/* * Copyright © 2018 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. */ #include "nir.h" #include "nir_builder.h" #include "nir_deref.h" static bool index_ssa_def_cb(nir_ssa_def *def, void *state) { unsigned *index = (unsigned *) state; def->index = (*index)++; return true; } static nir_deref_instr * get_deref_for_load_src(nir_src src, unsigned first_valid_load) { if (!src.is_ssa) return NULL; if (src.ssa->parent_instr->type != nir_instr_type_intrinsic) return NULL; nir_intrinsic_instr *load = nir_instr_as_intrinsic(src.ssa->parent_instr); if (load->intrinsic != nir_intrinsic_load_deref) return NULL; if (load->dest.ssa.index < first_valid_load) return NULL; return nir_src_as_deref(load->src[0]); } struct match_state { /* Index into the array of the last copy or -1 for no ongoing copy. */ unsigned next_array_idx; /* Length of the array we're copying */ unsigned array_len; /* Index into the deref path to the array we think is being copied */ int src_deref_array_idx; int dst_deref_array_idx; /* Deref paths of the first load/store pair or copy */ nir_deref_path first_src_path; nir_deref_path first_dst_path; }; static void match_state_init(struct match_state *state) { state->next_array_idx = 0; state->array_len = 0; state->src_deref_array_idx = -1; state->dst_deref_array_idx = -1; } static void match_state_finish(struct match_state *state) { if (state->next_array_idx > 0) { nir_deref_path_finish(&state->first_src_path); nir_deref_path_finish(&state->first_dst_path); } } static void match_state_reset(struct match_state *state) { match_state_finish(state); match_state_init(state); } static bool try_match_deref(nir_deref_path *base_path, int *path_array_idx, nir_deref_instr *deref, int arr_idx, void *mem_ctx) { nir_deref_path deref_path; nir_deref_path_init(&deref_path, deref, mem_ctx); bool found = false; for (int i = 0; ; i++) { nir_deref_instr *b = base_path->path[i]; nir_deref_instr *d = deref_path.path[i]; /* They have to be the same length */ if ((b == NULL) != (d == NULL)) goto fail; if (b == NULL) break; /* This can happen if one is a deref_array and the other a wildcard */ if (b->deref_type != d->deref_type) goto fail; switch (b->deref_type) { case nir_deref_type_var: if (b->var != d->var) goto fail; continue; case nir_deref_type_array: assert(b->arr.index.is_ssa && d->arr.index.is_ssa); const bool const_b_idx = nir_src_is_const(b->arr.index); const bool const_d_idx = nir_src_is_const(d->arr.index); const unsigned b_idx = const_b_idx ? nir_src_as_uint(b->arr.index) : 0; const unsigned d_idx = const_d_idx ? nir_src_as_uint(d->arr.index) : 0; /* If we don't have an index into the path yet or if this entry in * the path is at the array index, see if this is a candidate. We're * looking for an index which is zero in the base deref and arr_idx * in the search deref. */ if ((*path_array_idx < 0 || *path_array_idx == i) && const_b_idx && b_idx == 0 && const_d_idx && d_idx == arr_idx) { *path_array_idx = i; continue; } /* We're at the array index but not a candidate */ if (*path_array_idx == i) goto fail; /* If we're not the path array index, we must match exactly. We * could probably just compare SSA values and trust in copy * propagation but doing it ourselves means this pass can run a bit * earlier. */ if (b->arr.index.ssa == d->arr.index.ssa || (const_b_idx && const_d_idx && b_idx == d_idx)) continue; goto fail; case nir_deref_type_array_wildcard: continue; case nir_deref_type_struct: if (b->strct.index != d->strct.index) goto fail; continue; default: unreachable("Invalid deref type in a path"); } } /* If we got here without failing, we've matched. However, it isn't an * array match unless we found an altered array index. */ found = *path_array_idx > 0; fail: nir_deref_path_finish(&deref_path); return found; } static nir_deref_instr * build_wildcard_deref(nir_builder *b, nir_deref_path *path, unsigned wildcard_idx) { assert(path->path[wildcard_idx]->deref_type == nir_deref_type_array); nir_deref_instr *tail = nir_build_deref_array_wildcard(b, path->path[wildcard_idx - 1]); for (unsigned i = wildcard_idx + 1; path->path[i]; i++) tail = nir_build_deref_follower(b, tail, path->path[i]); return tail; } static bool opt_find_array_copies_block(nir_builder *b, nir_block *block, unsigned *num_ssa_defs, void *mem_ctx) { bool progress = false; struct match_state s; match_state_init(&s); nir_variable *dst_var = NULL; unsigned prev_dst_var_last_write = *num_ssa_defs; unsigned dst_var_last_write = *num_ssa_defs; nir_foreach_instr(instr, block) { /* Index the SSA defs before we do anything else. */ nir_foreach_ssa_def(instr, index_ssa_def_cb, num_ssa_defs); if (instr->type != nir_instr_type_intrinsic) continue; nir_intrinsic_instr *intrin = nir_instr_as_intrinsic(instr); if (intrin->intrinsic != nir_intrinsic_copy_deref && intrin->intrinsic != nir_intrinsic_store_deref) continue; nir_deref_instr *dst_deref = nir_src_as_deref(intrin->src[0]); /* The destination must be local. If we see a non-local store, we * continue on because it won't affect local stores or read-only * variables. */ if (dst_deref->mode != nir_var_function_temp) continue; /* We keep track of the SSA indices where the two last-written * variables are written. The prev_dst_var_last_write tells us when * the last store_deref to something other than dst happened. If the * SSA def index from a load is greater than or equal to this number * then we know it happened afterwards and no writes to anything other * than dst occur between the load and the current instruction. */ if (nir_deref_instr_get_variable(dst_deref) != dst_var) { prev_dst_var_last_write = dst_var_last_write; dst_var = nir_deref_instr_get_variable(dst_deref); } dst_var_last_write = *num_ssa_defs; /* If it's a full variable store or copy, reset. This will trigger * eventually because we'll fail to match an array element. However, * it's a cheap early-exit. */ if (dst_deref->deref_type == nir_deref_type_var) goto reset; nir_deref_instr *src_deref; if (intrin->intrinsic == nir_intrinsic_copy_deref) { src_deref = nir_src_as_deref(intrin->src[1]); } else { assert(intrin->intrinsic == nir_intrinsic_store_deref); src_deref = get_deref_for_load_src(intrin->src[1], prev_dst_var_last_write); /* We can only handle full writes */ if (nir_intrinsic_write_mask(intrin) != (1 << glsl_get_components(dst_deref->type)) - 1) goto reset; } /* If we didn't find a valid src, then we have an unknown store and it * could mess things up. */ if (src_deref == NULL) goto reset; /* The source must be either local or something that's guaranteed to be * read-only. */ const nir_variable_mode read_only_modes = nir_var_shader_in | nir_var_uniform | nir_var_system_value; if (!(src_deref->mode & (nir_var_function_temp | read_only_modes))) goto reset; /* If we don't yet have an active copy, then make this instruction the * active copy. */ if (s.next_array_idx == 0) { /* We can't combine a copy if there is any chance the source and * destination will end up aliasing. Just bail if they're the same * variable. */ if (nir_deref_instr_get_variable(src_deref) == dst_var) goto reset; /* The load/store pair is enough to guarantee the same bit size and * number of components but a copy_var requires the actual types to * match. */ if (dst_deref->type != src_deref->type) continue; /* The first time we see a store, we don't know which array in the * deref path is the one being copied so we just record the paths * as-is and continue. On the next iteration, it will try to match * based on which array index changed. */ nir_deref_path_init(&s.first_dst_path, dst_deref, mem_ctx); nir_deref_path_init(&s.first_src_path, src_deref, mem_ctx); s.next_array_idx = 1; continue; } if (!try_match_deref(&s.first_dst_path, &s.dst_deref_array_idx, dst_deref, s.next_array_idx, mem_ctx) || !try_match_deref(&s.first_src_path, &s.src_deref_array_idx, src_deref, s.next_array_idx, mem_ctx)) goto reset; if (s.next_array_idx == 1) { /* This is our first non-trivial match. We now have indices into * the search paths so we can do a couple more checks. */ assert(s.dst_deref_array_idx > 0 && s.src_deref_array_idx > 0); const struct glsl_type *dst_arr_type = s.first_dst_path.path[s.dst_deref_array_idx - 1]->type; const struct glsl_type *src_arr_type = s.first_src_path.path[s.src_deref_array_idx - 1]->type; assert(glsl_type_is_array(dst_arr_type) || glsl_type_is_matrix(dst_arr_type)); assert(glsl_type_is_array(src_arr_type) || glsl_type_is_matrix(src_arr_type)); /* They must be the same length */ s.array_len = glsl_get_length(dst_arr_type); if (s.array_len != glsl_get_length(src_arr_type)) goto reset; } s.next_array_idx++; if (s.next_array_idx == s.array_len) { /* Hooray, We found a copy! */ b->cursor = nir_after_instr(instr); nir_copy_deref(b, build_wildcard_deref(b, &s.first_dst_path, s.dst_deref_array_idx), build_wildcard_deref(b, &s.first_src_path, s.src_deref_array_idx)); match_state_reset(&s); progress = true; } continue; reset: match_state_reset(&s); } return progress; } static bool opt_find_array_copies_impl(nir_function_impl *impl) { nir_builder b; nir_builder_init(&b, impl); bool progress = false; void *mem_ctx = ralloc_context(NULL); /* We re-index the SSA defs as we go; it makes it easier to handle * resetting the state machine. */ unsigned num_ssa_defs = 0; nir_foreach_block(block, impl) { if (opt_find_array_copies_block(&b, block, &num_ssa_defs, mem_ctx)) progress = true; } impl->ssa_alloc = num_ssa_defs; ralloc_free(mem_ctx); if (progress) { nir_metadata_preserve(impl, nir_metadata_block_index | nir_metadata_dominance); } return progress; } /** * This peephole optimization looks for a series of load/store_deref or * copy_deref instructions that copy an array from one variable to another and * turns it into a copy_deref that copies the entire array. The pattern it * looks for is extremely specific but it's good enough to pick up on the * input array copies in DXVK and should also be able to pick up the sequence * generated by spirv_to_nir for a OpLoad of a large composite followed by * OpStore. * * TODO: Use a hash table approach to support out-of-order and interleaved * copies. */ bool nir_opt_find_array_copies(nir_shader *shader) { bool progress = false; nir_foreach_function(function, shader) { if (function->impl && opt_find_array_copies_impl(function->impl)) progress = true; } return progress; }