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/*
* Copyright © 2016 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"
static void
add_src(nir_src *src, struct set *invariants)
{
if (src->is_ssa) {
_mesa_set_add(invariants, src->ssa);
} else {
_mesa_set_add(invariants, src->reg.reg);
}
}
static bool
add_src_cb(nir_src *src, void *state)
{
add_src(src, state);
return true;
}
static bool
dest_is_invariant(nir_dest *dest, struct set *invariants)
{
if (dest->is_ssa) {
return _mesa_set_search(invariants, &dest->ssa);
} else {
return _mesa_set_search(invariants, dest->reg.reg);
}
}
static void
add_cf_node(nir_cf_node *cf, struct set *invariants)
{
if (cf->type == nir_cf_node_if) {
nir_if *if_stmt = nir_cf_node_as_if(cf);
add_src(&if_stmt->condition, invariants);
}
if (cf->parent)
add_cf_node(cf->parent, invariants);
}
static void
add_var(nir_variable *var, struct set *invariants)
{
/* Because we pass the result of nir_intrinsic_get_var directly to this
* function, it's possible for var to be NULL if, for instance, there's a
* cast somewhere in the chain.
*/
if (var != NULL)
_mesa_set_add(invariants, var);
}
static bool
var_is_invariant(nir_variable *var, struct set * invariants)
{
/* Because we pass the result of nir_intrinsic_get_var directly to this
* function, it's possible for var to be NULL if, for instance, there's a
* cast somewhere in the chain.
*/
return var && (var->data.invariant || _mesa_set_search(invariants, var));
}
static void
propagate_invariant_instr(nir_instr *instr, struct set *invariants)
{
switch (instr->type) {
case nir_instr_type_alu: {
nir_alu_instr *alu = nir_instr_as_alu(instr);
if (!dest_is_invariant(&alu->dest.dest, invariants))
break;
alu->exact = true;
nir_foreach_src(instr, add_src_cb, invariants);
break;
}
case nir_instr_type_tex: {
nir_tex_instr *tex = nir_instr_as_tex(instr);
if (dest_is_invariant(&tex->dest, invariants))
nir_foreach_src(instr, add_src_cb, invariants);
break;
}
case nir_instr_type_intrinsic: {
nir_intrinsic_instr *intrin = nir_instr_as_intrinsic(instr);
switch (intrin->intrinsic) {
case nir_intrinsic_copy_deref:
/* If the destination is invariant then so is the source */
if (var_is_invariant(nir_intrinsic_get_var(intrin, 0), invariants))
add_var(nir_intrinsic_get_var(intrin, 1), invariants);
break;
case nir_intrinsic_load_deref:
if (dest_is_invariant(&intrin->dest, invariants))
add_var(nir_intrinsic_get_var(intrin, 0), invariants);
break;
case nir_intrinsic_store_deref:
if (var_is_invariant(nir_intrinsic_get_var(intrin, 0), invariants))
add_src(&intrin->src[1], invariants);
break;
default:
/* Nothing to do */
break;
}
}
case nir_instr_type_deref:
case nir_instr_type_jump:
case nir_instr_type_ssa_undef:
case nir_instr_type_load_const:
break; /* Nothing to do */
case nir_instr_type_phi: {
nir_phi_instr *phi = nir_instr_as_phi(instr);
if (!dest_is_invariant(&phi->dest, invariants))
break;
nir_foreach_phi_src(src, phi) {
add_src(&src->src, invariants);
add_cf_node(&src->pred->cf_node, invariants);
}
break;
}
case nir_instr_type_call:
unreachable("This pass must be run after function inlining");
case nir_instr_type_parallel_copy:
default:
unreachable("Cannot have this instruction type");
}
}
static bool
propagate_invariant_impl(nir_function_impl *impl, struct set *invariants)
{
bool progress = false;
while (true) {
uint32_t prev_entries = invariants->entries;
nir_foreach_block_reverse(block, impl) {
nir_foreach_instr_reverse(instr, block)
propagate_invariant_instr(instr, invariants);
}
/* Keep running until we make no more progress. */
if (invariants->entries > prev_entries) {
progress = true;
continue;
} else {
break;
}
}
if (progress) {
nir_metadata_preserve(impl, nir_metadata_block_index |
nir_metadata_dominance |
nir_metadata_live_ssa_defs);
}
return progress;
}
bool
nir_propagate_invariant(nir_shader *shader)
{
/* Hash set of invariant things */
struct set *invariants = _mesa_pointer_set_create(NULL);
bool progress = false;
nir_foreach_function(function, shader) {
if (function->impl && propagate_invariant_impl(function->impl, invariants))
progress = true;
}
_mesa_set_destroy(invariants, NULL);
return progress;
}
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