/* * Copyright © 2014 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) * */ #include "nir.h" #include "nir_builder.h" /* * Implements "copy splitting" which is similar to structure splitting only * it works on copy operations rather than the datatypes themselves. The * GLSL language allows you to copy one variable to another an entire * structure (which may contain arrays or other structures) at a time. * Normally, in a language such as C this would be handled by a "structure * splitting" pass that breaks up the structures. Unfortunately for us, * structures used in inputs or outputs can't be split. Therefore, * regardlesss of what we do, we have to be able to copy to/from * structures. * * The primary purpose of structure splitting is to allow you to better * optimize variable access and lower things to registers where you can. * The primary issue here is that, if you lower the copy to a bunch of * loads and stores, you loose a lot of information about the copy * operation that you would like to keep around. To solve this problem, we * have a "copy splitting" pass that, instead of splitting the structures * or lowering the copy into loads and storres, splits the copy operation * into a bunch of copy operations one for each leaf of the structure tree. * If an intermediate array is encountered, it is referenced with a * wildcard reference to indicate that the entire array is to be copied. * * As things become direct, array copies may be able to be losslessly * lowered to having fewer and fewer wildcards. However, until that * happens we want to keep the information about the arrays intact. * * Prior to the copy splitting pass, there are no wildcard references but * there may be incomplete references where the tail of the deref chain is * an array or a structure and not a specific element. After the copy * splitting pass has completed, every variable deref will be a full-length * dereference pointing to a single leaf in the structure type tree with * possibly a few wildcard array dereferences. */ static void split_deref_copy_instr(nir_builder *b, nir_deref_instr *dst, nir_deref_instr *src) { assert(dst->type == src->type); if (glsl_type_is_vector_or_scalar(src->type)) { nir_copy_deref(b, dst, src); } else if (glsl_type_is_struct(src->type)) { for (unsigned i = 0; i < glsl_get_length(src->type); i++) { split_deref_copy_instr(b, nir_build_deref_struct(b, dst, i), nir_build_deref_struct(b, src, i)); } } else { assert(glsl_type_is_matrix(src->type) || glsl_type_is_array(src->type)); split_deref_copy_instr(b, nir_build_deref_array_wildcard(b, dst), nir_build_deref_array_wildcard(b, src)); } } static bool split_var_copies_impl(nir_function_impl *impl) { bool progress = false; nir_builder b; nir_builder_init(&b, impl); nir_foreach_block(block, impl) { nir_foreach_instr_safe(instr, block) { if (instr->type != nir_instr_type_intrinsic) continue; nir_intrinsic_instr *copy = nir_instr_as_intrinsic(instr); if (copy->intrinsic != nir_intrinsic_copy_deref) continue; b.cursor = nir_instr_remove(©->instr); nir_deref_instr *dst = nir_instr_as_deref(copy->src[0].ssa->parent_instr); nir_deref_instr *src = nir_instr_as_deref(copy->src[1].ssa->parent_instr); split_deref_copy_instr(&b, dst, src); progress = true; } } if (progress) { nir_metadata_preserve(impl, nir_metadata_block_index | nir_metadata_dominance); } else { #ifndef NDEBUG impl->valid_metadata &= ~nir_metadata_not_properly_reset; #endif } return progress; } bool nir_split_var_copies(nir_shader *shader) { bool progress = false; nir_foreach_function(function, shader) { if (function->impl) progress = split_var_copies_impl(function->impl) || progress; } return progress; }