| /* |
| * Copyright © 2010 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. |
| */ |
| |
| /** |
| * \file lower_discard.cpp |
| * |
| * This pass moves discards out of if-statements. |
| * |
| * Case 1: The "then" branch contains a conditional discard: |
| * --------------------------------------------------------- |
| * |
| * if (cond1) { |
| * s1; |
| * discard cond2; |
| * s2; |
| * } else { |
| * s3; |
| * } |
| * |
| * becomes: |
| * |
| * temp = false; |
| * if (cond1) { |
| * s1; |
| * temp = cond2; |
| * s2; |
| * } else { |
| * s3; |
| * } |
| * discard temp; |
| * |
| * Case 2: The "else" branch contains a conditional discard: |
| * --------------------------------------------------------- |
| * |
| * if (cond1) { |
| * s1; |
| * } else { |
| * s2; |
| * discard cond2; |
| * s3; |
| * } |
| * |
| * becomes: |
| * |
| * temp = false; |
| * if (cond1) { |
| * s1; |
| * } else { |
| * s2; |
| * temp = cond2; |
| * s3; |
| * } |
| * discard temp; |
| * |
| * Case 3: Both branches contain a conditional discard: |
| * ---------------------------------------------------- |
| * |
| * if (cond1) { |
| * s1; |
| * discard cond2; |
| * s2; |
| * } else { |
| * s3; |
| * discard cond3; |
| * s4; |
| * } |
| * |
| * becomes: |
| * |
| * temp = false; |
| * if (cond1) { |
| * s1; |
| * temp = cond2; |
| * s2; |
| * } else { |
| * s3; |
| * temp = cond3; |
| * s4; |
| * } |
| * discard temp; |
| * |
| * If there are multiple conditional discards, we need only deal with one of |
| * them. Repeatedly applying this pass will take care of the others. |
| * |
| * Unconditional discards are treated as having a condition of "true". |
| */ |
| |
| #include "glsl_types.h" |
| #include "ir.h" |
| |
| namespace { |
| |
| class lower_discard_visitor : public ir_hierarchical_visitor { |
| public: |
| lower_discard_visitor() |
| { |
| this->progress = false; |
| } |
| |
| ir_visitor_status visit_leave(ir_if *); |
| |
| bool progress; |
| }; |
| |
| } /* anonymous namespace */ |
| |
| bool |
| lower_discard(exec_list *instructions) |
| { |
| lower_discard_visitor v; |
| |
| visit_list_elements(&v, instructions); |
| |
| return v.progress; |
| } |
| |
| |
| static ir_discard * |
| find_discard(exec_list &instructions) |
| { |
| foreach_list(n, &instructions) { |
| ir_discard *ir = ((ir_instruction *) n)->as_discard(); |
| if (ir != NULL) |
| return ir; |
| } |
| return NULL; |
| } |
| |
| |
| static void |
| replace_discard(void *mem_ctx, ir_variable *var, ir_discard *ir) |
| { |
| ir_rvalue *condition = ir->condition; |
| |
| /* For unconditional discards, use "true" as the condition. */ |
| if (condition == NULL) |
| condition = new(mem_ctx) ir_constant(true); |
| |
| ir_assignment *assignment = |
| new(mem_ctx) ir_assignment(new(mem_ctx) ir_dereference_variable(var), |
| condition, NULL); |
| |
| ir->replace_with(assignment); |
| } |
| |
| |
| ir_visitor_status |
| lower_discard_visitor::visit_leave(ir_if *ir) |
| { |
| ir_discard *then_discard = find_discard(ir->then_instructions); |
| ir_discard *else_discard = find_discard(ir->else_instructions); |
| |
| if (then_discard == NULL && else_discard == NULL) |
| return visit_continue; |
| |
| void *mem_ctx = ralloc_parent(ir); |
| |
| ir_variable *temp = new(mem_ctx) ir_variable(glsl_type::bool_type, |
| "discard_cond_temp", |
| ir_var_temporary); |
| ir_assignment *temp_initializer = |
| new(mem_ctx) ir_assignment(new(mem_ctx) ir_dereference_variable(temp), |
| new(mem_ctx) ir_constant(false), NULL); |
| |
| ir->insert_before(temp); |
| ir->insert_before(temp_initializer); |
| |
| if (then_discard != NULL) |
| replace_discard(mem_ctx, temp, then_discard); |
| |
| if (else_discard != NULL) |
| replace_discard(mem_ctx, temp, else_discard); |
| |
| ir_discard *discard = then_discard != NULL ? then_discard : else_discard; |
| discard->condition = new(mem_ctx) ir_dereference_variable(temp); |
| ir->insert_after(discard); |
| |
| this->progress = true; |
| |
| return visit_continue; |
| } |