1 /*
2 * Copyright © 2014 Intel Corporation
3 *
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:
10 *
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.
14 *
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.
22 */
23
24 /**
25 * \file opt_conditional_discard.cpp
26 *
27 * Replace
28 *
29 * if (cond) discard;
30 *
31 * with
32 *
33 * (discard <condition>)
34 */
35
36 #include "compiler/glsl_types.h"
37 #include "ir.h"
38
39 namespace {
40
41 class opt_conditional_discard_visitor : public ir_hierarchical_visitor {
42 public:
opt_conditional_discard_visitor()43 opt_conditional_discard_visitor()
44 {
45 progress = false;
46 }
47
48 ir_visitor_status visit_leave(ir_if *);
49
50 bool progress;
51 };
52
53 } /* anonymous namespace */
54
55 bool
opt_conditional_discard(exec_list * instructions)56 opt_conditional_discard(exec_list *instructions)
57 {
58 opt_conditional_discard_visitor v;
59 v.run(instructions);
60 return v.progress;
61 }
62
63 ir_visitor_status
visit_leave(ir_if * ir)64 opt_conditional_discard_visitor::visit_leave(ir_if *ir)
65 {
66 /* Look for "if (...) discard" with no else clause or extra statements. */
67 if (ir->then_instructions.is_empty() ||
68 !ir->then_instructions.get_head_raw()->next->is_tail_sentinel() ||
69 !((ir_instruction *) ir->then_instructions.get_head_raw())->as_discard() ||
70 !ir->else_instructions.is_empty())
71 return visit_continue;
72
73 /* Move the condition and replace the ir_if with the ir_discard. */
74 ir_discard *discard = (ir_discard *) ir->then_instructions.get_head_raw();
75 if (!discard->condition)
76 discard->condition = ir->condition;
77 else {
78 void *ctx = ralloc_parent(ir);
79 discard->condition = new(ctx) ir_expression(ir_binop_logic_and,
80 ir->condition,
81 discard->condition);
82 }
83 ir->replace_with(discard);
84
85 progress = true;
86
87 return visit_continue;
88 }
89