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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_constant_expressions.h"
#include <math.h>
/*
* Implements SSA-based constant folding.
*/
struct constant_fold_state {
void *mem_ctx;
nir_function_impl *impl;
bool progress;
};
static bool
constant_fold_alu_instr(nir_alu_instr *instr, void *mem_ctx)
{
nir_const_value src[4];
if (!instr->dest.dest.is_ssa)
return false;
for (unsigned i = 0; i < nir_op_infos[instr->op].num_inputs; i++) {
if (!instr->src[i].src.is_ssa)
return false;
nir_instr *src_instr = instr->src[i].src.ssa->parent_instr;
if (src_instr->type != nir_instr_type_load_const)
return false;
nir_load_const_instr* load_const = nir_instr_as_load_const(src_instr);
for (unsigned j = 0; j < nir_ssa_alu_instr_src_components(instr, i);
j++) {
src[i].u[j] = load_const->value.u[instr->src[i].swizzle[j]];
}
/* We shouldn't have any source modifiers in the optimization loop. */
assert(!instr->src[i].abs && !instr->src[i].negate);
}
/* We shouldn't have any saturate modifiers in the optimization loop. */
assert(!instr->dest.saturate);
nir_const_value dest =
nir_eval_const_opcode(instr->op, instr->dest.dest.ssa.num_components,
src);
nir_load_const_instr *new_instr =
nir_load_const_instr_create(mem_ctx,
instr->dest.dest.ssa.num_components);
new_instr->value = dest;
nir_instr_insert_before(&instr->instr, &new_instr->instr);
nir_ssa_def_rewrite_uses(&instr->dest.dest.ssa,
nir_src_for_ssa(&new_instr->def));
nir_instr_remove(&instr->instr);
ralloc_free(instr);
return true;
}
static bool
constant_fold_deref(nir_instr *instr, nir_deref_var *deref)
{
bool progress = false;
for (nir_deref *tail = deref->deref.child; tail; tail = tail->child) {
if (tail->deref_type != nir_deref_type_array)
continue;
nir_deref_array *arr = nir_deref_as_array(tail);
if (arr->deref_array_type == nir_deref_array_type_indirect &&
arr->indirect.is_ssa &&
arr->indirect.ssa->parent_instr->type == nir_instr_type_load_const) {
nir_load_const_instr *indirect =
nir_instr_as_load_const(arr->indirect.ssa->parent_instr);
arr->base_offset += indirect->value.u[0];
/* Clear out the source */
nir_instr_rewrite_src(instr, &arr->indirect, nir_src_for_ssa(NULL));
arr->deref_array_type = nir_deref_array_type_direct;
progress = true;
}
}
return progress;
}
static bool
constant_fold_intrinsic_instr(nir_intrinsic_instr *instr)
{
bool progress = false;
unsigned num_vars = nir_intrinsic_infos[instr->intrinsic].num_variables;
for (unsigned i = 0; i < num_vars; i++) {
progress |= constant_fold_deref(&instr->instr, instr->variables[i]);
}
return progress;
}
static bool
constant_fold_tex_instr(nir_tex_instr *instr)
{
if (instr->sampler)
return constant_fold_deref(&instr->instr, instr->sampler);
else
return false;
}
static bool
constant_fold_block(nir_block *block, void *void_state)
{
struct constant_fold_state *state = void_state;
nir_foreach_instr_safe(block, instr) {
switch (instr->type) {
case nir_instr_type_alu:
state->progress |= constant_fold_alu_instr(nir_instr_as_alu(instr),
state->mem_ctx);
break;
case nir_instr_type_intrinsic:
state->progress |=
constant_fold_intrinsic_instr(nir_instr_as_intrinsic(instr));
break;
case nir_instr_type_tex:
state->progress |= constant_fold_tex_instr(nir_instr_as_tex(instr));
break;
default:
/* Don't know how to constant fold */
break;
}
}
return true;
}
static bool
nir_opt_constant_folding_impl(nir_function_impl *impl)
{
struct constant_fold_state state;
state.mem_ctx = ralloc_parent(impl);
state.impl = impl;
state.progress = false;
nir_foreach_block(impl, constant_fold_block, &state);
if (state.progress)
nir_metadata_preserve(impl, nir_metadata_block_index |
nir_metadata_dominance);
return state.progress;
}
bool
nir_opt_constant_folding(nir_shader *shader)
{
bool progress = false;
nir_foreach_overload(shader, overload) {
if (overload->impl)
progress |= nir_opt_constant_folding_impl(overload->impl);
}
return progress;
}
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