/* * Copyright © 2015 Intel Corporation * * 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. */ /* * Implements a pass that lowers output and/or input variables to a * temporary plus an output variable with a single copy at each exit * point of the shader and/or an input variable with a single copy * at the entrance point of the shader. This way the output variable * is only ever written once and/or input is only read once, and there * are no indirect outut/input accesses. */ #include "nir.h" #include "nir_builder.h" struct lower_io_state { nir_shader *shader; nir_function_impl *entrypoint; struct exec_list old_outputs; struct exec_list old_inputs; }; static void emit_copies(nir_builder *b, struct exec_list *dest_vars, struct exec_list *src_vars) { assert(exec_list_length(dest_vars) == exec_list_length(src_vars)); foreach_two_lists(dest_node, dest_vars, src_node, src_vars) { nir_variable *dest = exec_node_data(nir_variable, dest_node, node); nir_variable *src = exec_node_data(nir_variable, src_node, node); /* No need to copy the contents of a non-fb_fetch_output output variable * to the temporary allocated for it, since its initial value is * undefined. */ if (src->data.mode == nir_var_shader_out && !src->data.fb_fetch_output) continue; /* Can't copy the contents of the temporary back to a read-only * interface variable. The value of the temporary won't have been * modified by the shader anyway. */ if (dest->data.read_only) continue; nir_copy_var(b, dest, src); } } static void emit_output_copies_impl(struct lower_io_state *state, nir_function_impl *impl) { nir_builder b; nir_builder_init(&b, impl); if (state->shader->info.stage == MESA_SHADER_GEOMETRY) { /* For geometry shaders, we have to emit the output copies right * before each EmitVertex call. */ 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_emit_vertex) { b.cursor = nir_before_instr(&intrin->instr); emit_copies(&b, &state->shader->outputs, &state->old_outputs); } } } } else if (impl == state->entrypoint) { b.cursor = nir_before_block(nir_start_block(impl)); emit_copies(&b, &state->old_outputs, &state->shader->outputs); /* For all other shader types, we need to do the copies right before * the jumps to the end block. */ set_foreach(impl->end_block->predecessors, block_entry) { struct nir_block *block = (void *)block_entry->key; b.cursor = nir_after_block_before_jump(block); emit_copies(&b, &state->shader->outputs, &state->old_outputs); } } } static void emit_input_copies_impl(struct lower_io_state *state, nir_function_impl *impl) { if (impl == state->entrypoint) { nir_builder b; nir_builder_init(&b, impl); b.cursor = nir_before_block(nir_start_block(impl)); emit_copies(&b, &state->old_inputs, &state->shader->inputs); } } static nir_variable * create_shadow_temp(struct lower_io_state *state, nir_variable *var) { nir_variable *nvar = ralloc(state->shader, nir_variable); memcpy(nvar, var, sizeof *nvar); /* The original is now the temporary */ nir_variable *temp = var; /* Reparent the name to the new variable */ ralloc_steal(nvar, nvar->name); assert(nvar->constant_initializer == NULL); /* Give the original a new name with @-temp appended */ const char *mode = (temp->data.mode == nir_var_shader_in) ? "in" : "out"; temp->name = ralloc_asprintf(var, "%s@%s-temp", mode, nvar->name); temp->data.mode = nir_var_shader_temp; temp->data.read_only = false; temp->data.fb_fetch_output = false; temp->data.compact = false; return nvar; } void nir_lower_io_to_temporaries(nir_shader *shader, nir_function_impl *entrypoint, bool outputs, bool inputs) { struct lower_io_state state; if (shader->info.stage == MESA_SHADER_TESS_CTRL) return; state.shader = shader; state.entrypoint = entrypoint; if (inputs) exec_list_move_nodes_to(&shader->inputs, &state.old_inputs); else exec_list_make_empty(&state.old_inputs); if (outputs) exec_list_move_nodes_to(&shader->outputs, &state.old_outputs); else exec_list_make_empty(&state.old_outputs); /* Walk over all of the outputs turn each output into a temporary and * make a new variable for the actual output. */ nir_foreach_variable(var, &state.old_outputs) { nir_variable *output = create_shadow_temp(&state, var); exec_list_push_tail(&shader->outputs, &output->node); } /* and same for inputs: */ nir_foreach_variable(var, &state.old_inputs) { nir_variable *input = create_shadow_temp(&state, var); exec_list_push_tail(&shader->inputs, &input->node); } nir_foreach_function(function, shader) { if (function->impl == NULL) continue; if (inputs) emit_input_copies_impl(&state, function->impl); if (outputs) emit_output_copies_impl(&state, function->impl); nir_metadata_preserve(function->impl, nir_metadata_block_index | nir_metadata_dominance); } exec_list_append(&shader->globals, &state.old_inputs); exec_list_append(&shader->globals, &state.old_outputs); nir_fixup_deref_modes(shader); }