src/compiler/nir/nir_lower_samplers.c

   1 /*
   2  * Copyright (C) 2005-2007  Brian Paul   All Rights Reserved.
   3  * Copyright (C) 2008  VMware, Inc.   All Rights Reserved.
   4  * Copyright © 2014 Intel Corporation
   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
  22  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
  23  * DEALINGS IN THE SOFTWARE.
  24  */
  25
  26 #include "nir/nir.h"
  27 #include "nir_builder.h"
  28
  29 static void
  30 lower_tex_src_to_offset(nir_builder *b,
  31                         nir_tex_instr *instr, unsigned src_idx)
  32 {
  33    nir_ssa_def *index = NULL;
  34    unsigned base_index = 0;
  35    unsigned array_elements = 1;
  36    nir_tex_src *src = &instr->src[src_idx];
  37    bool is_sampler = src->src_type == nir_tex_src_sampler_deref;
  38
  39    /* We compute first the offsets */
  40    nir_deref_instr *deref = nir_instr_as_deref(src->src.ssa->parent_instr);
  41    while (deref->deref_type != nir_deref_type_var) {
  42       assert(deref->parent.is_ssa);
  43       nir_deref_instr *parent =
  44          nir_instr_as_deref(deref->parent.ssa->parent_instr);
  45
  46       assert(deref->deref_type == nir_deref_type_array);
  47
  48       if (nir_src_is_const(deref->arr.index) && index == NULL) {
  49          /* We're still building a direct index */
  50          base_index += nir_src_as_uint(deref->arr.index) * array_elements;
  51       } else {
  52          if (index == NULL) {
  53             /* We used to be direct but not anymore */
  54             index = nir_imm_int(b, base_index);
  55             base_index = 0;
  56          }
  57
  58          index = nir_iadd(b, index,
  59                           nir_imul(b, nir_imm_int(b, array_elements),
  60                                    nir_ssa_for_src(b, deref->arr.index, 1)));
  61       }
  62
  63       array_elements *= glsl_get_length(parent->type);
  64
  65       deref = parent;
  66    }
  67
  68    if (index)
  69       index = nir_umin(b, index, nir_imm_int(b, array_elements - 1));
  70
  71    /* We hit the deref_var.  This is the end of the line */
  72    assert(deref->deref_type == nir_deref_type_var);
  73
  74    base_index += deref->var->data.binding;
  75
  76    /* We have the offsets, we apply them, rewriting the source or removing
  77     * instr if needed
  78     */
  79    if (index) {
  80       nir_instr_rewrite_src(&instr->instr, &src->src,
  81                             nir_src_for_ssa(index));
  82
  83       src->src_type = is_sampler ?
  84          nir_tex_src_sampler_offset :
  85          nir_tex_src_texture_offset;
  86    } else {
  87       nir_tex_instr_remove_src(instr, src_idx);
  88    }
  89
  90    if (is_sampler) {
  91       instr->sampler_index = base_index;
  92    } else {
  93       instr->texture_index = base_index;
  94    }
  95 }
  96
  97 static bool
  98 lower_sampler(nir_builder *b, nir_tex_instr *instr)
  99 {
 100    int texture_idx =
 101       nir_tex_instr_src_index(instr, nir_tex_src_texture_deref);
 102
 103    if (texture_idx >= 0) {
 104       b->cursor = nir_before_instr(&instr->instr);
 105
 106       lower_tex_src_to_offset(b, instr, texture_idx);
 107    }
 108
 109    int sampler_idx =
 110       nir_tex_instr_src_index(instr, nir_tex_src_sampler_deref);
 111
 112    if (sampler_idx >= 0) {
 113       lower_tex_src_to_offset(b, instr, sampler_idx);
 114    }
 115
 116    if (texture_idx < 0 && sampler_idx < 0)
 117       return false;
 118
 119    return true;
 120 }
 121
 122 static bool
 123 lower_impl(nir_function_impl *impl)
 124 {
 125    nir_builder b;
 126    nir_builder_init(&b, impl);
 127    bool progress = false;
 128
 129    nir_foreach_block(block, impl) {
 130       nir_foreach_instr(instr, block) {
 131          if (instr->type == nir_instr_type_tex)
 132             progress |= lower_sampler(&b, nir_instr_as_tex(instr));
 133       }
 134    }
 135
 136    return progress;
 137 }
 138
 139 bool
 140 nir_lower_samplers(nir_shader *shader)
 141 {
 142    bool progress = false;
 143
 144    /* Next, lower derefs to offsets. */
 145    nir_foreach_function(function, shader) {
 146       if (function->impl)
 147          progress |= lower_impl(function->impl);
 148    }
 149
 150    return progress;
 151 }