decl.c

GCC编译器源代码

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

static 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;
}

void
declare_pseudo_global_level ()
{
  current_binding_level->pseudo_global = 1;
}

static void
declare_namespace_level ()
{
  current_binding_level->namespace_p = 1;
}

int
pseudo_global_level_p ()
{
  return current_binding_level->pseudo_global;
}

void
set_class_shadows (shadows)
     tree shadows;
{
  class_binding_level->class_shadowed = shadows;
}

/* Enter a new binding level.
   If TAG_TRANSPARENT is nonzero, do so only for the name space of variables,
   not for that of tags.  */

void
pushlevel (tag_transparent)
     int tag_transparent;
{
  register struct binding_level *newlevel = NULL_BINDING_LEVEL;

  /* If this is the top level of a function,
     just make sure that NAMED_LABELS is 0.
     They should have been set to 0 at the end of the previous function.  */

  if (current_binding_level == global_binding_level)
    my_friendly_assert (named_labels == NULL_TREE, 134);

  /* Reuse or create a struct for this binding level.  */

#if defined(DEBUG_CP_BINDING_LEVELS)
  if (0)
#else /* !defined(DEBUG_CP_BINDING_LEVELS) */
  if (free_binding_level)
#endif /* !defined(DEBUG_CP_BINDING_LEVELS) */
    {
      newlevel = free_binding_level;
      free_binding_level = free_binding_level->level_chain;
    }
  else
    {
      newlevel = make_binding_level ();
    }

  push_binding_level (newlevel, tag_transparent, keep_next_level_flag);
  GNU_xref_start_scope ((HOST_WIDE_INT) newlevel);
  keep_next_level_flag = 0;
}

void
note_level_for_for ()
{
  current_binding_level->is_for_scope = 1;
}

void
pushlevel_temporary (tag_transparent)
     int tag_transparent;
{
  pushlevel (tag_transparent);
  current_binding_level->keep = 2;
  clear_last_expr ();

  /* Note we don't call push_momentary() here.  Otherwise, it would cause
     cleanups to be allocated on the momentary obstack, and they will be
     overwritten by the next statement.  */

  expand_start_bindings (0);
}

/* Exit a binding level.
   Pop the level off, and restore the state of the identifier-decl mappings
   that were in effect when this level was entered.

   If KEEP == 1, this level had explicit declarations, so
   and create a "block" (a BLOCK node) for the level
   to record its declarations and subblocks for symbol table output.

   If KEEP == 2, this level's subblocks go to the front,
   not the back of the current binding level.  This happens,
   for instance, when code for constructors and destructors
   need to generate code at the end of a function which must
   be moved up to the front of the function.

   If FUNCTIONBODY is nonzero, this level is the body of a function,
   so create a block as if KEEP were set and also clear out all
   label names.

   If REVERSE is nonzero, reverse the order of decls before putting
   them into the BLOCK.  */

tree
poplevel (keep, reverse, functionbody)
     int keep;
     int reverse;
     int functionbody;
{
  register tree link;
  /* The chain of decls was accumulated in reverse order.
     Put it into forward order, just for cleanliness.  */
  tree decls;
  int tmp = functionbody;
  int real_functionbody = current_binding_level->keep == 2
    ? ((functionbody = 0), tmp) : functionbody;
  tree tags = functionbody >= 0 ? current_binding_level->tags : 0;
  tree subblocks = functionbody >= 0 ? current_binding_level->blocks : 0;
  tree block = NULL_TREE;
  tree decl;
  int block_previously_created;

  GNU_xref_end_scope ((HOST_WIDE_INT) current_binding_level,
		      (HOST_WIDE_INT) current_binding_level->level_chain,
		      current_binding_level->parm_flag,
		      current_binding_level->keep);

  if (current_binding_level->keep == 1)
    keep = 1;

  /* Get the decls in the order they were written.
     Usually current_binding_level->names is in reverse order.
     But parameter decls were previously put in forward order.  */

  if (reverse)
    current_binding_level->names
      = decls = nreverse (current_binding_level->names);
  else
    decls = current_binding_level->names;

  /* Output any nested inline functions within this block
     if they weren't already output.  */

  for (decl = decls; decl; decl = TREE_CHAIN (decl))
    if (TREE_CODE (decl) == FUNCTION_DECL
	&& ! TREE_ASM_WRITTEN (decl)
	&& DECL_INITIAL (decl) != NULL_TREE
	&& TREE_ADDRESSABLE (decl)
	&& decl_function_context (decl) == current_function_decl)
      {
	/* If this decl was copied from a file-scope decl
	   on account of a block-scope extern decl,
	   propagate TREE_ADDRESSABLE to the file-scope decl.  */
	if (DECL_ABSTRACT_ORIGIN (decl) != NULL_TREE)
	  TREE_ADDRESSABLE (DECL_ABSTRACT_ORIGIN (decl)) = 1;
	else
	  {
	    push_function_context ();
	    output_inline_function (decl);
	    pop_function_context ();
	  }
      }

  /* If there were any declarations or structure tags in that level,
     or if this level is a function body,
     create a BLOCK to record them for the life of this function.  */

  block = NULL_TREE;
  block_previously_created = (current_binding_level->this_block != NULL_TREE);
  if (block_previously_created)
    block = current_binding_level->this_block;
  else if (keep == 1 || functionbody)
    block = make_node (BLOCK);
  if (block != NULL_TREE)
    {
      if (block_previously_created)
	{
	  if (decls || tags || subblocks)
	    {
	      if (BLOCK_VARS (block) || BLOCK_TYPE_TAGS (block))
		{
		  warning ("internal compiler error: debugging info corrupted");
		}
	      BLOCK_VARS (block) = decls;
	      BLOCK_TYPE_TAGS (block) = tags;

	      /* We can have previous subblocks and new subblocks when
		 doing fixup_gotos with complex cleanups.  We chain the new
		 subblocks onto the end of any pre-existing subblocks.  */
	      BLOCK_SUBBLOCKS (block) = chainon (BLOCK_SUBBLOCKS (block),
						 subblocks);
	    }
	  /* If we created the block earlier on, and we are just
	     diddling it now, then it already should have a proper
	     BLOCK_END_NOTE value associated with it.  */
	}
      else
	{
	  BLOCK_VARS (block) = decls;
	  BLOCK_TYPE_TAGS (block) = tags;
	  BLOCK_SUBBLOCKS (block) = subblocks;
	  /* Otherwise, for a new block, install a new BLOCK_END_NOTE value.  */
	  remember_end_note (block);
	}
    }

  /* In each subblock, record that this is its superior.  */

  if (keep >= 0)
    for (link = subblocks; link; link = TREE_CHAIN (link))
      BLOCK_SUPERCONTEXT (link) = block;

  /* Clear out the meanings of the local variables of this level.  */

  if (current_binding_level->is_for_scope && flag_new_for_scope == 1)
    {
      struct binding_level *outer = current_binding_level->level_chain;
      for (link = decls; link; link = TREE_CHAIN (link))
	{
	  if (TREE_CODE (link) == VAR_DECL)
	    DECL_DEAD_FOR_LOCAL (link) = 1;
	  else
	    IDENTIFIER_LOCAL_VALUE (DECL_NAME (link)) = NULL_TREE;
	}

      /* Save declarations made in a 'for' statement so we can support pre-ANSI
	 'for' scoping semantics.  */

      for (link = current_binding_level->shadowed; link; link = TREE_CHAIN (link))
	{
	  tree id = TREE_PURPOSE (link);
	  tree decl = IDENTIFIER_LOCAL_VALUE (id);

	  if (decl && DECL_DEAD_FOR_LOCAL (decl))
	    {
	      /* In this case keep the dead for-decl visible,
		 but remember what (if anything) it shadowed.  */
	      DECL_SHADOWED_FOR_VAR (decl) = TREE_VALUE (link);
	      TREE_CHAIN (decl) = outer->dead_vars_from_for;
	      outer->dead_vars_from_for = decl;
	    }
	  else
	    IDENTIFIER_LOCAL_VALUE (id) = TREE_VALUE (link);
	}
    }
  else /* Not special for scope.  */
    {
      for (link = decls; link; link = TREE_CHAIN (link))
	{
	  if (DECL_NAME (link) != NULL_TREE)
	    {
	      /* If the ident. was used or addressed via a local extern decl,
		 don't forget that fact.  */
	      if (DECL_EXTERNAL (link))
		{
		  if (TREE_USED (link))
		    TREE_USED (DECL_ASSEMBLER_NAME (link)) = 1;
		  if (TREE_ADDRESSABLE (link))
		    TREE_ADDRESSABLE (DECL_ASSEMBLER_NAME (link)) = 1;
		}
	      IDENTIFIER_LOCAL_VALUE (DECL_NAME (link)) = NULL_TREE;
	    }
	}

      /* Restore all name-meanings of the outer levels
	 that were shadowed by this level.  */

      for (link = current_binding_level->shadowed;
	   link; link = TREE_CHAIN (link))
	IDENTIFIER_LOCAL_VALUE (TREE_PURPOSE (link)) = TREE_VALUE (link);

      /* We first restore the regular decls and *then* the dead_vars_from_for
	 to handle this case:

	 int i; // i#1
	 {
	   for (int i; ; ) { ...} // i#2
           int i; // i#3
	 } // we are here

	 In this case, we want remove the binding for i#3, restoring
	 that of i#2.  Then we want to remove the binding for i#2,
	 and restore that of i#1.  */

      link = current_binding_level->dead_vars_from_for;
      for (; link != NULL_TREE; link = TREE_CHAIN (link))
	{
	  tree id = DECL_NAME (link);
	  if (IDENTIFIER_LOCAL_VALUE (id) == link)
	    IDENTIFIER_LOCAL_VALUE (id) = DECL_SHADOWED_FOR_VAR (link);
	}

      for (link = current_binding_level->class_shadowed;
	   link; link = TREE_CHAIN (link))
	IDENTIFIER_CLASS_VALUE (TREE_PURPOSE (link)) = TREE_VALUE (link);
      for (link = current_binding_level->type_shadowed;
	   link; link = TREE_CHAIN (link))
	IDENTIFIER_TYPE_VALUE (TREE_PURPOSE (link)) = TREE_VALUE (link);
    }

  /* If the level being exited is the top level of a function,
     check over all the labels.  */

  if (functionbody)
    {
      /* If this is the top level block of a function,
         the vars are the function's parameters.
         Don't leave them in the BLOCK because they are
         found in the FUNCTION_DECL instead.  */

      BLOCK_VARS (block) = 0;

      /* Clear out the definitions of all label names,
	 since their scopes end here.  */

      for (link = named_labels; link; link = TREE_CHAIN (link))
	{
	  register tree label = TREE_VALUE (link);

	  if (DECL_INITIAL (label) == NULL_TREE)
	    {
	      cp_error_at ("label `%D' used but not defined", label);
	      /* Avoid crashing later.  */
	      define_label (input_filename, 1, DECL_NAME (label));
	    }
	  else if (warn_unused && !TREE_USED (label))
	    cp_warning_at ("label `%D' defined but not used", label);
	  SET_IDENTIFIER_LABEL_VALUE (DECL_NAME (label), NULL_TREE);

          /* Put the labels into the "variables" of the
             top-level block, so debugger can see them.  */
          TREE_CHAIN (label) = BLOCK_VARS (block);
          BLOCK_VARS (block) = label;
	}

      named_labels = NULL_TREE;
    }

  /* Any uses of undefined labels now operate under constraints
     of next binding contour.  */
  {
    struct binding_level *level_chain;
    level_chain = current_binding_level->level_chain;
    if (level_chain)
      {
	struct named_label_list *labels;
	for (labels = named_label_uses; labels; labels = labels->next)
	  if (labels->binding_level == current_binding_level)
	    {
	      labels->binding_level = level_chain;
	      labels->names_in_scope = level_chain->names;
	    }
      }
  }

  tmp = current_binding_level->keep;

  pop_binding_level ();
  if (functionbody)
    DECL_INITIAL (current_function_decl) = block;
  else if (block)
    {
      if (!block_previously_created)
        current_binding_level->blocks
          = chainon (current_binding_level->blocks, block);
    }
  /* If we did not make a block for the level just exited,
     any blocks made for inner levels
     (since they cannot be recorded as subblocks in that level)
     must be carried forward so they will later become subblocks
     of something else.  */
  else if (subblocks)
    {
      if (keep == 2)
	current_binding_level->blocks
	  = chainon (subblocks, current_binding_level->blocks);
      else
	current_binding_level->blocks
	  = chainon (current_binding_level->blocks, subblocks);
    }

  /* Take care of compiler's internal binding structures.  */
  if (tmp == 2)
    {
      expand_end_bindings (getdecls (), keep, 1);
      /* Each and every BLOCK node created here in `poplevel' is important
	 (e.g. for proper debugging information) so if we created one
	 earlier, mark it as "used".  */
      if (block)
	TREE_USED (block) = 1;
      block = poplevel (keep, reverse, real_functionbody);
    }

  /* Each and every BLOCK node created here in `poplevel' is important
     (e.g. for proper debugging information) so if we created one
     earlier, mark it as "used".  */
  if (block)
    TREE_USED (block) = 1;
  return block;
}

/* Resume a binding level for a namespace.  */

void
resume_level (b)
     struct binding_level *b;
{
  tree decls, link;

  resume_binding_level (b);