| /* |
| * 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; |
| } |