/* * Copyright © 2015 Broadcom * * 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" /** @file nir_opt_undef.c * * Handles optimization of operations involving ssa_undef. */ /** * Turn conditional selects between an undef and some other value into a move * of that other value (on the assumption that the condition's going to be * choosing the defined value). This reduces work after if flattening when * each side of the if is defining a variable. */ static bool opt_undef_csel(nir_alu_instr *instr) { if (instr->op != nir_op_bcsel && instr->op != nir_op_fcsel) return false; assert(instr->dest.dest.is_ssa); for (int i = 1; i <= 2; i++) { if (!instr->src[i].src.is_ssa) continue; nir_instr *parent = instr->src[i].src.ssa->parent_instr; if (parent->type != nir_instr_type_ssa_undef) continue; /* We can't just use nir_alu_src_copy, because we need the def/use * updated. */ nir_instr_rewrite_src(&instr->instr, &instr->src[0].src, instr->src[i == 1 ? 2 : 1].src); nir_alu_src_copy(&instr->src[0], &instr->src[i == 1 ? 2 : 1], ralloc_parent(instr)); nir_src empty_src; memset(&empty_src, 0, sizeof(empty_src)); nir_instr_rewrite_src(&instr->instr, &instr->src[1].src, empty_src); nir_instr_rewrite_src(&instr->instr, &instr->src[2].src, empty_src); instr->op = nir_op_mov; return true; } return false; } /** * Replace vecN(undef, undef, ...) with a single undef. */ static bool opt_undef_vecN(nir_builder *b, nir_alu_instr *alu) { if (!nir_op_is_vec(alu->op)) return false; assert(alu->dest.dest.is_ssa); for (unsigned i = 0; i < nir_op_infos[alu->op].num_inputs; i++) { if (!alu->src[i].src.is_ssa || alu->src[i].src.ssa->parent_instr->type != nir_instr_type_ssa_undef) return false; } b->cursor = nir_before_instr(&alu->instr); nir_ssa_def *undef = nir_ssa_undef(b, alu->dest.dest.ssa.num_components, nir_dest_bit_size(alu->dest.dest)); nir_ssa_def_rewrite_uses(&alu->dest.dest.ssa, nir_src_for_ssa(undef)); return true; } /** * Remove any store intrinsics whose value is undefined (the existing * value is a fine representation of "undefined"). */ static bool opt_undef_store(nir_intrinsic_instr *intrin) { int arg_index; switch (intrin->intrinsic) { case nir_intrinsic_store_deref: arg_index = 1; break; case nir_intrinsic_store_output: case nir_intrinsic_store_per_vertex_output: case nir_intrinsic_store_ssbo: case nir_intrinsic_store_shared: arg_index = 0; break; default: return false; } if (!intrin->src[arg_index].is_ssa || intrin->src[arg_index].ssa->parent_instr->type != nir_instr_type_ssa_undef) return false; nir_instr_remove(&intrin->instr); return true; } bool nir_opt_undef(nir_shader *shader) { nir_builder b; bool progress = false; nir_foreach_function(function, shader) { if (function->impl) { nir_builder_init(&b, function->impl); nir_foreach_block(block, function->impl) { nir_foreach_instr_safe(instr, block) { if (instr->type == nir_instr_type_alu) { nir_alu_instr *alu = nir_instr_as_alu(instr); progress = opt_undef_csel(alu) || progress; progress = opt_undef_vecN(&b, alu) || progress; } else if (instr->type == nir_instr_type_intrinsic) { nir_intrinsic_instr *intrin = nir_instr_as_intrinsic(instr); progress = opt_undef_store(intrin) || progress; } } } if (progress) { nir_metadata_preserve(function->impl, nir_metadata_block_index | nir_metadata_dominance); } else { #ifndef NDEBUG function->impl->valid_metadata &= ~nir_metadata_not_properly_reset; #endif } } } return progress; }