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 ((is_mad(consumer->opc) || is_madsh(consumer->opc)) &&
  78                         (n == 3)) {
  79                 /* special case, 3rd src to cat3 not required on first cycle */
  80                 return 1;
  81         } else {
  82                 return 3;
  83         }
  84 }
  85
  86 void
  87 ir3_insert_by_depth(struct ir3_instruction *instr, struct list_head *list)
  88 {
  89         /* remove from existing spot in list: */
  90         list_delinit(&instr->node);
  91
  92         /* find where to re-insert instruction: */
  93         list_for_each_entry (struct ir3_instruction, pos, list, node) {
  94                 if (pos->depth > instr->depth) {
  95                         list_add(&instr->node, &pos->node);
  96                         return;
  97                 }
  98         }
  99         /* if we get here, we didn't find an insertion spot: */
 100         list_addtail(&instr->node, list);
 101 }
 102
 103 static void
 104 ir3_instr_depth(struct ir3_instruction *instr)
 105 {
 106         struct ir3_instruction *src;
 107
 108         /* if we've already visited this instruction, bail now: */
 109         if (ir3_instr_check_mark(instr))
 110                 return;
 111
 112         instr->depth = 0;
 113
 114         foreach_ssa_src_n(src, i, instr) {
 115                 unsigned sd;
 116
 117                 /* visit child to compute it's depth: */
 118                 ir3_instr_depth(src);
 119
 120                 /* for array writes, no need to delay on previous write: */
 121                 if (i == 0)
 122                         continue;
 123
 124                 sd = ir3_delayslots(src, instr, i) + src->depth;
 125
 126                 instr->depth = MAX2(instr->depth, sd);
 127         }
 128
 129         if (!is_meta(instr))
 130                 instr->depth++;
 131
 132         ir3_insert_by_depth(instr, &instr->block->instr_list);
 133 }
 134
 135 static void
 136 remove_unused_by_block(struct ir3_block *block)
 137 {
 138         list_for_each_entry_safe (struct ir3_instruction, instr, &block->instr_list, node) {
 139                 if (!ir3_instr_check_mark(instr)) {
 140                         if (is_flow(instr) && (instr->opc == OPC_END))
 141                                 continue;
 142                         /* mark it, in case it is input, so we can
 143                          * remove unused inputs:
 144                          */
 145                         instr->flags |= IR3_INSTR_UNUSED;
 146                         /* and remove from instruction list: */
 147                         list_delinit(&instr->node);
 148                 }
 149         }
 150 }
 151
 152 void
 153 ir3_depth(struct ir3 *ir)
 154 {
 155         unsigned i;
 156
 157         ir3_clear_mark(ir);
 158         for (i = 0; i < ir->noutputs; i++)
 159                 if (ir->outputs[i])
 160                         ir3_instr_depth(ir->outputs[i]);
 161
 162         for (i = 0; i < ir->keeps_count; i++)
 163                 ir3_instr_depth(ir->keeps[i]);
 164
 165         /* We also need to account for if-condition: */
 166         list_for_each_entry (struct ir3_block, block, &ir->block_list, node) {
 167                 if (block->condition)
 168                         ir3_instr_depth(block->condition);
 169         }
 170
 171         /* mark un-used instructions: */
 172         list_for_each_entry (struct ir3_block, block, &ir->block_list, node) {
 173                 remove_unused_by_block(block);
 174         }
 175
 176         /* note that we can end up with unused indirects, but we should
 177          * not end up with unused predicates.
 178          */
 179         for (i = 0; i < ir->indirects_count; i++) {
 180                 struct ir3_instruction *instr = ir->indirects[i];
 181                 if (instr->flags & IR3_INSTR_UNUSED)
 182                         ir->indirects[i] = NULL;
 183         }
 184
 185         /* cleanup unused inputs: */
 186         for (i = 0; i < ir->ninputs; i++) {
 187                 struct ir3_instruction *in = ir->inputs[i];
 188                 if (in && (in->flags & IR3_INSTR_UNUSED))
 189                         ir->inputs[i] = NULL;
 190         }
 191 }