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gcc/gcc/attribs.c
Richard Sandiford 23a5b65a92 Update copyright years in gcc/ 
From-SVN: r206289
2014-01-02 22:23:26 +00:00

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/* Functions dealing with attribute handling, used by most front ends.
Copyright (C) 1992-2014 Free Software Foundation, 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 "tm.h"
#include "tree.h"
#include "stringpool.h"
#include "attribs.h"
#include "stor-layout.h"
#include "flags.h"
#include "diagnostic-core.h"
#include "ggc.h"
#include "tm_p.h"
#include "cpplib.h"
#include "target.h"
#include "langhooks.h"
#include "hash-table.h"
#include "plugin.h"
/* Table of the tables of attributes (common, language, format, machine)
searched. */
static const struct attribute_spec *attribute_tables[4];
/* Substring representation. */
struct substring
{
const char *str;
int length;
};
/* Simple hash function to avoid need to scan whole string. */
static inline hashval_t
substring_hash (const char *str, int l)
{
return str[0] + str[l - 1] * 256 + l * 65536;
}
/* Used for attribute_hash. */
struct attribute_hasher : typed_noop_remove <attribute_spec>
{
typedef attribute_spec value_type;
typedef substring compare_type;
static inline hashval_t hash (const value_type *);
static inline bool equal (const value_type *, const compare_type *);
};
inline hashval_t
attribute_hasher::hash (const value_type *spec)
{
const int l = strlen (spec->name);
return substring_hash (spec->name, l);
}
inline bool
attribute_hasher::equal (const value_type *spec, const compare_type *str)
{
return (strncmp (spec->name, str->str, str->length) == 0
&& !spec->name[str->length]);
}
/* Scoped attribute name representation. */
struct scoped_attributes
{
const char *ns;
vec<attribute_spec> attributes;
hash_table <attribute_hasher> attribute_hash;
};
/* The table of scope attributes. */
static vec<scoped_attributes> attributes_table;
static scoped_attributes* find_attribute_namespace (const char*);
static void register_scoped_attribute (const struct attribute_spec *,
scoped_attributes *);
static bool attributes_initialized = false;
/* Default empty table of attributes. */
static const struct attribute_spec empty_attribute_table[] =
{
{ NULL, 0, 0, false, false, false, NULL, false }
};
/* Return base name of the attribute. Ie '__attr__' is turned into 'attr'.
To avoid need for copying, we simply return length of the string. */
static void
extract_attribute_substring (struct substring *str)
{
if (str->length > 4 && str->str[0] == '_' && str->str[1] == '_'
&& str->str[str->length - 1] == '_' && str->str[str->length - 2] == '_')
{
str->length -= 4;
str->str += 2;
}
}
/* Insert an array of attributes ATTRIBUTES into a namespace. This
array must be NULL terminated. NS is the name of attribute
namespace. The function returns the namespace into which the
attributes have been registered. */
scoped_attributes*
register_scoped_attributes (const struct attribute_spec * attributes,
const char* ns)
{
scoped_attributes *result = NULL;
/* See if we already have attributes in the namespace NS. */
result = find_attribute_namespace (ns);
if (result == NULL)
{
/* We don't have any namespace NS yet. Create one. */
scoped_attributes sa;
if (!attributes_table.is_empty ())
attributes_table.create (64);
memset (&sa, 0, sizeof (sa));
sa.ns = ns;
sa.attributes.create (64);
result = attributes_table.safe_push (sa);
result->attribute_hash.create (200);
}
/* Really add the attributes to their namespace now. */
for (unsigned i = 0; attributes[i].name != NULL; ++i)
{
result->attributes.safe_push (attributes[i]);
register_scoped_attribute (&attributes[i], result);
}
gcc_assert (result != NULL);
return result;
}
/* Return the namespace which name is NS, NULL if none exist. */
static scoped_attributes*
find_attribute_namespace (const char* ns)
{
unsigned ix;
scoped_attributes *iter;
FOR_EACH_VEC_ELT (attributes_table, ix, iter)
if (ns == iter->ns
|| (iter->ns != NULL
&& ns != NULL
&& !strcmp (iter->ns, ns)))
return iter;
return NULL;
}
/* Initialize attribute tables, and make some sanity checks
if --enable-checking. */
void
init_attributes (void)
{
size_t i;
if (attributes_initialized)
return;
attribute_tables[0] = lang_hooks.common_attribute_table;
attribute_tables[1] = lang_hooks.attribute_table;
attribute_tables[2] = lang_hooks.format_attribute_table;
attribute_tables[3] = targetm.attribute_table;
/* Translate NULL pointers to pointers to the empty table. */
for (i = 0; i < ARRAY_SIZE (attribute_tables); i++)
if (attribute_tables[i] == NULL)
attribute_tables[i] = empty_attribute_table;
#ifdef ENABLE_CHECKING
/* Make some sanity checks on the attribute tables. */
for (i = 0; i < ARRAY_SIZE (attribute_tables); i++)
{
int j;
for (j = 0; attribute_tables[i][j].name != NULL; j++)
{
/* The name must not begin and end with __. */
const char *name = attribute_tables[i][j].name;
int len = strlen (name);
gcc_assert (!(name[0] == '_' && name[1] == '_'
&& name[len - 1] == '_' && name[len - 2] == '_'));
/* The minimum and maximum lengths must be consistent. */
gcc_assert (attribute_tables[i][j].min_length >= 0);
gcc_assert (attribute_tables[i][j].max_length == -1
|| (attribute_tables[i][j].max_length
>= attribute_tables[i][j].min_length));
/* An attribute cannot require both a DECL and a TYPE. */
gcc_assert (!attribute_tables[i][j].decl_required
|| !attribute_tables[i][j].type_required);
/* If an attribute requires a function type, in particular
it requires a type. */
gcc_assert (!attribute_tables[i][j].function_type_required
|| attribute_tables[i][j].type_required);
}
}
/* Check that each name occurs just once in each table. */
for (i = 0; i < ARRAY_SIZE (attribute_tables); i++)
{
int j, k;
for (j = 0; attribute_tables[i][j].name != NULL; j++)
for (k = j + 1; attribute_tables[i][k].name != NULL; k++)
gcc_assert (strcmp (attribute_tables[i][j].name,
attribute_tables[i][k].name));
}
/* Check that no name occurs in more than one table. Names that
begin with '*' are exempt, and may be overridden. */
for (i = 0; i < ARRAY_SIZE (attribute_tables); i++)
{
size_t j, k, l;
for (j = i + 1; j < ARRAY_SIZE (attribute_tables); j++)
for (k = 0; attribute_tables[i][k].name != NULL; k++)
for (l = 0; attribute_tables[j][l].name != NULL; l++)
gcc_assert (attribute_tables[i][k].name[0] == '*'
|| strcmp (attribute_tables[i][k].name,
attribute_tables[j][l].name));
}
#endif
for (i = 0; i < ARRAY_SIZE (attribute_tables); ++i)
/* Put all the GNU attributes into the "gnu" namespace. */
register_scoped_attributes (attribute_tables[i], "gnu");
invoke_plugin_callbacks (PLUGIN_ATTRIBUTES, NULL);
attributes_initialized = true;
}
/* Insert a single ATTR into the attribute table. */
void
register_attribute (const struct attribute_spec *attr)
{
register_scoped_attribute (attr, find_attribute_namespace ("gnu"));
}
/* Insert a single attribute ATTR into a namespace of attributes. */
static void
register_scoped_attribute (const struct attribute_spec *attr,
scoped_attributes *name_space)
{
struct substring str;
attribute_spec **slot;
gcc_assert (attr != NULL && name_space != NULL);
gcc_assert (name_space->attribute_hash.is_created ());
str.str = attr->name;
str.length = strlen (str.str);
/* Attribute names in the table must be in the form 'text' and not
in the form '__text__'. */
gcc_assert (str.length > 0 && str.str[0] != '_');
slot = name_space->attribute_hash
.find_slot_with_hash (&str, substring_hash (str.str, str.length),
INSERT);
gcc_assert (!*slot || attr->name[0] == '*');
*slot = CONST_CAST (struct attribute_spec *, attr);
}
/* Return the spec for the scoped attribute with namespace NS and
name NAME. */
static const struct attribute_spec *
lookup_scoped_attribute_spec (const_tree ns, const_tree name)
{
struct substring attr;
scoped_attributes *attrs;
const char *ns_str = (ns != NULL_TREE) ? IDENTIFIER_POINTER (ns): NULL;
attrs = find_attribute_namespace (ns_str);
if (attrs == NULL)
return NULL;
attr.str = IDENTIFIER_POINTER (name);
attr.length = IDENTIFIER_LENGTH (name);
extract_attribute_substring (&attr);
return attrs->attribute_hash.find_with_hash (&attr,
substring_hash (attr.str, attr.length));
}
/* Return the spec for the attribute named NAME. If NAME is a TREE_LIST,
it also specifies the attribute namespace. */
const struct attribute_spec *
lookup_attribute_spec (const_tree name)
{
tree ns;
if (TREE_CODE (name) == TREE_LIST)
{
ns = TREE_PURPOSE (name);
name = TREE_VALUE (name);
}
else
ns = get_identifier ("gnu");
return lookup_scoped_attribute_spec (ns, name);
}
/* Return the namespace of the attribute ATTR. This accessor works on
GNU and C++11 (scoped) attributes. On GNU attributes,
it returns an identifier tree for the string "gnu".
Please read the comments of cxx11_attribute_p to understand the
format of attributes. */
static tree
get_attribute_namespace (const_tree attr)
{
if (cxx11_attribute_p (attr))
return TREE_PURPOSE (TREE_PURPOSE (attr));
return get_identifier ("gnu");
}
/* Process the attributes listed in ATTRIBUTES and install them in *NODE,
which is either a DECL (including a TYPE_DECL) or a TYPE. If a DECL,
it should be modified in place; if a TYPE, a copy should be created
unless ATTR_FLAG_TYPE_IN_PLACE is set in FLAGS. FLAGS gives further
information, in the form of a bitwise OR of flags in enum attribute_flags
from tree.h. Depending on these flags, some attributes may be
returned to be applied at a later stage (for example, to apply
a decl attribute to the declaration rather than to its type). */
tree
decl_attributes (tree *node, tree attributes, int flags)
{
tree a;
tree returned_attrs = NULL_TREE;
if (TREE_TYPE (*node) == error_mark_node || attributes == error_mark_node)
return NULL_TREE;
if (!attributes_initialized)
init_attributes ();
/* If this is a function and the user used #pragma GCC optimize, add the
options to the attribute((optimize(...))) list. */
if (TREE_CODE (*node) == FUNCTION_DECL && current_optimize_pragma)
{
tree cur_attr = lookup_attribute ("optimize", attributes);
tree opts = copy_list (current_optimize_pragma);
if (! cur_attr)
attributes
= tree_cons (get_identifier ("optimize"), opts, attributes);
else
TREE_VALUE (cur_attr) = chainon (opts, TREE_VALUE (cur_attr));
}
if (TREE_CODE (*node) == FUNCTION_DECL
&& optimization_current_node != optimization_default_node
&& !DECL_FUNCTION_SPECIFIC_OPTIMIZATION (*node))
DECL_FUNCTION_SPECIFIC_OPTIMIZATION (*node) = optimization_current_node;
/* If this is a function and the user used #pragma GCC target, add the
options to the attribute((target(...))) list. */
if (TREE_CODE (*node) == FUNCTION_DECL
&& current_target_pragma
&& targetm.target_option.valid_attribute_p (*node, NULL_TREE,
current_target_pragma, 0))
{
tree cur_attr = lookup_attribute ("target", attributes);
tree opts = copy_list (current_target_pragma);
if (! cur_attr)
attributes = tree_cons (get_identifier ("target"), opts, attributes);
else
TREE_VALUE (cur_attr) = chainon (opts, TREE_VALUE (cur_attr));
}
/* A "naked" function attribute implies "noinline" and "noclone" for
those targets that support it. */
if (TREE_CODE (*node) == FUNCTION_DECL
&& attributes
&& lookup_attribute_spec (get_identifier ("naked"))
&& lookup_attribute ("naked", attributes) != NULL)
{
if (lookup_attribute ("noinline", attributes) == NULL)
attributes = tree_cons (get_identifier ("noinline"), NULL, attributes);
if (lookup_attribute ("noclone", attributes) == NULL)
attributes = tree_cons (get_identifier ("noclone"), NULL, attributes);
}
targetm.insert_attributes (*node, &attributes);
for (a = attributes; a; a = TREE_CHAIN (a))
{
tree ns = get_attribute_namespace (a);
tree name = get_attribute_name (a);
tree args = TREE_VALUE (a);
tree *anode = node;
const struct attribute_spec *spec =
lookup_scoped_attribute_spec (ns, name);
bool no_add_attrs = 0;
int fn_ptr_quals = 0;
tree fn_ptr_tmp = NULL_TREE;
if (spec == NULL)
{
if (!(flags & (int) ATTR_FLAG_BUILT_IN))
{
if (ns == NULL_TREE || !cxx11_attribute_p (a))
warning (OPT_Wattributes, "%qE attribute directive ignored",
name);
else
warning (OPT_Wattributes,
"%<%E::%E%> scoped attribute directive ignored",
ns, name);
}
continue;
}
else if (list_length (args) < spec->min_length
|| (spec->max_length >= 0
&& list_length (args) > spec->max_length))
{
error ("wrong number of arguments specified for %qE attribute",
name);
continue;
}
gcc_assert (is_attribute_p (spec->name, name));
if (TYPE_P (*node)
&& cxx11_attribute_p (a)
&& !(flags & ATTR_FLAG_TYPE_IN_PLACE))
{
/* This is a c++11 attribute that appertains to a
type-specifier, outside of the definition of, a class
type. Ignore it. */
warning (OPT_Wattributes, "attribute ignored");
inform (input_location,
"an attribute that appertains to a type-specifier "
"is ignored");
continue;
}
if (spec->decl_required && !DECL_P (*anode))
{
if (flags & ((int) ATTR_FLAG_DECL_NEXT
| (int) ATTR_FLAG_FUNCTION_NEXT
| (int) ATTR_FLAG_ARRAY_NEXT))
{
/* Pass on this attribute to be tried again. */
returned_attrs = tree_cons (name, args, returned_attrs);
continue;
}
else
{
warning (OPT_Wattributes, "%qE attribute does not apply to types",
name);
continue;
}
}
/* If we require a type, but were passed a decl, set up to make a
new type and update the one in the decl. ATTR_FLAG_TYPE_IN_PLACE
would have applied if we'd been passed a type, but we cannot modify
the decl's type in place here. */
if (spec->type_required && DECL_P (*anode))
{
anode = &TREE_TYPE (*anode);
/* Allow ATTR_FLAG_TYPE_IN_PLACE for the type's naming decl. */
if (!(TREE_CODE (*anode) == TYPE_DECL
&& *anode == TYPE_NAME (TYPE_MAIN_VARIANT
(TREE_TYPE (*anode)))))
flags &= ~(int) ATTR_FLAG_TYPE_IN_PLACE;
}
if (spec->function_type_required && TREE_CODE (*anode) != FUNCTION_TYPE
&& TREE_CODE (*anode) != METHOD_TYPE)
{
if (TREE_CODE (*anode) == POINTER_TYPE
&& (TREE_CODE (TREE_TYPE (*anode)) == FUNCTION_TYPE
|| TREE_CODE (TREE_TYPE (*anode)) == METHOD_TYPE))
{
/* OK, this is a bit convoluted. We can't just make a copy
of the pointer type and modify its TREE_TYPE, because if
we change the attributes of the target type the pointer
type needs to have a different TYPE_MAIN_VARIANT. So we
pull out the target type now, frob it as appropriate, and
rebuild the pointer type later.
This would all be simpler if attributes were part of the
declarator, grumble grumble. */
fn_ptr_tmp = TREE_TYPE (*anode);
fn_ptr_quals = TYPE_QUALS (*anode);
anode = &fn_ptr_tmp;
flags &= ~(int) ATTR_FLAG_TYPE_IN_PLACE;
}
else if (flags & (int) ATTR_FLAG_FUNCTION_NEXT)
{
/* Pass on this attribute to be tried again. */
returned_attrs = tree_cons (name, args, returned_attrs);
continue;
}
if (TREE_CODE (*anode) != FUNCTION_TYPE
&& TREE_CODE (*anode) != METHOD_TYPE)
{
warning (OPT_Wattributes,
"%qE attribute only applies to function types",
name);
continue;
}
}
if (TYPE_P (*anode)
&& (flags & (int) ATTR_FLAG_TYPE_IN_PLACE)
&& TYPE_SIZE (*anode) != NULL_TREE)
{
warning (OPT_Wattributes, "type attributes ignored after type is already defined");
continue;
}
if (spec->handler != NULL)
{
int cxx11_flag =
cxx11_attribute_p (a) ? ATTR_FLAG_CXX11 : 0;
returned_attrs = chainon ((*spec->handler) (anode, name, args,
flags|cxx11_flag,
&no_add_attrs),
returned_attrs);
}
/* Layout the decl in case anything changed. */
if (spec->type_required && DECL_P (*node)
&& (TREE_CODE (*node) == VAR_DECL
|| TREE_CODE (*node) == PARM_DECL
|| TREE_CODE (*node) == RESULT_DECL))
relayout_decl (*node);
if (!no_add_attrs)
{
tree old_attrs;
tree a;
if (DECL_P (*anode))
old_attrs = DECL_ATTRIBUTES (*anode);
else
old_attrs = TYPE_ATTRIBUTES (*anode);
for (a = lookup_attribute (spec->name, old_attrs);
a != NULL_TREE;
a = lookup_attribute (spec->name, TREE_CHAIN (a)))
{
if (simple_cst_equal (TREE_VALUE (a), args) == 1)
break;
}
if (a == NULL_TREE)
{
/* This attribute isn't already in the list. */
if (DECL_P (*anode))
DECL_ATTRIBUTES (*anode) = tree_cons (name, args, old_attrs);
else if (flags & (int) ATTR_FLAG_TYPE_IN_PLACE)
{
TYPE_ATTRIBUTES (*anode) = tree_cons (name, args, old_attrs);
/* If this is the main variant, also push the attributes
out to the other variants. */
if (*anode == TYPE_MAIN_VARIANT (*anode))
{
tree variant;
for (variant = *anode; variant;
variant = TYPE_NEXT_VARIANT (variant))
{
if (TYPE_ATTRIBUTES (variant) == old_attrs)
TYPE_ATTRIBUTES (variant)
= TYPE_ATTRIBUTES (*anode);
else if (!lookup_attribute
(spec->name, TYPE_ATTRIBUTES (variant)))
TYPE_ATTRIBUTES (variant) = tree_cons
(name, args, TYPE_ATTRIBUTES (variant));
}
}
}
else
*anode = build_type_attribute_variant (*anode,
tree_cons (name, args,
old_attrs));
}
}
if (fn_ptr_tmp)
{
/* Rebuild the function pointer type and put it in the
appropriate place. */
fn_ptr_tmp = build_pointer_type (fn_ptr_tmp);
if (fn_ptr_quals)
fn_ptr_tmp = build_qualified_type (fn_ptr_tmp, fn_ptr_quals);
if (DECL_P (*node))
TREE_TYPE (*node) = fn_ptr_tmp;
else
{
gcc_assert (TREE_CODE (*node) == POINTER_TYPE);
*node = fn_ptr_tmp;
}
}
}
return returned_attrs;
}
/* Return TRUE iff ATTR has been parsed by the front-end as a C++-11
attribute.
When G++ parses a C++11 attribute, it is represented as
a TREE_LIST which TREE_PURPOSE is itself a TREE_LIST. TREE_PURPOSE
(TREE_PURPOSE (ATTR)) is the namespace of the attribute, and the
TREE_VALUE (TREE_PURPOSE (ATTR)) is its non-qualified name. Please
use get_attribute_namespace and get_attribute_name to retrieve the
namespace and name of the attribute, as these accessors work with
GNU attributes as well. */
bool
cxx11_attribute_p (const_tree attr)
{
if (attr == NULL_TREE
|| TREE_CODE (attr) != TREE_LIST)
return false;
return (TREE_CODE (TREE_PURPOSE (attr)) == TREE_LIST);
}
/* Return the name of the attribute ATTR. This accessor works on GNU
and C++11 (scoped) attributes.
Please read the comments of cxx11_attribute_p to understand the
format of attributes. */
tree
get_attribute_name (const_tree attr)
{
if (cxx11_attribute_p (attr))
return TREE_VALUE (TREE_PURPOSE (attr));
return TREE_PURPOSE (attr);
}
/* Subroutine of set_method_tm_attributes. Apply TM attribute ATTR
to the method FNDECL. */
void
apply_tm_attr (tree fndecl, tree attr)
{
decl_attributes (&TREE_TYPE (fndecl), tree_cons (attr, NULL, NULL), 0);
}
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