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
37static nir_ssa_def *
38v3d_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
71static bool
72v3d_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
78void
79v3d_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}
86