1/*
2 * Copyright © 2014 Broadcom
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 * @file vc4_opt_small_immediates.c
26 *
27 * Turns references to small constant uniform values into small immediates
28 * fields.
29 */
30
31#include "vc4_qir.h"
32#include "vc4_qpu.h"
33
34static bool debug;
35
36bool
37qir_opt_small_immediates(struct vc4_compile *c)
38{
39        bool progress = false;
40
41        qir_for_each_inst_inorder(inst, c) {
42                /* The small immediate value sits in the raddr B field, so we
43                 * can't have 2 small immediates in one instruction (unless
44                 * they're the same value, but that should be optimized away
45                 * elsewhere).
46                 */
47                bool uses_small_imm = false;
48                for (int i = 0; i < qir_get_nsrc(inst); i++) {
49                        if (inst->src[i].file == QFILE_SMALL_IMM)
50                                uses_small_imm = true;
51                }
52                if (uses_small_imm)
53                        continue;
54
55                /* Don't propagate small immediates into the top-end bounds
56                 * checking for indirect UBO loads.  The kernel doesn't parse
57                 * small immediates and rejects the shader in this case.  UBO
58                 * loads are much more expensive than the uniform load, and
59                 * indirect UBO regions are usually much larger than a small
60                 * immediate, so it's not worth updating the kernel to allow
61                 * optimizing it.
62                 */
63                if (inst->op == QOP_MIN_NOIMM)
64                        continue;
65
66                for (int i = 0; i < qir_get_nsrc(inst); i++) {
67                        struct qreg src = qir_follow_movs(c, inst->src[i]);
68
69                        if (src.file != QFILE_UNIF ||
70                            src.pack ||
71                            c->uniform_contents[src.index] !=
72                            QUNIFORM_CONSTANT) {
73                                continue;
74                        }
75
76                        if (qir_is_tex(inst) &&
77                            i == qir_get_tex_uniform_src(inst)) {
78                                /* No turning the implicit uniform read into
79                                 * an immediate.
80                                 */
81                                continue;
82                        }
83
84                        uint32_t imm = c->uniform_data[src.index];
85                        uint32_t small_imm = qpu_encode_small_immediate(imm);
86                        if (small_imm == ~0)
87                                continue;
88
89                        if (debug) {
90                                fprintf(stderr, "opt_small_immediate() from: ");
91                                qir_dump_inst(c, inst);
92                                fprintf(stderr, "\n");
93                        }
94                        inst->src[i].file = QFILE_SMALL_IMM;
95                        inst->src[i].index = imm;
96                        if (debug) {
97                                fprintf(stderr, "to: ");
98                                qir_dump_inst(c, inst);
99                                fprintf(stderr, "\n");
100                        }
101                        progress = true;
102                        break;
103                }
104        }
105
106        return progress;
107}
108