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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"
/*
* Implements a quick-and-dirty out-of-ssa pass.
*/
struct from_ssa_state {
void *mem_ctx;
void *dead_ctx;
struct hash_table *ssa_table;
nir_function_impl *current_impl;
};
static bool
rewrite_ssa_src(nir_src *src, void *void_state)
{
struct from_ssa_state *state = void_state;
if (src->is_ssa) {
struct hash_entry *entry =
_mesa_hash_table_search(state->ssa_table, src->ssa);
assert(entry);
memset(src, 0, sizeof *src);
src->reg.reg = (nir_register *)entry->data;
}
return true;
}
static nir_register *
reg_create_from_def(nir_ssa_def *def, struct from_ssa_state *state)
{
nir_register *reg = nir_local_reg_create(state->current_impl);
reg->name = def->name;
reg->num_components = def->num_components;
reg->num_array_elems = 0;
/* Might as well steal the use-def information from SSA */
_mesa_set_destroy(reg->uses, NULL);
reg->uses = def->uses;
_mesa_set_destroy(reg->if_uses, NULL);
reg->if_uses = def->if_uses;
_mesa_set_add(reg->defs, _mesa_hash_pointer(def->parent_instr),
def->parent_instr);
/* Add the new register to the table and rewrite the destination */
_mesa_hash_table_insert(state->ssa_table, def, reg);
return reg;
}
static bool
rewrite_ssa_dest(nir_dest *dest, void *void_state)
{
struct from_ssa_state *state = void_state;
if (dest->is_ssa) {
nir_register *reg = reg_create_from_def(&dest->ssa, state);
memset(dest, 0, sizeof *dest);
dest->reg.reg = reg;
}
return true;
}
static bool
convert_from_ssa_block(nir_block *block, void *void_state)
{
struct from_ssa_state *state = void_state;
nir_foreach_instr_safe(block, instr) {
if (instr->type == nir_instr_type_ssa_undef) {
nir_ssa_undef_instr *undef = nir_instr_as_ssa_undef(instr);
reg_create_from_def(&undef->def, state);
exec_node_remove(&instr->node);
ralloc_steal(state->dead_ctx, instr);
} else {
nir_foreach_src(instr, rewrite_ssa_src, state);
nir_foreach_dest(instr, rewrite_ssa_dest, state);
}
}
nir_if *following_if = nir_block_following_if(block);
if (following_if)
rewrite_ssa_src(&following_if->condition, state);
return true;
}
static bool
remove_phi_nodes(nir_block *block, void *void_state)
{
struct from_ssa_state *state = void_state;
nir_foreach_instr_safe(block, instr) {
/* Phi nodes only ever come at the start of a block */
if (instr->type != nir_instr_type_phi)
break;
nir_foreach_dest(instr, rewrite_ssa_dest, state);
nir_phi_instr *phi = nir_instr_as_phi(instr);
foreach_list_typed(nir_phi_src, src, node, &phi->srcs) {
assert(src->src.is_ssa);
struct hash_entry *entry =
_mesa_hash_table_search(state->ssa_table, src->src.ssa);
nir_alu_instr *mov = nir_alu_instr_create(state->mem_ctx, nir_op_imov);
mov->dest.dest = nir_dest_copy(phi->dest, state->mem_ctx);
if (entry) {
nir_register *reg = (nir_register *)entry->data;
mov->src[0].src.reg.reg = reg;
mov->dest.write_mask = (1 << reg->num_components) - 1;
} else {
mov->src[0].src = nir_src_copy(src->src, state->mem_ctx);
mov->dest.write_mask = (1 << src->src.ssa->num_components) - 1;
}
nir_instr *block_end = nir_block_last_instr(src->pred);
if (block_end && block_end->type == nir_instr_type_jump) {
/* If the last instruction in the block is a jump, we want to
* place the moves after the jump. Otherwise, we want to place
* them at the very end.
*/
exec_node_insert_node_before(&block_end->node, &mov->instr.node);
} else {
exec_list_push_tail(&src->pred->instr_list, &mov->instr.node);
}
}
exec_node_remove(&instr->node);
ralloc_steal(state->dead_ctx, instr);
}
return true;
}
static void
nir_convert_from_ssa_impl(nir_function_impl *impl)
{
struct from_ssa_state state;
state.mem_ctx = ralloc_parent(impl);
state.dead_ctx = ralloc_context(NULL);
state.current_impl = impl;
state.ssa_table = _mesa_hash_table_create(NULL, _mesa_hash_pointer,
_mesa_key_pointer_equal);
nir_foreach_block(impl, remove_phi_nodes, &state);
nir_foreach_block(impl, convert_from_ssa_block, &state);
/* Clean up dead instructions and the hash table */
ralloc_free(state.dead_ctx);
_mesa_hash_table_destroy(state.ssa_table, NULL);
}
void
nir_convert_from_ssa(nir_shader *shader)
{
nir_foreach_overload(shader, overload) {
if (overload->impl)
nir_convert_from_ssa_impl(overload->impl);
}
}
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