1/*
2 * Copyright © 2022 Imagination Technologies Ltd.
3 *
4 * Permission is hereby granted, free of charge, to any person obtaining a copy
5 * of this software and associated documentation files (the "Software"), to deal
6 * in the Software without restriction, including without limitation the rights
7 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
8 * copies of the Software, and to permit persons to whom the Software is
9 * 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 THE
18 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
19 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
20 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
21 * SOFTWARE.
22 */
23
24#include "nir/nir.h"
25#include "nir/nir_builder.h"
26#include "nir/nir_search_helpers.h"
27#include "rogue_constreg.h"
28#include "rogue_nir.h"
29
30/* TODO: optimize: if value is in const regs, replace, else, use shared regs and
31 * notify driver they need to be populated?
32 */
33
34/* Replaces multiple ssa uses from load_const with a single use -> a register.
35 */
36void rogue_nir_constreg(nir_shader *shader)
37{
38   nir_function_impl *impl = nir_shader_get_entrypoint(shader);
39   nir_builder b;
40
41   nir_builder_init(&b, impl);
42
43   /* Find load_const instructions. */
44   nir_foreach_block (block, impl) {
45      nir_foreach_instr_safe (instr, block) {
46         if (instr->type != nir_instr_type_load_const)
47            continue;
48
49         nir_load_const_instr *load_const = nir_instr_as_load_const(instr);
50
51         /* Skip values that can be pulled from constant registers. */
52         uint32_t value = nir_const_value_as_uint(load_const->value[0], 32);
53         size_t const_reg = rogue_constreg_lookup(value);
54         if (const_reg != ROGUE_NO_CONST_REG)
55            continue;
56
57         b.cursor = nir_after_instr(&load_const->instr);
58         nir_ssa_def *mov = nir_mov(&b, &load_const->def);
59
60         nir_foreach_use_safe (use_src, &load_const->def) {
61            if (use_src->parent_instr == mov->parent_instr)
62               continue;
63
64            /* Skip when used as an index for intrinsics, as we want to
65             * access that value directly.
66             */
67            if (use_src->parent_instr->type == nir_instr_type_intrinsic)
68               continue;
69
70            nir_instr_rewrite_src_ssa(use_src->parent_instr, use_src, mov);
71         }
72      }
73   }
74}
75