decl.c

GUN开源阻止下的编译器GCC

/* Pointers to the base and current top of the language name stack.  */

extern tree *current_lang_base, *current_lang_stack;

/* C and C++ flags are in decl2.c.  */

/* Set to 0 at beginning of a constructor, set to 1
   if that function does an allocation before referencing its
   instance variable.  */
int current_function_assigns_this;
int current_function_just_assigned_this;

/* Set to 0 at beginning of a function.  Set non-zero when
   store_parm_decls is called.  Don't call store_parm_decls
   if this flag is non-zero!  */
int current_function_parms_stored;

/* Current end of entries in the gc obstack for stack pointer variables.  */

int current_function_obstack_index;

/* Flag saying whether we have used the obstack in this function or not.  */

int current_function_obstack_usage;

/* Flag used when debugging spew.c */

extern int spew_debug;

/* This is a copy of the class_shadowed list of the previous class binding
   contour when at global scope.  It's used to reset IDENTIFIER_CLASS_VALUEs
   when entering another class scope (i.e. a cache miss).  */
extern tree previous_class_values;


/* Allocate a level of searching.  */
struct stack_level *
push_decl_level (stack, obstack)
     struct stack_level *stack;
     struct obstack *obstack;
{
  struct stack_level tem;
  tem.prev = stack;

  return push_stack_level (obstack, (char *)&tem, sizeof (tem));
}

/* For each binding contour we allocate a binding_level structure
 * which records the names defined in that contour.
 * Contours include:
 *  0) the global one
 *  1) one for each function definition,
 *     where internal declarations of the parameters appear.
 *  2) one for each compound statement,
 *     to record its declarations.
 *
 * The current meaning of a name can be found by searching the levels from
 * the current one out to the global one.
 *
 * Off to the side, may be the class_binding_level.  This exists
 * only to catch class-local declarations.  It is otherwise
 * nonexistent.
 * 
 * Also there may be binding levels that catch cleanups that
 * must be run when exceptions occur.
 */

/* Note that the information in the `names' component of the global contour
   is duplicated in the IDENTIFIER_GLOBAL_VALUEs of all identifiers.  */

struct binding_level
  {
    /* A chain of _DECL nodes for all variables, constants, functions,
     * and typedef types.  These are in the reverse of the order supplied.
     */
    tree names;

    /* A list of structure, union and enum definitions,
     * for looking up tag names.
     * It is a chain of TREE_LIST nodes, each of whose TREE_PURPOSE is a name,
     * or NULL_TREE; and whose TREE_VALUE is a RECORD_TYPE, UNION_TYPE,
     * or ENUMERAL_TYPE node.
     *
     * C++: the TREE_VALUE nodes can be simple types for component_bindings.
     *
     */
    tree tags;

    /* For each level, a list of shadowed outer-level local definitions
       to be restored when this level is popped.
       Each link is a TREE_LIST whose TREE_PURPOSE is an identifier and
       whose TREE_VALUE is its old definition (a kind of ..._DECL node).  */
    tree shadowed;

    /* Same, for IDENTIFIER_CLASS_VALUE.  */
    tree class_shadowed;

    /* Same, for IDENTIFIER_TYPE_VALUE.  */
    tree type_shadowed;

    /* For each level (except not the global one),
       a chain of BLOCK nodes for all the levels
       that were entered and exited one level down.  */
    tree blocks;

    /* The BLOCK node for this level, if one has been preallocated.
       If 0, the BLOCK is allocated (if needed) when the level is popped.  */
    tree this_block;

    /* The binding level which this one is contained in (inherits from).  */
    struct binding_level *level_chain;

    /* List of decls in `names' that have incomplete
       structure or union types.  */
    tree incomplete;

    /* List of VAR_DECLS saved from a previous for statement.
       These would be dead in ANSI-conforming code, but might
       be referenced in traditional code. */
    tree dead_vars_from_for;

    /* 1 for the level that holds the parameters of a function.
       2 for the level that holds a class declaration.
       3 for levels that hold parameter declarations.  */
    unsigned parm_flag : 4;

    /* 1 means make a BLOCK for this level regardless of all else.
       2 for temporary binding contours created by the compiler.  */
    unsigned keep : 3;

    /* Nonzero if this level "doesn't exist" for tags.  */
    unsigned tag_transparent : 1;

    /* Nonzero if this level can safely have additional
       cleanup-needing variables added to it.  */
    unsigned more_cleanups_ok : 1;
    unsigned have_cleanups : 1;

    /* Nonzero if we should accept any name as an identifier in
       this scope.  This happens in some template definitions.  */
    unsigned accept_any : 1;

    /* Nonzero if this level is for completing a template class definition
       inside a binding level that temporarily binds the parameters.  This
       means that definitions here should not be popped off when unwinding
       this binding level.  (Not actually implemented this way,
       unfortunately.)  */
    unsigned pseudo_global : 1;

    /* This is set for a namespace binding level.  */
    unsigned namespace_p : 1;

    /* True if this level is that of a for-statement. */
    unsigned is_for_scope : 1;

    /* One bit left for this word.  */

#if defined(DEBUG_CP_BINDING_LEVELS)
    /* Binding depth at which this level began.  */
    unsigned binding_depth;
#endif /* defined(DEBUG_CP_BINDING_LEVELS) */
  };

#define NULL_BINDING_LEVEL ((struct binding_level *) NULL)
  
/* The (non-class) binding level currently in effect.  */

static struct binding_level *current_binding_level;

/* The binding level of the current class, if any.  */

static struct binding_level *class_binding_level;

/* The current (class or non-class) binding level currently in effect.  */

#define inner_binding_level \
  (class_binding_level ? class_binding_level : current_binding_level)

/* A chain of binding_level structures awaiting reuse.  */

static struct binding_level *free_binding_level;

/* The outermost binding level, for names of file scope.
   This is created when the compiler is started and exists
   through the entire run.  */

static struct binding_level *global_binding_level;

/* Binding level structures are initialized by copying this one.  */

static struct binding_level clear_binding_level;

/* Nonzero means unconditionally make a BLOCK for the next level pushed.  */

static int keep_next_level_flag;

#if defined(DEBUG_CP_BINDING_LEVELS)
static int binding_depth = 0;
static int is_class_level = 0;

static void
indent ()
{
  register unsigned i;

  for (i = 0; i < binding_depth*2; i++)
    putc (' ', stderr);
}
#endif /* defined(DEBUG_CP_BINDING_LEVELS) */

static tree pushdecl_with_scope	PROTO((tree, struct binding_level *));

static void
push_binding_level (newlevel, tag_transparent, keep)
     struct binding_level *newlevel;
     int tag_transparent, keep;
{
  /* Add this level to the front of the chain (stack) of levels that
     are active.  */
  *newlevel = clear_binding_level;
  if (class_binding_level)
    {
      newlevel->level_chain = class_binding_level;
      class_binding_level = (struct binding_level *)0;
    }
  else
    {
      newlevel->level_chain = current_binding_level;
    }
  current_binding_level = newlevel;
  newlevel->tag_transparent = tag_transparent;
  newlevel->more_cleanups_ok = 1;
  newlevel->keep = keep;
#if defined(DEBUG_CP_BINDING_LEVELS)
  newlevel->binding_depth = binding_depth;
  indent ();
  fprintf (stderr, "push %s level 0x%08x line %d\n",
	   (is_class_level) ? "class" : "block", newlevel, lineno);
  is_class_level = 0;
  binding_depth++;
#endif /* defined(DEBUG_CP_BINDING_LEVELS) */
}

static void
pop_binding_level ()
{
  if (class_binding_level)
    current_binding_level = class_binding_level;

  if (global_binding_level)
    {
      /* cannot pop a level, if there are none left to pop. */
      if (current_binding_level == global_binding_level)
	my_friendly_abort (123);
    }
  /* Pop the current level, and free the structure for reuse.  */
#if defined(DEBUG_CP_BINDING_LEVELS)
  binding_depth--;
  indent ();
  fprintf (stderr, "pop  %s level 0x%08x line %d\n",
	  (is_class_level) ? "class" : "block",
	  current_binding_level, lineno);
  if (is_class_level != (current_binding_level == class_binding_level))
#if 0 /* XXX Don't abort when we're watching how things are being managed.  */
    abort ();
#else
  {
    indent ();
    fprintf (stderr, "XXX is_class_level != (current_binding_level == class_binding_level)\n");
  }
#endif
  is_class_level = 0;
#endif /* defined(DEBUG_CP_BINDING_LEVELS) */
  {
    register struct binding_level *level = current_binding_level;
    current_binding_level = current_binding_level->level_chain;
    level->level_chain = free_binding_level;
#if 0 /* defined(DEBUG_CP_BINDING_LEVELS) */
    if (level->binding_depth != binding_depth)
      abort ();
#endif /* defined(DEBUG_CP_BINDING_LEVELS) */
      free_binding_level = level;

    class_binding_level = current_binding_level;
    if (class_binding_level->parm_flag != 2)
      class_binding_level = 0;
    while (current_binding_level->parm_flag == 2)
      current_binding_level = current_binding_level->level_chain;
  }
}

static void
suspend_binding_level ()
{
  if (class_binding_level)
    current_binding_level = class_binding_level;

  if (global_binding_level)
    {
      /* cannot suspend a level, if there are none left to suspend. */
      if (current_binding_level == global_binding_level)
	my_friendly_abort (123);
    }
  /* Suspend the current level.  */
#if defined(DEBUG_CP_BINDING_LEVELS)
  binding_depth--;
  indent ();
  fprintf (stderr, "suspend  %s level 0x%08x line %d\n",
	  (is_class_level) ? "class" : "block",
	  current_binding_level, lineno);
  if (is_class_level != (current_binding_level == class_binding_level))
#if 0 /* XXX Don't abort when we're watching how things are being managed.  */
    abort ();
#else
  {
    indent ();
    fprintf (stderr, "XXX is_class_level != (current_binding_level == class_binding_level)\n");
  }
#endif
  is_class_level = 0;
#endif /* defined(DEBUG_CP_BINDING_LEVELS) */
  {
    register struct binding_level *level = current_binding_level;
    current_binding_level = current_binding_level->level_chain;
#if 0 /* defined(DEBUG_CP_BINDING_LEVELS) */
    if (level->binding_depth != binding_depth)
      abort ();
#endif /* defined(DEBUG_CP_BINDING_LEVELS) */

    class_binding_level = current_binding_level;
    if (class_binding_level->parm_flag != 2)
      class_binding_level = 0;
    while (current_binding_level->parm_flag == 2)
      current_binding_level = current_binding_level->level_chain;
  }
}

void
resume_binding_level (b)
     struct binding_level *b;
{
  if (class_binding_level)
    {
#if 1
      /* These are here because we cannot deal with shadows yet. */
      sorry ("cannot resume a namespace inside class");
      return;
#else
      b->level_chain = class_binding_level;
      class_binding_level = (struct binding_level *)0;
#endif
    }
  else
    {
#if 1
      /* These are here because we cannot deal with shadows yet. */
      if (b->level_chain != current_binding_level)
	{
	  sorry ("cannot resume a namespace inside a different namespace");
	  return;
	}
#endif
      b->level_chain = current_binding_level;
    }
  current_binding_level = b;
#if defined(DEBUG_CP_BINDING_LEVELS)
  b->binding_depth = binding_depth;
  indent ();
  fprintf (stderr, "resume %s level 0x%08x line %d\n",
	   (is_class_level) ? "class" : "block", b, lineno);
  is_class_level = 0;
  binding_depth++;
#endif /* defined(DEBUG_CP_BINDING_LEVELS) */
}

/* Nonzero if we are currently in the global binding level.  */

int
global_bindings_p ()
{
  return current_binding_level == global_binding_level;
}

/* Nonzero if we are currently in a toplevel binding level.  This
   means either the global binding level or a namespace in a toplevel
   binding level.  */

int
toplevel_bindings_p ()
{
  struct binding_level *b = current_binding_level;

  while (1)
    {
      if (b == global_binding_level)
	return 1;
      if (! b->namespace_p)
	return 0;
      b=b->level_chain;
    }
}

/* Nonzero if this is a namespace scope.  */

int
namespace_bindings_p ()
{
  return current_binding_level->namespace_p;
}

void
keep_next_level ()
{
  keep_next_level_flag = 1;
}

/* Nonzero if the current level needs to have a BLOCK made.  */

int
kept_level_p ()
{
  return (current_binding_level->blocks != NULL_TREE
	  || current_binding_level->keep
	  || current_binding_level->names != NULL_TREE
	  || (current_binding_level->tags != NULL_TREE
	      && !current_binding_level->tag_transparent));
}

/* Identify this binding level as a level of parameters.  */

void
declare_parm_level ()
{
  current_binding_level->parm_flag = 1;
}