src/compiler/glsl/gl_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 "compiler/nir/nir.h"
  27 #include "compiler/nir/nir_builder.h"
  28 #include "gl_nir.h"
  29 #include "ir_uniform.h"
  30
  31 #include "main/compiler.h"
  32 #include "main/mtypes.h"
  33
  34 static void
  35 lower_tex_src_to_offset(nir_builder *b,
  36                         nir_tex_instr *instr, unsigned src_idx)
  37 {
  38    nir_ssa_def *index = NULL;
  39    unsigned base_index = 0;
  40    unsigned array_elements = 1;
  41    nir_tex_src *src = &instr->src[src_idx];
  42    bool is_sampler = src->src_type == nir_tex_src_sampler_deref;
  43
  44    /* We compute first the offsets */
  45    nir_deref_instr *deref = nir_instr_as_deref(src->src.ssa->parent_instr);
  46    while (deref->deref_type != nir_deref_type_var) {
  47       assert(deref->parent.is_ssa);
  48       nir_deref_instr *parent =
  49          nir_instr_as_deref(deref->parent.ssa->parent_instr);
  50
  51       assert(deref->deref_type == nir_deref_type_array);
  52
  53       if (nir_src_is_const(deref->arr.index) && index == NULL) {
  54          /* We're still building a direct index */
  55          base_index += nir_src_as_uint(deref->arr.index) * array_elements;
  56       } else {
  57          if (index == NULL) {
  58             /* We used to be direct but not anymore */
  59             index = nir_imm_int(b, base_index);
  60             base_index = 0;
  61          }
  62
  63          index = nir_iadd(b, index,
  64                           nir_imul(b, nir_imm_int(b, array_elements),
  65                                    nir_ssa_for_src(b, deref->arr.index, 1)));
  66       }
  67
  68       array_elements *= glsl_get_length(parent->type);
  69
  70       deref = parent;
  71    }
  72
  73    if (index)
  74       index = nir_umin(b, index, nir_imm_int(b, array_elements - 1));
  75
  76    /* We hit the deref_var.  This is the end of the line */
  77    assert(deref->deref_type == nir_deref_type_var);
  78
  79    base_index += deref->var->data.binding;
  80
  81    /* We have the offsets, we apply them, rewriting the source or removing
  82     * instr if needed
  83     */
  84    if (index) {
  85       nir_instr_rewrite_src(&instr->instr, &src->src,
  86                             nir_src_for_ssa(index));
  87
  88       src->src_type = is_sampler ?
  89          nir_tex_src_sampler_offset :
  90          nir_tex_src_texture_offset;
  91
  92       instr->texture_array_size = array_elements;
  93    } else {
  94       nir_tex_instr_remove_src(instr, src_idx);
  95    }
  96
  97    if (is_sampler) {
  98       instr->sampler_index = base_index;
  99    } else {
 100       instr->texture_index = base_index;
 101       instr->texture_array_size = array_elements;
 102    }
 103 }
 104
 105 static bool
 106 lower_sampler(nir_builder *b, nir_tex_instr *instr)
 107 {
 108    int texture_idx =
 109       nir_tex_instr_src_index(instr, nir_tex_src_texture_deref);
 110
 111    if (texture_idx >= 0) {
 112       b->cursor = nir_before_instr(&instr->instr);
 113
 114       lower_tex_src_to_offset(b, instr, texture_idx);
 115    }
 116
 117    int sampler_idx =
 118       nir_tex_instr_src_index(instr, nir_tex_src_sampler_deref);
 119
 120    if (sampler_idx >= 0) {
 121       lower_tex_src_to_offset(b, instr, sampler_idx);
 122    }
 123
 124    if (texture_idx < 0 && sampler_idx < 0)
 125       return false;
 126
 127    return true;
 128 }
 129
 130 static bool
 131 lower_impl(nir_function_impl *impl)
 132 {
 133    nir_builder b;
 134    nir_builder_init(&b, impl);
 135    bool progress = false;
 136
 137    nir_foreach_block(block, impl) {
 138       nir_foreach_instr(instr, block) {
 139          if (instr->type == nir_instr_type_tex)
 140             progress |= lower_sampler(&b, nir_instr_as_tex(instr));
 141       }
 142    }
 143
 144    return progress;
 145 }
 146
 147 bool
 148 gl_nir_lower_samplers(nir_shader *shader,
 149                       const struct gl_shader_program *shader_program)
 150 {
 151    bool progress = false;
 152
 153    /* First, use gl_nir_lower_samplers_as_derefs to set var->data.binding
 154     * based on the uniforms, and split structures to simplify derefs.
 155     */
 156    gl_nir_lower_samplers_as_deref(shader, shader_program);
 157
 158    /* Next, lower derefs to offsets. */
 159    nir_foreach_function(function, shader) {
 160       if (function->impl)
 161          progress |= lower_impl(function->impl);
 162    }
 163
 164    return progress;
 165 }