make MSYMBOL_VALUE_ADDRESS an rvalue

[binutils-gdb.git] / gdb / symtab.h

/* Symbol table definitions for GDB.

   Copyright (C) 1986-2014 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/>.  */

#if !defined (SYMTAB_H)
#define SYMTAB_H 1

#include "vec.h"
#include "gdb_vecs.h"
#include "gdbtypes.h"

/* Opaque declarations.  */
struct ui_file;
struct frame_info;
struct symbol;
struct obstack;
struct objfile;
struct block;
struct blockvector;
struct axs_value;
struct agent_expr;
struct program_space;
struct language_defn;
struct probe;
struct common_block;

/* Some of the structures in this file are space critical.
   The space-critical structures are:

     struct general_symbol_info
     struct symbol
     struct partial_symbol

   These structures are laid out to encourage good packing.
   They use ENUM_BITFIELD and short int fields, and they order the
   structure members so that fields less than a word are next
   to each other so they can be packed together.  */

/* Rearranged: used ENUM_BITFIELD and rearranged field order in
   all the space critical structures (plus struct minimal_symbol).
   Memory usage dropped from 99360768 bytes to 90001408 bytes.
   I measured this with before-and-after tests of
   "HEAD-old-gdb -readnow HEAD-old-gdb" and
   "HEAD-new-gdb -readnow HEAD-old-gdb" on native i686-pc-linux-gnu,
   red hat linux 8, with LD_LIBRARY_PATH=/usr/lib/debug,
   typing "maint space 1" at the first command prompt.

   Here is another measurement (from andrew c):
     # no /usr/lib/debug, just plain glibc, like a normal user
     gdb HEAD-old-gdb
     (gdb) break internal_error
     (gdb) run
     (gdb) maint internal-error
     (gdb) backtrace
     (gdb) maint space 1

   gdb gdb_6_0_branch  2003-08-19  space used: 8896512
   gdb HEAD            2003-08-19  space used: 8904704
   gdb HEAD            2003-08-21  space used: 8396800 (+symtab.h)
   gdb HEAD            2003-08-21  space used: 8265728 (+gdbtypes.h)

   The third line shows the savings from the optimizations in symtab.h.
   The fourth line shows the savings from the optimizations in
   gdbtypes.h.  Both optimizations are in gdb HEAD now.

   --chastain 2003-08-21  */

/* Struct for storing C++ specific information.  Allocated when needed.  */

struct cplus_specific
{
  const char *demangled_name;
};

/* Define a structure for the information that is common to all symbol types,
   including minimal symbols, partial symbols, and full symbols.  In a
   multilanguage environment, some language specific information may need to
   be recorded along with each symbol.  */

/* This structure is space critical.  See space comments at the top.  */

struct general_symbol_info
{
  /* Name of the symbol.  This is a required field.  Storage for the
     name is allocated on the objfile_obstack for the associated
     objfile.  For languages like C++ that make a distinction between
     the mangled name and demangled name, this is the mangled
     name.  */

  const char *name;

  /* Value of the symbol.  Which member of this union to use, and what
     it means, depends on what kind of symbol this is and its
     SYMBOL_CLASS.  See comments there for more details.  All of these
     are in host byte order (though what they point to might be in
     target byte order, e.g. LOC_CONST_BYTES).  */

  union
  {
    LONGEST ivalue;

    struct block *block;

    const gdb_byte *bytes;

    CORE_ADDR address;

    /* A common block.  Used with LOC_COMMON_BLOCK.  */

    struct common_block *common_block;

    /* For opaque typedef struct chain.  */

    struct symbol *chain;
  }
  value;

  /* Since one and only one language can apply, wrap the language specific
     information inside a union.  */

  union
  {
    /* A pointer to an obstack that can be used for storage associated
       with this symbol.  This is only used by Ada, and only when the
       'ada_mangled' field is zero.  */
    struct obstack *obstack;

    /* This is used by languages which wish to store a demangled name.
       currently used by Ada, Java, and Objective C.  */
    struct mangled_lang
    {
      const char *demangled_name;
    }
    mangled_lang;

    struct cplus_specific *cplus_specific;
  }
  language_specific;

  /* Record the source code language that applies to this symbol.
     This is used to select one of the fields from the language specific
     union above.  */

  ENUM_BITFIELD(language) language : 8;

  /* This is only used by Ada.  If set, then the 'mangled_lang' field
     of language_specific is valid.  Otherwise, the 'obstack' field is
     valid.  */
  unsigned int ada_mangled : 1;

  /* Which section is this symbol in?  This is an index into
     section_offsets for this objfile.  Negative means that the symbol
     does not get relocated relative to a section.  */

  short section;
};

extern void symbol_set_demangled_name (struct general_symbol_info *,
                                       const char *,
                                       struct obstack *);

extern const char *symbol_get_demangled_name
  (const struct general_symbol_info *);

extern CORE_ADDR symbol_overlayed_address (CORE_ADDR, struct obj_section *);

/* Note that all the following SYMBOL_* macros are used with the
   SYMBOL argument being either a partial symbol or
   a full symbol.  Both types have a ginfo field.  In particular
   the SYMBOL_SET_LANGUAGE, SYMBOL_DEMANGLED_NAME, etc.
   macros cannot be entirely substituted by
   functions, unless the callers are changed to pass in the ginfo
   field only, instead of the SYMBOL parameter.  */

#define SYMBOL_VALUE(symbol)            (symbol)->ginfo.value.ivalue
#define SYMBOL_VALUE_ADDRESS(symbol)    (symbol)->ginfo.value.address
#define SYMBOL_VALUE_BYTES(symbol)      (symbol)->ginfo.value.bytes
#define SYMBOL_VALUE_COMMON_BLOCK(symbol) (symbol)->ginfo.value.common_block
#define SYMBOL_BLOCK_VALUE(symbol)      (symbol)->ginfo.value.block
#define SYMBOL_VALUE_CHAIN(symbol)      (symbol)->ginfo.value.chain
#define SYMBOL_LANGUAGE(symbol)         (symbol)->ginfo.language
#define SYMBOL_SECTION(symbol)          (symbol)->ginfo.section
#define SYMBOL_OBJ_SECTION(objfile, symbol)                     \
  (((symbol)->ginfo.section >= 0)                               \
   ? (&(((objfile)->sections)[(symbol)->ginfo.section]))        \
   : NULL)

/* Initializes the language dependent portion of a symbol
   depending upon the language for the symbol.  */
#define SYMBOL_SET_LANGUAGE(symbol,language,obstack)    \
  (symbol_set_language (&(symbol)->ginfo, (language), (obstack)))
extern void symbol_set_language (struct general_symbol_info *symbol,
                                 enum language language,
                                 struct obstack *obstack);

/* Set just the linkage name of a symbol; do not try to demangle
   it.  Used for constructs which do not have a mangled name,
   e.g. struct tags.  Unlike SYMBOL_SET_NAMES, linkage_name must
   be terminated and either already on the objfile's obstack or
   permanently allocated.  */
#define SYMBOL_SET_LINKAGE_NAME(symbol,linkage_name) \
  (symbol)->ginfo.name = (linkage_name)

/* Set the linkage and natural names of a symbol, by demangling
   the linkage name.  */
#define SYMBOL_SET_NAMES(symbol,linkage_name,len,copy_name,objfile)     \
  symbol_set_names (&(symbol)->ginfo, linkage_name, len, copy_name, objfile)
extern void symbol_set_names (struct general_symbol_info *symbol,
                              const char *linkage_name, int len, int copy_name,
                              struct objfile *objfile);

/* Now come lots of name accessor macros.  Short version as to when to
   use which: Use SYMBOL_NATURAL_NAME to refer to the name of the
   symbol in the original source code.  Use SYMBOL_LINKAGE_NAME if you
   want to know what the linker thinks the symbol's name is.  Use
   SYMBOL_PRINT_NAME for output.  Use SYMBOL_DEMANGLED_NAME if you
   specifically need to know whether SYMBOL_NATURAL_NAME and
   SYMBOL_LINKAGE_NAME are different.  */

/* Return SYMBOL's "natural" name, i.e. the name that it was called in
   the original source code.  In languages like C++ where symbols may
   be mangled for ease of manipulation by the linker, this is the
   demangled name.  */

#define SYMBOL_NATURAL_NAME(symbol) \
  (symbol_natural_name (&(symbol)->ginfo))
extern const char *symbol_natural_name
  (const struct general_symbol_info *symbol);

/* Return SYMBOL's name from the point of view of the linker.  In
   languages like C++ where symbols may be mangled for ease of
   manipulation by the linker, this is the mangled name; otherwise,
   it's the same as SYMBOL_NATURAL_NAME.  */

#define SYMBOL_LINKAGE_NAME(symbol)     (symbol)->ginfo.name

/* Return the demangled name for a symbol based on the language for
   that symbol.  If no demangled name exists, return NULL.  */
#define SYMBOL_DEMANGLED_NAME(symbol) \
  (symbol_demangled_name (&(symbol)->ginfo))
extern const char *symbol_demangled_name
  (const struct general_symbol_info *symbol);

/* Macro that returns a version of the name of a symbol that is
   suitable for output.  In C++ this is the "demangled" form of the
   name if demangle is on and the "mangled" form of the name if
   demangle is off.  In other languages this is just the symbol name.
   The result should never be NULL.  Don't use this for internal
   purposes (e.g. storing in a hashtable): it's only suitable for output.

   N.B. symbol may be anything with a ginfo member,
   e.g., struct symbol or struct minimal_symbol.  */

#define SYMBOL_PRINT_NAME(symbol)                                       \
  (demangle ? SYMBOL_NATURAL_NAME (symbol) : SYMBOL_LINKAGE_NAME (symbol))
extern int demangle;

/* Macro that returns the name to be used when sorting and searching symbols.
   In  C++, Chill, and Java, we search for the demangled form of a name,
   and so sort symbols accordingly.  In Ada, however, we search by mangled
   name.  If there is no distinct demangled name, then SYMBOL_SEARCH_NAME
   returns the same value (same pointer) as SYMBOL_LINKAGE_NAME.  */
#define SYMBOL_SEARCH_NAME(symbol)                                       \
   (symbol_search_name (&(symbol)->ginfo))
extern const char *symbol_search_name (const struct general_symbol_info *);

/* Return non-zero if NAME matches the "search" name of SYMBOL.
   Whitespace and trailing parentheses are ignored.
   See strcmp_iw for details about its behavior.  */
#define SYMBOL_MATCHES_SEARCH_NAME(symbol, name)                        \
  (strcmp_iw (SYMBOL_SEARCH_NAME (symbol), (name)) == 0)

/* Classification types for a minimal symbol.  These should be taken as
   "advisory only", since if gdb can't easily figure out a
   classification it simply selects mst_unknown.  It may also have to
   guess when it can't figure out which is a better match between two
   types (mst_data versus mst_bss) for example.  Since the minimal
   symbol info is sometimes derived from the BFD library's view of a
   file, we need to live with what information bfd supplies.  */

enum minimal_symbol_type
{
  mst_unknown = 0,              /* Unknown type, the default */
  mst_text,                     /* Generally executable instructions */
  mst_text_gnu_ifunc,           /* Executable code returning address
                                   of executable code */
  mst_slot_got_plt,             /* GOT entries for .plt sections */
  mst_data,                     /* Generally initialized data */
  mst_bss,                      /* Generally uninitialized data */
  mst_abs,                      /* Generally absolute (nonrelocatable) */
  /* GDB uses mst_solib_trampoline for the start address of a shared
     library trampoline entry.  Breakpoints for shared library functions
     are put there if the shared library is not yet loaded.
     After the shared library is loaded, lookup_minimal_symbol will
     prefer the minimal symbol from the shared library (usually
     a mst_text symbol) over the mst_solib_trampoline symbol, and the
     breakpoints will be moved to their true address in the shared
     library via breakpoint_re_set.  */
  mst_solib_trampoline,         /* Shared library trampoline code */
  /* For the mst_file* types, the names are only guaranteed to be unique
     within a given .o file.  */
  mst_file_text,                /* Static version of mst_text */
  mst_file_data,                /* Static version of mst_data */
  mst_file_bss                  /* Static version of mst_bss */
};

/* Define a simple structure used to hold some very basic information about
   all defined global symbols (text, data, bss, abs, etc).  The only required
   information is the general_symbol_info.

   In many cases, even if a file was compiled with no special options for
   debugging at all, as long as was not stripped it will contain sufficient
   information to build a useful minimal symbol table using this structure.
   Even when a file contains enough debugging information to build a full
   symbol table, these minimal symbols are still useful for quickly mapping
   between names and addresses, and vice versa.  They are also sometimes
   used to figure out what full symbol table entries need to be read in.  */

struct minimal_symbol
{

  /* The general symbol info required for all types of symbols.

     The SYMBOL_VALUE_ADDRESS contains the address that this symbol
     corresponds to.  */

  struct general_symbol_info mginfo;

  /* Size of this symbol.  end_psymtab in dbxread.c uses this
     information to calculate the end of the partial symtab based on the
     address of the last symbol plus the size of the last symbol.  */

  unsigned long size;

  /* Which source file is this symbol in?  Only relevant for mst_file_*.  */
  const char *filename;

  /* Classification type for this minimal symbol.  */

  ENUM_BITFIELD(minimal_symbol_type) type : 8;

  /* Non-zero if this symbol was created by gdb.
     Such symbols do not appear in the output of "info var|fun".  */
  unsigned int created_by_gdb : 1;

  /* Two flag bits provided for the use of the target.  */
  unsigned int target_flag_1 : 1;
  unsigned int target_flag_2 : 1;

  /* Nonzero iff the size of the minimal symbol has been set.
     Symbol size information can sometimes not be determined, because
     the object file format may not carry that piece of information.  */
  unsigned int has_size : 1;

  /* Minimal symbols with the same hash key are kept on a linked
     list.  This is the link.  */

  struct minimal_symbol *hash_next;

  /* Minimal symbols are stored in two different hash tables.  This is
     the `next' pointer for the demangled hash table.  */

  struct minimal_symbol *demangled_hash_next;
};

#define MSYMBOL_TARGET_FLAG_1(msymbol)  (msymbol)->target_flag_1
#define MSYMBOL_TARGET_FLAG_2(msymbol)  (msymbol)->target_flag_2
#define MSYMBOL_SIZE(msymbol)           ((msymbol)->size + 0)
#define SET_MSYMBOL_SIZE(msymbol, sz)           \
  do                                            \
    {                                           \
      (msymbol)->size = sz;                     \
      (msymbol)->has_size = 1;                  \
    } while (0)
#define MSYMBOL_HAS_SIZE(msymbol)       ((msymbol)->has_size + 0)
#define MSYMBOL_TYPE(msymbol)           (msymbol)->type

#define MSYMBOL_VALUE(symbol)           (symbol)->mginfo.value.ivalue
#define MSYMBOL_VALUE_ADDRESS(symbol)   ((symbol)->mginfo.value.address + 0)
#define SET_MSYMBOL_VALUE_ADDRESS(symbol, new_value) \
  ((symbol)->mginfo.value.address = (new_value))
#define MSYMBOL_VALUE_BYTES(symbol)     (symbol)->mginfo.value.bytes
#define MSYMBOL_BLOCK_VALUE(symbol)     (symbol)->mginfo.value.block
#define MSYMBOL_VALUE_CHAIN(symbol)     (symbol)->mginfo.value.chain
#define MSYMBOL_LANGUAGE(symbol)        (symbol)->mginfo.language
#define MSYMBOL_SECTION(symbol)         (symbol)->mginfo.section
#define MSYMBOL_OBJ_SECTION(objfile, symbol)                    \
  (((symbol)->mginfo.section >= 0)                              \
   ? (&(((objfile)->sections)[(symbol)->mginfo.section]))       \
   : NULL)

#define MSYMBOL_NATURAL_NAME(symbol) \
  (symbol_natural_name (&(symbol)->mginfo))
#define MSYMBOL_LINKAGE_NAME(symbol)    (symbol)->mginfo.name
#define MSYMBOL_PRINT_NAME(symbol)                                      \
  (demangle ? MSYMBOL_NATURAL_NAME (symbol) : MSYMBOL_LINKAGE_NAME (symbol))
#define MSYMBOL_DEMANGLED_NAME(symbol) \
  (symbol_demangled_name (&(symbol)->mginfo))
#define MSYMBOL_SET_LANGUAGE(symbol,language,obstack)   \
  (symbol_set_language (&(symbol)->mginfo, (language), (obstack)))
#define MSYMBOL_SEARCH_NAME(symbol)                                      \
   (symbol_search_name (&(symbol)->mginfo))
#define MSYMBOL_MATCHES_SEARCH_NAME(symbol, name)                       \
  (strcmp_iw (MSYMBOL_SEARCH_NAME (symbol), (name)) == 0)
#define MSYMBOL_SET_NAMES(symbol,linkage_name,len,copy_name,objfile)    \
  symbol_set_names (&(symbol)->mginfo, linkage_name, len, copy_name, objfile)

#include "minsyms.h"

\f

/* Represent one symbol name; a variable, constant, function or typedef.  */

/* Different name domains for symbols.  Looking up a symbol specifies a
   domain and ignores symbol definitions in other name domains.  */

typedef enum domain_enum_tag
{
  /* UNDEF_DOMAIN is used when a domain has not been discovered or
     none of the following apply.  This usually indicates an error either
     in the symbol information or in gdb's handling of symbols.  */

  UNDEF_DOMAIN,

  /* VAR_DOMAIN is the usual domain.  In C, this contains variables,
     function names, typedef names and enum type values.  */

  VAR_DOMAIN,

  /* STRUCT_DOMAIN is used in C to hold struct, union and enum type names.
     Thus, if `struct foo' is used in a C program, it produces a symbol named
     `foo' in the STRUCT_DOMAIN.  */

  STRUCT_DOMAIN,

  /* MODULE_DOMAIN is used in Fortran to hold module type names.  */

  MODULE_DOMAIN,

  /* LABEL_DOMAIN may be used for names of labels (for gotos).  */

  LABEL_DOMAIN,

  /* Fortran common blocks.  Their naming must be separate from VAR_DOMAIN.
     They also always use LOC_COMMON_BLOCK.  */
  COMMON_BLOCK_DOMAIN
} domain_enum;

extern const char *domain_name (domain_enum);

/* Searching domains, used for `search_symbols'.  Element numbers are
   hardcoded in GDB, check all enum uses before changing it.  */

enum search_domain
{
  /* Everything in VAR_DOMAIN minus FUNCTIONS_DOMAIN and
     TYPES_DOMAIN.  */
  VARIABLES_DOMAIN = 0,

  /* All functions -- for some reason not methods, though.  */
  FUNCTIONS_DOMAIN = 1,

  /* All defined types */
  TYPES_DOMAIN = 2,

  /* Any type.  */
  ALL_DOMAIN = 3
};

extern const char *search_domain_name (enum search_domain);

/* An address-class says where to find the value of a symbol.  */

enum address_class
{
  /* Not used; catches errors.  */

  LOC_UNDEF,

  /* Value is constant int SYMBOL_VALUE, host byteorder.  */

  LOC_CONST,

  /* Value is at fixed address SYMBOL_VALUE_ADDRESS.  */

  LOC_STATIC,

  /* Value is in register.  SYMBOL_VALUE is the register number
     in the original debug format.  SYMBOL_REGISTER_OPS holds a
     function that can be called to transform this into the
     actual register number this represents in a specific target
     architecture (gdbarch).

     For some symbol formats (stabs, for some compilers at least),
     the compiler generates two symbols, an argument and a register.
     In some cases we combine them to a single LOC_REGISTER in symbol
     reading, but currently not for all cases (e.g. it's passed on the
     stack and then loaded into a register).  */

  LOC_REGISTER,

  /* It's an argument; the value is at SYMBOL_VALUE offset in arglist.  */

  LOC_ARG,

  /* Value address is at SYMBOL_VALUE offset in arglist.  */

  LOC_REF_ARG,

  /* Value is in specified register.  Just like LOC_REGISTER except the
     register holds the address of the argument instead of the argument
     itself.  This is currently used for the passing of structs and unions
     on sparc and hppa.  It is also used for call by reference where the
     address is in a register, at least by mipsread.c.  */

  LOC_REGPARM_ADDR,

  /* Value is a local variable at SYMBOL_VALUE offset in stack frame.  */

  LOC_LOCAL,

  /* Value not used; definition in SYMBOL_TYPE.  Symbols in the domain
     STRUCT_DOMAIN all have this class.  */

  LOC_TYPEDEF,

  /* Value is address SYMBOL_VALUE_ADDRESS in the code.  */

  LOC_LABEL,

  /* In a symbol table, value is SYMBOL_BLOCK_VALUE of a `struct block'.
     In a partial symbol table, SYMBOL_VALUE_ADDRESS is the start address
     of the block.  Function names have this class.  */

  LOC_BLOCK,

  /* Value is a constant byte-sequence pointed to by SYMBOL_VALUE_BYTES, in
     target byte order.  */

  LOC_CONST_BYTES,

  /* Value is at fixed address, but the address of the variable has
     to be determined from the minimal symbol table whenever the
     variable is referenced.
     This happens if debugging information for a global symbol is
     emitted and the corresponding minimal symbol is defined
     in another object file or runtime common storage.
     The linker might even remove the minimal symbol if the global
     symbol is never referenced, in which case the symbol remains
     unresolved.
     
     GDB would normally find the symbol in the minimal symbol table if it will
     not find it in the full symbol table.  But a reference to an external
     symbol in a local block shadowing other definition requires full symbol
     without possibly having its address available for LOC_STATIC.  Testcase
     is provided as `gdb.dwarf2/dw2-unresolved.exp'.  */

  LOC_UNRESOLVED,

  /* The variable does not actually exist in the program.
     The value is ignored.  */

  LOC_OPTIMIZED_OUT,

  /* The variable's address is computed by a set of location
     functions (see "struct symbol_computed_ops" below).  */
  LOC_COMPUTED,

  /* The variable uses general_symbol_info->value->common_block field.
     It also always uses COMMON_BLOCK_DOMAIN.  */
  LOC_COMMON_BLOCK,

  /* Not used, just notes the boundary of the enum.  */
  LOC_FINAL_VALUE
};

/* The methods needed to implement LOC_COMPUTED.  These methods can
   use the symbol's .aux_value for additional per-symbol information.

   At present this is only used to implement location expressions.  */

struct symbol_computed_ops
{

  /* Return the value of the variable SYMBOL, relative to the stack
     frame FRAME.  If the variable has been optimized out, return
     zero.

     Iff `read_needs_frame (SYMBOL)' is zero, then FRAME may be zero.  */

  struct value *(*read_variable) (struct symbol * symbol,
                                  struct frame_info * frame);

  /* Read variable SYMBOL like read_variable at (callee) FRAME's function
     entry.  SYMBOL should be a function parameter, otherwise
     NO_ENTRY_VALUE_ERROR will be thrown.  */
  struct value *(*read_variable_at_entry) (struct symbol *symbol,
                                           struct frame_info *frame);

  /* Return non-zero if we need a frame to find the value of the SYMBOL.  */
  int (*read_needs_frame) (struct symbol * symbol);

  /* Write to STREAM a natural-language description of the location of
     SYMBOL, in the context of ADDR.  */
  void (*describe_location) (struct symbol * symbol, CORE_ADDR addr,
                             struct ui_file * stream);

  /* Non-zero if this symbol's address computation is dependent on PC.  */
  unsigned char location_has_loclist;

  /* Tracepoint support.  Append bytecodes to the tracepoint agent
     expression AX that push the address of the object SYMBOL.  Set
     VALUE appropriately.  Note --- for objects in registers, this
     needn't emit any code; as long as it sets VALUE properly, then
     the caller will generate the right code in the process of
     treating this as an lvalue or rvalue.  */

  void (*tracepoint_var_ref) (struct symbol *symbol, struct gdbarch *gdbarch,
                              struct agent_expr *ax, struct axs_value *value);
};

/* The methods needed to implement LOC_BLOCK for inferior functions.
   These methods can use the symbol's .aux_value for additional
   per-symbol information.  */

struct symbol_block_ops
{
  /* Fill in *START and *LENGTH with DWARF block data of function
     FRAMEFUNC valid for inferior context address PC.  Set *LENGTH to
     zero if such location is not valid for PC; *START is left
     uninitialized in such case.  */
  void (*find_frame_base_location) (struct symbol *framefunc, CORE_ADDR pc,
                                    const gdb_byte **start, size_t *length);
};

/* Functions used with LOC_REGISTER and LOC_REGPARM_ADDR.  */

struct symbol_register_ops
{
  int (*register_number) (struct symbol *symbol, struct gdbarch *gdbarch);
};

/* Objects of this type are used to find the address class and the
   various computed ops vectors of a symbol.  */

struct symbol_impl
{
  enum address_class aclass;

  /* Used with LOC_COMPUTED.  */
  const struct symbol_computed_ops *ops_computed;

  /* Used with LOC_BLOCK.  */
  const struct symbol_block_ops *ops_block;

  /* Used with LOC_REGISTER and LOC_REGPARM_ADDR.  */
  const struct symbol_register_ops *ops_register;
};

/* The number of bits we reserve in a symbol for the aclass index.
   This is a #define so that we can have a assertion elsewhere to
   verify that we have reserved enough space for synthetic address
   classes.  */

#define SYMBOL_ACLASS_BITS 6

/* This structure is space critical.  See space comments at the top.  */

struct symbol
{

  /* The general symbol info required for all types of symbols.  */

  struct general_symbol_info ginfo;

  /* Data type of value */

  struct type *type;

  /* The symbol table containing this symbol.  This is the file
     associated with LINE.  It can be NULL during symbols read-in but it is
     never NULL during normal operation.  */
  struct symtab *symtab;

  /* Domain code.  */

  ENUM_BITFIELD(domain_enum_tag) domain : 6;

  /* Address class.  This holds an index into the 'symbol_impls'
     table.  The actual enum address_class value is stored there,
     alongside any per-class ops vectors.  */

  unsigned int aclass_index : SYMBOL_ACLASS_BITS;

  /* Whether this is an argument.  */

  unsigned is_argument : 1;

  /* Whether this is an inlined function (class LOC_BLOCK only).  */
  unsigned is_inlined : 1;

  /* True if this is a C++ function symbol with template arguments.
     In this case the symbol is really a "struct template_symbol".  */
  unsigned is_cplus_template_function : 1;

  /* Line number of this symbol's definition, except for inlined
     functions.  For an inlined function (class LOC_BLOCK and
     SYMBOL_INLINED set) this is the line number of the function's call
     site.  Inlined function symbols are not definitions, and they are
     never found by symbol table lookup.

     FIXME: Should we really make the assumption that nobody will try
     to debug files longer than 64K lines?  What about machine
     generated programs?  */

  unsigned short line;

  /* An arbitrary data pointer, allowing symbol readers to record
     additional information on a per-symbol basis.  Note that this data
     must be allocated using the same obstack as the symbol itself.  */
  /* So far it is only used by LOC_COMPUTED to
     find the location information.  For a LOC_BLOCK symbol
     for a function in a compilation unit compiled with DWARF 2
     information, this is information used internally by the DWARF 2
     code --- specifically, the location expression for the frame
     base for this function.  */
  /* FIXME drow/2003-02-21: For the LOC_BLOCK case, it might be better
     to add a magic symbol to the block containing this information,
     or to have a generic debug info annotation slot for symbols.  */

  void *aux_value;

  struct symbol *hash_next;
};

extern const struct symbol_impl *symbol_impls;

#define SYMBOL_DOMAIN(symbol)   (symbol)->domain
#define SYMBOL_IMPL(symbol)             (symbol_impls[(symbol)->aclass_index])
#define SYMBOL_ACLASS_INDEX(symbol)     (symbol)->aclass_index
#define SYMBOL_CLASS(symbol)            (SYMBOL_IMPL (symbol).aclass)
#define SYMBOL_IS_ARGUMENT(symbol)      (symbol)->is_argument
#define SYMBOL_INLINED(symbol)          (symbol)->is_inlined
#define SYMBOL_IS_CPLUS_TEMPLATE_FUNCTION(symbol) \
  (symbol)->is_cplus_template_function
#define SYMBOL_TYPE(symbol)             (symbol)->type
#define SYMBOL_LINE(symbol)             (symbol)->line
#define SYMBOL_SYMTAB(symbol)           (symbol)->symtab
#define SYMBOL_COMPUTED_OPS(symbol)     (SYMBOL_IMPL (symbol).ops_computed)
#define SYMBOL_BLOCK_OPS(symbol)        (SYMBOL_IMPL (symbol).ops_block)
#define SYMBOL_REGISTER_OPS(symbol)     (SYMBOL_IMPL (symbol).ops_register)
#define SYMBOL_LOCATION_BATON(symbol)   (symbol)->aux_value
#define SYMBOL_OBJFILE(symbol)          (SYMBOL_SYMTAB (symbol)->objfile)

extern int register_symbol_computed_impl (enum address_class,
                                          const struct symbol_computed_ops *);

extern int register_symbol_block_impl (enum address_class aclass,
                                       const struct symbol_block_ops *ops);

extern int register_symbol_register_impl (enum address_class,
                                          const struct symbol_register_ops *);

/* An instance of this type is used to represent a C++ template
   function.  It includes a "struct symbol" as a kind of base class;
   users downcast to "struct template_symbol *" when needed.  A symbol
   is really of this type iff SYMBOL_IS_CPLUS_TEMPLATE_FUNCTION is
   true.  */

struct template_symbol
{
  /* The base class.  */
  struct symbol base;

  /* The number of template arguments.  */
  int n_template_arguments;

  /* The template arguments.  This is an array with
     N_TEMPLATE_ARGUMENTS elements.  */
  struct symbol **template_arguments;
};

\f
/* Each item represents a line-->pc (or the reverse) mapping.  This is
   somewhat more wasteful of space than one might wish, but since only
   the files which are actually debugged are read in to core, we don't
   waste much space.  */

struct linetable_entry
{
  int line;
  CORE_ADDR pc;
};

/* The order of entries in the linetable is significant.  They should
   be sorted by increasing values of the pc field.  If there is more than
   one entry for a given pc, then I'm not sure what should happen (and
   I not sure whether we currently handle it the best way).

   Example: a C for statement generally looks like this

   10   0x100   - for the init/test part of a for stmt.
   20   0x200
   30   0x300
   10   0x400   - for the increment part of a for stmt.

   If an entry has a line number of zero, it marks the start of a PC
   range for which no line number information is available.  It is
   acceptable, though wasteful of table space, for such a range to be
   zero length.  */

struct linetable
{
  int nitems;

  /* Actually NITEMS elements.  If you don't like this use of the
     `struct hack', you can shove it up your ANSI (seriously, if the
     committee tells us how to do it, we can probably go along).  */
  struct linetable_entry item[1];
};

/* How to relocate the symbols from each section in a symbol file.
   Each struct contains an array of offsets.
   The ordering and meaning of the offsets is file-type-dependent;
   typically it is indexed by section numbers or symbol types or
   something like that.

   To give us flexibility in changing the internal representation
   of these offsets, the ANOFFSET macro must be used to insert and
   extract offset values in the struct.  */

struct section_offsets
{
  CORE_ADDR offsets[1];         /* As many as needed.  */
};

#define ANOFFSET(secoff, whichone) \
  ((whichone == -1)                       \
   ? (internal_error (__FILE__, __LINE__, \
                      _("Section index is uninitialized")), -1) \
   : secoff->offsets[whichone])

/* The size of a section_offsets table for N sections.  */
#define SIZEOF_N_SECTION_OFFSETS(n) \
  (sizeof (struct section_offsets) \
   + sizeof (((struct section_offsets *) 0)->offsets) * ((n)-1))

/* Each source file or header is represented by a struct symtab.
   These objects are chained through the `next' field.  */

struct symtab
{
  /* Unordered chain of all existing symtabs of this objfile.  */

  struct symtab *next;

  /* List of all symbol scope blocks for this symtab.  May be shared
     between different symtabs (and normally is for all the symtabs
     in a given compilation unit).  */

  struct blockvector *blockvector;

  /* Table mapping core addresses to line numbers for this file.
     Can be NULL if none.  Never shared between different symtabs.  */

  struct linetable *linetable;

  /* Section in objfile->section_offsets for the blockvector and
     the linetable.  Probably always SECT_OFF_TEXT.  */

  int block_line_section;

  /* If several symtabs share a blockvector, exactly one of them
     should be designated the primary, so that the blockvector
     is relocated exactly once by objfile_relocate.  */

  unsigned int primary : 1;

  /* Symtab has been compiled with both optimizations and debug info so that
     GDB may stop skipping prologues as variables locations are valid already
     at function entry points.  */

  unsigned int locations_valid : 1;

  /* DWARF unwinder for this CU is valid even for epilogues (PC at the return
     instruction).  This is supported by GCC since 4.5.0.  */

  unsigned int epilogue_unwind_valid : 1;

  /* The macro table for this symtab.  Like the blockvector, this
     may be shared between different symtabs --- and normally is for
     all the symtabs in a given compilation unit.  */
  struct macro_table *macro_table;

  /* Name of this source file.  This pointer is never NULL.  */

  const char *filename;

  /* Directory in which it was compiled, or NULL if we don't know.  */

  const char *dirname;

  /* Total number of lines found in source file.  */

  int nlines;

  /* line_charpos[N] is the position of the (N-1)th line of the
     source file.  "position" means something we can lseek() to; it
     is not guaranteed to be useful any other way.  */

  int *line_charpos;

  /* Language of this source file.  */

  enum language language;

  /* String that identifies the format of the debugging information, such
     as "stabs", "dwarf 1", "dwarf 2", "coff", etc.  This is mostly useful
     for automated testing of gdb but may also be information that is
     useful to the user.  */

  const char *debugformat;

  /* String of producer version information.  May be zero.  */

  const char *producer;

  /* Full name of file as found by searching the source path.
     NULL if not yet known.  */

  char *fullname;

  /* Object file from which this symbol information was read.  */

  struct objfile *objfile;

  /* struct call_site entries for this compilation unit or NULL.  */

  htab_t call_site_htab;

  /* If non-NULL, then this points to a NULL-terminated vector of
     included symbol tables.  When searching the static or global
     block of this symbol table, the corresponding block of all
     included symbol tables will also be searched.  Note that this
     list must be flattened -- the symbol reader is responsible for
     ensuring that this vector contains the transitive closure of all
     included symbol tables.  */

  struct symtab **includes;

  /* If this is an included symbol table, this points to one includer
     of the table.  This user is considered the canonical symbol table
     containing this one.  An included symbol table may itself be
     included by another.  */

  struct symtab *user;
};

#define BLOCKVECTOR(symtab)     (symtab)->blockvector
#define LINETABLE(symtab)       (symtab)->linetable
#define SYMTAB_PSPACE(symtab)   (symtab)->objfile->pspace

/* Call this to set the "primary" field in struct symtab.  */
extern void set_symtab_primary (struct symtab *, int primary);

typedef struct symtab *symtab_ptr;
DEF_VEC_P (symtab_ptr);

\f

/* The virtual function table is now an array of structures which have the
   form { int16 offset, delta; void *pfn; }. 

   In normal virtual function tables, OFFSET is unused.
   DELTA is the amount which is added to the apparent object's base
   address in order to point to the actual object to which the
   virtual function should be applied.
   PFN is a pointer to the virtual function.

   Note that this macro is g++ specific (FIXME).  */

#define VTBL_FNADDR_OFFSET 2

/* External variables and functions for the objects described above.  */

/* True if we are nested inside psymtab_to_symtab.  */

extern int currently_reading_symtab;

/* symtab.c lookup functions */

extern const char multiple_symbols_ask[];
extern const char multiple_symbols_all[];
extern const char multiple_symbols_cancel[];

const char *multiple_symbols_select_mode (void);

int symbol_matches_domain (enum language symbol_language, 
                           domain_enum symbol_domain,
                           domain_enum domain);

/* lookup a symbol table by source file name.  */

extern struct symtab *lookup_symtab (const char *);

/* An object of this type is passed as the 'is_a_field_of_this'
   argument to lookup_symbol and lookup_symbol_in_language.  */

struct field_of_this_result
{
  /* The type in which the field was found.  If this is NULL then the
     symbol was not found in 'this'.  If non-NULL, then one of the
     other fields will be non-NULL as well.  */

  struct type *type;

  /* If the symbol was found as an ordinary field of 'this', then this
     is non-NULL and points to the particular field.  */

  struct field *field;

  /* If the symbol was found as an function field of 'this', then this
     is non-NULL and points to the particular field.  */

  struct fn_fieldlist *fn_field;
};

/* lookup a symbol by name (optional block) in language.  */

extern struct symbol *lookup_symbol_in_language (const char *,
                                                 const struct block *,
                                                 const domain_enum,
                                                 enum language,
                                                 struct field_of_this_result *);

/* lookup a symbol by name (optional block, optional symtab)
   in the current language.  */

extern struct symbol *lookup_symbol (const char *, const struct block *,
                                     const domain_enum,
                                     struct field_of_this_result *);

/* A default version of lookup_symbol_nonlocal for use by languages
   that can't think of anything better to do.  */

extern struct symbol *basic_lookup_symbol_nonlocal (const char *,
                                                    const struct block *,
                                                    const domain_enum);

/* Some helper functions for languages that need to write their own
   lookup_symbol_nonlocal functions.  */

/* Lookup a symbol in the static block associated to BLOCK, if there
   is one; do nothing if BLOCK is NULL or a global block.  */

extern struct symbol *lookup_symbol_static (const char *name,
                                            const struct block *block,
                                            const domain_enum domain);

/* Lookup a symbol in all files' global blocks (searching psymtabs if
   necessary).  */

extern struct symbol *lookup_symbol_global (const char *name,
                                            const struct block *block,
                                            const domain_enum domain);

/* Lookup a symbol within the block BLOCK.  This, unlike
   lookup_symbol_block, will set SYMTAB and BLOCK_FOUND correctly, and
   will fix up the symbol if necessary.  */

extern struct symbol *lookup_symbol_aux_block (const char *name,
                                               const struct block *block,
                                               const domain_enum domain);

extern struct symbol *lookup_language_this (const struct language_defn *lang,
                                            const struct block *block);

/* Lookup a symbol only in the file static scope of all the objfiles.  */

struct symbol *lookup_static_symbol_aux (const char *name,
                                         const domain_enum domain);


/* lookup a symbol by name, within a specified block.  */

extern struct symbol *lookup_block_symbol (const struct block *, const char *,
                                           const domain_enum);

/* lookup a [struct, union, enum] by name, within a specified block.  */

extern struct type *lookup_struct (const char *, const struct block *);

extern struct type *lookup_union (const char *, const struct block *);

extern struct type *lookup_enum (const char *, const struct block *);

/* from blockframe.c: */

/* lookup the function symbol corresponding to the address.  */

extern struct symbol *find_pc_function (CORE_ADDR);

/* lookup the function corresponding to the address and section.  */

extern struct symbol *find_pc_sect_function (CORE_ADDR, struct obj_section *);

extern int find_pc_partial_function_gnu_ifunc (CORE_ADDR pc, const char **name,
                                               CORE_ADDR *address,
                                               CORE_ADDR *endaddr,
                                               int *is_gnu_ifunc_p);

/* lookup function from address, return name, start addr and end addr.  */

extern int find_pc_partial_function (CORE_ADDR, const char **, CORE_ADDR *,
                                     CORE_ADDR *);

extern void clear_pc_function_cache (void);

/* lookup partial symbol table by address and section.  */

extern struct symtab *find_pc_sect_symtab_via_partial (CORE_ADDR,
                                                       struct obj_section *);

/* lookup full symbol table by address.  */

extern struct symtab *find_pc_symtab (CORE_ADDR);

/* lookup full symbol table by address and section.  */

extern struct symtab *find_pc_sect_symtab (CORE_ADDR, struct obj_section *);

extern int find_pc_line_pc_range (CORE_ADDR, CORE_ADDR *, CORE_ADDR *);

extern void reread_symbols (void);

extern struct type *lookup_transparent_type (const char *);
extern struct type *basic_lookup_transparent_type (const char *);


/* Macro for name of symbol to indicate a file compiled with gcc.  */
#ifndef GCC_COMPILED_FLAG_SYMBOL
#define GCC_COMPILED_FLAG_SYMBOL "gcc_compiled."
#endif

/* Macro for name of symbol to indicate a file compiled with gcc2.  */
#ifndef GCC2_COMPILED_FLAG_SYMBOL
#define GCC2_COMPILED_FLAG_SYMBOL "gcc2_compiled."
#endif

extern int in_gnu_ifunc_stub (CORE_ADDR pc);

/* Functions for resolving STT_GNU_IFUNC symbols which are implemented only
   for ELF symbol files.  */

struct gnu_ifunc_fns
{
  /* See elf_gnu_ifunc_resolve_addr for its real implementation.  */
  CORE_ADDR (*gnu_ifunc_resolve_addr) (struct gdbarch *gdbarch, CORE_ADDR pc);

  /* See elf_gnu_ifunc_resolve_name for its real implementation.  */
  int (*gnu_ifunc_resolve_name) (const char *function_name,
                                 CORE_ADDR *function_address_p);

  /* See elf_gnu_ifunc_resolver_stop for its real implementation.  */
  void (*gnu_ifunc_resolver_stop) (struct breakpoint *b);

  /* See elf_gnu_ifunc_resolver_return_stop for its real implementation.  */
  void (*gnu_ifunc_resolver_return_stop) (struct breakpoint *b);
};

#define gnu_ifunc_resolve_addr gnu_ifunc_fns_p->gnu_ifunc_resolve_addr
#define gnu_ifunc_resolve_name gnu_ifunc_fns_p->gnu_ifunc_resolve_name
#define gnu_ifunc_resolver_stop gnu_ifunc_fns_p->gnu_ifunc_resolver_stop
#define gnu_ifunc_resolver_return_stop \
  gnu_ifunc_fns_p->gnu_ifunc_resolver_return_stop

extern const struct gnu_ifunc_fns *gnu_ifunc_fns_p;

extern CORE_ADDR find_solib_trampoline_target (struct frame_info *, CORE_ADDR);

struct symtab_and_line
{
  /* The program space of this sal.  */
  struct program_space *pspace;

  struct symtab *symtab;
  struct obj_section *section;
  /* Line number.  Line numbers start at 1 and proceed through symtab->nlines.
     0 is never a valid line number; it is used to indicate that line number
     information is not available.  */
  int line;

  CORE_ADDR pc;
  CORE_ADDR end;
  int explicit_pc;
  int explicit_line;

  /* The probe associated with this symtab_and_line.  */
  struct probe *probe;
};

extern void init_sal (struct symtab_and_line *sal);

struct symtabs_and_lines
{
  struct symtab_and_line *sals;
  int nelts;
};
\f

/* Given a pc value, return line number it is in.  Second arg nonzero means
   if pc is on the boundary use the previous statement's line number.  */

extern struct symtab_and_line find_pc_line (CORE_ADDR, int);

/* Same function, but specify a section as well as an address.  */

extern struct symtab_and_line find_pc_sect_line (CORE_ADDR,
                                                 struct obj_section *, int);

/* Given a symtab and line number, return the pc there.  */

extern int find_line_pc (struct symtab *, int, CORE_ADDR *);

extern int find_line_pc_range (struct symtab_and_line, CORE_ADDR *,
                               CORE_ADDR *);

extern void resolve_sal_pc (struct symtab_and_line *);

/* Symbol-reading stuff in symfile.c and solib.c.  */

extern void clear_solib (void);

/* source.c */

extern int identify_source_line (struct symtab *, int, int, CORE_ADDR);

/* Flags passed as 4th argument to print_source_lines.  */

enum print_source_lines_flags
  {
    /* Do not print an error message.  */
    PRINT_SOURCE_LINES_NOERROR = (1 << 0),

    /* Print the filename in front of the source lines.  */
    PRINT_SOURCE_LINES_FILENAME = (1 << 1)
  };

extern void print_source_lines (struct symtab *, int, int,
                                enum print_source_lines_flags);

extern void forget_cached_source_info_for_objfile (struct objfile *);
extern void forget_cached_source_info (void);

extern void select_source_symtab (struct symtab *);

extern VEC (char_ptr) *default_make_symbol_completion_list_break_on
  (const char *text, const char *word, const char *break_on,
   enum type_code code);
extern VEC (char_ptr) *default_make_symbol_completion_list (const char *,
                                                            const char *,
                                                            enum type_code);
extern VEC (char_ptr) *make_symbol_completion_list (const char *, const char *);
extern VEC (char_ptr) *make_symbol_completion_type (const char *, const char *,
                                                    enum type_code);
extern VEC (char_ptr) *make_symbol_completion_list_fn (struct cmd_list_element *,
                                                       const char *,
                                                       const char *);

extern VEC (char_ptr) *make_file_symbol_completion_list (const char *,
                                                         const char *,
                                                         const char *);

extern VEC (char_ptr) *make_source_files_completion_list (const char *,
                                                          const char *);

/* symtab.c */

int matching_obj_sections (struct obj_section *, struct obj_section *);

extern struct symtab *find_line_symtab (struct symtab *, int, int *, int *);

extern struct symtab_and_line find_function_start_sal (struct symbol *sym,
                                                       int);

extern void skip_prologue_sal (struct symtab_and_line *);

/* symfile.c */

extern void clear_symtab_users (int add_flags);

extern enum language deduce_language_from_filename (const char *);

/* symtab.c */

extern int in_prologue (struct gdbarch *gdbarch,
                        CORE_ADDR pc, CORE_ADDR func_start);

extern CORE_ADDR skip_prologue_using_sal (struct gdbarch *gdbarch,
                                          CORE_ADDR func_addr);

extern struct symbol *fixup_symbol_section (struct symbol *,
                                            struct objfile *);

/* Symbol searching */
/* Note: struct symbol_search, search_symbols, et.al. are declared here,
   instead of making them local to symtab.c, for gdbtk's sake.  */

/* When using search_symbols, a list of the following structs is returned.
   Callers must free the search list using free_search_symbols!  */
struct symbol_search
{
  /* The block in which the match was found.  Could be, for example,
     STATIC_BLOCK or GLOBAL_BLOCK.  */
  int block;

  /* Information describing what was found.

     If symtab and symbol are NOT NULL, then information was found
     for this match.  */
  struct symtab *symtab;
  struct symbol *symbol;

  /* If msymbol is non-null, then a match was made on something for
     which only minimal_symbols exist.  */
  struct bound_minimal_symbol msymbol;

  /* A link to the next match, or NULL for the end.  */
  struct symbol_search *next;
};

extern void search_symbols (char *, enum search_domain, int, char **,
                            struct symbol_search **);
extern void free_search_symbols (struct symbol_search *);
extern struct cleanup *make_cleanup_free_search_symbols (struct symbol_search
                                                         **);

/* The name of the ``main'' function.
   FIXME: cagney/2001-03-20: Can't make main_name() const since some
   of the calling code currently assumes that the string isn't
   const.  */
extern /*const */ char *main_name (void);
extern enum language main_language (void);

/* Check global symbols in objfile.  */
struct symbol *lookup_global_symbol_from_objfile (const struct objfile *,
                                                  const char *name,
                                                  const domain_enum domain);

/* Return 1 if the supplied producer string matches the ARM RealView
   compiler (armcc).  */
int producer_is_realview (const char *producer);

void fixup_section (struct general_symbol_info *ginfo,
                    CORE_ADDR addr, struct objfile *objfile);

struct objfile *lookup_objfile_from_block (const struct block *block);

extern unsigned int symtab_create_debug;

extern int basenames_may_differ;

int compare_filenames_for_search (const char *filename,
                                  const char *search_name);

int iterate_over_some_symtabs (const char *name,
                               const char *real_path,
                               int (*callback) (struct symtab *symtab,
                                                void *data),
                               void *data,
                               struct symtab *first,
                               struct symtab *after_last);

void iterate_over_symtabs (const char *name,
                           int (*callback) (struct symtab *symtab,
                                            void *data),
                           void *data);

DEF_VEC_I (CORE_ADDR);

VEC (CORE_ADDR) *find_pcs_for_symtab_line (struct symtab *symtab, int line,
                                           struct linetable_entry **best_entry);

/* Callback for LA_ITERATE_OVER_SYMBOLS.  The callback will be called
   once per matching symbol SYM, with DATA being the argument of the
   same name that was passed to LA_ITERATE_OVER_SYMBOLS.  The callback
   should return nonzero to indicate that LA_ITERATE_OVER_SYMBOLS
   should continue iterating, or zero to indicate that the iteration
   should end.  */

typedef int (symbol_found_callback_ftype) (struct symbol *sym, void *data);

void iterate_over_symbols (const struct block *block, const char *name,
                           const domain_enum domain,
                           symbol_found_callback_ftype *callback,
                           void *data);

struct cleanup *demangle_for_lookup (const char *name, enum language lang,
                                     const char **result_name);

struct symbol *allocate_symbol (struct objfile *);

void initialize_symbol (struct symbol *);

struct template_symbol *allocate_template_symbol (struct objfile *);

#endif /* !defined(SYMTAB_H) */