src/gallium/drivers/freedreno/ir3/ir3_depth.c

   1 /* -*- mode: C; c-file-style: "k&r"; tab-width 4; indent-tabs-mode: t; -*- */
   2
   3 /*
   4  * Copyright (C) 2014 Rob Clark <robclark@freedesktop.org>
   5  *
   6  * Permission is hereby granted, free of charge, to any person obtaining a
   7  * copy of this software and associated documentation files (the "Software"),
   8  * to deal in the Software without restriction, including without limitation
   9  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
  10  * and/or sell copies of the Software, and to permit persons to whom the
  11  * Software is furnished to do so, subject to the following conditions:
  12  *
  13  * The above copyright notice and this permission notice (including the next
  14  * paragraph) shall be included in all copies or substantial portions of the
  15  * Software.
  16  *
  17  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  18  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  19  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  20  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  21  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  22  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  23  * SOFTWARE.
  24  *
  25  * Authors:
  26  *    Rob Clark <robclark@freedesktop.org>
  27  */
  28
  29 #include "util/u_math.h"
  30
  31 #include "ir3.h"
  32
  33 /*
  34  * Instruction Depth:
  35  *
  36  * Calculates weighted instruction depth, ie. the sum of # of needed
  37  * instructions plus delay slots back to original input (ie INPUT or
  38  * CONST).  That is to say, an instructions depth is:
  39  *
  40  *   depth(instr) {
  41  *     d = 0;
  42  *     // for each src register:
  43  *     foreach (src in instr->regs[1..n])
  44  *       d = max(d, delayslots(src->instr, n) + depth(src->instr));
  45  *     return d + 1;
  46  *   }
  47  *
  48  * After an instruction's depth is calculated, it is inserted into the
  49  * blocks depth sorted list, which is used by the scheduling pass.
  50  */
  51
  52 /* calculate required # of delay slots between the instruction that
  53  * assigns a value and the one that consumes
  54  */
  55 int ir3_delayslots(struct ir3_instruction *assigner,
  56                 struct ir3_instruction *consumer, unsigned n)
  57 {
  58         /* worst case is cat1-3 (alu) -> cat4/5 needing 6 cycles, normal
  59          * alu -> alu needs 3 cycles, cat4 -> alu and texture fetch
  60          * handled with sync bits
  61          */
  62
  63         if (is_meta(assigner))
  64                 return 0;
  65
  66         if (writes_addr(assigner))
  67                 return 6;
  68
  69         /* handled via sync flags: */
  70         if (is_sfu(assigner) || is_tex(assigner) || is_mem(assigner))
  71                 return 0;
  72
  73         /* assigner must be alu: */
  74         if (is_flow(consumer) || is_sfu(consumer) || is_tex(consumer) ||
  75                         is_mem(consumer)) {
  76                 return 6;
  77         } else if ((consumer->category == 3) &&
  78                         (is_mad(consumer->opc) || is_madsh(consumer->opc)) &&
  79                         (n == 2)) {
  80                 /* special case, 3rd src to cat3 not required on first cycle */
  81                 return 1;
  82         } else {
  83                 return 3;
  84         }
  85 }
  86
  87 void
  88 ir3_insert_by_depth(struct ir3_instruction *instr, struct list_head *list)
  89 {
  90         /* remove from existing spot in list: */
  91         list_delinit(&instr->node);
  92
  93         /* find where to re-insert instruction: */
  94         list_for_each_entry (struct ir3_instruction, pos, list, node) {
  95                 if (pos->depth > instr->depth) {
  96                         list_add(&instr->node, &pos->node);
  97                         return;
  98                 }
  99         }
 100         /* if we get here, we didn't find an insertion spot: */
 101         list_addtail(&instr->node, list);
 102 }
 103
 104 static void
 105 ir3_instr_depth(struct ir3_instruction *instr)
 106 {
 107         struct ir3_instruction *src;
 108
 109         /* if we've already visited this instruction, bail now: */
 110         if (ir3_instr_check_mark(instr))
 111                 return;
 112
 113         instr->depth = 0;
 114
 115         foreach_ssa_src_n(src, i, instr) {
 116                 unsigned sd;
 117
 118                 /* visit child to compute it's depth: */
 119                 ir3_instr_depth(src);
 120
 121                 sd = ir3_delayslots(src, instr, i) + src->depth;
 122
 123                 instr->depth = MAX2(instr->depth, sd);
 124         }
 125
 126         if (!is_meta(instr))
 127                 instr->depth++;
 128
 129         ir3_insert_by_depth(instr, &instr->block->instr_list);
 130 }
 131
 132 static void
 133 remove_unused_by_block(struct ir3_block *block)
 134 {
 135         list_for_each_entry_safe (struct ir3_instruction, instr, &block->instr_list, node) {
 136                 if (!ir3_instr_check_mark(instr)) {
 137                         if (is_flow(instr) && (instr->opc == OPC_END))
 138                                 continue;
 139                         /* mark it, in case it is input, so we can
 140                          * remove unused inputs:
 141                          */
 142                         instr->depth = DEPTH_UNUSED;
 143                         /* and remove from instruction list: */
 144                         list_delinit(&instr->node);
 145                 }
 146         }
 147 }
 148
 149 void
 150 ir3_depth(struct ir3 *ir)
 151 {
 152         unsigned i;
 153
 154         ir3_clear_mark(ir);
 155         for (i = 0; i < ir->noutputs; i++)
 156                 if (ir->outputs[i])
 157                         ir3_instr_depth(ir->outputs[i]);
 158
 159         for (i = 0; i < ir->keeps_count; i++)
 160                 ir3_instr_depth(ir->keeps[i]);
 161
 162         /* We also need to account for if-condition: */
 163         list_for_each_entry (struct ir3_block, block, &ir->block_list, node) {
 164                 if (block->condition)
 165                         ir3_instr_depth(block->condition);
 166         }
 167
 168         /* mark un-used instructions: */
 169         list_for_each_entry (struct ir3_block, block, &ir->block_list, node) {
 170                 remove_unused_by_block(block);
 171         }
 172
 173         /* note that we can end up with unused indirects, but we should
 174          * not end up with unused predicates.
 175          */
 176         for (i = 0; i < ir->indirects_count; i++) {
 177                 struct ir3_instruction *instr = ir->indirects[i];
 178                 if (instr->depth == DEPTH_UNUSED)
 179                         ir->indirects[i] = NULL;
 180         }
 181
 182         /* cleanup unused inputs: */
 183         for (i = 0; i < ir->ninputs; i++) {
 184                 struct ir3_instruction *in = ir->inputs[i];
 185                 if (in && (in->depth == DEPTH_UNUSED))
 186                         ir->inputs[i] = NULL;
 187         }
 188 }