Files
third_party_mesa3d/src/compiler/nir/nir_opt_large_constants.c
2018-10-22 14:24:15 -05:00

306 lines
11 KiB
C

/*
* Copyright © 2018 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 "nir_builder.h"
#include "nir_deref.h"
struct var_info {
bool is_constant;
bool found_read;
};
static nir_ssa_def *
build_constant_load(nir_builder *b, nir_deref_instr *deref,
glsl_type_size_align_func size_align)
{
nir_variable *var = nir_deref_instr_get_variable(deref);
const unsigned bit_size = glsl_get_bit_size(deref->type);
const unsigned num_components = glsl_get_vector_elements(deref->type);
UNUSED unsigned var_size, var_align;
size_align(var->type, &var_size, &var_align);
assert(var->data.location % var_align == 0);
nir_intrinsic_instr *load =
nir_intrinsic_instr_create(b->shader, nir_intrinsic_load_constant);
load->num_components = num_components;
nir_intrinsic_set_base(load, var->data.location);
nir_intrinsic_set_range(load, var_size);
load->src[0] = nir_src_for_ssa(nir_build_deref_offset(b, deref, size_align));
nir_ssa_dest_init(&load->instr, &load->dest,
num_components, bit_size, NULL);
nir_builder_instr_insert(b, &load->instr);
return &load->dest.ssa;
}
static void
handle_constant_store(nir_builder *b, nir_intrinsic_instr *store,
glsl_type_size_align_func size_align)
{
nir_deref_instr *deref = nir_src_as_deref(store->src[0]);
assert(!nir_deref_instr_has_indirect(deref));
nir_variable *var = nir_deref_instr_get_variable(deref);
const unsigned bit_size = glsl_get_bit_size(deref->type);
const unsigned num_components = glsl_get_vector_elements(deref->type);
char *dst = (char *)b->shader->constant_data +
var->data.location +
nir_deref_instr_get_const_offset(deref, size_align);
nir_const_value *val = nir_src_as_const_value(store->src[1]);
switch (bit_size) {
case 8:
for (unsigned i = 0; i < num_components; i++)
((uint8_t *)dst)[i] = val->u8[i];
break;
case 16:
for (unsigned i = 0; i < num_components; i++)
((uint16_t *)dst)[i] = val->u16[i];
break;
case 32:
for (unsigned i = 0; i < num_components; i++)
((uint32_t *)dst)[i] = val->u32[i];
break;
case 64:
for (unsigned i = 0; i < num_components; i++)
((uint64_t *)dst)[i] = val->u64[i];
break;
default:
unreachable("Invalid bit size");
}
}
/** Lower large constant variables to shader constant data
*
* This pass looks for large (type_size(var->type) > threshold) variables
* which are statically constant and moves them into shader constant data.
* This is especially useful when large tables are baked into the shader
* source code because they can be moved into a UBO by the driver to reduce
* register pressure and make indirect access cheaper.
*/
bool
nir_opt_large_constants(nir_shader *shader,
glsl_type_size_align_func size_align,
unsigned threshold)
{
/* Default to a natural alignment if none is provided */
if (size_align == NULL)
size_align = glsl_get_natural_size_align_bytes;
/* This only works with a single entrypoint */
nir_function_impl *impl = nir_shader_get_entrypoint(shader);
/* This pass can only be run once */
assert(shader->constant_data == NULL && shader->constant_data_size == 0);
/* The index parameter is unused for local variables so we'll use it for
* indexing into our array of variable metadata.
*/
unsigned num_locals = 0;
nir_foreach_variable(var, &impl->locals)
var->data.index = num_locals++;
struct var_info *var_infos = malloc(num_locals * sizeof(struct var_info));
for (unsigned i = 0; i < num_locals; i++) {
var_infos[i] = (struct var_info) {
.is_constant = true,
.found_read = false,
};
}
/* First, walk through the shader and figure out what variables we can
* lower to the constant blob.
*/
bool first_block = true;
nir_foreach_block(block, impl) {
nir_foreach_instr(instr, block) {
if (instr->type != nir_instr_type_intrinsic)
continue;
nir_intrinsic_instr *intrin = nir_instr_as_intrinsic(instr);
bool src_is_const = false;
nir_deref_instr *src_deref = NULL, *dst_deref = NULL;
switch (intrin->intrinsic) {
case nir_intrinsic_store_deref:
dst_deref = nir_src_as_deref(intrin->src[0]);
src_is_const = nir_src_is_const(intrin->src[1]);
break;
case nir_intrinsic_load_deref:
src_deref = nir_src_as_deref(intrin->src[0]);
break;
case nir_intrinsic_copy_deref:
/* We always assume the src and therefore the dst are not
* constants here. Copy and constant propagation passes should
* have taken care of this in most cases anyway.
*/
dst_deref = nir_src_as_deref(intrin->src[0]);
src_deref = nir_src_as_deref(intrin->src[1]);
src_is_const = false;
break;
default:
continue;
}
if (dst_deref && dst_deref->mode == nir_var_local) {
nir_variable *var = nir_deref_instr_get_variable(dst_deref);
assert(var->data.mode == nir_var_local);
/* We only consider variables constant if they only have constant
* stores, all the stores come before any reads, and all stores
* come in the first block. We also can't handle indirect stores.
*/
struct var_info *info = &var_infos[var->data.index];
if (!src_is_const || info->found_read || !first_block ||
nir_deref_instr_has_indirect(dst_deref))
info->is_constant = false;
}
if (src_deref && src_deref->mode == nir_var_local) {
nir_variable *var = nir_deref_instr_get_variable(src_deref);
assert(var->data.mode == nir_var_local);
var_infos[var->data.index].found_read = true;
}
}
first_block = false;
}
shader->constant_data_size = 0;
nir_foreach_variable(var, &impl->locals) {
struct var_info *info = &var_infos[var->data.index];
if (!info->is_constant)
continue;
unsigned var_size, var_align;
size_align(var->type, &var_size, &var_align);
if (var_size <= threshold || !info->found_read) {
/* Don't bother lowering small stuff or data that's never read */
info->is_constant = false;
continue;
}
var->data.location = ALIGN_POT(shader->constant_data_size, var_align);
shader->constant_data_size = var->data.location + var_size;
}
if (shader->constant_data_size == 0) {
free(var_infos);
return false;
}
shader->constant_data = rzalloc_size(shader, shader->constant_data_size);
nir_builder b;
nir_builder_init(&b, impl);
nir_foreach_block(block, impl) {
nir_foreach_instr_safe(instr, block) {
if (instr->type != nir_instr_type_intrinsic)
continue;
nir_intrinsic_instr *intrin = nir_instr_as_intrinsic(instr);
switch (intrin->intrinsic) {
case nir_intrinsic_load_deref: {
nir_deref_instr *deref = nir_src_as_deref(intrin->src[0]);
if (deref->mode != nir_var_local)
continue;
nir_variable *var = nir_deref_instr_get_variable(deref);
struct var_info *info = &var_infos[var->data.index];
if (info->is_constant) {
b.cursor = nir_after_instr(&intrin->instr);
nir_ssa_def *val = build_constant_load(&b, deref, size_align);
nir_ssa_def_rewrite_uses(&intrin->dest.ssa,
nir_src_for_ssa(val));
nir_instr_remove(&intrin->instr);
nir_deref_instr_remove_if_unused(deref);
}
break;
}
case nir_intrinsic_store_deref: {
nir_deref_instr *deref = nir_src_as_deref(intrin->src[0]);
if (deref->mode != nir_var_local)
continue;
nir_variable *var = nir_deref_instr_get_variable(deref);
struct var_info *info = &var_infos[var->data.index];
if (info->is_constant) {
b.cursor = nir_after_instr(&intrin->instr);
handle_constant_store(&b, intrin, size_align);
nir_instr_remove(&intrin->instr);
nir_deref_instr_remove_if_unused(deref);
}
break;
}
case nir_intrinsic_copy_deref: {
nir_deref_instr *deref = nir_src_as_deref(intrin->src[1]);
if (deref->mode != nir_var_local)
continue;
nir_variable *var = nir_deref_instr_get_variable(deref);
struct var_info *info = &var_infos[var->data.index];
if (info->is_constant) {
b.cursor = nir_after_instr(&intrin->instr);
nir_ssa_def *val = build_constant_load(&b, deref, size_align);
nir_store_deref(&b, nir_src_as_deref(intrin->src[0]), val, ~0);
nir_instr_remove(&intrin->instr);
nir_deref_instr_remove_if_unused(deref);
}
break;
}
default:
continue;
}
}
}
/* Clean up the now unused variables */
nir_foreach_variable_safe(var, &impl->locals) {
if (var_infos[var->data.index].is_constant)
exec_node_remove(&var->node);
}
free(var_infos);
nir_metadata_preserve(impl, nir_metadata_block_index |
nir_metadata_dominance);
return true;
}