path: root/gcc/c-semantics.c

/* This file contains the definitions and documentation for the common
   tree codes used in the GNU C and C++ compilers (see c-common.def
   for the standard codes).
   Copyright (C) 2000, 2001, 2002, 2003, 2004 Free Software Foundation, Inc.
   Written by Benjamin Chelf (chelf@codesourcery.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 "function.h"
#include "splay-tree.h"
#include "varray.h"
#include "c-common.h"
#include "except.h"
/* In order for the format checking to accept the C frontend
   diagnostic framework extensions, you must define this token before
   including toplev.h.  */
#define GCC_DIAG_STYLE __gcc_cdiag__
#include "toplev.h"
#include "flags.h"
#include "ggc.h"
#include "rtl.h"
#include "output.h"
#include "timevar.h"
#include "predict.h"
#include "tree-inline.h"
#include "tree-gimple.h"
#include "langhooks.h"

/* Create an empty statement tree rooted at T.  */

tree
push_stmt_list (void)
{
  tree t;
  t = alloc_stmt_list ();
  TREE_CHAIN (t) = cur_stmt_list;
  cur_stmt_list = t;
  return t;
}

/* Similarly, except that T may have already been pushed/popped, and
   thus may already contain statement(s).  Arrage for new statements
   to be appended.  */

tree
re_push_stmt_list (tree t)
{
  if (t)
    {
      if (TREE_CODE (t) != STATEMENT_LIST)
	{
	  tree u = alloc_stmt_list ();
	  append_to_statement_list_force (t, &u);
	  t = u;
	}
    }
  else
    t = alloc_stmt_list ();
  TREE_CHAIN (t) = cur_stmt_list;
  cur_stmt_list = t;
  return t;
}

/* Finish the statement tree rooted at T.  */

tree
pop_stmt_list (tree t)
{
  tree u = cur_stmt_list, chain;

  /* Pop statement lists until we reach the target level.  The extra
     nestings will be due to outstanding cleanups.  */
  while (1)
    {
      chain = TREE_CHAIN (u);
      TREE_CHAIN (u) = NULL_TREE;
      if (t == u)
	break;
      u = chain;
    }
  cur_stmt_list = chain;

  /* If the statement list is completely empty, just return it.  This is
     just as good small as build_empty_stmt, with the advantage that 
     statement lists are merged when they appended to one another.  So
     using the STATEMENT_LIST avoids pathological buildup of EMPTY_STMT_P
     statements.  */
  if (TREE_SIDE_EFFECTS (t))
    {
      tree_stmt_iterator i = tsi_start (t);

      /* If the statement list contained exactly one statement, then
	 extract it immediately.  */
      if (tsi_one_before_end_p (i))
	{
	  u = tsi_stmt (i);
	  tsi_delink (&i);
	  free_stmt_list (t);
	  t = u;
	}
    }

  return t;
}

/* T is a statement.  Add it to the statement-tree.  */

tree
add_stmt (tree t)
{
  if (EXPR_P (t) || STATEMENT_CODE_P (TREE_CODE (t)))
    {
      if (!EXPR_LOCUS (t))
	annotate_with_locus (t, input_location);

      /* When we expand a statement-tree, we must know whether or not the
	 statements are full-expressions.  We record that fact here.  */
      STMT_IS_FULL_EXPR_P (t) = stmts_are_full_exprs_p ();
    }

  /* Add T to the statement-tree.  Non-side-effect statements need to be
     recorded during statement expressions.  */
  append_to_statement_list_force (t, &cur_stmt_list);

  return t;
}

/* Build a generic statement based on the given type of node and
   arguments. Similar to `build_nt', except that we set
   EXPR_LOCUS to be the current source location.  */
/* ??? This should be obsolete with the lineno_stmt productions
   in the grammar.  */

tree
build_stmt (enum tree_code code, ...)
{
  tree ret;
  int length, i;
  va_list p;
  bool side_effects;

  va_start (p, code);

  ret = make_node (code);
  TREE_TYPE (ret) = void_type_node;
  length = TREE_CODE_LENGTH (code);
  annotate_with_locus (ret, input_location);

  /* Most statements have implicit side effects all on their own, 
     such as control transfer.  For those that do, we'll compute
     the real value of TREE_SIDE_EFFECTS from its arguments.  */
  switch (code)
    {
    case EXPR_STMT:
      side_effects = false;
      break;
    default:
      side_effects = true;
      break;
    }

  for (i = 0; i < length; i++)
    {
      tree t = va_arg (p, tree);
      if (t && IS_NON_TYPE_CODE_CLASS (TREE_CODE_CLASS (TREE_CODE (t))))
        side_effects |= TREE_SIDE_EFFECTS (t);
      TREE_OPERAND (ret, i) = t;
    }

  TREE_SIDE_EFFECTS (ret) = side_effects;

  va_end (p);
  return ret;
}

/* Create RTL for the local static variable DECL.  */

void
make_rtl_for_local_static (tree decl)
{
  const char *asmspec = NULL;

  /* If we inlined this variable, we could see it's declaration
     again.  */
  if (TREE_ASM_WRITTEN (decl))
    return;

  /* If the DECL_ASSEMBLER_NAME is not the same as the DECL_NAME, then
     either we already created RTL for this DECL (and since it was a
     local variable, its DECL_ASSEMBLER_NAME got hacked up to prevent
     clashes with other local statics with the same name by a previous
     call to make_decl_rtl), or the user explicitly requested a
     particular assembly name for this variable, using the GNU
     extension for this purpose:

       int i asm ("j");

     There's no way to know which case we're in, here.  But, it turns
     out we're safe.  If there's already RTL, then
     rest_of_decl_compilation ignores the ASMSPEC parameter, so we
     may as well not pass it in.  If there isn't RTL, then we didn't
     already create RTL, which means that the modification to
     DECL_ASSEMBLER_NAME came only via the explicit extension.  */
  if (DECL_ASSEMBLER_NAME (decl) != DECL_NAME (decl)
      && !DECL_RTL_SET_P (decl))
    asmspec = IDENTIFIER_POINTER (DECL_ASSEMBLER_NAME (decl));

  rest_of_decl_compilation (decl, asmspec, /*top_level=*/0, /*at_end=*/0);
}

/* Let the back-end know about DECL.  */

void
emit_local_var (tree decl)
{
  /* Create RTL for this variable.  */
  if (!DECL_RTL_SET_P (decl))
    {
      if (DECL_HARD_REGISTER (decl))
	/* The user specified an assembler name for this variable.
	   Set that up now.  */
	rest_of_decl_compilation
	  (decl, IDENTIFIER_POINTER (DECL_ASSEMBLER_NAME (decl)),
	   /*top_level=*/0, /*at_end=*/0);
      else
	expand_decl (decl);
    }
}

/* Build a break statement node and return it.  */

tree
build_break_stmt (void)
{
  return (build_stmt (BREAK_STMT));
}

/* Build a continue statement node and return it.  */

tree
build_continue_stmt (void)
{
  return (build_stmt (CONTINUE_STMT));
}

/* Create a CASE_LABEL_EXPR tree node and return it.  */

tree
build_case_label (tree low_value, tree high_value, tree label_decl)
{
  return build_stmt (CASE_LABEL_EXPR, low_value, high_value, label_decl);
}