diff --git a/src/compiler/nir/meson.build b/src/compiler/nir/meson.build index cd588303672..339b37200e2 100644 --- a/src/compiler/nir/meson.build +++ b/src/compiler/nir/meson.build @@ -223,6 +223,7 @@ files_libnir = files( 'nir_opt_dead_cf.c', 'nir_opt_dead_write_vars.c', 'nir_opt_find_array_copies.c', + 'nir_opt_fragdepth.c', 'nir_opt_gcm.c', 'nir_opt_idiv_const.c', 'nir_opt_if.c', diff --git a/src/compiler/nir/nir.h b/src/compiler/nir/nir.h index 006a25debc9..167806a32bb 100644 --- a/src/compiler/nir/nir.h +++ b/src/compiler/nir/nir.h @@ -5444,6 +5444,8 @@ bool nir_opt_deref(nir_shader *shader); bool nir_opt_find_array_copies(nir_shader *shader); +bool nir_opt_fragdepth(nir_shader *shader); + bool nir_opt_gcm(nir_shader *shader, bool value_number); bool nir_opt_idiv_const(nir_shader *shader, unsigned min_bit_size); diff --git a/src/compiler/nir/nir_opt_fragdepth.c b/src/compiler/nir/nir_opt_fragdepth.c new file mode 100644 index 00000000000..96da27cf94e --- /dev/null +++ b/src/compiler/nir/nir_opt_fragdepth.c @@ -0,0 +1,111 @@ +/* + * Copyright © 2021 Advanced Micro Devices, Inc. + * + * 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 "nir.h" +#include "nir_builder.h" + +/** + * This pass removes no-op assignment to gl_FragDepth. + * + * gl_FragDepth implicit value is gl_FragCoord.z, so if a shader only assign + * this value to gl_FragDepth, the store instruction is removed. + */ + +static bool +ssa_def_is_source_depth(nir_ssa_def *def) +{ + nir_ssa_scalar scalar = nir_ssa_scalar_resolved(def, 0); + nir_instr *instr = scalar.def->parent_instr; + if (instr->type != nir_instr_type_intrinsic) + return false; + + nir_intrinsic_instr *intrin = nir_instr_as_intrinsic(instr); + if (intrin->intrinsic != nir_intrinsic_load_frag_coord) + return false; + + /* Depth is gl_FragCoord.z */ + return scalar.comp == 2; +} + +bool +nir_opt_fragdepth(nir_shader *shader) +{ + bool progress = false; + nir_intrinsic_instr *store_intrin = NULL; + + if (shader->info.stage != MESA_SHADER_FRAGMENT) + goto end; + + nir_function_impl *impl = nir_shader_get_entrypoint(shader); + nir_foreach_block(block, impl) { + nir_foreach_instr(instr, block) { + if (instr->type != nir_instr_type_intrinsic) + continue; + + nir_intrinsic_instr *intrin = nir_instr_as_intrinsic(instr); + if (intrin->intrinsic != nir_intrinsic_store_deref) + continue; + + nir_deref_instr *deref = nir_src_as_deref(intrin->src[0]); + if (!nir_deref_mode_is(deref, nir_var_shader_out)) + continue; + + nir_variable *var = nir_deref_instr_get_variable(deref); + if (var->data.location != FRAG_RESULT_DEPTH) + continue; + + /* We found a write to gl_FragDepth */ + if (store_intrin) { + /* This isn't the only write: give up on this optimization */ + goto end; + } else { + if (ssa_def_is_source_depth(intrin->src[1].ssa)) { + /* We're writing gl_FragCoord.z in gl_FragDepth: remember + * intrin so we can try to remove it later. */ + store_intrin = intrin; + } else { + /* We're writing something else: give up. */ + goto end; + } + } + } + } + + if (store_intrin) { + /* Found a single store to gl_FragDepth, and it writes gl_FragCoord.z to it. + * Remove it since that's the implicit value of gl_FragDepth. + */ + nir_instr_remove(&store_intrin->instr); + + nir_metadata_preserve(impl, nir_metadata_block_index | + nir_metadata_dominance | + nir_metadata_loop_analysis | + nir_metadata_instr_index); + progress = true; + } + +end: + if (!progress) + nir_shader_preserve_all_metadata(shader); + return progress; +} diff --git a/src/mesa/state_tracker/st_glsl_to_nir.cpp b/src/mesa/state_tracker/st_glsl_to_nir.cpp index caeb195518a..5f4419358aa 100644 --- a/src/mesa/state_tracker/st_glsl_to_nir.cpp +++ b/src/mesa/state_tracker/st_glsl_to_nir.cpp @@ -530,6 +530,7 @@ st_glsl_to_nir_post_opts(struct st_context *st, struct gl_program *prog, NIR_PASS_V(nir, gl_nir_lower_atomics, shader_program, true); NIR_PASS_V(nir, nir_opt_intrinsics); + NIR_PASS_V(nir, nir_opt_fragdepth); /* Lower 64-bit ops. */ if (nir->options->lower_int64_options ||