| /* |
| * 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. |
| */ |
| |
| /** |
| * \file propagate_invariance.cpp |
| * Propagate the "invariant" and "precise" qualifiers to variables used to |
| * compute invariant or precise values. |
| * |
| * The GLSL spec (depending on what version you read) says, among the |
| * conditions for getting bit-for-bit the same values on an invariant output: |
| * |
| * "All operations in the consuming expressions and any intermediate |
| * expressions must be the same, with the same order of operands and same |
| * associativity, to give the same order of evaluation." |
| * |
| * This effectively means that if a variable is used to compute an invariant |
| * value then that variable becomes invariant. The same should apply to the |
| * "precise" qualifier. |
| */ |
| |
| #include "ir.h" |
| #include "ir_visitor.h" |
| #include "ir_rvalue_visitor.h" |
| #include "ir_optimization.h" |
| #include "compiler/glsl_types.h" |
| |
| namespace { |
| |
| class ir_invariance_propagation_visitor : public ir_hierarchical_visitor { |
| public: |
| ir_invariance_propagation_visitor() |
| { |
| this->progress = false; |
| this->dst_var = NULL; |
| } |
| |
| virtual ~ir_invariance_propagation_visitor() |
| { |
| /* empty */ |
| } |
| |
| virtual ir_visitor_status visit_enter(ir_assignment *ir); |
| virtual ir_visitor_status visit_leave(ir_assignment *ir); |
| virtual ir_visitor_status visit(ir_dereference_variable *ir); |
| |
| ir_variable *dst_var; |
| bool progress; |
| }; |
| |
| } /* unnamed namespace */ |
| |
| ir_visitor_status |
| ir_invariance_propagation_visitor::visit_enter(ir_assignment *ir) |
| { |
| assert(this->dst_var == NULL); |
| ir_variable *var = ir->lhs->variable_referenced(); |
| if (var->data.invariant || var->data.precise) { |
| this->dst_var = var; |
| return visit_continue; |
| } else { |
| return visit_continue_with_parent; |
| } |
| } |
| |
| ir_visitor_status |
| ir_invariance_propagation_visitor::visit_leave(ir_assignment *) |
| { |
| this->dst_var = NULL; |
| |
| return visit_continue; |
| } |
| |
| ir_visitor_status |
| ir_invariance_propagation_visitor::visit(ir_dereference_variable *ir) |
| { |
| if (this->dst_var == NULL) |
| return visit_continue; |
| |
| if (this->dst_var->data.invariant) { |
| if (!ir->var->data.invariant) |
| this->progress = true; |
| |
| ir->var->data.invariant = true; |
| } |
| |
| if (this->dst_var->data.precise) { |
| if (!ir->var->data.precise) |
| this->progress = true; |
| |
| ir->var->data.precise = true; |
| } |
| |
| return visit_continue; |
| } |
| |
| void |
| propagate_invariance(exec_list *instructions) |
| { |
| ir_invariance_propagation_visitor visitor; |
| |
| do { |
| visitor.progress = false; |
| visit_list_elements(&visitor, instructions); |
| } while (visitor.progress); |
| } |