diff options
Diffstat (limited to 'src/compiler/nir/nir_lower_locals_to_regs.c')
| -rw-r--r-- | src/compiler/nir/nir_lower_locals_to_regs.c | 396 |
1 files changed, 396 insertions, 0 deletions
diff --git a/src/compiler/nir/nir_lower_locals_to_regs.c b/src/compiler/nir/nir_lower_locals_to_regs.c new file mode 100644 index 0000000..51b0fa7 --- /dev/null +++ b/src/compiler/nir/nir_lower_locals_to_regs.c @@ -0,0 +1,396 @@ +/* + * 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_array.h" + +struct locals_to_regs_state { + nir_shader *shader; + nir_function_impl *impl; + + /* A hash table mapping derefs to registers */ + struct hash_table *regs_table; + + /* A growing array of derefs that we have encountered. There is exactly + * one element of this array per element in the hash table. This is + * used to make adding register initialization code deterministic. + */ + nir_array derefs_array; + + bool progress; +}; + +/* The following two functions implement a hash and equality check for + * variable dreferences. When the hash or equality function encounters an + * array, it ignores the offset and whether it is direct or indirect + * entirely. + */ +static uint32_t +hash_deref(const void *void_deref) +{ + uint32_t hash = _mesa_fnv32_1a_offset_bias; + + const nir_deref_var *deref_var = void_deref; + hash = _mesa_fnv32_1a_accumulate(hash, deref_var->var); + + for (const nir_deref *deref = deref_var->deref.child; + deref; deref = deref->child) { + if (deref->deref_type == nir_deref_type_struct) { + const nir_deref_struct *deref_struct = nir_deref_as_struct(deref); + hash = _mesa_fnv32_1a_accumulate(hash, deref_struct->index); + } + } + + return hash; +} + +static bool +derefs_equal(const void *void_a, const void *void_b) +{ + const nir_deref_var *a_var = void_a; + const nir_deref_var *b_var = void_b; + + if (a_var->var != b_var->var) + return false; + + for (const nir_deref *a = a_var->deref.child, *b = b_var->deref.child; + a != NULL; a = a->child, b = b->child) { + if (a->deref_type != b->deref_type) + return false; + + if (a->deref_type == nir_deref_type_struct) { + if (nir_deref_as_struct(a)->index != nir_deref_as_struct(b)->index) + return false; + } + /* Do nothing for arrays. They're all the same. */ + + assert((a->child == NULL) == (b->child == NULL)); + if((a->child == NULL) != (b->child == NULL)) + return false; + } + + return true; +} + +static nir_register * +get_reg_for_deref(nir_deref_var *deref, struct locals_to_regs_state *state) +{ + uint32_t hash = hash_deref(deref); + + struct hash_entry *entry = + _mesa_hash_table_search_pre_hashed(state->regs_table, hash, deref); + if (entry) + return entry->data; + + unsigned array_size = 1; + nir_deref *tail = &deref->deref; + while (tail->child) { + if (tail->child->deref_type == nir_deref_type_array) + array_size *= glsl_get_length(tail->type); + tail = tail->child; + } + + assert(glsl_type_is_vector(tail->type) || glsl_type_is_scalar(tail->type)); + + nir_register *reg = nir_local_reg_create(state->impl); + reg->num_components = glsl_get_vector_elements(tail->type); + reg->num_array_elems = array_size > 1 ? array_size : 0; + + _mesa_hash_table_insert_pre_hashed(state->regs_table, hash, deref, reg); + nir_array_add(&state->derefs_array, nir_deref_var *, deref); + + return reg; +} + +static nir_src +get_deref_reg_src(nir_deref_var *deref, nir_instr *instr, + struct locals_to_regs_state *state) +{ + nir_src src; + + src.is_ssa = false; + src.reg.reg = get_reg_for_deref(deref, state); + src.reg.base_offset = 0; + src.reg.indirect = NULL; + + /* It is possible for a user to create a shader that has an array with a + * single element and then proceed to access it indirectly. Indirectly + * accessing a non-array register is not allowed in NIR. In order to + * handle this case we just convert it to a direct reference. + */ + if (src.reg.reg->num_array_elems == 0) + return src; + + nir_deref *tail = &deref->deref; + while (tail->child != NULL) { + const struct glsl_type *parent_type = tail->type; + tail = tail->child; + + if (tail->deref_type != nir_deref_type_array) + continue; + + nir_deref_array *deref_array = nir_deref_as_array(tail); + + src.reg.base_offset *= glsl_get_length(parent_type); + src.reg.base_offset += deref_array->base_offset; + + if (src.reg.indirect) { + nir_load_const_instr *load_const = + nir_load_const_instr_create(state->shader, 1); + load_const->value.u[0] = glsl_get_length(parent_type); + nir_instr_insert_before(instr, &load_const->instr); + + nir_alu_instr *mul = nir_alu_instr_create(state->shader, nir_op_imul); + mul->src[0].src = *src.reg.indirect; + mul->src[1].src.is_ssa = true; + mul->src[1].src.ssa = &load_const->def; + mul->dest.write_mask = 1; + nir_ssa_dest_init(&mul->instr, &mul->dest.dest, 1, NULL); + nir_instr_insert_before(instr, &mul->instr); + + src.reg.indirect->is_ssa = true; + src.reg.indirect->ssa = &mul->dest.dest.ssa; + } + + if (deref_array->deref_array_type == nir_deref_array_type_indirect) { + if (src.reg.indirect == NULL) { + src.reg.indirect = ralloc(state->shader, nir_src); + nir_src_copy(src.reg.indirect, &deref_array->indirect, + state->shader); + } else { + nir_alu_instr *add = nir_alu_instr_create(state->shader, + nir_op_iadd); + add->src[0].src = *src.reg.indirect; + nir_src_copy(&add->src[1].src, &deref_array->indirect, add); + add->dest.write_mask = 1; + nir_ssa_dest_init(&add->instr, &add->dest.dest, 1, NULL); + nir_instr_insert_before(instr, &add->instr); + + src.reg.indirect->is_ssa = true; + src.reg.indirect->ssa = &add->dest.dest.ssa; + } + } + } + + return src; +} + +static bool +lower_locals_to_regs_block(nir_block *block, void *void_state) +{ + struct locals_to_regs_state *state = void_state; + + nir_foreach_instr_safe(block, instr) { + if (instr->type != nir_instr_type_intrinsic) + continue; + + nir_intrinsic_instr *intrin = nir_instr_as_intrinsic(instr); + + switch (intrin->intrinsic) { + case nir_intrinsic_load_var: { + if (intrin->variables[0]->var->data.mode != nir_var_local) + continue; + + nir_alu_instr *mov = nir_alu_instr_create(state->shader, nir_op_imov); + mov->src[0].src = get_deref_reg_src(intrin->variables[0], + &intrin->instr, state); + mov->dest.write_mask = (1 << intrin->num_components) - 1; + if (intrin->dest.is_ssa) { + nir_ssa_dest_init(&mov->instr, &mov->dest.dest, + intrin->num_components, NULL); + nir_ssa_def_rewrite_uses(&intrin->dest.ssa, + nir_src_for_ssa(&mov->dest.dest.ssa)); + } else { + nir_dest_copy(&mov->dest.dest, &intrin->dest, &mov->instr); + } + nir_instr_insert_before(&intrin->instr, &mov->instr); + + nir_instr_remove(&intrin->instr); + state->progress = true; + break; + } + + case nir_intrinsic_store_var: { + if (intrin->variables[0]->var->data.mode != nir_var_local) + continue; + + nir_src reg_src = get_deref_reg_src(intrin->variables[0], + &intrin->instr, state); + + nir_alu_instr *mov = nir_alu_instr_create(state->shader, nir_op_imov); + nir_src_copy(&mov->src[0].src, &intrin->src[0], mov); + mov->dest.write_mask = intrin->const_index[0]; + mov->dest.dest.is_ssa = false; + mov->dest.dest.reg.reg = reg_src.reg.reg; + mov->dest.dest.reg.base_offset = reg_src.reg.base_offset; + mov->dest.dest.reg.indirect = reg_src.reg.indirect; + + nir_instr_insert_before(&intrin->instr, &mov->instr); + + nir_instr_remove(&intrin->instr); + state->progress = true; + break; + } + + case nir_intrinsic_copy_var: + unreachable("There should be no copies whatsoever at this point"); + break; + + default: + continue; + } + } + + return true; +} + +static nir_block * +compute_reg_usedef_lca(nir_register *reg) +{ + nir_block *lca = NULL; + + list_for_each_entry(nir_dest, def_dest, ®->defs, reg.def_link) + lca = nir_dominance_lca(lca, def_dest->reg.parent_instr->block); + + list_for_each_entry(nir_src, use_src, ®->uses, use_link) + lca = nir_dominance_lca(lca, use_src->parent_instr->block); + + list_for_each_entry(nir_src, use_src, ®->if_uses, use_link) { + nir_cf_node *prev_node = nir_cf_node_prev(&use_src->parent_if->cf_node); + assert(prev_node->type == nir_cf_node_block); + lca = nir_dominance_lca(lca, nir_cf_node_as_block(prev_node)); + } + + return lca; +} + +static void +insert_constant_initializer(nir_deref_var *deref_head, nir_deref *deref_tail, + nir_block *block, + struct locals_to_regs_state *state) +{ + if (deref_tail->child) { + switch (deref_tail->child->deref_type) { + case nir_deref_type_array: { + unsigned array_elems = glsl_get_length(deref_tail->type); + + nir_deref_array arr_deref; + arr_deref.deref = *deref_tail->child; + arr_deref.deref_array_type = nir_deref_array_type_direct; + + nir_deref *old_child = deref_tail->child; + deref_tail->child = &arr_deref.deref; + for (unsigned i = 0; i < array_elems; i++) { + arr_deref.base_offset = i; + insert_constant_initializer(deref_head, &arr_deref.deref, + block, state); + } + deref_tail->child = old_child; + return; + } + + case nir_deref_type_struct: + insert_constant_initializer(deref_head, deref_tail->child, + block, state); + return; + + default: + unreachable("Invalid deref child type"); + } + } + + assert(deref_tail->child == NULL); + + nir_load_const_instr *load = + nir_deref_get_const_initializer_load(state->shader, deref_head); + nir_instr_insert_before_block(block, &load->instr); + + nir_src reg_src = get_deref_reg_src(deref_head, &load->instr, state); + + nir_alu_instr *mov = nir_alu_instr_create(state->shader, nir_op_imov); + mov->src[0].src = nir_src_for_ssa(&load->def); + mov->dest.write_mask = (1 << load->def.num_components) - 1; + mov->dest.dest.is_ssa = false; + mov->dest.dest.reg.reg = reg_src.reg.reg; + mov->dest.dest.reg.base_offset = reg_src.reg.base_offset; + mov->dest.dest.reg.indirect = reg_src.reg.indirect; + + nir_instr_insert_after(&load->instr, &mov->instr); + state->progress = true; +} + +static bool +nir_lower_locals_to_regs_impl(nir_function_impl *impl) +{ + struct locals_to_regs_state state; + + state.shader = impl->function->shader; + state.impl = impl; + state.progress = false; + state.regs_table = _mesa_hash_table_create(NULL, hash_deref, derefs_equal); + nir_array_init(&state.derefs_array, NULL); + + nir_metadata_require(impl, nir_metadata_dominance); + + nir_foreach_block(impl, lower_locals_to_regs_block, &state); + + nir_array_foreach(&state.derefs_array, nir_deref_var *, deref_ptr) { + nir_deref_var *deref = *deref_ptr; + struct hash_entry *deref_entry = + _mesa_hash_table_search(state.regs_table, deref); + assert(deref_entry && deref_entry->key == deref); + nir_register *reg = (nir_register *)deref_entry->data; + + if (deref->var->constant_initializer == NULL) + continue; + + nir_block *usedef_lca = compute_reg_usedef_lca(reg); + + insert_constant_initializer(deref, &deref->deref, usedef_lca, &state); + } + + nir_metadata_preserve(impl, nir_metadata_block_index | + nir_metadata_dominance); + + nir_array_fini(&state.derefs_array); + _mesa_hash_table_destroy(state.regs_table, NULL); + + return state.progress; +} + +bool +nir_lower_locals_to_regs(nir_shader *shader) +{ + bool progress = false; + + nir_foreach_function(shader, function) { + if (function->impl) + progress = nir_lower_locals_to_regs_impl(function->impl) || progress; + } + + return progress; +} |