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