src/panfrost/util/nir_mod_helpers.c

   1 /*
   2  * Copyright (C) 2020 Collabora, Ltd.
   3  * Copyright (C) 2014 Intel Corporation
   4  *
   5  * Permission is hereby granted, free of charge, to any person obtaining a
   6  * copy of this software and associated documentation files (the "Software"),
   7  * to deal in the Software without restriction, including without limitation
   8  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
   9  * and/or sell copies of the Software, and to permit persons to whom the
  10  * Software is furnished to do so, subject to the following conditions:
  11  *
  12  * The above copyright notice and this permission notice (including the next
  13  * paragraph) shall be included in all copies or substantial portions of the
  14  * Software.
  15  *
  16  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  17  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  18  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  19  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  20  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  21  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
  22  * IN THE SOFTWARE.
  23  *
  24  * Authors:
  25  *    Alyssa Rosenzweig <alyssa@collabora.com>
  26  *    Jason Ekstrand (jason@jlekstrand.net)
  27  *
  28  */
  29
  30 #include "nir.h"
  31 #include "pan_ir.h"
  32
  33 /* Check if a given ALU source is the result of a particular componentwise 1-op
  34  * ALU source (principally fneg or fabs). If so, return true and rewrite the
  35  * source to be the argument, respecting swizzles as needed. If not (or it
  36  * cannot be proven), return false and leave the source untouched.
  37 */
  38
  39 bool
  40 pan_has_source_mod(nir_alu_src *src, nir_op op)
  41 {
  42    if (!src->src.is_ssa || src->src.ssa->parent_instr->type != nir_instr_type_alu)
  43       return false;
  44
  45    nir_alu_instr *alu = nir_instr_as_alu(src->src.ssa->parent_instr);
  46
  47    if (alu->op != op)
  48       return false;
  49
  50    /* This only works for unary ops */
  51    assert(nir_op_infos[op].num_inputs == 1);
  52
  53    /* If the copied source is not SSA, moving it might not be valid */
  54    if (!alu->src[0].src.is_ssa)
  55       return false;
  56
  57    /* Okay - we've found the modifier we wanted. Let's construct the new ALU
  58     * src. In a scalar world, this is just psrc, but for vector archs we need
  59     * to respect the swizzle, so we compose.
  60     */
  61
  62    nir_alu_src nsrc = {
  63       .src = alu->src[0].src,
  64    };
  65
  66    for (unsigned i = 0; i < NIR_MAX_VEC_COMPONENTS; ++i) {
  67       /* (a o b)(i) = a(b(i)) ... swizzle composition is intense. */
  68       nsrc.swizzle[i] = alu->src[0].swizzle[src->swizzle[i]];
  69    }
  70
  71    *src = nsrc;
  72    return true;
  73 }
  74
  75 /* Check if a given instruction's result will be fed into a
  76  * componentwise 1-op ALU instruction (principally fsat without
  77  * swizzles). If so, return true and rewrite the destination. The
  78  * backend will need to track the new destinations to avoid
  79  * incorrect double-emits. */
  80
  81 bool
  82 pan_has_dest_mod(nir_dest **odest, nir_op op)
  83 {
  84    /* This only works for unary ops */
  85    assert(nir_op_infos[op].num_inputs == 1);
  86
  87    /* If not SSA, this might not be legal */
  88    nir_dest *dest = *odest;
  89    if (!dest->is_ssa)
  90       return false;
  91
  92    /* Check the uses. We want a single use, with the op `op` */
  93    if (!list_is_empty(&dest->ssa.if_uses))
  94       return false;
  95
  96    if (!list_is_singular(&dest->ssa.uses))
  97       return false;
  98
  99    nir_src *use = list_first_entry(&dest->ssa.uses, nir_src, use_link);
 100    nir_instr *parent = use->parent_instr;
 101
 102    /* Check if the op is `op` */
 103    if (parent->type != nir_instr_type_alu)
 104       return false;
 105
 106    nir_alu_instr *alu = nir_instr_as_alu(parent);
 107    if (alu->op != op)
 108       return false;
 109
 110    /* We can't do expansions without a move in the middle */
 111    unsigned nr_components = nir_dest_num_components(alu->dest.dest);
 112
 113    if (nir_dest_num_components(*dest) != nr_components)
 114       return false;
 115
 116    /* We don't handle swizzles here, so check for the identity */
 117    for (unsigned i = 0; i < nr_components; ++i) {
 118       if (alu->src[0].swizzle[i] != i)
 119          return false;
 120    }
 121
 122    if (!alu->dest.dest.is_ssa)
 123       return false;
 124
 125    /* Otherwise, we're good */
 126    *odest = &alu->dest.dest;
 127    return true;
 128 }