src/compiler/nir/nir_lower_locals_to_regs.c - platform/external/mesa3d - Git at Google

 /*
  * 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"

 struct locals_to_regs_state {
    nir_builder builder;

    /* A hash table mapping derefs to registers */
    struct hash_table *regs_table;

    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 = 0;

    for (const nir_deref_instr *deref = void_deref; deref;
         deref = nir_deref_instr_parent(deref)) {
       switch (deref->deref_type) {
       case nir_deref_type_var:
          return XXH32(&deref->var, sizeof(deref->var), hash);

       case nir_deref_type_array:
          continue; /* Do nothing */

       case nir_deref_type_struct:
          hash = XXH32(&deref->strct.index, sizeof(deref->strct.index), hash);
          continue;

       default:
          unreachable("Invalid deref type");
       }
    }

    unreachable("We should have hit a variable dereference");
 }

 static bool
 derefs_equal(const void *void_a, const void *void_b)
 {
    for (const nir_deref_instr *a = void_a, *b = void_b; a || b;
         a = nir_deref_instr_parent(a), b = nir_deref_instr_parent(b)) {
       if (a->deref_type != b->deref_type)
          return false;

       switch (a->deref_type) {
       case nir_deref_type_var:
          return a->var == b->var;

       case nir_deref_type_array:
          continue; /* Do nothing */

       case nir_deref_type_struct:
          if (a->strct.index != b->strct.index)
             return false;
          continue;

       default:
          unreachable("Invalid deref type");
       }
    }

    unreachable("We should have hit a variable dereference");
 }

 static nir_register *
 get_reg_for_deref(nir_deref_instr *deref, struct locals_to_regs_state *state)
 {
    uint32_t hash = hash_deref(deref);

    assert(nir_deref_instr_get_variable(deref)->constant_initializer == NULL &&
           nir_deref_instr_get_variable(deref)->pointer_initializer == NULL);

    struct hash_entry *entry =
       _mesa_hash_table_search_pre_hashed(state->regs_table, hash, deref);
    if (entry)
       return entry->data;

    unsigned array_size = 1;
    for (nir_deref_instr *d = deref; d; d = nir_deref_instr_parent(d)) {
       if (d->deref_type == nir_deref_type_array)
          array_size *= glsl_get_length(nir_deref_instr_parent(d)->type);
    }

    assert(glsl_type_is_vector_or_scalar(deref->type));

    nir_register *reg = nir_local_reg_create(state->builder.impl);
    reg->num_components = glsl_get_vector_elements(deref->type);
    reg->num_array_elems = array_size > 1 ? array_size : 0;
    reg->bit_size = glsl_get_bit_size(deref->type);

    _mesa_hash_table_insert_pre_hashed(state->regs_table, hash, deref, reg);

    return reg;
 }

 static nir_src
 get_deref_reg_src(nir_deref_instr *deref, struct locals_to_regs_state *state)
 {
    nir_builder *b = &state->builder;

    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;

    unsigned inner_array_size = 1;
    for (const nir_deref_instr *d = deref; d; d = nir_deref_instr_parent(d)) {
       if (d->deref_type != nir_deref_type_array)
          continue;

       if (nir_src_is_const(d->arr.index) && !src.reg.indirect) {
          src.reg.base_offset += nir_src_as_uint(d->arr.index) *
                                 inner_array_size;
       } else {
          if (src.reg.indirect) {
             assert(src.reg.base_offset == 0);
          } else {
             src.reg.indirect = ralloc(b->shader, nir_src);
             *src.reg.indirect =
                nir_src_for_ssa(nir_imm_int(b, src.reg.base_offset));
             src.reg.base_offset = 0;
          }

          assert(src.reg.indirect->is_ssa);
          nir_ssa_def *index = nir_i2i(b, nir_ssa_for_src(b, d->arr.index, 1), 32);
          src.reg.indirect->ssa =
             nir_iadd(b, src.reg.indirect->ssa,
                         nir_imul(b, index, nir_imm_int(b, inner_array_size)));
       }

       inner_array_size *= glsl_get_length(nir_deref_instr_parent(d)->type);
    }

    return src;
 }

 static bool
 lower_locals_to_regs_block(nir_block *block,
                            struct locals_to_regs_state *state)
 {
    nir_builder *b = &state->builder;

    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_deref: {
          nir_deref_instr *deref = nir_src_as_deref(intrin->src[0]);
          if (deref->mode != nir_var_function_temp)
             continue;

          b->cursor = nir_before_instr(&intrin->instr);

          nir_alu_instr *mov = nir_alu_instr_create(b->shader, nir_op_mov);
          mov->src[0].src = get_deref_reg_src(deref, 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_builder_instr_insert(b, &mov->instr);

          nir_instr_remove(&intrin->instr);
          state->progress = true;
          break;
       }

       case nir_intrinsic_store_deref: {
          nir_deref_instr *deref = nir_src_as_deref(intrin->src[0]);
          if (deref->mode != nir_var_function_temp)
             continue;

          b->cursor = nir_before_instr(&intrin->instr);

          nir_src reg_src = get_deref_reg_src(deref, state);

          nir_alu_instr *mov = nir_alu_instr_create(b->shader, nir_op_mov);
          nir_src_copy(&mov->src[0].src, &intrin->src[1], 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_builder_instr_insert(b, &mov->instr);

          nir_instr_remove(&intrin->instr);
          state->progress = true;
          break;
       }

       case nir_intrinsic_copy_deref:
          unreachable("There should be no copies whatsoever at this point");
          break;

       default:
          continue;
       }
    }

    return true;
 }

 static bool
 nir_lower_locals_to_regs_impl(nir_function_impl *impl)
 {
    struct locals_to_regs_state state;

    nir_builder_init(&state.builder, impl);
    state.progress = false;
    state.regs_table = _mesa_hash_table_create(NULL, hash_deref, derefs_equal);

    nir_metadata_require(impl, nir_metadata_dominance);

    nir_foreach_block(block, impl) {
       lower_locals_to_regs_block(block, &state);
    }

    nir_metadata_preserve(impl, nir_metadata_block_index |
                                nir_metadata_dominance);

    _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_builder.h"

	struct locals_to_regs_state {
	nir_builder builder;

	/* A hash table mapping derefs to registers */
	struct hash_table *regs_table;

	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 = 0;

	for (const nir_deref_instr *deref = void_deref; deref;
	deref = nir_deref_instr_parent(deref)) {
	switch (deref->deref_type) {
	case nir_deref_type_var:
	return XXH32(&deref->var, sizeof(deref->var), hash);

	case nir_deref_type_array:
	continue; /* Do nothing */

	case nir_deref_type_struct:
	hash = XXH32(&deref->strct.index, sizeof(deref->strct.index), hash);
	continue;

	default:
	unreachable("Invalid deref type");
	}
	}

	unreachable("We should have hit a variable dereference");
	}

	static bool
	derefs_equal(const void void_a, const void void_b)
	{
	for (const nir_deref_instr a = void_a, b = void_b; a \|\| b;
	a = nir_deref_instr_parent(a), b = nir_deref_instr_parent(b)) {
	if (a->deref_type != b->deref_type)
	return false;

	switch (a->deref_type) {
	case nir_deref_type_var:
	return a->var == b->var;

	case nir_deref_type_array:
	continue; /* Do nothing */

	case nir_deref_type_struct:
	if (a->strct.index != b->strct.index)
	return false;
	continue;

	default:
	unreachable("Invalid deref type");
	}
	}

	unreachable("We should have hit a variable dereference");
	}

	static nir_register *
	get_reg_for_deref(nir_deref_instr deref, struct locals_to_regs_state state)
	{
	uint32_t hash = hash_deref(deref);

	assert(nir_deref_instr_get_variable(deref)->constant_initializer == NULL &&
	nir_deref_instr_get_variable(deref)->pointer_initializer == NULL);

	struct hash_entry *entry =
	_mesa_hash_table_search_pre_hashed(state->regs_table, hash, deref);
	if (entry)
	return entry->data;

	unsigned array_size = 1;
	for (nir_deref_instr *d = deref; d; d = nir_deref_instr_parent(d)) {
	if (d->deref_type == nir_deref_type_array)
	array_size *= glsl_get_length(nir_deref_instr_parent(d)->type);
	}

	assert(glsl_type_is_vector_or_scalar(deref->type));

	nir_register *reg = nir_local_reg_create(state->builder.impl);
	reg->num_components = glsl_get_vector_elements(deref->type);
	reg->num_array_elems = array_size > 1 ? array_size : 0;
	reg->bit_size = glsl_get_bit_size(deref->type);

	_mesa_hash_table_insert_pre_hashed(state->regs_table, hash, deref, reg);

	return reg;
	}

	static nir_src
	get_deref_reg_src(nir_deref_instr deref, struct locals_to_regs_state state)
	{
	nir_builder *b = &state->builder;

	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;

	unsigned inner_array_size = 1;
	for (const nir_deref_instr *d = deref; d; d = nir_deref_instr_parent(d)) {
	if (d->deref_type != nir_deref_type_array)
	continue;

	if (nir_src_is_const(d->arr.index) && !src.reg.indirect) {
	src.reg.base_offset += nir_src_as_uint(d->arr.index) *
	inner_array_size;
	} else {
	if (src.reg.indirect) {
	assert(src.reg.base_offset == 0);
	} else {
	src.reg.indirect = ralloc(b->shader, nir_src);
	*src.reg.indirect =
	nir_src_for_ssa(nir_imm_int(b, src.reg.base_offset));
	src.reg.base_offset = 0;
	}

	assert(src.reg.indirect->is_ssa);
	nir_ssa_def *index = nir_i2i(b, nir_ssa_for_src(b, d->arr.index, 1), 32);
	src.reg.indirect->ssa =
	nir_iadd(b, src.reg.indirect->ssa,
	nir_imul(b, index, nir_imm_int(b, inner_array_size)));
	}

	inner_array_size *= glsl_get_length(nir_deref_instr_parent(d)->type);
	}

	return src;
	}

	static bool
	lower_locals_to_regs_block(nir_block *block,
	struct locals_to_regs_state *state)
	{
	nir_builder *b = &state->builder;

	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_deref: {
	nir_deref_instr *deref = nir_src_as_deref(intrin->src[0]);
	if (deref->mode != nir_var_function_temp)
	continue;

	b->cursor = nir_before_instr(&intrin->instr);

	nir_alu_instr *mov = nir_alu_instr_create(b->shader, nir_op_mov);
	mov->src[0].src = get_deref_reg_src(deref, 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_builder_instr_insert(b, &mov->instr);

	nir_instr_remove(&intrin->instr);
	state->progress = true;
	break;
	}

	case nir_intrinsic_store_deref: {
	nir_deref_instr *deref = nir_src_as_deref(intrin->src[0]);
	if (deref->mode != nir_var_function_temp)
	continue;

	b->cursor = nir_before_instr(&intrin->instr);

	nir_src reg_src = get_deref_reg_src(deref, state);

	nir_alu_instr *mov = nir_alu_instr_create(b->shader, nir_op_mov);
	nir_src_copy(&mov->src[0].src, &intrin->src[1], 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_builder_instr_insert(b, &mov->instr);

	nir_instr_remove(&intrin->instr);
	state->progress = true;
	break;
	}

	case nir_intrinsic_copy_deref:
	unreachable("There should be no copies whatsoever at this point");
	break;

	default:
	continue;
	}
	}

	return true;
	}

	static bool
	nir_lower_locals_to_regs_impl(nir_function_impl *impl)
	{
	struct locals_to_regs_state state;

	nir_builder_init(&state.builder, impl);
	state.progress = false;
	state.regs_table = _mesa_hash_table_create(NULL, hash_deref, derefs_equal);

	nir_metadata_require(impl, nir_metadata_dominance);

	nir_foreach_block(block, impl) {
	lower_locals_to_regs_block(block, &state);
	}

	nir_metadata_preserve(impl, nir_metadata_block_index \|
	nir_metadata_dominance);

	_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;
	}