src/panfrost/bifrost/bi_ra.c

   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
  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 *
  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
  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
 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
 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
 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
 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 }