1/*
2 * Copyright © 2015 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_constant_folding.c
26 *
27 * Simple constant folding pass to clean up operations on only constants,
28 * which we might have generated within vc4_program.c.
29 */
30
31#include "vc4_qir.h"
32#include "util/u_math.h"
33
34static bool debug;
35
36static void
37dump_from(struct vc4_compile *c, struct qinst *inst)
38{
39        if (!debug)
40                return;
41
42        fprintf(stderr, "optimizing: ");
43        qir_dump_inst(c, inst);
44        fprintf(stderr, "\n");
45}
46
47static void
48dump_to(struct vc4_compile *c, struct qinst *inst)
49{
50        if (!debug)
51                return;
52
53        fprintf(stderr, "to: ");
54        qir_dump_inst(c, inst);
55        fprintf(stderr, "\n");
56}
57
58static bool
59constant_fold(struct vc4_compile *c, struct qinst *inst)
60{
61        int nsrc = qir_get_nsrc(inst);
62        uint32_t ui[nsrc];
63
64        for (int i = 0; i < nsrc; i++) {
65                struct qreg reg = inst->src[i];
66                if (reg.file == QFILE_UNIF &&
67                    c->uniform_contents[reg.index] == QUNIFORM_CONSTANT) {
68                        ui[i] = c->uniform_data[reg.index];
69                } else if (reg.file == QFILE_SMALL_IMM) {
70                        ui[i] = reg.index;
71                } else {
72                        return false;
73                }
74        }
75
76        uint32_t result = 0;
77        switch (inst->op) {
78        case QOP_SHR:
79                result = ui[0] >> ui[1];
80                break;
81
82        default:
83                return false;
84        }
85
86        dump_from(c, inst);
87
88        inst->src[0] = qir_uniform_ui(c, result);
89        for (int i = 1; i < nsrc; i++)
90                inst->src[i] = c->undef;
91        inst->op = QOP_MOV;
92
93        dump_to(c, inst);
94        return true;
95}
96
97bool
98qir_opt_constant_folding(struct vc4_compile *c)
99{
100        bool progress = false;
101
102        qir_for_each_inst_inorder(inst, c) {
103                if (constant_fold(c, inst))
104                        progress = true;
105        }
106
107        return progress;
108}
109