gcc/config/vxworks.c

/* Common VxWorks target definitions for GNU compiler.
   Copyright (C) 2007, 2008, 2010, 2012
   Free Software Foundation, Inc.
   Contributed by CodeSourcery, Inc.

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 3, 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 COPYING3.  If not see
<http://www.gnu.org/licenses/>.  */

#include "config.h"
#include "system.h"
#include "coretypes.h"
#include "target.h"
#include "diagnostic-core.h"
#include "output.h"
#include "tm.h"
#include "tree.h"

/* Like default_named_section_asm_out_constructor, except that even
   constructors with DEFAULT_INIT_PRIORITY must go in a numbered
   section on VxWorks.  The VxWorks runtime uses a clever trick to get
   the sentinel entry (-1) inserted at the beginning of the .ctors
   segment.  This trick will not work if we ever generate any entries
   in plain .ctors sections; we must always use .ctors.PRIORITY.  */

void
vxworks_asm_out_constructor (rtx symbol, int priority)
{
  section *sec;

  sec = get_cdtor_priority_section (priority,
				    /*constructor_p=*/true);
  assemble_addr_to_section (symbol, sec);
}

/* See comment for vxworks_asm_out_constructor.  */

void
vxworks_asm_out_destructor (rtx symbol, int priority)
{
  section *sec;

  sec = get_cdtor_priority_section (priority,
				    /*constructor_p=*/false);
  assemble_addr_to_section (symbol, sec);
}

/* Return the list of FIELD_DECLs that make up an emulated TLS
   variable's control object.  TYPE is the structure these are fields
   of and *NAME will be filled in with the structure tag that should
   be used.  */

static tree
vxworks_emutls_var_fields (tree type, tree *name)
{
  tree field, next_field;
  
  *name = get_identifier ("__tls_var");
  
  field = build_decl (BUILTINS_LOCATION, FIELD_DECL,
		      get_identifier ("size"), unsigned_type_node);
  DECL_CONTEXT (field) = type;
  next_field = field;

  field = build_decl (BUILTINS_LOCATION, FIELD_DECL,
		      get_identifier ("module_id"), unsigned_type_node);
  DECL_CONTEXT (field) = type;
  DECL_CHAIN (field) = next_field;
  next_field = field;

  field = build_decl (BUILTINS_LOCATION, FIELD_DECL,
		      get_identifier ("offset"), unsigned_type_node);
  DECL_CONTEXT (field) = type;
  DECL_CHAIN (field) = next_field;

  return field;
}

/* Return the CONSTRUCTOR to initialize an emulated TLS control
   object.  VAR is the control object.  DECL is the TLS object itself
   and TMPL_ADDR is the address (an ADDR_EXPR) of the initializer for
   that object.  */

static tree
vxworks_emutls_var_init (tree var, tree decl, tree tmpl_addr)
{
  VEC(constructor_elt,gc) *v = VEC_alloc (constructor_elt, gc, 3);
  
  tree type = TREE_TYPE (var);
  tree field = TYPE_FIELDS (type);
  
  constructor_elt elt = {field, fold_convert (TREE_TYPE (field), tmpl_addr)};
  VEC_quick_push (constructor_elt, v, elt);
  
  field = DECL_CHAIN (field);
  elt.index = field;
  elt.value = build_int_cst (TREE_TYPE (field), 0);
  VEC_quick_push (constructor_elt, v, elt);
  
  field = DECL_CHAIN (field);
  elt.index = field;
  elt.value = fold_convert (TREE_TYPE (field), DECL_SIZE_UNIT (decl));
  VEC_quick_push (constructor_elt, v, elt);
  
  return build_constructor (type, v);
}

/* Do VxWorks-specific parts of TARGET_OPTION_OVERRIDE.  */

void
vxworks_override_options (void)
{
  /* We don't support __thread via target hooks.  */
  targetm.have_tls = false;

  targetm.emutls.get_address = "__builtin___tls_lookup";
  targetm.emutls.register_common = NULL;
  targetm.emutls.var_section = ".tls_vars";
  targetm.emutls.tmpl_section = ".tls_data";
  targetm.emutls.var_prefix = "__tls__";
  targetm.emutls.tmpl_prefix = "";
  targetm.emutls.var_fields = vxworks_emutls_var_fields;
  targetm.emutls.var_init = vxworks_emutls_var_init;
  targetm.emutls.var_align_fixed = true;
  targetm.emutls.debug_form_tls_address = true;
  
  /* We can use .ctors/.dtors sections only in RTP mode.  */
  targetm.have_ctors_dtors = TARGET_VXWORKS_RTP;

  /* PIC is only supported for RTPs.  */
  if (flag_pic && !TARGET_VXWORKS_RTP)
    error ("PIC is only supported for RTPs");

  /* Default to strict dwarf-2 to prevent potential difficulties observed with
     non-gdb debuggers on extensions > 2.  */
  if (!global_options_set.x_dwarf_strict)
    dwarf_strict = 1;

  if (!global_options_set.x_dwarf_version)
    dwarf_version = 2;
}