gdb/doc/

[deliverable/binutils-gdb.git] / gdb / block.c

/* Block-related functions for the GNU debugger, GDB.

   Copyright (C) 2003, 2007, 2008, 2009, 2010, 2011
   Free Software Foundation, Inc.

   This file is part of GDB.

   This program 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
   (at your option) any later version.

   This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.  */

#include "defs.h"
#include "block.h"
#include "symtab.h"
#include "symfile.h"
#include "gdb_obstack.h"
#include "cp-support.h"
#include "addrmap.h"

/* This is used by struct block to store namespace-related info for
   C++ files, namely using declarations and the current namespace in
   scope.  */

struct block_namespace_info
{
  const char *scope;
  struct using_direct *using;
};

static void block_initialize_namespace (struct block *block,
					struct obstack *obstack);

/* Return Nonzero if block a is lexically nested within block b,
   or if a and b have the same pc range.
   Return zero otherwise.  */

int
contained_in (const struct block *a, const struct block *b)
{
  if (!a || !b)
    return 0;

  do
    {
      if (a == b)
	return 1;
      /* If A is a function block, then A cannot be contained in B,
         except if A was inlined.  */
      if (BLOCK_FUNCTION (a) != NULL && !block_inlined_p (a))
        return 0;
      a = BLOCK_SUPERBLOCK (a);
    }
  while (a != NULL);

  return 0;
}


/* Return the symbol for the function which contains a specified
   lexical block, described by a struct block BL.  The return value
   will not be an inlined function; the containing function will be
   returned instead.  */

struct symbol *
block_linkage_function (const struct block *bl)
{
  while ((BLOCK_FUNCTION (bl) == NULL || block_inlined_p (bl))
	 && BLOCK_SUPERBLOCK (bl) != NULL)
    bl = BLOCK_SUPERBLOCK (bl);

  return BLOCK_FUNCTION (bl);
}

/* Return one if BL represents an inlined function.  */

int
block_inlined_p (const struct block *bl)
{
  return BLOCK_FUNCTION (bl) != NULL && SYMBOL_INLINED (BLOCK_FUNCTION (bl));
}

/* Return the blockvector immediately containing the innermost lexical
   block containing the specified pc value and section, or 0 if there
   is none.  PBLOCK is a pointer to the block.  If PBLOCK is NULL, we
   don't pass this information back to the caller.  */

struct blockvector *
blockvector_for_pc_sect (CORE_ADDR pc, struct obj_section *section,
			 struct block **pblock, struct symtab *symtab)
{
  struct block *b;
  int bot, top, half;
  struct blockvector *bl;

  if (symtab == 0)		/* if no symtab specified by caller */
    {
      /* First search all symtabs for one whose file contains our pc */
      symtab = find_pc_sect_symtab (pc, section);
      if (symtab == 0)
	return 0;
    }

  bl = BLOCKVECTOR (symtab);

  /* Then search that symtab for the smallest block that wins.  */

  /* If we have an addrmap mapping code addresses to blocks, then use
     that.  */
  if (BLOCKVECTOR_MAP (bl))
    {
      b = addrmap_find (BLOCKVECTOR_MAP (bl), pc);
      if (b)
        {
          if (pblock)
            *pblock = b;
          return bl;
        }
      else
        return 0;
    }


  /* Otherwise, use binary search to find the last block that starts
     before PC.  */
  bot = 0;
  top = BLOCKVECTOR_NBLOCKS (bl);

  while (top - bot > 1)
    {
      half = (top - bot + 1) >> 1;
      b = BLOCKVECTOR_BLOCK (bl, bot + half);
      if (BLOCK_START (b) <= pc)
	bot += half;
      else
	top = bot + half;
    }

  /* Now search backward for a block that ends after PC.  */

  while (bot >= 0)
    {
      b = BLOCKVECTOR_BLOCK (bl, bot);
      if (BLOCK_END (b) > pc)
	{
	  if (pblock)
	    *pblock = b;
	  return bl;
	}
      bot--;
    }
  return 0;
}

/* Return the blockvector immediately containing the innermost lexical block
   containing the specified pc value, or 0 if there is none.
   Backward compatibility, no section.  */

struct blockvector *
blockvector_for_pc (CORE_ADDR pc, struct block **pblock)
{
  return blockvector_for_pc_sect (pc, find_pc_mapped_section (pc),
				  pblock, NULL);
}

/* Return the innermost lexical block containing the specified pc value
   in the specified section, or 0 if there is none.  */

struct block *
block_for_pc_sect (CORE_ADDR pc, struct obj_section *section)
{
  struct blockvector *bl;
  struct block *b;

  bl = blockvector_for_pc_sect (pc, section, &b, NULL);
  if (bl)
    return b;
  return 0;
}

/* Return the innermost lexical block containing the specified pc value,
   or 0 if there is none.  Backward compatibility, no section.  */

struct block *
block_for_pc (CORE_ADDR pc)
{
  return block_for_pc_sect (pc, find_pc_mapped_section (pc));
}

/* Now come some functions designed to deal with C++ namespace issues.
   The accessors are safe to use even in the non-C++ case.  */

/* This returns the namespace that BLOCK is enclosed in, or "" if it
   isn't enclosed in a namespace at all.  This travels the chain of
   superblocks looking for a scope, if necessary.  */

const char *
block_scope (const struct block *block)
{
  for (; block != NULL; block = BLOCK_SUPERBLOCK (block))
    {
      if (BLOCK_NAMESPACE (block) != NULL
	  && BLOCK_NAMESPACE (block)->scope != NULL)
	return BLOCK_NAMESPACE (block)->scope;
    }

  return "";
}

/* Set BLOCK's scope member to SCOPE; if needed, allocate memory via
   OBSTACK.  (It won't make a copy of SCOPE, however, so that already
   has to be allocated correctly.)  */

void
block_set_scope (struct block *block, const char *scope,
		 struct obstack *obstack)
{
  block_initialize_namespace (block, obstack);

  BLOCK_NAMESPACE (block)->scope = scope;
}

/* This returns the using directives list associated with BLOCK, if
   any.  */

struct using_direct *
block_using (const struct block *block)
{
  if (block == NULL || BLOCK_NAMESPACE (block) == NULL)
    return NULL;
  else
    return BLOCK_NAMESPACE (block)->using;
}

/* Set BLOCK's using member to USING; if needed, allocate memory via
   OBSTACK.  (It won't make a copy of USING, however, so that already
   has to be allocated correctly.)  */

void
block_set_using (struct block *block,
		 struct using_direct *using,
		 struct obstack *obstack)
{
  block_initialize_namespace (block, obstack);

  BLOCK_NAMESPACE (block)->using = using;
}

/* If BLOCK_NAMESPACE (block) is NULL, allocate it via OBSTACK and
   ititialize its members to zero.  */

static void
block_initialize_namespace (struct block *block, struct obstack *obstack)
{
  if (BLOCK_NAMESPACE (block) == NULL)
    {
      BLOCK_NAMESPACE (block)
	= obstack_alloc (obstack, sizeof (struct block_namespace_info));
      BLOCK_NAMESPACE (block)->scope = NULL;
      BLOCK_NAMESPACE (block)->using = NULL;
    }
}

/* Return the static block associated to BLOCK.  Return NULL if block
   is NULL or if block is a global block.  */

const struct block *
block_static_block (const struct block *block)
{
  if (block == NULL || BLOCK_SUPERBLOCK (block) == NULL)
    return NULL;

  while (BLOCK_SUPERBLOCK (BLOCK_SUPERBLOCK (block)) != NULL)
    block = BLOCK_SUPERBLOCK (block);

  return block;
}

/* Return the static block associated to BLOCK.  Return NULL if block
   is NULL.  */

const struct block *
block_global_block (const struct block *block)
{
  if (block == NULL)
    return NULL;

  while (BLOCK_SUPERBLOCK (block) != NULL)
    block = BLOCK_SUPERBLOCK (block);

  return block;
}

/* Allocate a block on OBSTACK, and initialize its elements to
   zero/NULL.  This is useful for creating "dummy" blocks that don't
   correspond to actual source files.

   Warning: it sets the block's BLOCK_DICT to NULL, which isn't a
   valid value.  If you really don't want the block to have a
   dictionary, then you should subsequently set its BLOCK_DICT to
   dict_create_linear (obstack, NULL).  */

struct block *
allocate_block (struct obstack *obstack)
{
  struct block *bl = obstack_alloc (obstack, sizeof (struct block));

  BLOCK_START (bl) = 0;
  BLOCK_END (bl) = 0;
  BLOCK_FUNCTION (bl) = NULL;
  BLOCK_SUPERBLOCK (bl) = NULL;
  BLOCK_DICT (bl) = NULL;
  BLOCK_NAMESPACE (bl) = NULL;

  return bl;
}