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/*
* Copyright © 2015 Intel Corporation
*
* 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 "util/set.h"
#include "util/hash_table.h"
/* This file contains various little helpers for doing simple linking in
* NIR. Eventually, we'll probably want a full-blown varying packing
* implementation in here. Right now, it just deletes unused things.
*/
/**
* Returns the bits in the inputs_read, outputs_written, or
* system_values_read bitfield corresponding to this variable.
*/
static uint64_t
get_variable_io_mask(nir_variable *var, gl_shader_stage stage)
{
/* TODO: add support for tess patches */
if (var->data.patch || var->data.location < 0)
return 0;
assert(var->data.mode == nir_var_shader_in ||
var->data.mode == nir_var_shader_out ||
var->data.mode == nir_var_system_value);
assert(var->data.location >= 0);
const struct glsl_type *type = var->type;
if (nir_is_per_vertex_io(var, stage)) {
assert(glsl_type_is_array(type));
type = glsl_get_array_element(type);
}
unsigned slots = glsl_count_attribute_slots(type, false);
return ((1ull << slots) - 1) << var->data.location;
}
static uint64_t
tcs_output_read_bitmask(nir_shader *shader)
{
uint64_t read = 0;
nir_foreach_function(function, shader) {
if (function->impl) {
nir_foreach_block(block, function->impl) {
nir_foreach_instr(instr, block) {
if (instr->type != nir_instr_type_intrinsic)
continue;
nir_intrinsic_instr *intrin_instr =
nir_instr_as_intrinsic(instr);
if (intrin_instr->intrinsic == nir_intrinsic_load_var &&
intrin_instr->variables[0]->var->data.mode ==
nir_var_shader_out) {
read |= get_variable_io_mask(intrin_instr->variables[0]->var,
shader->stage);
}
}
}
}
}
return read;
}
static bool
remove_unused_io_vars(nir_shader *shader, struct exec_list *var_list,
uint64_t used_by_other_stage)
{
bool progress = false;
nir_foreach_variable_safe(var, var_list) {
/* TODO: add patch support */
if (var->data.patch)
continue;
if (var->data.location < VARYING_SLOT_VAR0 && var->data.location >= 0)
continue;
if (var->data.always_active_io)
continue;
if (!(used_by_other_stage & get_variable_io_mask(var, shader->stage))) {
/* This one is invalid, make it a global variable instead */
var->data.location = 0;
var->data.mode = nir_var_global;
exec_node_remove(&var->node);
exec_list_push_tail(&shader->globals, &var->node);
progress = true;
}
}
return progress;
}
bool
nir_remove_unused_varyings(nir_shader *producer, nir_shader *consumer)
{
assert(producer->stage != MESA_SHADER_FRAGMENT);
assert(consumer->stage != MESA_SHADER_VERTEX);
uint64_t read = 0, written = 0;
nir_foreach_variable(var, &producer->outputs)
written |= get_variable_io_mask(var, producer->stage);
nir_foreach_variable(var, &consumer->inputs)
read |= get_variable_io_mask(var, consumer->stage);
/* Each TCS invocation can read data written by other TCS invocations,
* so even if the outputs are not used by the TES we must also make
* sure they are not read by the TCS before demoting them to globals.
*/
if (producer->stage == MESA_SHADER_TESS_CTRL)
read |= tcs_output_read_bitmask(producer);
bool progress = false;
progress = remove_unused_io_vars(producer, &producer->outputs, read);
progress =
remove_unused_io_vars(consumer, &consumer->inputs, written) || progress;
return progress;
}
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