/* * © Copyright 2018 Alyssa Rosenzweig * * Permission is hereby granted, free of charge, to any person obtaining a * copy of this software and associated documentation files (the "Software"), * to deal in the Software without restriction, including without limitation * the rights to use, copy, modify, merge, publish, distribute, sublicense, * and/or sell copies of the Software, and to permit persons to whom the * Software is furnished to do so, subject to the following conditions: * * The above copyright notice and this permission notice (including the next * paragraph) shall be included in all copies or substantial portions of the * Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE * SOFTWARE. * */ #include #include "pan_blend_shaders.h" #include "pan_util.h" #include "midgard/midgard_compile.h" #include "compiler/nir/nir_builder.h" //#include "gallium/auxiliary/nir/nir_lower_blend.h" /* * Implements the command stream portion of programmatic blend shaders. * * On Midgard, common blending operations are accelerated by the fixed-function * blending pipeline. Panfrost supports this fast path via the code in * pan_blending.c. Nevertheless, uncommon blend modes (including some seemingly * simple modes present in ES2) require "blend shaders", a special internal * shader type used for programmable blending. * * Blend shaders operate during the normal blending time, but they bypass the * fixed-function blending pipeline and instead go straight to the Midgard * shader cores. The shaders themselves are essentially just fragment shaders, * making heavy use of uint8 arithmetic to manipulate RGB values for the * framebuffer. * * As is typical with Midgard, shader binaries must be accompanied by * information about the first tag (ORed with the bottom nibble of address, * like usual) and work registers. Work register count is specified in the * blend descriptor, as well as in the coresponding fragment shader's work * count. This suggests that blend shader invocation is tied to fragment shader * execution. * * --- * * As for blend shaders, they use the standard ISA. * * The source pixel colour, including alpha, is preloaded into r0 as a vec4 of * float32. * * The destination pixel colour must be loaded explicitly via load/store ops. * TODO: Investigate. * * They use fragment shader writeout; however, instead of writing a vec4 of * float32 for RGBA encoding, we writeout a vec4 of uint8, using 8-bit imov * instead of 32-bit fmov. The net result is that r0 encodes a single uint32 * containing all four channels of the color. Accordingly, the blend shader * epilogue has to scale all four channels by 255 and then type convert to a * uint8. * * --- * * Blend shaders hardcode constants. Naively, this requires recompilation each * time the blend color changes, which is a performance risk. Accordingly, we * 'cheat' a bit: instead of loading the constant, we compile a shader with a * dummy constant, exporting the offset to the immediate in the shader binary, * storing this generic binary and metadata in the CSO itself at CSO create * time. * * We then hot patch in the color into this shader at attachment / color change * time, allowing for CSO create to be the only expensive operation * (compilation). */ static nir_ssa_def * nir_blending_f(const struct pipe_rt_blend_state *blend, nir_builder *b, nir_ssa_def *s_src, nir_ssa_def *s_dst, nir_ssa_def *s_con) { /* Stub, to be replaced by the real implementation when that is * upstream (pending on a rewrite to be Gallium agnostic) */ return s_src; } void panfrost_make_blend_shader(struct panfrost_context *ctx, struct panfrost_blend_state *cso, const struct pipe_blend_color *blend_color) { const struct pipe_rt_blend_state *blend = &cso->base.rt[0]; mali_ptr *out = &cso->blend_shader; /* Build the shader */ nir_shader *shader = nir_shader_create(NULL, MESA_SHADER_FRAGMENT, &midgard_nir_options, NULL); nir_function *fn = nir_function_create(shader, "main"); nir_function_impl *impl = nir_function_impl_create(fn); /* Create the blend variables */ nir_variable *c_src = nir_variable_create(shader, nir_var_shader_in, glsl_vector_type(GLSL_TYPE_FLOAT, 4), "gl_Color"); nir_variable *c_dst = nir_variable_create(shader, nir_var_shader_in, glsl_vector_type(GLSL_TYPE_FLOAT, 4), "gl_SecondaryColor"); nir_variable *c_out = nir_variable_create(shader, nir_var_shader_out, glsl_vector_type(GLSL_TYPE_FLOAT, 4), "gl_FragColor"); nir_variable *c_con = nir_variable_create(shader, nir_var_uniform, glsl_vector_type(GLSL_TYPE_FLOAT, 4), "constant"); c_src->data.location = VARYING_SLOT_COL0; c_dst->data.location = VARYING_SLOT_COL1; c_out->data.location = FRAG_RESULT_COLOR; /* Setup nir_builder */ nir_builder _b; nir_builder *b = &_b; nir_builder_init(b, impl); b->cursor = nir_before_block(nir_start_block(impl)); /* Setup inputs */ nir_ssa_def *s_src = nir_load_var(b, c_src); nir_ssa_def *s_dst = nir_load_var(b, c_dst); nir_ssa_def *s_con = nir_load_var(b, c_con); /* Build a trivial blend shader */ nir_store_var(b, c_out, nir_blending_f(blend, b, s_src, s_dst, s_con), 0xFF); if (pan_debug & PAN_DBG_SHADERS) nir_print_shader(shader, stdout); /* Compile the built shader */ midgard_program program; midgard_compile_shader_nir(shader, &program, true); /* Upload the shader */ int size = program.compiled.size; uint8_t *dst = program.compiled.data; /* Hot patch in constant color */ if (program.blend_patch_offset >= 0) { float *hot_color = (float *) (dst + program.blend_patch_offset); for (int c = 0; c < 4; ++c) hot_color[c] = blend_color->color[c]; } *out = panfrost_upload(&ctx->shaders, dst, size, true) | program.first_tag; /* We need to switch to shader mode */ cso->has_blend_shader = true; /* At least two work registers are needed due to an encoding quirk */ cso->blend_work_count = MAX2(program.work_register_count, 2); }