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/*

 * Copyright © 2010 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.

 */

/**

 * \file opt_structure_splitting.cpp

 *

 * If a structure is only ever referenced by its components, then

 * split those components out to individual variables so they can be

 * handled normally by other optimization passes.

 *

 * This skips structures like uniforms, which need to be accessible as

 * structures for their access by the GL.

 */

#include "ir.h"

#include "ir_visitor.h"

#include "ir_rvalue_visitor.h"

#include "glsl_types.h"

namespace {

static bool debug = false;

class variable_entry : public exec_node

{

public:

   variable_entry(ir_variable *var)

   {

      this->var = var;

      this->whole_structure_access = 0;

      this->declaration = false;

      this->components = NULL;

      this->mem_ctx = NULL;

   }

   ir_variable *var; /* The key: the variable's pointer. */

   /** Number of times the variable is referenced, including assignments. */

   unsigned whole_structure_access;

   /* If the variable had a decl we can work with in the instruction

    * stream.  We can't do splitting on function arguments, which

    * don't get this variable set.

    */

   bool declaration;

   ir_variable **components;

   /** ralloc_parent(this->var) -- the shader's ralloc context. */

   void *mem_ctx;

};

class ir_structure_reference_visitor : public ir_hierarchical_visitor {

public:

   ir_structure_reference_visitor(void)

   {

      this->mem_ctx = ralloc_context(NULL);

      this->variable_list.make_empty();

   }

   ~ir_structure_reference_visitor(void)

   {

      ralloc_free(mem_ctx);

   }

   virtual ir_visitor_status visit(ir_variable *);

   virtual ir_visitor_status visit(ir_dereference_variable *);

   virtual ir_visitor_status visit_enter(ir_dereference_record *);

   virtual ir_visitor_status visit_enter(ir_assignment *);

   virtual ir_visitor_status visit_enter(ir_function_signature *);

   variable_entry *get_variable_entry(ir_variable *var);

   /* List of variable_entry */

   exec_list variable_list;

   void *mem_ctx;

};

variable_entry *

ir_structure_reference_visitor::get_variable_entry(ir_variable *var)

{

   assert(var);

   if (!var->type->is_record() || var->mode == ir_var_uniform

       || var->mode == ir_var_shader_in || var->mode == ir_var_shader_out)

      return NULL;

   foreach_iter(exec_list_iterator, iter, this->variable_list) {

      variable_entry *entry = (variable_entry *)iter.get();

      if (entry->var == var)

	 return entry;

   }

   variable_entry *entry = new(mem_ctx) variable_entry(var);

   this->variable_list.push_tail(entry);

   return entry;

}

ir_visitor_status

ir_structure_reference_visitor::visit(ir_variable *ir)

{

   variable_entry *entry = this->get_variable_entry(ir);

   if (entry)

      entry->declaration = true;

   return visit_continue;

}

ir_visitor_status

ir_structure_reference_visitor::visit(ir_dereference_variable *ir)

{

   ir_variable *const var = ir->variable_referenced();

   variable_entry *entry = this->get_variable_entry(var);

   if (entry)

      entry->whole_structure_access++;

   return visit_continue;

}

ir_visitor_status

ir_structure_reference_visitor::visit_enter(ir_dereference_record *ir)

{

   (void) ir;

   /* Don't descend into the ir_dereference_variable below. */

   return visit_continue_with_parent;

}

ir_visitor_status

ir_structure_reference_visitor::visit_enter(ir_assignment *ir)

{

   /* If there are no structure references yet, no need to bother with

    * processing the expression tree.

    */

   if (this->variable_list.is_empty())

      return visit_continue_with_parent;

   if (ir->lhs->as_dereference_variable() &&

       ir->rhs->as_dereference_variable() &&

       !ir->condition) {

      /* We'll split copies of a structure to copies of components, so don't

       * descend to the ir_dereference_variables.

       */

      return visit_continue_with_parent;

   }

   return visit_continue;

}

ir_visitor_status

ir_structure_reference_visitor::visit_enter(ir_function_signature *ir)

{

   /* We don't have logic for structure-splitting function arguments,

    * so just look at the body instructions and not the parameter

    * declarations.

    */

   visit_list_elements(this, &ir->body);

   return visit_continue_with_parent;

}

class ir_structure_splitting_visitor : public ir_rvalue_visitor {

public:

   ir_structure_splitting_visitor(exec_list *vars)

   {

      this->variable_list = vars;

   }

   virtual ~ir_structure_splitting_visitor()

   {

   }

   virtual ir_visitor_status visit_leave(ir_assignment *);

   void split_deref(ir_dereference **deref);

   void handle_rvalue(ir_rvalue **rvalue);

   variable_entry *get_splitting_entry(ir_variable *var);

   exec_list *variable_list;

};

variable_entry *

ir_structure_splitting_visitor::get_splitting_entry(ir_variable *var)

{

   assert(var);

   if (!var->type->is_record())

      return NULL;

   foreach_iter(exec_list_iterator, iter, *this->variable_list) {

      variable_entry *entry = (variable_entry *)iter.get();

      if (entry->var == var) {

	 return entry;

      }

   }

   return NULL;

}

void

ir_structure_splitting_visitor::split_deref(ir_dereference **deref)

{

   if ((*deref)->ir_type != ir_type_dereference_record)

      return;

   ir_dereference_record *deref_record = (ir_dereference_record *)*deref;

   ir_dereference_variable *deref_var = deref_record->record->as_dereference_variable();

   if (!deref_var)

      return;

   variable_entry *entry = get_splitting_entry(deref_var->var);

   if (!entry)

      return;

   unsigned int i;

   for (i = 0; i < entry->var->type->length; i++) {

      if (strcmp(deref_record->field,

		 entry->var->type->fields.structure[i].name) == 0)

	 break;

   }

   assert(i != entry->var->type->length);

   *deref = new(entry->mem_ctx) ir_dereference_variable(entry->components[i]);

}

void

ir_structure_splitting_visitor::handle_rvalue(ir_rvalue **rvalue)

{

   if (!*rvalue)

      return;

   ir_dereference *deref = (*rvalue)->as_dereference();

   if (!deref)

      return;

   split_deref(&deref);

   *rvalue = deref;

}

ir_visitor_status

ir_structure_splitting_visitor::visit_leave(ir_assignment *ir)

{

   ir_dereference_variable *lhs_deref = ir->lhs->as_dereference_variable();

   ir_dereference_variable *rhs_deref = ir->rhs->as_dereference_variable();

   variable_entry *lhs_entry = lhs_deref ? get_splitting_entry(lhs_deref->var) : NULL;

   variable_entry *rhs_entry = rhs_deref ? get_splitting_entry(rhs_deref->var) : NULL;

   const glsl_type *type = ir->rhs->type;

   if ((lhs_entry || rhs_entry) && !ir->condition) {

      for (unsigned int i = 0; i < type->length; i++) {

	 ir_dereference *new_lhs, *new_rhs;

	 void *mem_ctx = lhs_entry ? lhs_entry->mem_ctx : rhs_entry->mem_ctx;

	 if (lhs_entry) {

	    new_lhs = new(mem_ctx) ir_dereference_variable(lhs_entry->components[i]);

	 } else {

	    new_lhs = new(mem_ctx)

	       ir_dereference_record(ir->lhs->clone(mem_ctx, NULL),

				     type->fields.structure[i].name);

	 }

	 if (rhs_entry) {

	    new_rhs = new(mem_ctx) ir_dereference_variable(rhs_entry->components[i]);

	 } else {

	    new_rhs = new(mem_ctx)

	       ir_dereference_record(ir->rhs->clone(mem_ctx, NULL),

				     type->fields.structure[i].name);

	 }

	 ir->insert_before(new(mem_ctx) ir_assignment(new_lhs,

						      new_rhs,

						      NULL));

      }

      ir->remove();

   } else {

      handle_rvalue(&ir->rhs);

      split_deref(&ir->lhs);

   }

   handle_rvalue(&ir->condition);

   return visit_continue;

}

} /* unnamed namespace */

bool

do_structure_splitting(exec_list *instructions)

{

   ir_structure_reference_visitor refs;

   visit_list_elements(&refs, instructions);

   /* Trim out variables we can't split. */

   foreach_iter(exec_list_iterator, iter, refs.variable_list) {

      variable_entry *entry = (variable_entry *)iter.get();

      if (debug) {

	 printf("structure %s@%p: decl %d, whole_access %d\n",

		entry->var->name, (void *) entry->var, entry->declaration,

		entry->whole_structure_access);

      }

      if (!entry->declaration || entry->whole_structure_access) {

	 entry->remove();

      }

   }

   if (refs.variable_list.is_empty())

      return false;

   void *mem_ctx = ralloc_context(NULL);

   /* Replace the decls of the structures to be split with their split

    * components.

    */

   foreach_iter(exec_list_iterator, iter, refs.variable_list) {

      variable_entry *entry = (variable_entry *)iter.get();

      const struct glsl_type *type = entry->var->type;

      entry->mem_ctx = ralloc_parent(entry->var);

      entry->components = ralloc_array(mem_ctx,

				       ir_variable *,

				       type->length);

      for (unsigned int i = 0; i < entry->var->type->length; i++) {

	 const char *name = ralloc_asprintf(mem_ctx, "%s_%s",

					    entry->var->name,

					    type->fields.structure[i].name);

	 entry->components[i] =

	    new(entry->mem_ctx) ir_variable(type->fields.structure[i].type,

					    name,

					    ir_var_temporary);

	 entry->var->insert_before(entry->components[i]);

      }

      entry->var->remove();

   }

   ir_structure_splitting_visitor split(&refs.variable_list);

   visit_list_elements(&split, instructions);

   ralloc_free(mem_ctx);

   return true;

}