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/*
* Copyright © 2014 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.
*
* Authors:
* Jason Ekstrand (jason@jlekstrand.net)
*
*/
#include "nir.h"
#include "compiler/nir_types.h"
/*
* Lowers all copy intrinsics to sequences of load/store intrinsics.
*/
/* Walks down the deref chain and returns the next deref in the chain whose
* child is a wildcard. In other words, given the chain a[1].foo[*].bar,
* this function will return the deref to foo. Calling it a second time
* with the [*].bar, it will return NULL.
*/
static nir_deref *
deref_next_wildcard_parent(nir_deref *deref)
{
for (nir_deref *tail = deref; tail->child; tail = tail->child) {
if (tail->child->deref_type != nir_deref_type_array)
continue;
nir_deref_array *arr = nir_deref_as_array(tail->child);
if (arr->deref_array_type == nir_deref_array_type_wildcard)
return tail;
}
return NULL;
}
/* This function recursively walks the given deref chain and replaces the
* given copy instruction with an equivalent sequence load/store
* operations.
*
* @copy_instr The copy instruction to replace; new instructions will be
* inserted before this one
*
* @dest_head The head of the destination variable deref chain
*
* @src_head The head of the source variable deref chain
*
* @dest_tail The current tail of the destination variable deref chain;
* this is used for recursion and external callers of this
* function should call it with tail == head
*
* @src_tail The current tail of the source variable deref chain;
* this is used for recursion and external callers of this
* function should call it with tail == head
*
* @state The current variable lowering state
*/
static void
emit_copy_load_store(nir_intrinsic_instr *copy_instr,
nir_deref_var *dest_head, nir_deref_var *src_head,
nir_deref *dest_tail, nir_deref *src_tail,
nir_shader *shader)
{
/* Find the next pair of wildcards */
nir_deref *src_arr_parent = deref_next_wildcard_parent(src_tail);
nir_deref *dest_arr_parent = deref_next_wildcard_parent(dest_tail);
if (src_arr_parent || dest_arr_parent) {
/* Wildcards had better come in matched pairs */
assert(src_arr_parent && dest_arr_parent);
nir_deref_array *src_arr = nir_deref_as_array(src_arr_parent->child);
nir_deref_array *dest_arr = nir_deref_as_array(dest_arr_parent->child);
unsigned length = glsl_get_length(src_arr_parent->type);
/* The wildcards should represent the same number of elements */
assert(length == glsl_get_length(dest_arr_parent->type));
assert(length > 0);
/* Walk over all of the elements that this wildcard refers to and
* call emit_copy_load_store on each one of them */
src_arr->deref_array_type = nir_deref_array_type_direct;
dest_arr->deref_array_type = nir_deref_array_type_direct;
for (unsigned i = 0; i < length; i++) {
src_arr->base_offset = i;
dest_arr->base_offset = i;
emit_copy_load_store(copy_instr, dest_head, src_head,
&dest_arr->deref, &src_arr->deref, shader);
}
src_arr->deref_array_type = nir_deref_array_type_wildcard;
dest_arr->deref_array_type = nir_deref_array_type_wildcard;
} else {
/* In this case, we have no wildcards anymore, so all we have to do
* is just emit the load and store operations. */
src_tail = nir_deref_tail(src_tail);
dest_tail = nir_deref_tail(dest_tail);
assert(src_tail->type == dest_tail->type);
unsigned num_components = glsl_get_vector_elements(src_tail->type);
unsigned bit_size = glsl_get_bit_size(src_tail->type);
nir_intrinsic_instr *load =
nir_intrinsic_instr_create(shader, nir_intrinsic_load_var);
load->num_components = num_components;
load->variables[0] = nir_deref_var_clone(src_head, load);
nir_ssa_dest_init(&load->instr, &load->dest, num_components, bit_size,
NULL);
nir_instr_insert_before(©_instr->instr, &load->instr);
nir_intrinsic_instr *store =
nir_intrinsic_instr_create(shader, nir_intrinsic_store_var);
store->num_components = num_components;
nir_intrinsic_set_write_mask(store, (1 << num_components) - 1);
store->variables[0] = nir_deref_var_clone(dest_head, store);
store->src[0].is_ssa = true;
store->src[0].ssa = &load->dest.ssa;
nir_instr_insert_before(©_instr->instr, &store->instr);
}
}
/* Lowers a copy instruction to a sequence of load/store instructions
*
* The new instructions are placed before the copy instruction in the IR.
*/
void
nir_lower_var_copy_instr(nir_intrinsic_instr *copy, nir_shader *shader)
{
assert(copy->intrinsic == nir_intrinsic_copy_var);
emit_copy_load_store(copy, copy->variables[0], copy->variables[1],
©->variables[0]->deref,
©->variables[1]->deref, shader);
}
static bool
lower_var_copies_impl(nir_function_impl *impl)
{
nir_shader *shader = impl->function->shader;
bool progress = false;
nir_foreach_block(block, impl) {
nir_foreach_instr_safe(instr, block) {
if (instr->type != nir_instr_type_intrinsic)
continue;
nir_intrinsic_instr *copy = nir_instr_as_intrinsic(instr);
if (copy->intrinsic != nir_intrinsic_copy_var)
continue;
nir_lower_var_copy_instr(copy, shader);
nir_instr_remove(©->instr);
progress = true;
ralloc_free(copy);
}
}
if (progress)
nir_metadata_preserve(impl, nir_metadata_block_index |
nir_metadata_dominance);
return progress;
}
/* Lowers every copy_var instruction in the program to a sequence of
* load/store instructions.
*/
bool
nir_lower_var_copies(nir_shader *shader)
{
bool progress = false;
nir_foreach_function(function, shader) {
if (function->impl)
progress |= lower_var_copies_impl(function->impl);
}
return progress;
}
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