1 /*
2 * Copyright © 2019 Valve 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 DEALINGS
21 * IN THE SOFTWARE.
22 *
23 */
24
25 #include "aco_ir.h"
26
27 #include <algorithm>
28 #include <vector>
29
30 /*
31 * Implements an analysis pass to determine the number of uses
32 * for each SSA-definition.
33 *
34 * This pass assumes that no loop header phis are dead code.
35 */
36
37 namespace aco {
38 namespace {
39
40 void
process_loop_header_phis(std::vector<uint16_t> & uses,Block & block)41 process_loop_header_phis(std::vector<uint16_t>& uses, Block& block)
42 {
43 for (aco_ptr<Instruction>& instr : block.instructions) {
44 if (!is_phi(instr))
45 return;
46 for (const Operand& op : instr->operands) {
47 if (op.isTemp())
48 uses[op.tempId()]++;
49 }
50 }
51 }
52
53 void
process_block(std::vector<uint16_t> & uses,Block & block)54 process_block(std::vector<uint16_t>& uses, Block& block)
55 {
56 for (auto it = block.instructions.rbegin(); it != block.instructions.rend(); it++) {
57 aco_ptr<Instruction>& instr = *it;
58 if ((block.kind & block_kind_loop_header) && is_phi(instr))
59 break;
60
61 if (!is_dead(uses, instr.get())) {
62 for (const Operand& op : instr->operands) {
63 if (op.isTemp())
64 uses[op.tempId()]++;
65 }
66 }
67 }
68 }
69
70 } /* end namespace */
71
72 std::vector<uint16_t>
dead_code_analysis(Program * program)73 dead_code_analysis(Program* program)
74 {
75 std::vector<uint16_t> uses(program->peekAllocationId());
76
77 for (Block& block : program->blocks) {
78 if (block.kind & block_kind_loop_header)
79 process_loop_header_phis(uses, block);
80 }
81
82 for (auto it = program->blocks.rbegin(); it != program->blocks.rend(); it++)
83 process_block(uses, *it);
84
85 return uses;
86 }
87
88 } // namespace aco
89