1 /*
2 * Copyright © 2013 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 DEALINGS
21 * IN THE SOFTWARE.
22 */
23
24 #include "brw_fs.h"
25 #include "brw_fs_live_variables.h"
26 #include "brw_cfg.h"
27
28 using namespace brw;
29
30 /** @file brw_fs_saturate_propagation.cpp
31 *
32 * Implements a pass that propagates the SAT modifier from a MOV.SAT into the
33 * instruction that produced the source of the MOV.SAT, thereby allowing the
34 * MOV's src and dst to be coalesced and the MOV removed.
35 *
36 * For instance,
37 *
38 * ADD tmp, src0, src1
39 * MOV.SAT dst, tmp
40 *
41 * would be transformed into
42 *
43 * ADD.SAT tmp, src0, src1
44 * MOV dst, tmp
45 */
46
47 static bool
opt_saturate_propagation_local(const fs_live_variables & live,bblock_t * block)48 opt_saturate_propagation_local(const fs_live_variables &live, bblock_t *block)
49 {
50 bool progress = false;
51 int ip = block->end_ip + 1;
52
53 foreach_inst_in_block_reverse(fs_inst, inst, block) {
54 ip--;
55
56 if (inst->opcode != BRW_OPCODE_MOV ||
57 !inst->saturate ||
58 inst->dst.file != VGRF ||
59 inst->dst.type != inst->src[0].type ||
60 inst->src[0].file != VGRF ||
61 inst->src[0].abs)
62 continue;
63
64 int src_var = live.var_from_reg(inst->src[0]);
65 int src_end_ip = live.end[src_var];
66
67 bool interfered = false;
68 foreach_inst_in_block_reverse_starting_from(fs_inst, scan_inst, inst) {
69 if (scan_inst->exec_size == inst->exec_size &&
70 regions_overlap(scan_inst->dst, scan_inst->size_written,
71 inst->src[0], inst->size_read(0))) {
72 if (scan_inst->is_partial_write() ||
73 (scan_inst->dst.type != inst->dst.type &&
74 !scan_inst->can_change_types()))
75 break;
76
77 if (scan_inst->saturate) {
78 inst->saturate = false;
79 progress = true;
80 } else if (src_end_ip == ip || inst->dst.equals(inst->src[0])) {
81 if (scan_inst->can_do_saturate()) {
82 if (scan_inst->dst.type != inst->dst.type) {
83 scan_inst->dst.type = inst->dst.type;
84 for (int i = 0; i < scan_inst->sources; i++) {
85 scan_inst->src[i].type = inst->dst.type;
86 }
87 }
88
89 if (inst->src[0].negate) {
90 if (scan_inst->opcode == BRW_OPCODE_MUL) {
91 scan_inst->src[0].negate = !scan_inst->src[0].negate;
92 inst->src[0].negate = false;
93 } else if (scan_inst->opcode == BRW_OPCODE_MAD) {
94 for (int i = 0; i < 2; i++) {
95 if (scan_inst->src[i].file == IMM) {
96 brw_negate_immediate(scan_inst->src[i].type,
97 &scan_inst->src[i].as_brw_reg());
98 } else {
99 scan_inst->src[i].negate = !scan_inst->src[i].negate;
100 }
101 }
102 inst->src[0].negate = false;
103 } else if (scan_inst->opcode == BRW_OPCODE_ADD) {
104 if (scan_inst->src[1].file == IMM) {
105 if (!brw_negate_immediate(scan_inst->src[1].type,
106 &scan_inst->src[1].as_brw_reg())) {
107 break;
108 }
109 } else {
110 scan_inst->src[1].negate = !scan_inst->src[1].negate;
111 }
112 scan_inst->src[0].negate = !scan_inst->src[0].negate;
113 inst->src[0].negate = false;
114 } else {
115 break;
116 }
117 }
118
119 scan_inst->saturate = true;
120 inst->saturate = false;
121 progress = true;
122 }
123 }
124 break;
125 }
126 for (int i = 0; i < scan_inst->sources; i++) {
127 if (scan_inst->src[i].file == VGRF &&
128 scan_inst->src[i].nr == inst->src[0].nr &&
129 scan_inst->src[i].offset / REG_SIZE ==
130 inst->src[0].offset / REG_SIZE) {
131 if (scan_inst->opcode != BRW_OPCODE_MOV ||
132 !scan_inst->saturate ||
133 scan_inst->src[0].abs ||
134 scan_inst->src[0].negate ||
135 scan_inst->src[0].abs != inst->src[0].abs ||
136 scan_inst->src[0].negate != inst->src[0].negate) {
137 interfered = true;
138 break;
139 }
140 }
141 }
142
143 if (interfered)
144 break;
145 }
146 }
147
148 return progress;
149 }
150
151 bool
opt_saturate_propagation()152 fs_visitor::opt_saturate_propagation()
153 {
154 const fs_live_variables &live = live_analysis.require();
155 bool progress = false;
156
157 foreach_block (block, cfg) {
158 progress = opt_saturate_propagation_local(live, block) || progress;
159 }
160
161 /* Live intervals are still valid. */
162
163 return progress;
164 }
165