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[AROS.git] / workbench / libs / mesa / src / glsl / opt_if_simplification.cpp
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1 /*
2 * Copyright © 2010 Intel Corporation
4 * Permission is hereby granted, free of charge, to any person obtaining a
5 * copy of this software and associated documentation files (the "Software"),
6 * to deal in the Software without restriction, including without limitation
7 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
8 * and/or sell copies of the Software, and to permit persons to whom the
9 * Software is furnished to do so, subject to the following conditions:
11 * The above copyright notice and this permission notice (including the next
12 * paragraph) shall be included in all copies or substantial portions of the
13 * Software.
15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
16 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
17 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
18 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
19 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
20 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
21 * DEALINGS IN THE SOFTWARE.
24 /**
25 * \file opt_if_simplification.cpp
27 * Moves constant branches of if statements out to the surrounding
28 * instruction stream.
31 #include "ir.h"
33 class ir_if_simplification_visitor : public ir_hierarchical_visitor {
34 public:
35 ir_if_simplification_visitor()
37 this->made_progress = false;
40 ir_visitor_status visit_leave(ir_if *);
41 ir_visitor_status visit_enter(ir_assignment *);
43 bool made_progress;
46 /* We only care about the top level "if" instructions, so don't
47 * descend into expressions.
49 ir_visitor_status
50 ir_if_simplification_visitor::visit_enter(ir_assignment *ir)
52 return visit_continue_with_parent;
55 bool
56 do_if_simplification(exec_list *instructions)
58 ir_if_simplification_visitor v;
60 v.run(instructions);
61 return v.made_progress;
65 ir_visitor_status
66 ir_if_simplification_visitor::visit_leave(ir_if *ir)
68 /* FINISHME: Ideally there would be a way to note that the condition results
69 * FINISHME: in a constant before processing both of the other subtrees.
70 * FINISHME: This can probably be done with some flags, but it would take
71 * FINISHME: some work to get right.
73 ir_constant *condition_constant = ir->condition->constant_expression_value();
74 if (condition_constant) {
75 /* Move the contents of the one branch of the conditional
76 * that matters out.
78 if (condition_constant->value.b[0]) {
79 foreach_iter(exec_list_iterator, then_iter, ir->then_instructions) {
80 ir_instruction *then_ir = (ir_instruction *)then_iter.get();
81 ir->insert_before(then_ir);
83 } else {
84 foreach_iter(exec_list_iterator, else_iter, ir->else_instructions) {
85 ir_instruction *else_ir = (ir_instruction *)else_iter.get();
86 ir->insert_before(else_ir);
89 ir->remove();
90 this->made_progress = true;
93 return visit_continue;