| /* |
| * Copyright © 2016 Red Hat |
| * |
| * 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" |
| |
| /** @file nir_opt_conditional_discard.c |
| * |
| * Handles optimization of lowering of |
| * - if (cond) discard to discard_if(cond) and |
| * - if (cond) demote to demote_if(cond) |
| */ |
| |
| static bool |
| nir_opt_conditional_discard_block(nir_builder *b, nir_block *block) |
| { |
| if (nir_cf_node_is_first(&block->cf_node)) |
| return false; |
| |
| nir_cf_node *prev_node = nir_cf_node_prev(&block->cf_node); |
| if (prev_node->type != nir_cf_node_if) |
| return false; |
| |
| nir_if *if_stmt = nir_cf_node_as_if(prev_node); |
| nir_block *then_block = nir_if_first_then_block(if_stmt); |
| nir_block *else_block = nir_if_first_else_block(if_stmt); |
| |
| /* check there is only one else block and it is empty */ |
| if (nir_if_last_else_block(if_stmt) != else_block) |
| return false; |
| if (!exec_list_is_empty(&else_block->instr_list)) |
| return false; |
| |
| /* check there is only one then block and it has only one instruction in it */ |
| if (nir_if_last_then_block(if_stmt) != then_block) |
| return false; |
| if (exec_list_is_empty(&then_block->instr_list)) |
| return false; |
| if (exec_list_length(&then_block->instr_list) > 1) |
| return false; |
| /* |
| * make sure no subsequent phi nodes point at this if. |
| */ |
| nir_block *after = nir_cf_node_as_block(nir_cf_node_next(&if_stmt->cf_node)); |
| nir_foreach_instr_safe(instr, after) { |
| if (instr->type != nir_instr_type_phi) |
| break; |
| nir_phi_instr *phi = nir_instr_as_phi(instr); |
| |
| nir_foreach_phi_src(phi_src, phi) { |
| if (phi_src->pred == then_block || |
| phi_src->pred == else_block) |
| return false; |
| } |
| } |
| |
| /* Get the first instruction in the then block and confirm it is |
| * a discard or a demote instruction. |
| */ |
| nir_instr *instr = nir_block_first_instr(then_block); |
| if (instr->type != nir_instr_type_intrinsic) |
| return false; |
| |
| nir_intrinsic_instr *intrin = nir_instr_as_intrinsic(instr); |
| nir_intrinsic_op op = intrin->intrinsic; |
| assert(if_stmt->condition.is_ssa); |
| nir_ssa_def *cond = if_stmt->condition.ssa; |
| b->cursor = nir_before_cf_node(prev_node); |
| |
| switch (intrin->intrinsic) { |
| case nir_intrinsic_discard: |
| op = nir_intrinsic_discard_if; |
| break; |
| case nir_intrinsic_demote: |
| op = nir_intrinsic_demote_if; |
| break; |
| case nir_intrinsic_discard_if: |
| case nir_intrinsic_demote_if: |
| assert(intrin->src[0].is_ssa); |
| cond = nir_iand(b, cond, intrin->src[0].ssa); |
| break; |
| default: |
| return false; |
| } |
| |
| nir_intrinsic_instr *discard_if = |
| nir_intrinsic_instr_create(b->shader, op); |
| discard_if->src[0] = nir_src_for_ssa(cond); |
| |
| nir_instr_insert_before_cf(prev_node, &discard_if->instr); |
| nir_instr_remove(&intrin->instr); |
| nir_cf_node_remove(&if_stmt->cf_node); |
| |
| return true; |
| } |
| |
| bool |
| nir_opt_conditional_discard(nir_shader *shader) |
| { |
| bool progress = false; |
| |
| nir_builder builder; |
| |
| nir_foreach_function(function, shader) { |
| if (function->impl) { |
| nir_builder_init(&builder, function->impl); |
| |
| bool impl_progress = false; |
| nir_foreach_block_safe(block, function->impl) { |
| if (nir_opt_conditional_discard_block(&builder, block)) |
| impl_progress = true; |
| } |
| |
| if (impl_progress) { |
| nir_metadata_preserve(function->impl, nir_metadata_none); |
| progress = true; |
| } else { |
| nir_metadata_preserve(function->impl, nir_metadata_all); |
| } |
| } |
| } |
| return progress; |
| } |