2 * Copyright © 2014 Broadcom
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:
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
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
25 * @file vc4_opt_dead_code.c
27 * This is a simmple dead code eliminator for QIR with no control flow.
29 * It walks from the bottom of the instruction list, removing instructions
30 * with a destination that is never used, and marking the sources of non-dead
31 * instructions as used.
37 qir_opt_dead_code(struct vc4_compile
*c
)
39 bool progress
= false;
41 bool *used
= calloc(c
->num_temps
, sizeof(bool));
43 struct simple_node
*node
, *t
;
44 for (node
= c
->instructions
.prev
, t
= node
->prev
;
45 &c
->instructions
!= node
;
46 node
= t
, t
= t
->prev
) {
47 struct qinst
*inst
= (struct qinst
*)node
;
49 if (inst
->dst
.file
== QFILE_TEMP
&&
50 !used
[inst
->dst
.index
] &&
51 !qir_has_side_effects(inst
)) {
53 fprintf(stderr
, "Removing: ");
54 qir_dump_inst(c
, inst
);
55 fprintf(stderr
, "\n");
57 qir_remove_instruction(inst
);
62 for (int i
= 0; i
< qir_get_op_nsrc(inst
->op
); i
++) {
63 if (inst
->src
[i
].file
== QFILE_TEMP
)
64 used
[inst
->src
[i
].index
] = true;