/*

  $Id$

  Copyright 1989-2016 MINES ParisTech

  This file is part of PIPS.

  PIPS is free software: you can redistribute it and/or modify it
  under the terms of the GNU General Public License as published by
  the Free Software Foundation, either version 3 of the License, or
  any later version.

  PIPS is distributed in the hope that it will be useful, but WITHOUT ANY
  WARRANTY; without even the implied warranty of MERCHANTABILITY or
  FITNESS FOR A PARTICULAR PURPOSE.

  See the GNU General Public License for more details.

  You should have received a copy of the GNU General Public License
  along with PIPS.  If not, see <http://www.gnu.org/licenses/>.

*/
#ifdef HAVE_CONFIG_H
    #include "pips_config.h"
#endif

#include <stdio.h>
#include <string.h>

#include "genC.h"

#include "linear.h"
#include "ri.h"
#include "effects.h"

#include "ri-util.h"
#include "prettyprint.h"
#include "effects-util.h"
#include "misc.h"
#include "properties.h"

/* void atomize_as_required(stat, ref_decide, call_decide, test_decide, range_decide, while_decide, new)
 * statement stat;
 * bool (*ref_decide)(ref r, expression e);
 * bool (*call_decide)(call r, expression e);
 * bool (*test_decide)(test t, expression e);
 * bool (*range_decide)(range r, expression e), 
 * bool (*while_decide)(whileloop w, expression e), 
 * entity (*new)(entity m, basic b);
 *
 * atomizes the given statement as driven by the given functions.
 * ??? does not care of any side effect and so.
 * 
 * - ref_decide tells whether or not to atomize for reference r
 *   and expression indice e of this reference. If yes, expression e
 *   is computed outside.
 * - call_decide tells whether or not to atomize for call c
 *   and argument expression e...
 * - test_decide tells whether expression condition e of a test
 *   should be atomized or not.
 * - new creates a new entity in the current module, the basic type
 *   of which should be t.
 */

static void atomize_object(gen_chunk*);

/* static functions used
 */
static bool (*ref_atomize_decision)(/* ref r, expression e */) = NULL;
static bool (*call_atomize_decision)(/* call c, expression e */)= NULL;
static bool (*test_atomize_decision)(/* expression e */) = NULL;
static bool (*range_atomize_decision)(/* range r, expression e */)= NULL;
static bool (*while_atomize_decision)(/* whileloop w, expression e */)= NULL;

static entity (*create_new_variable)(/* entity m, tag t */) = NULL;


/* the stack of the encoutered statements is maintained
 * to be able to insert the needed computations just before the
 * very last statement encountered.
 *
 * The use of a stack is not necessary, since there are no effective rewrite.
 * but it could have been... It enables some recursive calls that would have
 * required to save the current statement explicitely otherwise.
 */
DEFINE_LOCAL_STACK(current_statement, statement)
DEFINE_LOCAL_STACK(current_control, control)

static void simple_atomize_error_handler()
{
  error_reset_current_statement_stack();
  error_reset_current_control_stack();
}

/* s is inserted before the current statement.
 * if it is a block, it is added just before the last statement of the block,
 * else a block statement is created in place of the current statement.
 */
static void insert_before_current_statement(statement s)
{
  statement   cs = current_statement_head();
  instruction  i = statement_instruction(cs);
  control     cc = current_control_empty_p() ?
    control_undefined : current_control_head() ;

  if (!control_undefined_p(cc) && control_statement(cc)==cs)
  {
    /* it is in an unstructured, and s is to be inserted properly
     */
    bool seen;
    control newc;

    pips_debug(8, "unstructured\n");

    newc = make_control(s, control_predecessors(cc), 
                        CONS(CONTROL, cc, NIL));
    control_predecessors(cc) = CONS(CONTROL, newc, NIL);

    /*   update the other lists
     */
    MAPL(c1,
         {
           seen=false;

           MAPL(c2,
                {
                  if (CONTROL(CAR(c2))==cc) 
                  {
                    CONTROL_(CAR(c2))=newc;
                    seen=true;
                  }
                },
                control_successors(CONTROL(CAR(c1))));

           assert(seen);
         },
         control_predecessors(newc));

	/*   new current statement, to avoid other control insertions
	 */
    current_statement_replace(s);
    gen_recurse_stop(newc);
  }
  else
  {
    pips_debug(7, "statement\n");

    if (instruction_block_p(i)) {
	  list /* of statement */ block = instruction_block(i);
	  /* insert statement before the last one */
	  block = gen_insert_before(s,
                              STATEMENT(CAR(gen_last(block))),
                              block);
    }
    else {
      statement_instruction(cs) =
        make_instruction_block(
          CONS(STATEMENT, s,
               CONS(STATEMENT,
                    make_statement(statement_label(cs),
                                   statement_number(cs),
                                   statement_ordering(cs),
                                   statement_comments(cs),
                                   statement_instruction(cs),
                                   NIL, NULL,
                                   statement_extensions(cs),
                                   make_synchronization_none()),
                    NIL)));
      statement_label(cs) = entity_empty_label();
      statement_number(cs) = STATEMENT_NUMBER_UNDEFINED;
      statement_ordering(cs) = STATEMENT_ORDERING_UNDEFINED;
      statement_comments(cs) = empty_comments;
      statement_extensions(cs) = empty_extensions ();
    }
  }
}

/* returns the assignment statement is moved, or NULL if not.
 */
statement atomize_this_expression(
  entity (*create)(entity, basic),
  expression e)
{
    /* it does not make sense to atomize a range...
    */
    if (syntax_range_p(expression_syntax(e))) return NULL;

    basic bofe = basic_of_expression(e);
    statement out = NULL;
    if(!basic_undefined_p(bofe)) {
        if (!basic_overloaded_p(bofe))
        {
            bool skip_this_expression = false;
            if( get_bool_property("COMMON_SUBEXPRESSION_ELIMINATION_SKIP_ADDED_CONSTANT") && expression_call_p(e) )
            {
                call c = expression_call(e);
                entity op = call_function(c);
                if(ENTITY_PLUS_P(op) || ENTITY_PLUS_C_P(op) || ENTITY_PLUS_UPDATE_P(op))
                {
                    FOREACH(EXPRESSION,arg,call_arguments(c))
                        skip_this_expression|=expression_constant_p(arg);
                }

            }

            if(!skip_this_expression) {
                ifdebug(1) {
                    pips_debug(1,"atomizing expression:\n");
                    print_expression(e);
                }
                entity newvar = (*create)(get_current_module_entity(), copy_basic(bofe));
                AddEntityToCurrentModule(newvar);
                expression rhs = make_expression(expression_syntax(e), normalized_undefined);
                normalize_all_expressions_of(rhs);

                syntax ref = make_syntax_reference(make_reference(newvar, NIL));

                out = make_assign_statement(make_expression(copy_syntax(ref), normalized_undefined), rhs);
                expression_syntax(e) = ref;
            }
        }
    }
    free_basic(bofe);
    return out;
}

static void compute_before_current_statement(expression *pe)
{
    statement stat = atomize_this_expression(create_new_variable,*pe);
    if (stat) insert_before_current_statement(stat);
}

static void ref_rwt(reference r)
{
  MAPL(ce,
       {
         expression *pe = (expression*) REFCAR(ce);

         if ((*ref_atomize_decision)(r, *pe))
         {
           /* syntax saved = expression_syntax(*pe);*/
           compute_before_current_statement(pe);
           /* atomize_object(saved); */
         }
       },
       reference_indices(r));

  /* return(false);*/
}

static void call_rwt(call c)
{
  if (same_string_p(entity_local_name(call_function(c)), IMPLIED_DO_NAME))
    return; /* (panic mode:-) */

  MAPL(ce,
       {
         expression *pe = (expression*) REFCAR(ce);

         if ((*call_atomize_decision)(c, *pe))
         {
           /* syntax saved = expression_syntax(*pe);*/

           compute_before_current_statement(pe);
           /* atomize_object(saved); */
         }
       },
       call_arguments(c));
}


static void exp_range_rwt (range r, expression * pe)
{
  if ((*range_atomize_decision)(r, *pe))
  {
    /* syntax saved = expression_syntax(*pe); */
    compute_before_current_statement(pe);
    /* atomize_object(saved);*/
  }
}

static void range_rwt(range r)
{
  /* lower */
  exp_range_rwt(r, &range_lower(r));

  /* upper */
  exp_range_rwt(r, &range_upper(r));

  /* increment */
  exp_range_rwt(r, &range_increment(r));
}


static void test_rwt(test t)
{
  expression *pe = &test_condition(t);

  if ((*test_atomize_decision)(t, *pe))
  {
    /* syntax saved = expression_syntax(*pe);*/
    /*   else I have to break the condition
     *   and to complete the recursion.
     */
    compute_before_current_statement(pe);
    /* atomize_object(saved); */
  }
}

static void whileloop_rwt(whileloop w)
{
  expression *pe = &whileloop_condition(w);

  if ((*while_atomize_decision)(w, *pe))
  {
    /* syntax saved = expression_syntax(*pe); */
    /*   else I have to break the condition
     *   and to complete the recursion.
     */
    compute_before_current_statement(pe);
    /* atomize_object(saved);*/
  }
}

static void cleanup_subscript(expression e)
{
  if(syntax_subscript_p(expression_syntax(e)))
  {
    subscript s = syntax_subscript(expression_syntax(e));
    if(expression_reference_p(subscript_array(s)))
      /* the subscript could be a reference ! */
    {
      syntax sa = expression_syntax(subscript_array(s));

      /* update reference with additionnal indices */
      reference r = syntax_reference(sa);
      reference_indices(r)=gen_nconc(reference_indices(r),subscript_indices(s));
      /* prepare to free subscript */
      subscript_indices(s)=NIL;
      expression_syntax(subscript_array(s))=syntax_undefined;
      free_subscript(s);
      /* transform subscript into reference */
      syntax_tag(expression_syntax(e))=is_syntax_reference;
      syntax_reference(expression_syntax(e))=r;
    }
  }
}

static void cleanup_subscript_pre(expression exp)
{
  if(expression_call_p(exp)) {
    call c = expression_call(exp);
    if(ENTITY_DEREFERENCING_P(call_function(c))) {
      expression lhs = binary_call_lhs(c);
      if(expression_call_p(lhs)) {
        call c = expression_call(lhs);
        if(ENTITY_ADDRESS_OF_P(call_function(c))) {
          expression lhs = binary_call_lhs(c);
          syntax syn = expression_syntax(lhs);
          expression_syntax(lhs)=syntax_undefined;
          update_expression_syntax(exp,syn);
        }
      }
    }
  }
}

void cleanup_subscripts(void* obj)
{
  gen_recurse(obj, expression_domain, gen_true, cleanup_subscript_pre);
  gen_recurse(obj, expression_domain, gen_true, cleanup_subscript);
}

static void atomize_object(gen_chunk *obj)
{
  gen_multi_recurse
    (obj,
     control_domain, current_control_filter,
     current_control_rewrite,     /* CONTROL */
     statement_domain, current_statement_filter,
     current_statement_rewrite,   /* STATEMENT */
     reference_domain, gen_true, ref_rwt,      /* REFERENCE */
     test_domain, gen_true, test_rwt,          /* TEST */
     call_domain, gen_true, call_rwt,          /* CALL */
     range_domain, gen_true, range_rwt,        /* RANGE */
     whileloop_domain, gen_true, whileloop_rwt,/* WHILELOOP */
     NULL);
  cleanup_subscripts(obj);
}

void atomize_as_required(
  statement stat,
  bool (*ref_decide)(reference, expression), /* reference */
  bool (*call_decide)(call, expression), /* call */
  bool (*test_decide)(test, expression), /* test */
  bool (*range_decide)(range, expression), /* range */
  bool (*while_decide)(whileloop, expression), /* whileloop */
  entity (*new)(entity, basic))
{
  ifdebug(5) {
    pips_debug(5,
               "Statement at entry:\n");
    print_statement(stat);
  }
  reset_hooks_register(simple_atomize_error_handler);
  make_current_statement_stack();
  make_current_control_stack();
  ref_atomize_decision = ref_decide;
  call_atomize_decision = call_decide;
  test_atomize_decision = test_decide;
  range_atomize_decision = range_decide;
  while_atomize_decision = while_decide;
  create_new_variable = new;

  atomize_object((gen_chunkp) stat);

  ref_atomize_decision = NULL;
  call_atomize_decision = NULL;
  test_atomize_decision = NULL;
  range_atomize_decision = NULL;
  while_atomize_decision = NULL;
  create_new_variable = NULL;
  free_current_statement_stack();
  free_current_control_stack();
  reset_hooks_unregister(simple_atomize_error_handler);

  ifdebug(5) {
    pips_debug(5,
               "Statement at exit:\n");
    print_statement(stat);
  }
}

/*  that is all
 */