gimplify.c

/* Tree lowering pass.  This pass converts the GENERIC functions-as-trees
   tree representation into the GIMPLE form.
   Copyright (C) 2002, 2003, 2004 Free Software Foundation, Inc.
   Major work done by Sebastian Pop <s.pop@laposte.net>,
   Diego Novillo <dnovillo@redhat.com> and Jason Merrill <jason@redhat.com>.

This file is part of GCC.

GCC 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 2, or (at your option) any later
version.

GCC 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 GCC; see the file COPYING.  If not, write to the Free
Software Foundation, 59 Temple Place - Suite 330, Boston, MA
02111-1307, USA.  */

#include "config.h"
#include "system.h"
#include "coretypes.h"
#include "tm.h"
#include "tree.h"
#include "rtl.h"
#include "errors.h"
#include "varray.h"
#include "tree-gimple.h"
#include "tree-inline.h"
#include "diagnostic.h"
#include "langhooks.h"
#include "langhooks-def.h"
#include "tree-flow.h"
#include "cgraph.h"
#include "timevar.h"
#include "except.h"
#include "hashtab.h"
#include "flags.h"
#include "real.h"
#include "function.h"
#include "output.h"
#include "expr.h"
#include "ggc.h"
#include "target.h"

static struct gimplify_ctx
{
  tree current_bind_expr;
  bool save_stack;
  tree temps;
  tree conditional_cleanups;
  int conditions;
  tree exit_label;
  tree return_temp;
  varray_type case_labels;
  /* The formal temporary table.  Should this be persistent?  */
  htab_t temp_htab;
} *gimplify_ctxp;


/* Formal (expression) temporary table handling: Multiple occurrences of
   the same scalar expression are evaluated into the same temporary.  */

typedef struct gimple_temp_hash_elt
{
  tree val;   /* Key */
  tree temp;  /* Value */
} elt_t;

/* Forward declarations.  */
static enum gimplify_status gimplify_compound_expr (tree *, tree *, bool);


/* Return a hash value for a formal temporary table entry.  */

static hashval_t
gimple_tree_hash (const void *p)
{
  tree t = ((const elt_t *) p)->val;
  return iterative_hash_expr (t, 0);
}

/* Compare two formal temporary table entries.  */

static int
gimple_tree_eq (const void *p1, const void *p2)
{
  tree t1 = ((const elt_t *) p1)->val;
  tree t2 = ((const elt_t *) p2)->val;
  enum tree_code code = TREE_CODE (t1);

  if (TREE_CODE (t2) != code
      || TREE_TYPE (t1) != TREE_TYPE (t2))
    return 0;

  if (!operand_equal_p (t1, t2, 0))
    return 0;

  /* Only allow them to compare equal if they also hash equal; otherwise
     results are nondeterminate, and we fail bootstrap comparison.  */
  if (gimple_tree_hash (p1) != gimple_tree_hash (p2))
    abort ();

  return 1;
}

/* Set up a context for the gimplifier.  */

void
push_gimplify_context (void)
{
  if (gimplify_ctxp)
    abort ();
  gimplify_ctxp
    = (struct gimplify_ctx *) xcalloc (1, sizeof (struct gimplify_ctx));
  gimplify_ctxp->temp_htab
    = htab_create (1000, gimple_tree_hash, gimple_tree_eq, free);
}

/* Tear down a context for the gimplifier.  If BODY is non-null, then
   put the temporaries into the outer BIND_EXPR.  Otherwise, put them
   in the unexpanded_var_list.  */

void
pop_gimplify_context (tree body)
{
  if (!gimplify_ctxp || gimplify_ctxp->current_bind_expr)
    abort ();

  if (body)
    declare_tmp_vars (gimplify_ctxp->temps, body);
  else
    record_vars (gimplify_ctxp->temps);

#if 0
  if (!quiet_flag)
    fprintf (stderr, " collisions: %f ",
	     htab_collisions (gimplify_ctxp->temp_htab));
#endif

  htab_delete (gimplify_ctxp->temp_htab);
  free (gimplify_ctxp);
  gimplify_ctxp = NULL;
}

void
gimple_push_bind_expr (tree bind)
{
  TREE_CHAIN (bind) = gimplify_ctxp->current_bind_expr;
  gimplify_ctxp->current_bind_expr = bind;
}

void
gimple_pop_bind_expr (void)
{
  gimplify_ctxp->current_bind_expr
    = TREE_CHAIN (gimplify_ctxp->current_bind_expr);
}

tree
gimple_current_bind_expr (void)
{
  return gimplify_ctxp->current_bind_expr;
}

/* Returns true iff there is a COND_EXPR between us and the innermost
   CLEANUP_POINT_EXPR.  This info is used by gimple_push_cleanup.  */

static bool
gimple_conditional_context (void)
{
  return gimplify_ctxp->conditions > 0;
}

/* Note that we've entered a COND_EXPR.  */

static void
gimple_push_condition (void)
{
  ++(gimplify_ctxp->conditions);
}

/* Note that we've left a COND_EXPR.  If we're back at unconditional scope
   now, add any conditional cleanups we've seen to the prequeue.  */

static void
gimple_pop_condition (tree *pre_p)
{
  int conds = --(gimplify_ctxp->conditions);

  if (conds == 0)
    {
      append_to_statement_list (gimplify_ctxp->conditional_cleanups, pre_p);
      gimplify_ctxp->conditional_cleanups = NULL_TREE;
    }
  else if (conds < 0)