[pf3gnuchains/gcc-fork.git] / gcc / ada / gcc-interface / gigi.h

/****************************************************************************
 *                                                                          *
 *                         GNAT COMPILER COMPONENTS                         *
 *                                                                          *
 *                                 G I G I                                  *
 *                                                                          *
 *                              C Header File                               *
 *                                                                          *
 *          Copyright (C) 1992-2010, Free Software Foundation, Inc.         *
 *                                                                          *
 * GNAT is free software;  you can  redistribute it  and/or modify it under *
 * terms of the  GNU General Public License as published  by the Free Soft- *
 * ware  Foundation;  either version 3,  or (at your option) any later ver- *
 * sion.  GNAT is distributed in the hope that it will be useful, but WITH- *
 * OUT 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  distributed  with GNAT;  see file  COPYING3.  If not see *
 * <http://www.gnu.org/licenses/>.                                          *
 *                                                                          *
 * GNAT was originally developed  by the GNAT team at  New York University. *
 * Extensive contributions were provided by Ada Core Technologies Inc.      *
 *                                                                          *
 ****************************************************************************/

/* Declare all functions and types used by gigi.  */

/* Given GNAT_ENTITY, a GNAT defining identifier node, which denotes some Ada
   entity, this routine returns the equivalent GCC tree for that entity
   (an ..._DECL node) and associates the ..._DECL node with the input GNAT
   defining identifier.

   If GNAT_ENTITY is a variable or a constant declaration, GNU_EXPR gives its
   initial value (in GCC tree form). This is optional for variables.
   For renamed entities, GNU_EXPR gives the object being renamed.

   DEFINITION is nonzero if this call is intended for a definition.  This is
   used for separate compilation where it necessary to know whether an
   external declaration or a definition should be created if the GCC equivalent
   was not created previously.  The value of 1 is normally used for a nonzero
   DEFINITION, but a value of 2 is used in special circumstances, defined in
   the code.  */
extern tree gnat_to_gnu_entity (Entity_Id gnat_entity, tree gnu_expr,
                                int definition);

/* Similar, but if the returned value is a COMPONENT_REF, return the
   FIELD_DECL.  */
extern tree gnat_to_gnu_field_decl (Entity_Id gnat_entity);

/* Similar, but GNAT_ENTITY is assumed to refer to a GNAT type.  Return
   the GCC type corresponding to that entity.  */
extern tree gnat_to_gnu_type (Entity_Id gnat_entity);

/* Wrap up compilation of T, a TYPE_DECL, possibly deferring it.  */
extern void rest_of_type_decl_compilation (tree t);

/* Start a new statement group chained to the previous group.  */
extern void start_stmt_group (void);

/* Add GNU_STMT to the current BLOCK_STMT node.  */
extern void add_stmt (tree gnu_stmt);

/* Similar, but set the location of GNU_STMT to that of GNAT_NODE.  */
extern void add_stmt_with_node (tree gnu_stmt, Node_Id gnat_node);

/* Return code corresponding to the current code group.  It is normally
   a STATEMENT_LIST, but may also be a BIND_EXPR or TRY_FINALLY_EXPR if
   BLOCK or cleanups were set.  */
extern tree end_stmt_group (void);

/* Set the BLOCK node corresponding to the current code group to GNU_BLOCK.  */
extern void set_block_for_group (tree);

/* Add a declaration statement for GNU_DECL to the current BLOCK_STMT node.
   Get SLOC from GNAT_ENTITY.  */
extern void add_decl_expr (tree gnu_decl, Entity_Id gnat_entity);

/* Mark nodes rooted at T with TREE_VISITED and types as having their
   sized gimplified.  We use this to indicate all variable sizes and
   positions in global types may not be shared by any subprogram.  */
extern void mark_visited (tree t);

/* This macro calls the above function but short-circuits the common
   case of a constant to save time and also checks for NULL.  */

#define MARK_VISITED(EXP)               \
do {                                    \
  if((EXP) && !CONSTANT_CLASS_P (EXP))  \
    mark_visited (EXP);                 \
} while (0)

/* Finalize any From_With_Type incomplete types.  We do this after processing
   our compilation unit and after processing its spec, if this is a body.  */
extern void finalize_from_with_types (void);

/* Return the equivalent type to be used for GNAT_ENTITY, if it's a
   kind of type (such E_Task_Type) that has a different type which Gigi
   uses for its representation.  If the type does not have a special type
   for its representation, return GNAT_ENTITY.  If a type is supposed to
   exist, but does not, abort unless annotating types, in which case
   return Empty.   If GNAT_ENTITY is Empty, return Empty.  */
extern Entity_Id Gigi_Equivalent_Type (Entity_Id gnat_entity);

/* Given GNAT_ENTITY, elaborate all expressions that are required to
   be elaborated at the point of its definition, but do nothing else.  */
extern void elaborate_entity (Entity_Id gnat_entity);

/* Mark GNAT_ENTITY as going out of scope at this point.  Recursively mark
   any entities on its entity chain similarly.  */
extern void mark_out_of_scope (Entity_Id gnat_entity);

/* Get the unpadded version of a GNAT type.  */
extern tree get_unpadded_type (Entity_Id gnat_entity);

/* Create a record type that contains a SIZE bytes long field of TYPE with a
    starting bit position so that it is aligned to ALIGN bits, and leaving at
    least ROOM bytes free before the field.  BASE_ALIGN is the alignment the
    record is guaranteed to get.  */
extern tree make_aligning_type (tree type, unsigned int align, tree size,
                                unsigned int base_align, int room);

/* Ensure that TYPE has SIZE and ALIGN.  Make and return a new padded type
   if needed.  We have already verified that SIZE and TYPE are large enough.
   GNAT_ENTITY is used to name the resulting record and to issue a warning.
   IS_COMPONENT_TYPE is true if this is being done for the component type
   of an array.  IS_USER_TYPE is true if we must complete the original type.
   DEFINITION is true if this type is being defined.  SAME_RM_SIZE is true
   if the RM size of the resulting type is to be set to SIZE too; otherwise,
   it's set to the RM size of the original type.  */
extern tree maybe_pad_type (tree type, tree size, unsigned int align,
                            Entity_Id gnat_entity, bool is_component_type,
                            bool is_user_type, bool definition,
                            bool same_rm_size);

/* Given a GNU tree and a GNAT list of choices, generate an expression to test
   the value passed against the list of choices.  */
extern tree choices_to_gnu (tree operand, Node_Id choices);

/* Given GNAT_ENTITY, an object (constant, variable, parameter, exception)
   and GNU_TYPE, its corresponding GCC type, set Esize and Alignment to the
   size and alignment used by Gigi.  Prefer SIZE over TYPE_SIZE if non-null.
   BY_REF is true if the object is used by reference.  */
extern void annotate_object (Entity_Id gnat_entity, tree gnu_type, tree size,
                             bool by_ref);

/* Given a type T, a FIELD_DECL F, and a replacement value R, return a new
   type with all size expressions that contain F updated by replacing F
   with R.  If F is NULL_TREE, always make a new RECORD_TYPE, even if
   nothing has changed.  */
extern tree substitute_in_type (tree t, tree f, tree r);

/* Return the RM size of GNU_TYPE.  This is the actual number of bits
   needed to represent the object.  */
extern tree rm_size (tree gnu_type);

/* Return the name to be used for GNAT_ENTITY.  If a type, create a
   fully-qualified name, possibly with type information encoding.
   Otherwise, return the name.  */
extern tree get_entity_name (Entity_Id gnat_entity);

/* Return an identifier representing the external name to be used for
   GNAT_ENTITY.  If SUFFIX is specified, the name is followed by "___"
   and the specified suffix.  */
extern tree create_concat_name (Entity_Id gnat_entity, const char *suffix);

/* Given GNU_NAME, an IDENTIFIER_NODE containing a name and SUFFIX, a
   string, return a new IDENTIFIER_NODE that is the concatenation of
   the name followed by "___" and the specified suffix.  */
extern tree concat_name (tree gnu_name, const char *suffix);

/* Highest number in the front-end node table.  */
extern int max_gnat_nodes;

/* Current node being treated, in case abort called.  */
extern Node_Id error_gnat_node;

/* True when gigi is being called on an analyzed but unexpanded
   tree, and the only purpose of the call is to properly annotate
   types with representation information.  */
extern bool type_annotate_only;

/* Current file name without path.  */
extern const char *ref_filename;

/* This structure must be kept synchronized with Call_Back_End.  */
struct File_Info_Type
{
  File_Name_Type File_Name;
  Nat Num_Source_Lines;
};

/* This is the main program of the back-end.  It sets up all the table
   structures and then generates code.  */
extern void gigi (Node_Id gnat_root, int max_gnat_node,
                  int number_name ATTRIBUTE_UNUSED,
                  struct Node *nodes_ptr, Node_Id *next_node_ptr,
                  Node_Id *prev_node_ptr, struct Elist_Header *elists_ptr,
                  struct Elmt_Item *elmts_ptr,
                  struct String_Entry *strings_ptr,
                  Char_Code *strings_chars_ptr,
                  struct List_Header *list_headers_ptr,
                  Nat number_file,
                  struct File_Info_Type *file_info_ptr,
                  Entity_Id standard_boolean,
                  Entity_Id standard_integer,
                  Entity_Id standard_character,
                  Entity_Id standard_long_long_float,
                  Entity_Id standard_exception_type,
                  Int gigi_operating_mode);

/* GNAT_NODE is the root of some GNAT tree.  Return the root of the
   GCC tree corresponding to that GNAT tree.  Normally, no code is generated;
   we just return an equivalent tree which is used elsewhere to generate
   code.  */
extern tree gnat_to_gnu (Node_Id gnat_node);

/* GNU_STMT is a statement.  We generate code for that statement.  */
extern void gnat_expand_stmt (tree gnu_stmt);

/* Generate GIMPLE in place for the expression at *EXPR_P.  */
extern int gnat_gimplify_expr (tree *expr_p, gimple_seq *pre_p,
                               gimple_seq *post_p ATTRIBUTE_UNUSED);

/* Do the processing for the declaration of a GNAT_ENTITY, a type.  If
   a separate Freeze node exists, delay the bulk of the processing.  Otherwise
   make a GCC type for GNAT_ENTITY and set up the correspondence.  */
extern void process_type (Entity_Id gnat_entity);

/* Convert SLOC into LOCUS.  Return true if SLOC corresponds to a source code
   location and false if it doesn't.  In the former case, set the Gigi global
   variable REF_FILENAME to the simple debug file name as given by sinput.  */
extern bool Sloc_to_locus (Source_Ptr Sloc, location_t *locus);

/* Post an error message.  MSG is the error message, properly annotated.
   NODE is the node at which to post the error and the node to use for the
   '&' substitution.  */
extern void post_error (const char *msg, Node_Id node);

/* Similar to post_error, but NODE is the node at which to post the error and
   ENT is the node to use for the '&' substitution.  */
extern void post_error_ne (const char *msg, Node_Id node, Entity_Id ent);

/* Similar, but NODE is the node at which to post the error, ENT is the node
   to use for the "&" substitution, and NUM is the number to use for ^.  */
extern void post_error_ne_num (const char *msg, Node_Id node, Entity_Id ent,
                               int num);

/* Similar to post_error_ne, but T is a GCC tree representing the number to
   write.  If T represents a constant, the text inside curly brackets in
   MSG will be output (presumably including a '^').  Otherwise it will not
   be output and the text inside square brackets will be output instead.  */
extern void post_error_ne_tree (const char *msg, Node_Id node, Entity_Id ent,
                                tree t);

/* Similar to post_error_ne_tree, except that NUM is a second integer to write
   in the message.  */
extern void post_error_ne_tree_2 (const char *msg, Node_Id node, Entity_Id ent,
                                  tree t, int num);

/* Return a label to branch to for the exception type in KIND or NULL_TREE
   if none.  */
extern tree get_exception_label (char kind);

/* If nonzero, pretend we are allocating at global level.  */
extern int force_global;

/* The default alignment of "double" floating-point types, i.e. floating
   point types whose size is equal to 64 bits, or 0 if this alignment is
   not specifically capped.  */
extern int double_float_alignment;

/* The default alignment of "double" or larger scalar types, i.e. scalar
   types whose size is greater or equal to 64 bits, or 0 if this alignment
   is not specifically capped.  */
extern int double_scalar_alignment;
\f
/* Data structures used to represent attributes.  */

enum attr_type
{
  ATTR_MACHINE_ATTRIBUTE,
  ATTR_LINK_ALIAS,
  ATTR_LINK_SECTION,
  ATTR_LINK_CONSTRUCTOR,
  ATTR_LINK_DESTRUCTOR,
  ATTR_THREAD_LOCAL_STORAGE,
  ATTR_WEAK_EXTERNAL
};

struct attrib
{
  struct attrib *next;
  enum attr_type type;
  tree name;
  tree args;
  Node_Id error_point;
};

/* Table of machine-independent internal attributes.  */
extern const struct attribute_spec gnat_internal_attribute_table[];

/* Define the entries in the standard data array.  */
enum standard_datatypes
{
  /* The longest floating-point type.  */
  ADT_longest_float_type,

  /* The type of an exception.  */
  ADT_except_type,

  /* Type declaration node  <==> typedef void *T */
  ADT_ptr_void_type,

  /* Function type declaration -- void T() */
  ADT_void_ftype,

  /* Type declaration node  <==> typedef void *T() */
  ADT_ptr_void_ftype,

  /* Type declaration node  <==> typedef virtual void *T() */
  ADT_fdesc_type,

  /* Null pointer for above type.  */
  ADT_null_fdesc,

  /* Value 1 in signed bitsizetype.  */
  ADT_sbitsize_one_node,

  /* Value BITS_PER_UNIT in signed bitsizetype.  */
  ADT_sbitsize_unit_node,

  /* Function declaration nodes for run-time functions for allocating memory.
     Ada allocators cause calls to these functions to be generated.  Malloc32
     is used only on 64bit systems needing to allocate 32bit memory.  */
  ADT_malloc_decl,
  ADT_malloc32_decl,

  /* Likewise for freeing memory.  */
  ADT_free_decl,

  /* Function decl node for 64-bit multiplication with overflow checking.  */
  ADT_mulv64_decl,

  /* Identifier for the name of the _Parent field in tagged record types.  */
  ADT_parent_name_id,

  /* Types and decls used by our temporary exception mechanism.  See
     init_gigi_decls for details.  */
  ADT_jmpbuf_type,
  ADT_jmpbuf_ptr_type,
  ADT_get_jmpbuf_decl,
  ADT_set_jmpbuf_decl,
  ADT_get_excptr_decl,
  ADT_setjmp_decl,
  ADT_longjmp_decl,
  ADT_update_setjmp_buf_decl,
  ADT_raise_nodefer_decl,
  ADT_begin_handler_decl,
  ADT_end_handler_decl,
  ADT_others_decl,
  ADT_all_others_decl,
  ADT_LAST};

extern GTY(()) tree gnat_std_decls[(int) ADT_LAST];
extern GTY(()) tree gnat_raise_decls[(int) LAST_REASON_CODE + 1];

#define longest_float_type_node gnat_std_decls[(int) ADT_longest_float_type]
#define except_type_node gnat_std_decls[(int) ADT_except_type]
#define ptr_void_type_node gnat_std_decls[(int) ADT_ptr_void_type]
#define void_ftype gnat_std_decls[(int) ADT_void_ftype]
#define ptr_void_ftype gnat_std_decls[(int) ADT_ptr_void_ftype]
#define fdesc_type_node gnat_std_decls[(int) ADT_fdesc_type]
#define null_fdesc_node gnat_std_decls[(int) ADT_null_fdesc]
#define sbitsize_one_node gnat_std_decls[(int) ADT_sbitsize_one_node]
#define sbitsize_unit_node gnat_std_decls[(int) ADT_sbitsize_unit_node]
#define malloc_decl gnat_std_decls[(int) ADT_malloc_decl]
#define malloc32_decl gnat_std_decls[(int) ADT_malloc32_decl]
#define free_decl gnat_std_decls[(int) ADT_free_decl]
#define mulv64_decl gnat_std_decls[(int) ADT_mulv64_decl]
#define parent_name_id gnat_std_decls[(int) ADT_parent_name_id]
#define jmpbuf_type gnat_std_decls[(int) ADT_jmpbuf_type]
#define jmpbuf_ptr_type gnat_std_decls[(int) ADT_jmpbuf_ptr_type]
#define get_jmpbuf_decl gnat_std_decls[(int) ADT_get_jmpbuf_decl]
#define set_jmpbuf_decl gnat_std_decls[(int) ADT_set_jmpbuf_decl]
#define get_excptr_decl gnat_std_decls[(int) ADT_get_excptr_decl]
#define setjmp_decl gnat_std_decls[(int) ADT_setjmp_decl]
#define longjmp_decl gnat_std_decls[(int) ADT_longjmp_decl]
#define update_setjmp_buf_decl gnat_std_decls[(int) ADT_update_setjmp_buf_decl]
#define raise_nodefer_decl gnat_std_decls[(int) ADT_raise_nodefer_decl]
#define begin_handler_decl gnat_std_decls[(int) ADT_begin_handler_decl]
#define others_decl gnat_std_decls[(int) ADT_others_decl]
#define all_others_decl gnat_std_decls[(int) ADT_all_others_decl]
#define end_handler_decl gnat_std_decls[(int) ADT_end_handler_decl]

/* Routines expected by the gcc back-end. They must have exactly the same
   prototype and names as below.  */

/* Returns nonzero if we are currently in the global binding level.  */
extern int global_bindings_p (void);

/* Enter and exit a new binding level.  */
extern void gnat_pushlevel (void);
extern void gnat_poplevel (void);

/* Set SUPERCONTEXT of the BLOCK for the current binding level to FNDECL
   and point FNDECL to this BLOCK.  */
extern void set_current_block_context (tree fndecl);

/* Set the jmpbuf_decl for the current binding level to DECL.  */
extern void set_block_jmpbuf_decl (tree decl);

/* Get the setjmp_decl, if any, for the current binding level.  */
extern tree get_block_jmpbuf_decl (void);

/* Records a ..._DECL node DECL as belonging to the current lexical scope
   and uses GNAT_NODE for location information.  */
extern void gnat_pushdecl (tree decl, Node_Id gnat_node);

extern void gnat_init_gcc_eh (void);
extern void gnat_install_builtins (void);

/* Return an integer type with the number of bits of precision given by
   PRECISION.  UNSIGNEDP is nonzero if the type is unsigned; otherwise
   it is a signed type.  */
extern tree gnat_type_for_size (unsigned precision, int unsignedp);

/* Return a data type that has machine mode MODE.  UNSIGNEDP selects
   an unsigned type; otherwise a signed type is returned.  */
extern tree gnat_type_for_mode (enum machine_mode mode, int unsignedp);

/* Emit debug info for all global variable declarations.  */
extern void gnat_write_global_declarations (void);

/* Return the unsigned version of a TYPE_NODE, a scalar type.  */
extern tree gnat_unsigned_type (tree type_node);

/* Return the signed version of a TYPE_NODE, a scalar type.  */
extern tree gnat_signed_type (tree type_node);

/* Return 1 if the types T1 and T2 are compatible, i.e. if they can be
   transparently converted to each other.  */
extern int gnat_types_compatible_p (tree t1, tree t2);

/* Create an expression whose value is that of EXPR,
   converted to type TYPE.  The TREE_TYPE of the value
   is always TYPE.  This function implements all reasonable
   conversions; callers should filter out those that are
   not permitted by the language being compiled.  */
extern tree convert (tree type, tree expr);

/* Routines created solely for the tree translator's sake. Their prototypes
   can be changed as desired.  */

/* Initialize the association of GNAT nodes to GCC trees.  */
extern void init_gnat_to_gnu (void);

/* GNAT_ENTITY is a GNAT tree node for a defining identifier.
   GNU_DECL is the GCC tree which is to be associated with
   GNAT_ENTITY. Such gnu tree node is always an ..._DECL node.
   If NO_CHECK is nonzero, the latter check is suppressed.
   If GNU_DECL is zero, a previous association is to be reset.  */
extern void save_gnu_tree (Entity_Id gnat_entity, tree gnu_decl,
                           bool no_check);

/* GNAT_ENTITY is a GNAT tree node for a defining identifier.
   Return the ..._DECL node that was associated with it.  If there is no tree
   node associated with GNAT_ENTITY, abort.  */
extern tree get_gnu_tree (Entity_Id gnat_entity);

/* Return nonzero if a GCC tree has been associated with GNAT_ENTITY.  */
extern bool present_gnu_tree (Entity_Id gnat_entity);

/* Initialize the association of GNAT nodes to GCC trees as dummies.  */
extern void init_dummy_type (void);

/* Make a dummy type corresponding to GNAT_TYPE.  */
extern tree make_dummy_type (Entity_Id gnat_type);

/* Record TYPE as a builtin type for Ada.  NAME is the name of the type.  */
extern void record_builtin_type (const char *name, tree type);

/* Given a record type RECORD_TYPE and a list of FIELD_DECL nodes FIELD_LIST,
   finish constructing the record or union type.  If REP_LEVEL is zero, this
   record has no representation clause and so will be entirely laid out here.
   If REP_LEVEL is one, this record has a representation clause and has been
   laid out already; only set the sizes and alignment.  If REP_LEVEL is two,
   this record is derived from a parent record and thus inherits its layout;
   only make a pass on the fields to finalize them.  DEBUG_INFO_P is true if
   we need to write debug information about this type.  */
extern void finish_record_type (tree record_type, tree field_list,
                                int rep_level, bool debug_info_p);

/* Wrap up compilation of RECORD_TYPE, i.e. output all the debug information
   associated with it.  It need not be invoked directly in most cases since
   finish_record_type takes care of doing so, but this can be necessary if
   a parallel type is to be attached to the record type.  */
extern void rest_of_record_type_compilation (tree record_type);

/* Append PARALLEL_TYPE on the chain of parallel types for decl.  */
extern void add_parallel_type (tree decl, tree parallel_type);

/* Return the parallel type associated to a type, if any.  */
extern tree get_parallel_type (tree type);

/* Return a FUNCTION_TYPE node.  RETURN_TYPE is the type returned by the
   subprogram.  If it is VOID_TYPE, then we are dealing with a procedure,
   otherwise we are dealing with a function.  PARAM_DECL_LIST is a list of
   PARM_DECL nodes that are the subprogram parameters.  CICO_LIST is the
   copy-in/copy-out list to be stored into the TYPE_CICO_LIST field.
   RETURN_UNCONSTRAINED_P is true if the function returns an unconstrained
   object.  RETURN_BY_DIRECT_REF_P is true if the function returns by direct
   reference.  RETURN_BY_INVISI_REF_P is true if the function returns by
   invisible reference.  */
extern tree create_subprog_type (tree return_type, tree param_decl_list,
                                 tree cico_list, bool return_unconstrained_p,
                                 bool return_by_direct_ref_p,
                                 bool return_by_invisi_ref_p);

/* Return a copy of TYPE, but safe to modify in any way.  */
extern tree copy_type (tree type);

/* Return a subtype of sizetype with range MIN to MAX and whose
   TYPE_INDEX_TYPE is INDEX.  GNAT_NODE is used for the position
   of the associated TYPE_DECL.  */
extern tree create_index_type (tree min, tree max, tree index,
                               Node_Id gnat_node);

/* Return a subtype of TYPE with range MIN to MAX.  If TYPE is NULL,
   sizetype is used.  */
extern tree create_range_type (tree type, tree min, tree max);

/* Return a TYPE_DECL node suitable for the TYPE_STUB_DECL field of a type.
   TYPE_NAME gives the name of the type and TYPE is a ..._TYPE node giving
   its data type.  */
extern tree create_type_stub_decl (tree type_name, tree type);

/* Return a TYPE_DECL node.  TYPE_NAME gives the name of the type and TYPE
   is a ..._TYPE node giving its data type.  ARTIFICIAL_P is true if this
   is a declaration that was generated by the compiler.  DEBUG_INFO_P is
   true if we need to write debug information about this type.  GNAT_NODE
   is used for the position of the decl.  */
extern tree create_type_decl (tree type_name, tree type,
                              struct attrib *attr_list,
                              bool artificial_p, bool debug_info_p,
                              Node_Id gnat_node);

/* Return a VAR_DECL or CONST_DECL node.

   VAR_NAME gives the name of the variable.  ASM_NAME is its assembler name
   (if provided).  TYPE is its data type (a GCC ..._TYPE node).  VAR_INIT is
   the GCC tree for an optional initial expression; NULL_TREE if none.

   CONST_FLAG is true if this variable is constant, in which case we might
   return a CONST_DECL node unless CONST_DECL_ALLOWED_P is false.

   PUBLIC_FLAG is true if this definition is to be made visible outside of
   the current compilation unit. This flag should be set when processing the
   variable definitions in a package specification.

   EXTERN_FLAG is nonzero when processing an external variable declaration (as
   opposed to a definition: no storage is to be allocated for the variable).

   STATIC_FLAG is only relevant when not at top level.  In that case
   it indicates whether to always allocate storage to the variable.

   GNAT_NODE is used for the position of the decl.  */
extern tree
create_var_decl_1 (tree var_name, tree asm_name, tree type, tree var_init,
                   bool const_flag, bool public_flag, bool extern_flag,
                   bool static_flag, bool const_decl_allowed_p,
                   struct attrib *attr_list, Node_Id gnat_node);

/* Wrapper around create_var_decl_1 for cases where we don't care whether
   a VAR or a CONST decl node is created.  */
#define create_var_decl(var_name, asm_name, type, var_init,     \
                        const_flag, public_flag, extern_flag,   \
                        static_flag, attr_list, gnat_node)      \
  create_var_decl_1 (var_name, asm_name, type, var_init,        \
                     const_flag, public_flag, extern_flag,      \
                     static_flag, true, attr_list, gnat_node)

/* Wrapper around create_var_decl_1 for cases where a VAR_DECL node is
   required.  The primary intent is for DECL_CONST_CORRESPONDING_VARs, which
   must be VAR_DECLs and on which we want TREE_READONLY set to have them
   possibly assigned to a readonly data section.  */
#define create_true_var_decl(var_name, asm_name, type, var_init,        \
                             const_flag, public_flag, extern_flag,      \
                             static_flag, attr_list, gnat_node)         \
  create_var_decl_1 (var_name, asm_name, type, var_init,                \
                     const_flag, public_flag, extern_flag,              \
                     static_flag, false, attr_list, gnat_node)

/* Record DECL as a global renaming pointer.  */
extern void record_global_renaming_pointer (tree decl);

/* Invalidate the global renaming pointers.  */
extern void invalidate_global_renaming_pointers (void);

/* Return a FIELD_DECL node.  FIELD_NAME is the field's name, FIELD_TYPE is
   its type and RECORD_TYPE is the type of the enclosing record.  If SIZE is
   nonzero, it is the specified size of the field.  If POS is nonzero, it is
   the bit position.  PACKED is 1 if the enclosing record is packed, -1 if it
   has Component_Alignment of Storage_Unit.  If ADDRESSABLE is nonzero, it
   means we are allowed to take the address of the field; if it is negative,
   we should not make a bitfield, which is used by make_aligning_type.  */
extern tree create_field_decl (tree field_name, tree field_type,
                               tree record_type, tree size, tree pos,
                               int packed, int addressable);

/* Returns a PARM_DECL node. PARAM_NAME is the name of the parameter,
   PARAM_TYPE is its type.  READONLY is true if the parameter is
   readonly (either an In parameter or an address of a pass-by-ref
   parameter).  */
extern tree create_param_decl (tree param_name, tree param_type,
                               bool readonly);

/* Returns a FUNCTION_DECL node.  SUBPROG_NAME is the name of the subprogram,
   ASM_NAME is its assembler name, SUBPROG_TYPE is its type (a FUNCTION_TYPE
   node), PARAM_DECL_LIST is the list of the subprogram arguments (a list of
   PARM_DECL nodes chained through the TREE_CHAIN field).

   INLINE_FLAG, PUBLIC_FLAG, EXTERN_FLAG, and ATTR_LIST are used to set the
   appropriate fields in the FUNCTION_DECL.  GNAT_NODE gives the location.  */
extern tree create_subprog_decl (tree subprog_name, tree asm_name,
                                 tree subprog_type, tree param_decl_list,
                                 bool inlinee_flag, bool public_flag,
                                 bool extern_flag,
                                 struct attrib *attr_list, Node_Id gnat_node);

/* Returns a LABEL_DECL node for LABEL_NAME.  */
extern tree create_label_decl (tree label_name);

/* Set up the framework for generating code for SUBPROG_DECL, a subprogram
   body. This routine needs to be invoked before processing the declarations
   appearing in the subprogram.  */
extern void begin_subprog_body (tree subprog_decl);

/* Finish the definition of the current subprogram BODY and finalize it.  */
extern void end_subprog_body (tree body);

/* Build a template of type TEMPLATE_TYPE from the array bounds of ARRAY_TYPE.
   EXPR is an expression that we can use to locate any PLACEHOLDER_EXPRs.
   Return a constructor for the template.  */
extern tree build_template (tree template_type, tree array_type, tree expr);

/* Build a 64bit VMS descriptor from a Mechanism_Type, which must specify
   a descriptor type, and the GCC type of an object.  Each FIELD_DECL
   in the type contains in its DECL_INITIAL the expression to use when
   a constructor is made for the type.  GNAT_ENTITY is a gnat node used
   to print out an error message if the mechanism cannot be applied to
   an object of that type and also for the name.  */
extern tree build_vms_descriptor (tree type, Mechanism_Type mech,
                                  Entity_Id gnat_entity);

/* Build a 32bit VMS descriptor from a Mechanism_Type. See above.  */
extern tree build_vms_descriptor32 (tree type, Mechanism_Type mech,
                                  Entity_Id gnat_entity);

/* Build a stub for the subprogram specified by the GCC tree GNU_SUBPROG
   and the GNAT node GNAT_SUBPROG.  */
extern void build_function_stub (tree gnu_subprog, Entity_Id gnat_subprog);

/* Build a type to be used to represent an aliased object whose nominal type
   is an unconstrained array.  This consists of a RECORD_TYPE containing a
   field of TEMPLATE_TYPE and a field of OBJECT_TYPE, which is an ARRAY_TYPE.
   If ARRAY_TYPE is that of an unconstrained array, this is used to represent
   an arbitrary unconstrained object.  Use NAME as the name of the record.
   DEBUG_INFO_P is true if we need to write debug information for the type.  */
extern tree build_unc_object_type (tree template_type, tree object_type,
                                   tree name, bool debug_info_p);

/* Same as build_unc_object_type, but taking a thin or fat pointer type
   instead of the template type.  */
extern tree build_unc_object_type_from_ptr (tree thin_fat_ptr_type,
                                            tree object_type, tree name,
                                            bool debug_info_p);

/* Shift the component offsets within an unconstrained object TYPE to make it
   suitable for use as a designated type for thin pointers.  */
extern void shift_unc_components_for_thin_pointers (tree type);

/* Update anything previously pointing to OLD_TYPE to point to NEW_TYPE.  In
   the normal case this is just two adjustments, but we have more to do
   if NEW is an UNCONSTRAINED_ARRAY_TYPE.  */
extern void update_pointer_to (tree old_type, tree new_type);

/* EXP is an expression for the size of an object.  If this size contains
   discriminant references, replace them with the maximum (if MAX_P) or
   minimum (if !MAX_P) possible value of the discriminant.  */
extern tree max_size (tree exp, bool max_p);

/* Remove all conversions that are done in EXP.  This includes converting
   from a padded type or to a left-justified modular type.  If TRUE_ADDRESS
   is true, always return the address of the containing object even if
   the address is not bit-aligned.  */
extern tree remove_conversions (tree exp, bool true_address);

/* If EXP's type is an UNCONSTRAINED_ARRAY_TYPE, return an expression that
   refers to the underlying array.  If its type has TYPE_CONTAINS_TEMPLATE_P,
   likewise return an expression pointing to the underlying array.  */
extern tree maybe_unconstrained_array (tree exp);

/* If EXP's type is a VECTOR_TYPE, return EXP converted to the associated
   TYPE_REPRESENTATIVE_ARRAY.  */
extern tree maybe_vector_array (tree exp);

/* Return an expression that does an unchecked conversion of EXPR to TYPE.
   If NOTRUNC_P is true, truncation operations should be suppressed.  */
extern tree unchecked_convert (tree type, tree expr, bool notrunc_p);

/* Return the appropriate GCC tree code for the specified GNAT_TYPE,
   the latter being a record type as predicated by Is_Record_Type.  */
extern enum tree_code tree_code_for_record_type (Entity_Id gnat_type);

/* Return true if GNAT_TYPE is a "double" floating-point type, i.e. whose
   size is equal to 64 bits, or an array of such a type.  Set ALIGN_CLAUSE
   according to the presence of an alignment clause on the type or, if it
   is an array, on the component type.  */
extern bool is_double_float_or_array (Entity_Id gnat_type,
                                      bool *align_clause);

/* Return true if GNAT_TYPE is a "double" or larger scalar type, i.e. whose
   size is greater or equal to 64 bits, or an array of such a type.  Set
   ALIGN_CLAUSE according to the presence of an alignment clause on the
   type or, if it is an array, on the component type.  */
extern bool is_double_scalar_or_array (Entity_Id gnat_type,
                                       bool *align_clause);

/* Return true if GNU_TYPE is suitable as the type of a non-aliased
   component of an aggregate type.  */
extern bool type_for_nonaliased_component_p (tree gnu_type);

/* Return the base type of TYPE.  */
extern tree get_base_type (tree type);

/* EXP is a GCC tree representing an address.  See if we can find how
   strictly the object at that address is aligned.   Return that alignment
   strictly the object at that address is aligned.   Return that alignment
   in bits.  If we don't know anything about the alignment, return 0.  */
extern unsigned int known_alignment (tree exp);

/* Return true if VALUE is a multiple of FACTOR. FACTOR must be a power
   of 2.  */
extern bool value_factor_p (tree value, HOST_WIDE_INT factor);

/* Make a binary operation of kind OP_CODE.  RESULT_TYPE is the type
   desired for the result.  Usually the operation is to be performed
   in that type.  For MODIFY_EXPR and ARRAY_REF, RESULT_TYPE may be 0
   in which case the type to be used will be derived from the operands.  */
extern tree build_binary_op (enum tree_code op_code, tree result_type,
                             tree left_operand, tree right_operand);

/* Similar, but make unary operation.  */
extern tree build_unary_op (enum tree_code op_code, tree result_type,
                            tree operand);

/* Similar, but for COND_EXPR.  */
extern tree build_cond_expr (tree result_type, tree condition_operand,
                             tree true_operand, tree false_operand);

/* Similar, but for RETURN_EXPR.  */
extern tree build_return_expr (tree ret_obj, tree ret_val);

/* Build a CALL_EXPR to call FUNDECL with one argument, ARG.  Return
   the CALL_EXPR.  */
extern tree build_call_1_expr (tree fundecl, tree arg);

/* Build a CALL_EXPR to call FUNDECL with two argument, ARG1 & ARG2.  Return
   the CALL_EXPR.  */
extern tree build_call_2_expr (tree fundecl, tree arg1, tree arg2);

/* Likewise to call FUNDECL with no arguments.  */
extern tree build_call_0_expr (tree fundecl);

/* Call a function that raises an exception and pass the line number and file
   name, if requested.  MSG says which exception function to call.

   GNAT_NODE is the gnat node conveying the source location for which the
   error should be signaled, or Empty in which case the error is signaled on
   the current ref_file_name/input_line.

   KIND says which kind of exception this is for
    (N_Raise_{Constraint,Storage,Program}_Error).  */
extern tree build_call_raise (int msg, Node_Id gnat_node, char kind);

/* Return a CONSTRUCTOR of TYPE whose list is LIST.  This is not the
   same as build_constructor in the language-independent tree.c.  */
extern tree gnat_build_constructor (tree type, tree list);

/* Return a COMPONENT_REF to access a field that is given by COMPONENT,
   an IDENTIFIER_NODE giving the name of the field, FIELD, a FIELD_DECL,
   for the field, or both.  Don't fold the result if NO_FOLD_P.  */
extern tree build_component_ref (tree record_variable, tree component,
                                 tree field, bool no_fold_p);

/* Build a GCC tree to call an allocation or deallocation function.
   If GNU_OBJ is nonzero, it is an object to deallocate.  Otherwise,
   generate an allocator.

   GNU_SIZE is the number of bytes to allocate and GNU_TYPE is the contained
   object type, used to determine the to-be-honored address alignment.
   GNAT_PROC, if present, is a procedure to call and GNAT_POOL is the storage
   pool to use.  If not present, malloc and free are used.  GNAT_NODE is used
   to provide an error location for restriction violation messages.  */
extern tree build_call_alloc_dealloc (tree gnu_obj, tree gnu_size,
                                      tree gnu_type, Entity_Id gnat_proc,
                                      Entity_Id gnat_pool, Node_Id gnat_node);

/* Build a GCC tree to correspond to allocating an object of TYPE whose
   initial value if INIT, if INIT is nonzero.  Convert the expression to
   RESULT_TYPE, which must be some type of pointer.  Return the tree.

   GNAT_PROC and GNAT_POOL optionally give the procedure to call and
   the storage pool to use.  GNAT_NODE is used to provide an error
   location for restriction violation messages.  If IGNORE_INIT_TYPE is
   true, ignore the type of INIT for the purpose of determining the size;
   this will cause the maximum size to be allocated if TYPE is of
   self-referential size.  */
extern tree build_allocator (tree type, tree init, tree result_type,
                             Entity_Id gnat_proc, Entity_Id gnat_pool,
                             Node_Id gnat_node, bool);

/* Fill in a VMS descriptor for EXPR and return a constructor for it.
   GNAT_FORMAL is how we find the descriptor record. GNAT_ACTUAL is how
   we derive the source location on a C_E */
extern tree fill_vms_descriptor (tree expr, Entity_Id gnat_formal,
                                 Node_Id gnat_actual);

/* Indicate that we need to take the address of T and that it therefore
   should not be allocated in a register.  Returns true if successful.  */
extern bool gnat_mark_addressable (tree t);

/* Save EXP for later use or reuse.  This is equivalent to save_expr in tree.c
   but we know how to handle our own nodes.  */
extern tree gnat_save_expr (tree exp);

/* Protect EXP for immediate reuse.  This is a variant of gnat_save_expr that
   is optimized under the assumption that EXP's value doesn't change before
   its subsequent reuse(s) except through its potential reevaluation.  */
extern tree gnat_protect_expr (tree exp);

/* This is equivalent to stabilize_reference in tree.c but we know how to
   handle our own nodes and we take extra arguments.  FORCE says whether to
   force evaluation of everything.  We set SUCCESS to true unless we walk
   through something we don't know how to stabilize.  */
extern tree gnat_stabilize_reference (tree ref, bool force, bool *success);

/* Implementation of the builtin_function langhook.  */
extern tree gnat_builtin_function (tree decl);

/* Search the chain of currently reachable declarations for a builtin
   FUNCTION_DECL node corresponding to function NAME (an IDENTIFIER_NODE).
   Return the first node found, if any, or NULL_TREE otherwise.  */
extern tree builtin_decl_for (tree name);

/* GNU_TYPE is a type. Determine if it should be passed by reference by
   default.  */
extern bool default_pass_by_ref (tree gnu_type);

/* GNU_TYPE is the type of a subprogram parameter.  Determine from the type
   if it should be passed by reference.  */
extern bool must_pass_by_ref (tree gnu_type);

/* This function is called by the front end to enumerate all the supported
   modes for the machine.  We pass a function which is called back with
   the following integer parameters:

   FLOAT_P      nonzero if this represents a floating-point mode
   COMPLEX_P    nonzero is this represents a complex mode
   COUNT        count of number of items, nonzero for vector mode
   PRECISION    number of bits in data representation
   MANTISSA     number of bits in mantissa, if FP and known, else zero.
   SIZE         number of bits used to store data
   ALIGN        number of bits to which mode is aligned.  */
extern void enumerate_modes (void (*f) (int, int, int, int, int, int,
                                        unsigned int));

/* Return the size of the FP mode with precision PREC.  */
extern int fp_prec_to_size (int prec);

/* Return the precision of the FP mode with size SIZE.  */
extern int fp_size_to_prec (int size);

/* These functions return the basic data type sizes and related parameters
   about the target machine.  */

extern Pos get_target_bits_per_unit (void);
extern Pos get_target_bits_per_word (void);
extern Pos get_target_char_size (void);
extern Pos get_target_wchar_t_size (void);
extern Pos get_target_short_size (void);
extern Pos get_target_int_size (void);
extern Pos get_target_long_size (void);
extern Pos get_target_long_long_size (void);
extern Pos get_target_float_size (void);
extern Pos get_target_double_size (void);
extern Pos get_target_long_double_size (void);
extern Pos get_target_pointer_size (void);
extern Pos get_target_maximum_default_alignment (void);
extern Pos get_target_default_allocator_alignment (void);
extern Pos get_target_maximum_allowed_alignment (void);
extern Pos get_target_maximum_alignment (void);
extern Nat get_float_words_be (void);
extern Nat get_words_be (void);
extern Nat get_bytes_be (void);
extern Nat get_bits_be (void);
extern Nat get_target_strict_alignment (void);
extern Nat get_target_double_float_alignment (void);
extern Nat get_target_double_scalar_alignment (void);

/* Let code know whether we are targetting VMS without need of
   intrusive preprocessor directives.  */
#ifndef TARGET_ABI_OPEN_VMS
#define TARGET_ABI_OPEN_VMS 0
#endif

/* VMS macro set by default, when clear forces 32bit mallocs and 32bit
   Descriptors. Always used in combination with TARGET_ABI_OPEN_VMS
   so no effect on non-VMS systems.  */
#ifndef TARGET_MALLOC64
#define TARGET_MALLOC64 0
#endif

/* Convenient shortcuts.  */
#define VECTOR_TYPE_P(TYPE) (TREE_CODE (TYPE) == VECTOR_TYPE)