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 nir_ssa_def *
  38 v3d_nir_lower_txf_ms_instr(nir_builder *b, nir_instr *in_instr, void *data)
  39 {
  40         nir_tex_instr *instr = nir_instr_as_tex(in_instr);
  41
  42         b->cursor = nir_before_instr(&instr->instr);
  43
  44         int coord_index = nir_tex_instr_src_index(instr, nir_tex_src_coord);
  45         int sample_index = nir_tex_instr_src_index(instr, nir_tex_src_ms_index);
  46         nir_ssa_def *coord = instr->src[coord_index].src.ssa;
  47         nir_ssa_def *sample = instr->src[sample_index].src.ssa;
  48
  49         nir_ssa_def *one = nir_imm_int(b, 1);
  50         nir_ssa_def *x = nir_iadd(b,
  51                                   nir_ishl(b, nir_channel(b, coord, 0), one),
  52                                   nir_iand(b, sample, one));
  53         nir_ssa_def *y = nir_iadd(b,
  54                                   nir_ishl(b, nir_channel(b, coord, 1), one),
  55                                   nir_iand(b, nir_ushr(b, sample, one), one));
  56         if (instr->is_array)
  57                 coord = nir_vec3(b, x, y, nir_channel(b, coord, 2));
  58         else
  59                 coord = nir_vec2(b, x, y);
  60
  61         nir_instr_rewrite_src(&instr->instr,
  62                               &instr->src[nir_tex_src_coord].src,
  63                               nir_src_for_ssa(coord));
  64         nir_tex_instr_remove_src(instr, sample_index);
  65         instr->op = nir_texop_txf;
  66         instr->sampler_dim = GLSL_SAMPLER_DIM_2D;
  67
  68         return NIR_LOWER_INSTR_PROGRESS;
  69 }
  70
  71 static bool
  72 v3d_nir_lower_txf_ms_filter(const nir_instr *instr, const void *data)
  73 {
  74         return (instr->type == nir_instr_type_tex &&
  75                 nir_instr_as_tex(instr)->op == nir_texop_txf_ms);
  76 }
  77
  78 void
  79 v3d_nir_lower_txf_ms(nir_shader *s, struct v3d_compile *c)
  80 {
  81         nir_shader_lower_instructions(s,
  82                                       v3d_nir_lower_txf_ms_filter,
  83                                       v3d_nir_lower_txf_ms_instr,
  84                                       NULL);
  85 }