, src, dst));
case PIPE_LOGICOP_AND_INVERTED:
return nir_iand(b, nir_inot(b, src), dst);
case PIPE_LOGICOP_COPY_INVERTED:
return nir_inot(b, src);
case PIPE_LOGICOP_AND_REVERSE:
return nir_iand(b, src, nir_inot(b, dst));
case PIPE_LOGICOP_INVERT:
return nir_inot(b, dst);
case PIPE_LOGICOP_XOR:
return nir_ixor(b, src, dst);
case PIPE_LOGICOP_NAND:
return nir_inot(b, nir_iand(b, src, dst));
case PIPE_LOGICOP_AND:
return nir_iand(b, src, dst);
case PIPE_LOGICOP_EQUIV:
return nir_inot(b, nir_ixor(b, src, dst));
case PIPE_LOGICOP_NOOP:
return dst;
case PIPE_LOGICOP_OR_INVERTED:
return nir_ior(b, nir_inot(b, src), dst);
case PIPE_LOGICOP_OR_REVERSE:
return nir_ior(b, src, nir_inot(b, dst));
case PIPE_LOGICOP_OR:
return nir_ior(b, src, dst);
case PIPE_LOGICOP_SET:
return nir_imm_int(b, ~0);
default:
fprintf(stderr, "Unknown logic op %d\n", logicop_func);
/* FALLTHROUGH */
case PIPE_LOGICOP_COPY:
return src;
}
}
static nir_ssa_def *
vc4_nir_swizzle_and_pack(struct vc4_compile *c, nir_builder *b,
nir_ssa_def **colors)
{
enum pipe_format color_format = c->fs_key->color_format;
const uint8_t *format_swiz = vc4_get_format_swizzle(color_format);
nir_ssa_def *swizzled[4];
for (int i = 0; i < 4; i++) {
swizzled[i] = vc4_nir_get_swizzled_channel(b, colors,
format_swiz[i]);
}
return nir_pack_unorm_4x8(b,
nir_vec4(b,
swizzled[0], swizzled[1],
swizzled[2], swizzled[3]));
}
static nir_ssa_def *
vc4_nir_blend_pipeline(struct vc4_compile *c, nir_builder *b, nir_ssa_def *src,
int sample)
{
enum pipe_format color_format = c->fs_key->color_format;
const uint8_t *format_swiz = vc4_get_format_swizzle(color_format);
bool srgb = util_format_is_srgb(color_format);
/* Pull out the float src/dst color components. */
nir_ssa_def *packed_dst_color = vc4_nir_get_dst_color(b, sample);
nir_ssa_def *dst_vec4 = nir_unpack_unorm_4x8(b, packed_dst_color);
nir_ssa_def *src_color[4], *unpacked_dst_color[4];
for (unsigned i = 0; i < 4; i++) {
src_color[i] = nir_channel(b, src, i);
unpacked_dst_color[i] = nir_channel(b, dst_vec4, i);
}
if (c->fs_key->sample_alpha_to_one && c->fs_key->msaa)
src_color[3] = nir_imm_float(b, 1.0);
nir_ssa_def *packed_color;
if (srgb) {
/* Unswizzle the destination color. */
nir_ssa_def *dst_color[4];
for (unsigned i = 0; i < 4; i++) {
dst_color[i] = vc4_nir_get_swizzled_channel(b,
unpacked_dst_color,
format_swiz[i]);
}
/* Turn dst color to linear. */
for (int i = 0; i < 3; i++)
dst_color[i] = vc4_nir_srgb_decode(b, dst_color[i]);
nir_ssa_def *blend_color[4];
vc4_do_blending_f(c, b, blend_color, src_color, dst_color);
/* sRGB encode the output color */
for (int i = 0; i < 3; i++)
blend_color[i] = vc4_nir_srgb_encode(b, blend_color[i]);
packed_color = vc4_nir_swizzle_and_pack(c, b, blend_color);
} else {
nir_ssa_def *packed_src_color =
vc4_nir_swizzle_and_pack(c, b, src_color);
packed_color =
vc4_do_blending_i(c, b,
packed_src_color, packed_dst_color,
src_color[3]);
}
packed_color = vc4_logicop(b, c->fs_key->logicop_func,
packed_color, packed_dst_color);
/* If the bit isn't set in the color mask, then just return the
* original dst color, instead.
*/
uint32_t colormask = 0xffffffff;
for (int i = 0; i < 4; i++) {
if (format_swiz[i] < 4 &&
!(c->fs_key->blend.colormask & (1 << format_swiz[i]))) {
colormask &= ~(0xff << (i * 8));
}
}
return nir_ior(b,
nir_iand(b, packed_color,
nir_imm_int(b, colormask)),
nir_iand(b, packed_dst_color,
nir_imm_int(b, ~colormask)));
}
static int
vc4_nir_next_output_driver_location(nir_shader *s)
{
int maxloc = -1;
nir_foreach_variable(var, &s->outputs)
maxloc = MAX2(maxloc, (int)var->data.driver_location);
return maxloc + 1;
}
static void
vc4_nir_store_sample_mask(struct vc4_compile *c, nir_builder *b,
nir_ssa_def *val)
{
nir_variable *sample_mask = nir_variable_create(c->s, nir_var_shader_out,
glsl_uint_type(),
"sample_mask");
sample_mask->data.driver_location =
vc4_nir_next_output_driver_location(c->s);
sample_mask->data.location = FRAG_RESULT_SAMPLE_MASK;
nir_intrinsic_instr *intr =
nir_intrinsic_instr_create(c->s, nir_intrinsic_store_output);
intr->num_components = 1;
nir_intrinsic_set_base(intr, sample_mask->data.driver_location);
intr->src[0] = nir_src_for_ssa(val);
intr->src[1] = nir_src_for_ssa(nir_imm_int(b, 0));
nir_builder_instr_insert(b, &intr->instr);
}
static void
vc4_nir_lower_blend_instr(struct vc4_compile *c, nir_builder *b,
nir_intrinsic_instr *intr)
{
nir_ssa_def *frag_color = intr->src[0].ssa;
if (c->fs_key->sample_alpha_to_coverage) {
nir_ssa_def *a = nir_channel(b, frag_color, 3);
/* XXX: We should do a nice dither based on the fragment
* coordinate, instead.
*/
nir_ssa_def *num_samples = nir_imm_float(b, VC4_MAX_SAMPLES);
nir_ssa_def *num_bits = nir_f2i32(b, nir_fmul(b, a, num_samples));
nir_ssa_def *bitmask = nir_isub(b,
nir_ishl(b,
nir_imm_int(b, 1),
num_bits),
nir_imm_int(b, 1));
vc4_nir_store_sample_mask(c, b, bitmask);
}
/* The TLB color read returns each sample in turn, so if our blending
* depends on the destination color, we're going to have to run the
* blending function separately for each destination sample value, and
* then output the per-sample color using TLB_COLOR_MS.
*/
nir_ssa_def *blend_output;
if (c->fs_key->msaa && blend_depends_on_dst_color(c)) {
c->msaa_per_sample_output = true;
nir_ssa_def *samples[4];
for (int i = 0; i < VC4_MAX_SAMPLES; i++)
samples[i] = vc4_nir_blend_pipeline(c, b, frag_color, i);
blend_output = nir_vec4(b,
samples[0], samples[1],
samples[2], samples[3]);
} else {
blend_output = vc4_nir_blend_pipeline(c, b, frag_color, 0);
}
nir_instr_rewrite_src(&intr->instr, &intr->src[0],
nir_src_for_ssa(blend_output));
intr->num_components = blend_output->num_components;
}
static bool
vc4_nir_lower_blend_block(nir_block *block, struct vc4_compile *c)
{
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_store_output)
continue;
nir_variable *output_var = NULL;
nir_foreach_variable(var, &c->s->outputs) {
if (var->data.driver_location ==
nir_intrinsic_base(intr)) {
output_var = var;
break;
}
}
assert(output_var);
if (output_var->data.location != FRAG_RESULT_COLOR &&
output_var->data.location != FRAG_RESULT_DATA0) {
continue;
}
nir_function_impl *impl =
nir_cf_node_get_function(&block->cf_node);
nir_builder b;
nir_builder_init(&b, impl);
b.cursor = nir_before_instr(&intr->instr);
vc4_nir_lower_blend_instr(c, &b, intr);
}
return true;
}
void
vc4_nir_lower_blend(nir_shader *s, struct vc4_compile *c)
{
nir_foreach_function(function, s) {
if (function->impl) {
nir_foreach_block(block, function->impl) {
vc4_nir_lower_blend_block(block, c);
}
nir_metadata_preserve(function->impl,
nir_metadata_block_index |
nir_metadata_dominance);
}
}
/* If we didn't do alpha-to-coverage on the output color, we still
* need to pass glSampleMask() through.
*/
if (c->fs_key->sample_coverage && !c->fs_key->sample_alpha_to_coverage) {
nir_function_impl *impl = nir_shader_get_entrypoint(s);
nir_builder b;
nir_builder_init(&b, impl);
b.cursor = nir_after_block(nir_impl_last_block(impl));
vc4_nir_store_sample_mask(c, &b, nir_load_sample_mask_in(&b));
}
}