1 /*
2 * Copyright (C) 2020 Collabora Ltd.
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 FROM,
20 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
21 * SOFTWARE.
22 *
23 * Authors (Collabora):
24 * Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
25 */
26
27 #include "compiler.h"
28 #include "bi_print.h"
29 #include "panfrost/util/lcra.h"
30 #include "util/u_memory.h"
31
32 static void
bi_compute_interference(bi_context * ctx,struct lcra_state * l)33 bi_compute_interference(bi_context *ctx, struct lcra_state *l)
34 {
35 bi_compute_liveness(ctx);
36
37 bi_foreach_block(ctx, _blk) {
38 bi_block *blk = (bi_block *) _blk;
39 uint16_t *live = mem_dup(_blk->live_out, l->node_count * sizeof(uint16_t));
40
41 bi_foreach_instr_in_block_rev(blk, ins) {
42 /* Mark all registers live after the instruction as
43 * interfering with the destination */
44
45 if (ins->dest && (ins->dest < l->node_count)) {
46 for (unsigned i = 1; i < l->node_count; ++i) {
47 if (live[i])
48 lcra_add_node_interference(l, ins->dest, bi_writemask(ins), i, live[i]);
49 }
50 }
51
52 /* Update live_in */
53 bi_liveness_ins_update(live, ins, l->node_count);
54 }
55
56 free(live);
57 }
58 }
59
60 enum {
61 BI_REG_CLASS_WORK = 0,
62 } bi_reg_class;
63
64 static struct lcra_state *
bi_allocate_registers(bi_context * ctx,bool * success)65 bi_allocate_registers(bi_context *ctx, bool *success)
66 {
67 unsigned node_count = bi_max_temp(ctx);
68
69 struct lcra_state *l =
70 lcra_alloc_equations(node_count, 1);
71
72 l->class_start[BI_REG_CLASS_WORK] = 0;
73 l->class_size[BI_REG_CLASS_WORK] = 64 * 4; /* R0 - R63, all 32-bit */
74
75 bi_foreach_instr_global(ctx, ins) {
76 unsigned dest = ins->dest;
77
78 if (!dest || (dest >= node_count))
79 continue;
80
81 l->class[dest] = BI_REG_CLASS_WORK;
82 lcra_set_alignment(l, dest, 2, 16); /* 2^2 = 4 */
83 lcra_restrict_range(l, dest, 4);
84 }
85
86 bi_compute_interference(ctx, l);
87
88 *success = lcra_solve(l);
89
90 return l;
91 }
92
93 static unsigned
bi_reg_from_index(struct lcra_state * l,unsigned index,unsigned offset)94 bi_reg_from_index(struct lcra_state *l, unsigned index, unsigned offset)
95 {
96 /* Did we run RA for this index at all */
97 if (index >= l->node_count)
98 return index;
99
100 /* LCRA didn't bother solving this index (how lazy!) */
101 signed solution = l->solutions[index];
102 if (solution < 0)
103 return index;
104
105 assert((solution & 0x3) == 0);
106 unsigned reg = solution / 4;
107 reg += offset;
108
109 return BIR_INDEX_REGISTER | reg;
110 }
111
112 static void
bi_adjust_src_ra(bi_instruction * ins,struct lcra_state * l,unsigned src)113 bi_adjust_src_ra(bi_instruction *ins, struct lcra_state *l, unsigned src)
114 {
115 if (ins->src[src] >= l->node_count)
116 return;
117
118 bool vector = (bi_class_props[ins->type] & BI_VECTOR) && src == 0;
119 unsigned offset = 0;
120
121 if (vector) {
122 /* TODO: Do we do anything here? */
123 } else {
124 /* Use the swizzle as component select */
125 unsigned components = bi_get_component_count(ins, src);
126
127 nir_alu_type T = ins->src_types[src];
128 unsigned size = nir_alu_type_get_type_size(T);
129
130 /* TODO: 64-bit? */
131 unsigned components_per_word = MAX2(32 / size, 1);
132
133 for (unsigned i = 0; i < components; ++i) {
134 unsigned off = ins->swizzle[src][i] / components_per_word;
135
136 /* We can't cross register boundaries in a swizzle */
137 if (i == 0)
138 offset = off;
139 else
140 assert(off == offset);
141
142 ins->swizzle[src][i] %= components_per_word;
143 }
144 }
145
146 ins->src[src] = bi_reg_from_index(l, ins->src[src], offset);
147 }
148
149 static void
bi_adjust_dest_ra(bi_instruction * ins,struct lcra_state * l)150 bi_adjust_dest_ra(bi_instruction *ins, struct lcra_state *l)
151 {
152 if (ins->dest >= l->node_count)
153 return;
154
155 ins->dest = bi_reg_from_index(l, ins->dest, ins->dest_offset);
156 ins->dest_offset = 0;
157 }
158
159 static void
bi_install_registers(bi_context * ctx,struct lcra_state * l)160 bi_install_registers(bi_context *ctx, struct lcra_state *l)
161 {
162 bi_foreach_instr_global(ctx, ins) {
163 bi_adjust_dest_ra(ins, l);
164
165 bi_foreach_src(ins, s)
166 bi_adjust_src_ra(ins, l, s);
167 }
168 }
169
170 void
bi_register_allocate(bi_context * ctx)171 bi_register_allocate(bi_context *ctx)
172 {
173 struct lcra_state *l = NULL;
174 bool success = false;
175
176 do {
177 if (l) {
178 lcra_free(l);
179 l = NULL;
180 }
181
182 bi_invalidate_liveness(ctx);
183 l = bi_allocate_registers(ctx, &success);
184
185 /* TODO: Spilling */
186 assert(success);
187 } while(!success);
188
189 bi_install_registers(ctx, l);
190
191 lcra_free(l);
192 }
193