/* * 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" #include "nir_deref.h" struct lower_io_state { nir_shader *shader; nir_function_impl *entrypoint; struct exec_list old_outputs; struct exec_list old_inputs; /* map from temporary to new input */ struct hash_table *input_map; }; 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 || intrin->intrinsic == nir_intrinsic_emit_vertex_with_counter) { 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); } } } /* For fragment shader inputs, when we lower to temporaries we'll invalidate * interpolateAt*() because now they'll be pointing to the temporary instead * of the actual variable. Since the caller presumably doesn't support * indirect indexing of inputs, we'll need to lower something like: * * in vec4 foo[3]; * * ... = interpolateAtCentroid(foo[i]); * * to a sequence of interpolations that store to our temporary, then a * load at the end: * * in vec4 foo[3]; * vec4 foo_tmp[3]; * * foo_tmp[0] = interpolateAtCentroid(foo[0]); * foo_tmp[1] = interpolateAtCentroid(foo[1]); * ... = foo_tmp[i]; */ /* * Recursively emit the interpolation instructions. Here old_interp_deref * refers to foo[i], temp_deref is foo_tmp[0/1], and new_interp_deref is * foo[0/1]. */ static void emit_interp(nir_builder *b, nir_deref_instr **old_interp_deref, nir_deref_instr *temp_deref, nir_deref_instr *new_interp_deref, nir_intrinsic_instr *interp) { while (*old_interp_deref) { switch ((*old_interp_deref)->deref_type) { case nir_deref_type_struct: temp_deref = nir_build_deref_struct(b, temp_deref, (*old_interp_deref)->strct.index); new_interp_deref = nir_build_deref_struct(b, new_interp_deref, (*old_interp_deref)->strct.index); break; case nir_deref_type_array: if (nir_src_is_const((*old_interp_deref)->arr.index)) { temp_deref = nir_build_deref_array(b, temp_deref, (*old_interp_deref)->arr.index.ssa); new_interp_deref = nir_build_deref_array(b, new_interp_deref, (*old_interp_deref)->arr.index.ssa); break; } else { /* We have an indirect deref, so we have to emit interpolations * for every index. Recurse in case we have an array of arrays. */ unsigned length = glsl_get_length(temp_deref->type); for (unsigned i = 0; i < length; i++) { nir_deref_instr *new_temp = nir_build_deref_array_imm(b, temp_deref, i); nir_deref_instr *new_interp = nir_build_deref_array_imm(b, new_interp_deref, i); emit_interp(b, old_interp_deref + 1, new_temp, new_interp, interp); } return; } case nir_deref_type_var: case nir_deref_type_array_wildcard: case nir_deref_type_ptr_as_array: case nir_deref_type_cast: unreachable("bad deref type"); } old_interp_deref++; } /* Now that we've constructed a fully-qualified deref with all the indirect * derefs replaced with direct ones, it's time to actually emit the new * interpolation instruction. */ nir_intrinsic_instr *new_interp = nir_intrinsic_instr_create(b->shader, interp->intrinsic); new_interp->src[0] = nir_src_for_ssa(&new_interp_deref->dest.ssa); if (interp->intrinsic == nir_intrinsic_interp_deref_at_sample || interp->intrinsic == nir_intrinsic_interp_deref_at_offset || interp->intrinsic == nir_intrinsic_interp_deref_at_vertex) { new_interp->src[1] = interp->src[1]; } new_interp->num_components = interp->num_components; nir_ssa_dest_init(&new_interp->instr, &new_interp->dest, interp->dest.ssa.num_components, interp->dest.ssa.bit_size, NULL); nir_builder_instr_insert(b, &new_interp->instr); nir_store_deref(b, temp_deref, &new_interp->dest.ssa, (1 << interp->dest.ssa.num_components) - 1); } static void fixup_interpolation_instr(struct lower_io_state *state, nir_intrinsic_instr *interp, nir_builder *b) { nir_deref_path interp_path; nir_deref_path_init(&interp_path, nir_src_as_deref(interp->src[0]), NULL); b->cursor = nir_before_instr(&interp->instr); /* The original interpolation instruction should contain a deref path * starting with the original variable, which is now the temporary. */ nir_deref_instr *temp_root = interp_path.path[0]; /* Fish out the newly-created input variable. */ assert(temp_root->deref_type == nir_deref_type_var); struct hash_entry *entry = _mesa_hash_table_search(state->input_map, temp_root->var); assert(entry); nir_variable *input = entry->data; nir_deref_instr *input_root = nir_build_deref_var(b, input); /* Emit the interpolation instructions. */ emit_interp(b, interp_path.path + 1, temp_root, input_root, interp); /* Now the temporary contains the interpolation results, and we can just * load from it. We can reuse the original deref, since it points to the * correct part of the temporary. */ nir_ssa_def *load = nir_load_deref(b, nir_src_as_deref(interp->src[0])); nir_ssa_def_rewrite_uses(&interp->dest.ssa, nir_src_for_ssa(load)); nir_instr_remove(&interp->instr); nir_deref_path_finish(&interp_path); } static void fixup_interpolation(struct lower_io_state *state, nir_function_impl *impl, nir_builder *b) { nir_foreach_block(block, impl) { nir_foreach_instr_safe(instr, block) { if (instr->type != nir_instr_type_intrinsic) continue; nir_intrinsic_instr *interp = nir_instr_as_intrinsic(instr); if (interp->intrinsic == nir_intrinsic_interp_deref_at_centroid || interp->intrinsic == nir_intrinsic_interp_deref_at_sample || interp->intrinsic == nir_intrinsic_interp_deref_at_offset || interp->intrinsic == nir_intrinsic_interp_deref_at_vertex) { fixup_interpolation_instr(state, interp, b); } } } } 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); if (state->shader->info.stage == MESA_SHADER_FRAGMENT) fixup_interpolation(state, impl, &b); } } 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); nvar->data.cannot_coalesce = true; /* 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 && nvar->pointer_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; state.input_map = _mesa_pointer_hash_table_create(NULL); 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); _mesa_hash_table_insert(state.input_map, var, input); } 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); _mesa_hash_table_destroy(state.input_map, NULL); }