src/gallium/drivers/panfrost/pan_blend_shaders.c

   1 /*
   2  * © Copyright 2018 Alyssa Rosenzweig
   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 FROM,
  20  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  21  * SOFTWARE.
  22  *
  23  */
  24
  25 #include <stdio.h>
  26 #include "pan_blend_shaders.h"
  27 #include "pan_util.h"
  28 #include "midgard/midgard_compile.h"
  29 #include "compiler/nir/nir_builder.h"
  30 #include "nir/nir_lower_blend.h"
  31 #include "panfrost/util/pan_lower_framebuffer.h"
  32 #include "gallium/auxiliary/util/u_blend.h"
  33 #include "util/u_memory.h"
  34
  35 /*
  36  * Implements the command stream portion of programmatic blend shaders.
  37  *
  38  * On Midgard, common blending operations are accelerated by the fixed-function
  39  * blending pipeline. Panfrost supports this fast path via the code in
  40  * pan_blending.c. Nevertheless, uncommon blend modes (including some seemingly
  41  * simple modes present in ES2) require "blend shaders", a special internal
  42  * shader type used for programmable blending.
  43  *
  44  * Blend shaders operate during the normal blending time, but they bypass the
  45  * fixed-function blending pipeline and instead go straight to the Midgard
  46  * shader cores. The shaders themselves are essentially just fragment shaders,
  47  * making heavy use of uint8 arithmetic to manipulate RGB values for the
  48  * framebuffer.
  49  *
  50  * As is typical with Midgard, shader binaries must be accompanied by
  51  * information about the first tag (ORed with the bottom nibble of address,
  52  * like usual) and work registers. Work register count is assumed to be less
  53  * than or equal to the coresponding fragment shader's work count. This
  54  * suggests that blend shader invocation is tied to fragment shader
  55  * execution.
  56  *
  57  * The shaders themselves use the standard ISA. The source pixel colour,
  58  * including alpha, is preloaded into r0 as a vec4 of float32. The destination
  59  * pixel colour must be loaded explicitly via load/store ops, possibly
  60  * performing conversions in software. The blended colour must be stored with a
  61  * fragment writeout in the correct framebuffer format, either in software or
  62  * via conversion opcodes on the load/store pipe.
  63  *
  64  * Blend shaders hardcode constants. Naively, this requires recompilation each
  65  * time the blend color changes, which is a performance risk. Accordingly, we
  66  * 'cheat' a bit: instead of loading the constant, we compile a shader with a
  67  * dummy constant, exporting the offset to the immediate in the shader binary,
  68  * storing this generic binary and metadata in the CSO itself at CSO create
  69  * time.
  70  *
  71  * We then hot patch in the color into this shader at attachment / color change
  72  * time, allowing for CSO create to be the only expensive operation
  73  * (compilation).
  74  */
  75
  76 static nir_lower_blend_options
  77 nir_make_options(const struct pipe_blend_state *blend, unsigned i)
  78 {
  79         nir_lower_blend_options options = { 0 };
  80
  81         if (blend->logicop_enable) {
  82             options.logicop_enable = true;
  83             options.logicop_func = blend->logicop_func;
  84             return options;
  85         }
  86
  87         options.logicop_enable = false;
  88
  89         if (!blend->independent_blend_enable)
  90                 i = 0;
  91
  92         /* If blend is disabled, we just use replace mode */
  93
  94         nir_lower_blend_channel rgb = {
  95                 .func = BLEND_FUNC_ADD,
  96                 .src_factor = BLEND_FACTOR_ZERO,
  97                 .invert_src_factor = true,
  98                 .dst_factor = BLEND_FACTOR_ZERO,
  99                 .invert_dst_factor = false
 100         };
 101
 102         nir_lower_blend_channel alpha = rgb;
 103
 104         if (blend->rt[i].blend_enable) {
 105                 rgb.func = util_blend_func_to_shader(blend->rt[i].rgb_func);
 106                 rgb.src_factor = util_blend_factor_to_shader(blend->rt[i].rgb_src_factor);
 107                 rgb.dst_factor = util_blend_factor_to_shader(blend->rt[i].rgb_dst_factor);
 108                 rgb.invert_src_factor = util_blend_factor_is_inverted(blend->rt[i].rgb_src_factor);
 109                 rgb.invert_dst_factor = util_blend_factor_is_inverted(blend->rt[i].rgb_dst_factor);
 110
 111                 alpha.func = util_blend_func_to_shader(blend->rt[i].alpha_func);
 112                 alpha.src_factor = util_blend_factor_to_shader(blend->rt[i].alpha_src_factor);
 113                 alpha.dst_factor = util_blend_factor_to_shader(blend->rt[i].alpha_dst_factor);
 114                 alpha.invert_src_factor = util_blend_factor_is_inverted(blend->rt[i].alpha_src_factor);
 115                 alpha.invert_dst_factor = util_blend_factor_is_inverted(blend->rt[i].alpha_dst_factor);
 116         }
 117
 118         options.rgb = rgb;
 119         options.alpha = alpha;
 120
 121         options.colormask = blend->rt[i].colormask;
 122
 123         return options;
 124 }
 125
 126 static nir_ssa_def *
 127 nir_iclamp(nir_builder *b, nir_ssa_def *v, int32_t lo, int32_t hi)
 128 {
 129         return nir_imin(b, nir_imax(b, v, nir_imm_int(b, lo)), nir_imm_int(b, hi));
 130 }
 131
 132 struct panfrost_blend_shader
 133 panfrost_compile_blend_shader(
 134         struct panfrost_context *ctx,
 135         struct pipe_blend_state *cso,
 136         enum pipe_format format,
 137         unsigned rt)
 138 {
 139         struct panfrost_device *dev = pan_device(ctx->base.screen);
 140         struct panfrost_blend_shader res;
 141
 142         res.ctx = ctx;
 143
 144         /* Build the shader */
 145
 146         nir_shader *shader = nir_shader_create(NULL, MESA_SHADER_FRAGMENT, &midgard_nir_options, NULL);
 147         nir_function *fn = nir_function_create(shader, "main");
 148         nir_function_impl *impl = nir_function_impl_create(fn);
 149
 150         const struct util_format_description *format_desc =
 151                 util_format_description(format);
 152
 153         nir_alu_type T = pan_unpacked_type_for_format(format_desc);
 154         enum glsl_base_type g =
 155                 (T == nir_type_float16) ? GLSL_TYPE_FLOAT16 :
 156                 (T == nir_type_float32) ? GLSL_TYPE_FLOAT :
 157                 (T == nir_type_int8) ? GLSL_TYPE_INT8 :
 158                 (T == nir_type_int16) ? GLSL_TYPE_INT16 :
 159                 (T == nir_type_int32) ? GLSL_TYPE_INT :
 160                 (T == nir_type_uint8) ? GLSL_TYPE_UINT8 :
 161                 (T == nir_type_uint16) ? GLSL_TYPE_UINT16 :
 162                 (T == nir_type_uint32) ? GLSL_TYPE_UINT :
 163                 GLSL_TYPE_FLOAT;
 164
 165         /* Create the blend variables */
 166
 167         nir_variable *c_src = nir_variable_create(shader, nir_var_shader_in, glsl_vector_type(GLSL_TYPE_FLOAT, 4), "gl_Color");
 168         nir_variable *c_src1 = nir_variable_create(shader, nir_var_shader_in, glsl_vector_type(GLSL_TYPE_FLOAT, 4), "gl_Color1");
 169         nir_variable *c_out = nir_variable_create(shader, nir_var_shader_out, glsl_vector_type(g, 4), "gl_FragColor");
 170
 171         c_src->data.location = VARYING_SLOT_COL0;
 172         c_src1->data.location = VARYING_SLOT_VAR0;
 173         c_out->data.location = FRAG_RESULT_COLOR;
 174
 175         c_src1->data.driver_location = 1;
 176
 177         /* Setup nir_builder */
 178
 179         nir_builder _b;
 180         nir_builder *b = &_b;
 181         nir_builder_init(b, impl);
 182         b->cursor = nir_before_block(nir_start_block(impl));
 183
 184         /* Setup inputs */
 185
 186         nir_ssa_def *s_src[] = {nir_load_var(b, c_src), nir_load_var(b, c_src1)};
 187
 188         for (int i = 0; i < ARRAY_SIZE(s_src); ++i) {
 189                 if (T == nir_type_float16)
 190                         s_src[i] = nir_f2f16(b, s_src[i]);
 191                 else if (T == nir_type_int16)
 192                         s_src[i] = nir_i2i16(b, nir_iclamp(b, s_src[i], -32768, 32767));
 193                 else if (T == nir_type_uint16)
 194                         s_src[i] = nir_u2u16(b, nir_umin(b, s_src[i], nir_imm_int(b, 65535)));
 195                 else if (T == nir_type_int8)
 196                         s_src[i] = nir_i2i8(b, nir_iclamp(b, s_src[i], -128, 127));
 197                 else if (T == nir_type_uint8)
 198                         s_src[i] = nir_u2u8(b, nir_umin(b, s_src[i], nir_imm_int(b, 255)));
 199         }
 200
 201         /* Build a trivial blend shader */
 202         nir_store_var(b, c_out, s_src[0], 0xFF);
 203
 204         nir_lower_blend_options options =
 205                 nir_make_options(cso, rt);
 206         options.format = format;
 207         options.src1 = s_src[1];
 208
 209         if (T == nir_type_float16)
 210                 options.half = true;
 211
 212         NIR_PASS_V(shader, nir_lower_blend, options);
 213
 214         /* Compile the built shader */
 215
 216         panfrost_program program = {
 217            .rt_formats = {format}
 218         };
 219
 220         midgard_compile_shader_nir(shader, &program, true, rt, dev->gpu_id, false);
 221
 222         /* Allow us to patch later */
 223         res.patch_index = program.blend_patch_offset;
 224         res.first_tag = program.first_tag;
 225         res.size = program.compiled.size;
 226         res.buffer = program.compiled.data;
 227         res.work_count = program.work_register_count;
 228
 229         return res;
 230 }