src/broadcom/compiler/v3d_nir_lower_txf_ms.c

   1 /*
   2  * Copyright © 2015 Broadcom
   3  *
   4  * Permission is hereby granted, free of charge, to any person obtaining a
   5  * copy of this software and associated documentation files (the "Software"),
   6  * to deal in the Software without restriction, including without limitation
   7  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
   8  * and/or sell copies of the Software, and to permit persons to whom the
   9  * Software is furnished to do so, subject to the following conditions:
  10  *
  11  * The above copyright notice and this permission notice (including the next
  12  * paragraph) shall be included in all copies or substantial portions of the
  13  * Software.
  14  *
  15  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  16  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  18  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  19  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  20  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
  21  * IN THE SOFTWARE.
  22  */
  23
  24 #include "v3d_compiler.h"
  25 #include "compiler/nir/nir_builder.h"
  26
  27 /** @file v3d_nir_lower_txf_ms.c
  28  *
  29  * V3D's MSAA surfaces are laid out in UIF textures where each pixel is a 2x2
  30  * quad in the texture.  This pass lowers the txf_ms with a ms_index source to
  31  * a plain txf with the sample_index pulling out the correct texel from the
  32  * 2x2 quad.
  33  */
  34
  35 #define V3D_MAX_SAMPLES 4
  36
  37 static void
  38 vc4_nir_lower_txf_ms_instr(struct v3d_compile *c, nir_builder *b,
  39                            nir_tex_instr *instr)
  40 {
  41         if (instr->op != nir_texop_txf_ms)
  42                 return;
  43
  44         b->cursor = nir_before_instr(&instr->instr);
  45
  46         int coord_index = nir_tex_instr_src_index(instr, nir_tex_src_coord);
  47         int sample_index = nir_tex_instr_src_index(instr, nir_tex_src_ms_index);
  48         nir_ssa_def *coord = instr->src[coord_index].src.ssa;
  49         nir_ssa_def *sample = instr->src[sample_index].src.ssa;
  50
  51         nir_ssa_def *one = nir_imm_int(b, 1);
  52         nir_ssa_def *x = nir_iadd(b,
  53                                   nir_ishl(b, nir_channel(b, coord, 0), one),
  54                                   nir_iand(b, sample, one));
  55         nir_ssa_def *y = nir_iadd(b,
  56                                   nir_ishl(b, nir_channel(b, coord, 1), one),
  57                                   nir_iand(b, nir_ushr(b, sample, one), one));
  58         if (instr->is_array)
  59                 coord = nir_vec3(b, x, y, nir_channel(b, coord, 2));
  60         else
  61                 coord = nir_vec2(b, x, y);
  62
  63         nir_instr_rewrite_src(&instr->instr,
  64                               &instr->src[nir_tex_src_coord].src,
  65                               nir_src_for_ssa(coord));
  66         nir_tex_instr_remove_src(instr, sample_index);
  67         instr->op = nir_texop_txf;
  68         instr->sampler_dim = GLSL_SAMPLER_DIM_2D;
  69 }
  70
  71 void
  72 v3d_nir_lower_txf_ms(nir_shader *s, struct v3d_compile *c)
  73 {
  74         nir_foreach_function(function, s) {
  75                 if (!function->impl)
  76                         continue;
  77
  78                 nir_builder b;
  79                 nir_builder_init(&b, function->impl);
  80
  81                 nir_foreach_block(block, function->impl) {
  82                         nir_foreach_instr_safe(instr, block) {
  83                                 if (instr->type != nir_instr_type_tex)
  84                                         continue;
  85
  86                                 vc4_nir_lower_txf_ms_instr(c, &b,
  87                                                            nir_instr_as_tex(instr));
  88                         }
  89                 }
  90
  91                 nir_metadata_preserve(function->impl,
  92                                       nir_metadata_block_index |
  93                                       nir_metadata_dominance);
  94         }
  95 }