src/gallium/drivers/vc4/vc4_qir_lower_uniforms.c

   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_algebraic.c
  26  *
  27  * This is the optimization pass for miscellaneous changes to instructions
  28  * where we can simplify the operation by some knowledge about the specific
  29  * operations.
  30  *
  31  * Mostly this will be a matter of turning things into MOVs so that they can
  32  * later be copy-propagated out.
  33  */
  34
  35 #include "vc4_qir.h"
  36 #include "util/hash_table.h"
  37 #include "util/u_math.h"
  38
  39 static inline uint32_t
  40 index_hash(const void *key)
  41 {
  42         return (uintptr_t)key;
  43 }
  44
  45 static inline bool
  46 index_compare(const void *a, const void *b)
  47 {
  48         return a == b;
  49 }
  50
  51 static void
  52 add_uniform(struct hash_table *ht, struct qreg reg)
  53 {
  54         struct hash_entry *entry;
  55         void *key = (void *)(uintptr_t)(reg.index + 1);
  56
  57         entry = _mesa_hash_table_search(ht, key);
  58         if (entry) {
  59                 entry->data++;
  60         } else {
  61                 _mesa_hash_table_insert(ht, key, (void *)(uintptr_t)1);
  62         }
  63 }
  64
  65 static void
  66 remove_uniform(struct hash_table *ht, struct qreg reg)
  67 {
  68         struct hash_entry *entry;
  69         void *key = (void *)(uintptr_t)(reg.index + 1);
  70
  71         entry = _mesa_hash_table_search(ht, key);
  72         assert(entry);
  73         entry->data--;
  74         if (entry->data == NULL)
  75                 _mesa_hash_table_remove(ht, entry);
  76 }
  77
  78 static bool
  79 is_lowerable_uniform(struct qinst *inst, int i)
  80 {
  81         if (inst->src[i].file != QFILE_UNIF)
  82                 return false;
  83         if (qir_is_tex(inst))
  84                 return i != 1;
  85         return true;
  86 }
  87
  88 void
  89 qir_lower_uniforms(struct vc4_compile *c)
  90 {
  91         struct hash_table *ht =
  92                 _mesa_hash_table_create(c, index_hash, index_compare);
  93
  94         /* Walk the instruction list, finding which instructions have more
  95          * than one uniform referenced, and add those uniform values to the
  96          * ht.
  97          */
  98         list_for_each_entry(struct qinst, inst, &c->instructions, link) {
  99                 uint32_t nsrc = qir_get_op_nsrc(inst->op);
 100
 101                 uint32_t count = 0;
 102                 for (int i = 0; i < nsrc; i++) {
 103                         if (inst->src[i].file == QFILE_UNIF)
 104                                 count++;
 105                 }
 106
 107                 if (count <= 1)
 108                         continue;
 109
 110                 for (int i = 0; i < nsrc; i++) {
 111                         if (is_lowerable_uniform(inst, i))
 112                                 add_uniform(ht, inst->src[i]);
 113                 }
 114         }
 115
 116         while (ht->entries) {
 117                 /* Find the most commonly used uniform in instructions that
 118                  * need a uniform lowered.
 119                  */
 120                 uint32_t max_count = 0;
 121                 uint32_t max_index = 0;
 122                 struct hash_entry *entry;
 123                 hash_table_foreach(ht, entry) {
 124                         uint32_t count = (uintptr_t)entry->data;
 125                         uint32_t index = (uintptr_t)entry->key - 1;
 126                         if (count > max_count) {
 127                                 max_count = count;
 128                                 max_index = index;
 129                         }
 130                 }
 131
 132                 /* Now, find the instructions using this uniform and make them
 133                  * reference a temp instead.
 134                  */
 135                 struct qreg temp = qir_get_temp(c);
 136                 struct qreg unif = { QFILE_UNIF, max_index };
 137                 struct qinst *mov = qir_inst(QOP_MOV, temp, unif, c->undef);
 138                 list_add(&mov->link, &c->instructions);
 139                 c->defs[temp.index] = mov;
 140                 list_for_each_entry(struct qinst, inst, &c->instructions, link) {
 141                         uint32_t nsrc = qir_get_op_nsrc(inst->op);
 142
 143                         uint32_t count = 0;
 144                         for (int i = 0; i < nsrc; i++) {
 145                                 if (inst->src[i].file == QFILE_UNIF)
 146                                         count++;
 147                         }
 148
 149                         if (count <= 1)
 150                                 continue;
 151
 152                         for (int i = 0; i < nsrc; i++) {
 153                                 if (is_lowerable_uniform(inst, i) &&
 154                                     inst->src[i].index == max_index) {
 155                                         inst->src[i] = temp;
 156                                         remove_uniform(ht, unif);
 157                                         count--;
 158                                 }
 159                         }
 160
 161                         /* If the instruction doesn't need lowering any more,
 162                          * then drop it from the list.
 163                          */
 164                         if (count <= 1) {
 165                                 for (int i = 0; i < nsrc; i++) {
 166                                         if (is_lowerable_uniform(inst, i))
 167                                                 remove_uniform(ht, inst->src[i]);
 168                                 }
 169                         }
 170                 }
 171         }
 172
 173         _mesa_hash_table_destroy(ht, NULL);
 174 }