From 9cebdd78d8cbdc4915c26811cadac4a57f9d6426 Mon Sep 17 00:00:00 2001 From: Jason Ekstrand Date: Fri, 28 Aug 2015 17:09:02 -0700 Subject: [PATCH] nir: Add a pass to lower outputs to temporary variables This pass can be used as a helper for NIR producers so they don't have to worry about creating the temporaries themselves. --- src/glsl/Makefile.sources | 1 + src/glsl/nir/nir.h | 2 + src/glsl/nir/nir_lower_outputs_to_temporaries.c | 97 +++++++++++++++++++++++++ 3 files changed, 100 insertions(+) create mode 100644 src/glsl/nir/nir_lower_outputs_to_temporaries.c diff --git a/src/glsl/Makefile.sources b/src/glsl/Makefile.sources index da38e35..acd13ef 100644 --- a/src/glsl/Makefile.sources +++ b/src/glsl/Makefile.sources @@ -40,6 +40,7 @@ NIR_FILES = \ nir/nir_lower_locals_to_regs.c \ nir/nir_lower_idiv.c \ nir/nir_lower_io.c \ + nir/nir_lower_outputs_to_temporaries.c \ nir/nir_lower_phis_to_scalar.c \ nir/nir_lower_samplers.cpp \ nir/nir_lower_system_values.c \ diff --git a/src/glsl/nir/nir.h b/src/glsl/nir/nir.h index f78596d..8a23964 100644 --- a/src/glsl/nir/nir.h +++ b/src/glsl/nir/nir.h @@ -1652,6 +1652,8 @@ void nir_lower_global_vars_to_local(nir_shader *shader); void nir_lower_locals_to_regs(nir_shader *shader); +void nir_lower_outputs_to_temporaries(nir_shader *shader); + void nir_assign_var_locations(struct exec_list *var_list, unsigned *size, int (*type_size)(const struct glsl_type *)); diff --git a/src/glsl/nir/nir_lower_outputs_to_temporaries.c b/src/glsl/nir/nir_lower_outputs_to_temporaries.c new file mode 100644 index 0000000..715f1f8 --- /dev/null +++ b/src/glsl/nir/nir_lower_outputs_to_temporaries.c @@ -0,0 +1,97 @@ +/* + * 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. + * + * Authors: + * Jason Ekstrand (jason@jlekstrand.net) + * + */ + +/* + * Implements a pass that lowers output variables to a temporary plus an + * output variable with a single copy at each exit point of the shader. + * This way the output variable is only ever written. + * + * Because valid NIR requires that output variables are never read, this + * pass is more of a helper for NIR producers and must be run before the + * shader is ever validated. + */ + +#include "nir.h" + +static void +emit_output_copies(nir_shader *shader, nir_variable *temp, nir_variable *output) +{ + nir_foreach_overload(shader, overload) { + if (!overload->impl || strcmp(overload->function->name, "main")) + continue; + + struct set_entry *block_entry; + set_foreach(overload->impl->end_block->predecessors, block_entry) { + struct nir_block *block = (void *)block_entry->key; + + nir_intrinsic_instr *copy = + nir_intrinsic_instr_create(shader, nir_intrinsic_copy_var); + copy->variables[0] = nir_deref_var_create(copy, output); + copy->variables[1] = nir_deref_var_create(copy, temp); + + nir_instr *last_instr = nir_block_last_instr(block); + if (last_instr && last_instr->type == nir_instr_type_jump) + nir_instr_insert_before(last_instr, ©->instr); + else + nir_instr_insert_after_block(block, ©->instr); + } + } +} + +void +nir_lower_outputs_to_temporaries(nir_shader *shader) +{ + struct exec_list old_outputs; + + exec_list_move_nodes_to(&shader->outputs, &old_outputs); + + /* Walk over all of the outputs turn each output into a temporary and + * make a new variable for the actual output. + */ + foreach_list_typed(nir_variable, var, node, &old_outputs) { + nir_variable *output = ralloc(shader, nir_variable); + memcpy(output, var, sizeof *output); + + /* The orignal is now the temporary */ + nir_variable *temp = var; + + /* Move the original name over to the new output */ + if (output->name) + ralloc_steal(output, output->name); + + /* Give the temporary a new name with @out-temp appended */ + temp->name = ralloc_asprintf(temp, "%s@out-temp", output->name); + temp->data.mode = nir_var_global; + temp->constant_initializer = NULL; + + exec_list_push_tail(&shader->outputs, &output->node); + + emit_output_copies(shader, temp, output); + } + + exec_list_append(&shader->globals, &old_outputs); +} -- 2.7.4