1 /*
2 * Copyright (C) 2018 Alyssa Rosenzweig
3 * Copyright (C) 2019-2020 Collabora, Ltd.
4 *
5 * Permission is hereby granted, free of charge, to any person obtaining a
6 * copy of this software and associated documentation files (the "Software"),
7 * to deal in the Software without restriction, including without limitation
8 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
9 * and/or sell copies of the Software, and to permit persons to whom the
10 * Software is furnished to do so, subject to the following conditions:
11 *
12 * The above copyright notice and this permission notice (including the next
13 * paragraph) shall be included in all copies or substantial portions of the
14 * Software.
15 *
16 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
17 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
18 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
19 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
20 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
21 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
22 * SOFTWARE.
23 */
24
25 #include "compiler.h"
26 #include "bi_builder.h"
27
28 /* A simple scalar-only SSA-based copy-propagation pass. TODO: vectors */
29
30 static bool
bi_is_copy(bi_instr * ins)31 bi_is_copy(bi_instr *ins)
32 {
33 return (ins->op == BI_OPCODE_MOV_I32) && bi_is_ssa(ins->dest[0])
34 && (bi_is_ssa(ins->src[0]) || ins->src[0].type == BI_INDEX_FAU
35 || ins->src[0].type == BI_INDEX_CONSTANT);
36 }
37
38 static bool
bi_reads_fau(bi_instr * ins)39 bi_reads_fau(bi_instr *ins)
40 {
41 bi_foreach_src(ins, s) {
42 if (ins->src[s].type == BI_INDEX_FAU)
43 return true;
44 }
45
46 return false;
47 }
48
49 void
bi_opt_copy_prop(bi_context * ctx)50 bi_opt_copy_prop(bi_context *ctx)
51 {
52 /* Chase SPLIT of COLLECT. Instruction selection usually avoids this
53 * pattern (due to the split cache), but it is inevitably generated by
54 * the UBO pushing pass.
55 */
56 bi_instr **collects = calloc(sizeof(bi_instr *), ctx->ssa_alloc);
57 bi_foreach_instr_global_safe(ctx, I) {
58 if (I->op == BI_OPCODE_COLLECT_I32) {
59 /* Rewrite trivial collects while we're at it */
60 if (I->nr_srcs == 1)
61 I->op = BI_OPCODE_MOV_I32;
62
63 if (bi_is_ssa(I->dest[0]))
64 collects[I->dest[0].value] = I;
65 } else if (I->op == BI_OPCODE_SPLIT_I32) {
66 /* Rewrite trivial splits while we're at it */
67 if (I->nr_dests == 1)
68 I->op = BI_OPCODE_MOV_I32;
69
70 if (!bi_is_ssa(I->src[0]))
71 continue;
72
73 bi_instr *collect = collects[I->src[0].value];
74 if (!collect)
75 continue;
76
77 /* Lower the split to moves, copyprop cleans up */
78 bi_builder b = bi_init_builder(ctx, bi_before_instr(I));
79
80 for (unsigned d = 0; d < I->nr_dests; ++d)
81 bi_mov_i32_to(&b, I->dest[d], collect->src[d]);
82
83 bi_remove_instruction(I);
84 }
85 }
86
87 free(collects);
88
89 bi_index *replacement = calloc(sizeof(bi_index), ctx->ssa_alloc);
90
91 bi_foreach_instr_global_safe(ctx, ins) {
92 if (bi_is_copy(ins)) {
93 bi_index replace = ins->src[0];
94
95 /* Peek through one layer so copyprop converges in one
96 * iteration for chained moves */
97 if (bi_is_ssa(replace)) {
98 bi_index chained = replacement[replace.value];
99
100 if (!bi_is_null(chained))
101 replace = chained;
102 }
103
104 replacement[ins->dest[0].value] = replace;
105 }
106
107 bi_foreach_src(ins, s) {
108 bi_index use = ins->src[s];
109
110 if (use.type != BI_INDEX_NORMAL || use.reg) continue;
111 if (bi_is_staging_src(ins, s)) continue;
112
113 bi_index repl = replacement[use.value];
114
115 if (repl.type == BI_INDEX_CONSTANT && bi_reads_fau(ins))
116 continue;
117
118 if (!bi_is_null(repl))
119 ins->src[s] = bi_replace_index(ins->src[s], repl);
120 }
121 }
122
123 free(replacement);
124 }
125