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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 
34 static bool debug;
35 
36 bool
qir_opt_small_immediates(struct vc4_compile * c)37 qir_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