src/compiler/nir/nir_lower_locals_to_regs.c - platform/external/mesa3d - Gitiles

 /*
  * 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;
    reg->bit_size = glsl_get_bit_size(tail->type);

    _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, 32);
          load_const->value.u32[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, 32, 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, 32, 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,
                            struct locals_to_regs_state *state)
 {
    nir_foreach_instr_safe(instr, block) {
       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,
                               intrin->dest.ssa.bit_size, 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 = nir_intrinsic_write_mask(intrin);
          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, &reg->defs, reg.def_link)
       lca = nir_dominance_lca(lca, def_dest->reg.parent_instr->block);

    list_for_each_entry(nir_src, use_src, &reg->uses, use_link)
       lca = nir_dominance_lca(lca, use_src->parent_instr->block);

    list_for_each_entry(nir_src, use_src, &reg->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(block, impl) {
       lower_locals_to_regs_block(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(function, shader) {
       if (function->impl)
          progress = nir_lower_locals_to_regs_impl(function->impl) || progress;
    }

    return progress;
 }
	/*
	* 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;
	reg->bit_size = glsl_get_bit_size(tail->type);

	_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, 32);
	load_const->value.u32[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, 32, 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, 32, 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,
	struct locals_to_regs_state *state)
	{
	nir_foreach_instr_safe(instr, block) {
	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,
	intrin->dest.ssa.bit_size, 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 = nir_intrinsic_write_mask(intrin);
	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, &reg->defs, reg.def_link)
	lca = nir_dominance_lca(lca, def_dest->reg.parent_instr->block);

	list_for_each_entry(nir_src, use_src, &reg->uses, use_link)
	lca = nir_dominance_lca(lca, use_src->parent_instr->block);

	list_for_each_entry(nir_src, use_src, &reg->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(block, impl) {
	lower_locals_to_regs_block(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(function, shader) {
	if (function->impl)
	progress = nir_lower_locals_to_regs_impl(function->impl) \|\| progress;
	}

	return progress;
	}