Add the entry for g++.dg/warn/unused-result1.C.

[official-gcc.git] / gcc / toplev.c

/* Top level of GCC compilers (cc1, cc1plus, etc.)
   Copyright (C) 1987, 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
   1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006
   Free Software Foundation, Inc.

This file is part of GCC.

GCC is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free
Software Foundation; either version 2, or (at your option) any later
version.

GCC is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
for more details.

You should have received a copy of the GNU General Public License
along with GCC; see the file COPYING.  If not, write to the Free
Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
02110-1301, USA.  */

/* This is the top level of cc1/c++.
   It parses command args, opens files, invokes the various passes
   in the proper order, and counts the time used by each.
   Error messages and low-level interface to malloc also handled here.  */

#include "config.h"
#undef FLOAT /* This is for hpux. They should change hpux.  */
#undef FFS  /* Some systems define this in param.h.  */
#include "system.h"
#include "coretypes.h"
#include "tm.h"
#include <signal.h>

#ifdef HAVE_SYS_RESOURCE_H
# include <sys/resource.h>
#endif

#ifdef HAVE_SYS_TIMES_H
# include <sys/times.h>
#endif

#include "line-map.h"
#include "input.h"
#include "tree.h"
#include "version.h"
#include "rtl.h"
#include "tm_p.h"
#include "flags.h"
#include "insn-attr.h"
#include "insn-config.h"
#include "insn-flags.h"
#include "hard-reg-set.h"
#include "recog.h"
#include "output.h"
#include "except.h"
#include "function.h"
#include "toplev.h"
#include "expr.h"
#include "basic-block.h"
#include "intl.h"
#include "ggc.h"
#include "graph.h"
#include "regs.h"
#include "timevar.h"
#include "diagnostic.h"
#include "params.h"
#include "reload.h"
#include "dwarf2asm.h"
#include "integrate.h"
#include "real.h"
#include "debug.h"
#include "target.h"
#include "langhooks.h"
#include "cfglayout.h"
#include "cfgloop.h"
#include "hosthooks.h"
#include "cgraph.h"
#include "opts.h"
#include "coverage.h"
#include "value-prof.h"
#include "alloc-pool.h"
#include "tree-mudflap.h"

#if defined (DWARF2_UNWIND_INFO) || defined (DWARF2_DEBUGGING_INFO)
#include "dwarf2out.h"
#endif

#if defined(DBX_DEBUGGING_INFO) || defined(XCOFF_DEBUGGING_INFO)
#include "dbxout.h"
#endif

#ifdef SDB_DEBUGGING_INFO
#include "sdbout.h"
#endif

#ifdef XCOFF_DEBUGGING_INFO
#include "xcoffout.h"           /* Needed for external data
                                   declarations for e.g. AIX 4.x.  */
#endif

static void general_init (const char *);
static void do_compile (void);
static void process_options (void);
static void backend_init (void);
static int lang_dependent_init (const char *);
static void init_asm_output (const char *);
static void finalize (void);

static void crash_signal (int) ATTRIBUTE_NORETURN;
static void setup_core_dumping (void);
static void compile_file (void);

static int print_single_switch (FILE *, int, int, const char *,
                                const char *, const char *,
                                const char *, const char *);
static void print_switch_values (FILE *, int, int, const char *,
                                 const char *, const char *);

/* Nonzero to dump debug info whilst parsing (-dy option).  */
static int set_yydebug;

/* True if we don't need a backend (e.g. preprocessing only).  */
static bool no_backend;

/* Length of line when printing switch values.  */
#define MAX_LINE 75

/* Name of program invoked, sans directories.  */

const char *progname;

/* Copy of argument vector to toplev_main.  */
static const char **save_argv;

/* Name of top-level original source file (what was input to cpp).
   This comes from the #-command at the beginning of the actual input.
   If there isn't any there, then this is the cc1 input file name.  */

const char *main_input_filename;

#ifndef USE_MAPPED_LOCATION
location_t unknown_location = { NULL, 0 };
#endif

/* Used to enable -fvar-tracking, -fweb and -frename-registers according
   to optimize and default_debug_hooks in process_options ().  */
#define AUTODETECT_VALUE 2

/* Current position in real source file.  */

location_t input_location;

struct line_maps line_table;

/* Nonzero if it is unsafe to create any new pseudo registers.  */
int no_new_pseudos;

/* Stack of currently pending input files.  */

struct file_stack *input_file_stack;

/* Incremented on each change to input_file_stack.  */
int input_file_stack_tick;

/* Record of input_file_stack at each tick.  */
typedef struct file_stack *fs_p;
DEF_VEC_P(fs_p);
DEF_VEC_ALLOC_P(fs_p,heap);
static VEC(fs_p,heap) *input_file_stack_history;

/* Whether input_file_stack has been restored to a previous state (in
   which case there should be no more pushing).  */
static bool input_file_stack_restored;

/* Name to use as base of names for dump output files.  */

const char *dump_base_name;

/* Name to use as a base for auxiliary output files.  */

const char *aux_base_name;

/* Bit flags that specify the machine subtype we are compiling for.
   Bits are tested using macros TARGET_... defined in the tm.h file
   and set by `-m...' switches.  Must be defined in rtlanal.c.  */

extern int target_flags;

/* A mask of target_flags that includes bit X if X was set or cleared
   on the command line.  */

int target_flags_explicit;

/* Debug hooks - dependent upon command line options.  */

const struct gcc_debug_hooks *debug_hooks;

/* Debug hooks - target default.  */

static const struct gcc_debug_hooks *default_debug_hooks;

/* Other flags saying which kinds of debugging dump have been requested.  */

int rtl_dump_and_exit;
int flag_print_asm_name;
enum graph_dump_types graph_dump_format;

/* Name for output file of assembly code, specified with -o.  */

const char *asm_file_name;

/* Nonzero means do optimizations.  -O.
   Particular numeric values stand for particular amounts of optimization;
   thus, -O2 stores 2 here.  However, the optimizations beyond the basic
   ones are not controlled directly by this variable.  Instead, they are
   controlled by individual `flag_...' variables that are defaulted
   based on this variable.  */

int optimize = 0;

/* Nonzero means optimize for size.  -Os.
   The only valid values are zero and nonzero. When optimize_size is
   nonzero, optimize defaults to 2, but certain individual code
   bloating optimizations are disabled.  */

int optimize_size = 0;

/* The FUNCTION_DECL for the function currently being compiled,
   or 0 if between functions.  */
tree current_function_decl;

/* Set to the FUNC_BEGIN label of the current function, or NULL
   if none.  */
const char * current_function_func_begin_label;

/* Temporarily suppress certain warnings.
   This is set while reading code from a system header file.  */

int in_system_header = 0;

/* Nonzero means to collect statistics which might be expensive
   and to print them when we are done.  */
int flag_detailed_statistics = 0;

/* A random sequence of characters, unless overridden by user.  */
const char *flag_random_seed;

/* A local time stamp derived from the time of compilation. It will be
   zero if the system cannot provide a time.  It will be -1u, if the
   user has specified a particular random seed.  */
unsigned local_tick;

/* -f flags.  */

/* Nonzero means `char' should be signed.  */

int flag_signed_char;

/* Nonzero means give an enum type only as many bytes as it needs.  A value
   of 2 means it has not yet been initialized.  */

int flag_short_enums;

/* Nonzero if structures and unions should be returned in memory.

   This should only be defined if compatibility with another compiler or
   with an ABI is needed, because it results in slower code.  */

#ifndef DEFAULT_PCC_STRUCT_RETURN
#define DEFAULT_PCC_STRUCT_RETURN 1
#endif

/* Nonzero for -fpcc-struct-return: return values the same way PCC does.  */

int flag_pcc_struct_return = DEFAULT_PCC_STRUCT_RETURN;

/* 0 means straightforward implementation of complex divide acceptable.
   1 means wide ranges of inputs must work for complex divide.
   2 means C99-like requirements for complex multiply and divide.  */

int flag_complex_method = 1;

/* Nonzero means that we don't want inlining by virtue of -fno-inline,
   not just because the tree inliner turned us off.  */

int flag_really_no_inline = 2;

/* Nonzero means we should be saving declaration info into a .X file.  */

int flag_gen_aux_info = 0;

/* Specified name of aux-info file.  */

const char *aux_info_file_name;

/* Nonzero if we are compiling code for a shared library, zero for
   executable.  */

int flag_shlib;

/* Generate code for GNU or NeXT Objective-C runtime environment.  */

#ifdef NEXT_OBJC_RUNTIME
int flag_next_runtime = 1;
#else
int flag_next_runtime = 0;
#endif

/* Set to the default thread-local storage (tls) model to use.  */

enum tls_model flag_tls_default = TLS_MODEL_GLOBAL_DYNAMIC;

/* Nonzero means change certain warnings into errors.
   Usually these are warnings about failure to conform to some standard.  */

int flag_pedantic_errors = 0;

/* -dA causes debug commentary information to be produced in
   the generated assembly code (to make it more readable).  This option
   is generally only of use to those who actually need to read the
   generated assembly code (perhaps while debugging the compiler itself).
   Currently, this switch is only used by dwarfout.c; however, it is intended
   to be a catchall for printing debug information in the assembler file.  */

int flag_debug_asm = 0;

/* -dP causes the rtl to be emitted as a comment in assembly.  */

int flag_dump_rtl_in_asm = 0;

/* When non-NULL, indicates that whenever space is allocated on the
   stack, the resulting stack pointer must not pass this
   address---that is, for stacks that grow downward, the stack pointer
   must always be greater than or equal to this address; for stacks
   that grow upward, the stack pointer must be less than this address.
   At present, the rtx may be either a REG or a SYMBOL_REF, although
   the support provided depends on the backend.  */
rtx stack_limit_rtx;

/* If one, renumber instruction UIDs to reduce the number of
   unused UIDs if there are a lot of instructions.  If greater than
   one, unconditionally renumber instruction UIDs.  */
int flag_renumber_insns = 1;

/* Nonzero if we should track variables.  When
   flag_var_tracking == AUTODETECT_VALUE it will be set according
   to optimize, debug_info_level and debug_hooks in process_options ().  */
int flag_var_tracking = AUTODETECT_VALUE;

/* True if the user has tagged the function with the 'section'
   attribute.  */

bool user_defined_section_attribute = false;

/* Values of the -falign-* flags: how much to align labels in code.
   0 means `use default', 1 means `don't align'.
   For each variable, there is an _log variant which is the power
   of two not less than the variable, for .align output.  */

int align_loops_log;
int align_loops_max_skip;
int align_jumps_log;
int align_jumps_max_skip;
int align_labels_log;
int align_labels_max_skip;
int align_functions_log;

/* Like align_functions_log above, but used by front-ends to force the
   minimum function alignment.  Zero means no alignment is forced.  */
int force_align_functions_log;

typedef struct
{
  const char *const string;
  int *const variable;
  const int on_value;
}
lang_independent_options;

/* Nonzero if subexpressions must be evaluated from left-to-right.  */
int flag_evaluation_order = 0;

/* The user symbol prefix after having resolved same.  */
const char *user_label_prefix;

static const param_info lang_independent_params[] = {
#define DEFPARAM(ENUM, OPTION, HELP, DEFAULT, MIN, MAX) \
  { OPTION, DEFAULT, MIN, MAX, HELP },
#include "params.def"
#undef DEFPARAM
  { NULL, 0, 0, 0, NULL }
};

/* Output files for assembler code (real compiler output)
   and debugging dumps.  */

FILE *asm_out_file;
FILE *aux_info_file;
FILE *dump_file = NULL;
const char *dump_file_name;

/* The current working directory of a translation.  It's generally the
   directory from which compilation was initiated, but a preprocessed
   file may specify the original directory in which it was
   created.  */

static const char *src_pwd;

/* Initialize src_pwd with the given string, and return true.  If it
   was already initialized, return false.  As a special case, it may
   be called with a NULL argument to test whether src_pwd has NOT been
   initialized yet.  */

bool
set_src_pwd (const char *pwd)
{
  if (src_pwd)
    {
      if (strcmp (src_pwd, pwd) == 0)
        return true;
      else
        return false;
    }

  src_pwd = xstrdup (pwd);
  return true;
}

/* Return the directory from which the translation unit was initiated,
   in case set_src_pwd() was not called before to assign it a
   different value.  */

const char *
get_src_pwd (void)
{
  if (! src_pwd)
    {
      src_pwd = getpwd ();
      if (!src_pwd)
        src_pwd = ".";
    }

   return src_pwd;
}

/* Called when the start of a function definition is parsed,
   this function prints on stderr the name of the function.  */
void
announce_function (tree decl)
{
  if (!quiet_flag)
    {
      if (rtl_dump_and_exit)
        fprintf (stderr, "%s ", IDENTIFIER_POINTER (DECL_NAME (decl)));
      else
        fprintf (stderr, " %s", lang_hooks.decl_printable_name (decl, 2));
      fflush (stderr);
      pp_needs_newline (global_dc->printer) = true;
      diagnostic_set_last_function (global_dc);
    }
}

/* Set up a default flag_random_seed and local_tick, unless the user
   already specified one.  */

static void
randomize (void)
{
  if (!flag_random_seed)
    {
      unsigned HOST_WIDE_INT value;
      static char random_seed[HOST_BITS_PER_WIDE_INT / 4 + 3];

      /* Get some more or less random data.  */
#ifdef HAVE_GETTIMEOFDAY
      {
        struct timeval tv;

        gettimeofday (&tv, NULL);
        local_tick = tv.tv_sec * 1000 + tv.tv_usec / 1000;
      }
#else
      {
        time_t now = time (NULL);

        if (now != (time_t)-1)
          local_tick = (unsigned) now;
      }
#endif
      value = local_tick ^ getpid ();

      sprintf (random_seed, HOST_WIDE_INT_PRINT_HEX, value);
      flag_random_seed = random_seed;
    }
  else if (!local_tick)
    local_tick = -1;
}


/* Decode the string P as an integral parameter.
   If the string is indeed an integer return its numeric value else
   issue an Invalid Option error for the option PNAME and return DEFVAL.
   If PNAME is zero just return DEFVAL, do not call error.  */

int
read_integral_parameter (const char *p, const char *pname, const int  defval)
{
  const char *endp = p;

  while (*endp)
    {
      if (ISDIGIT (*endp))
        endp++;
      else
        break;
    }

  if (*endp != 0)
    {
      if (pname != 0)
        error ("invalid option argument %qs", pname);
      return defval;
    }

  return atoi (p);
}

/* When compiling with a recent enough GCC, we use the GNU C "extern inline"
   for floor_log2 and exact_log2; see toplev.h.  That construct, however,
   conflicts with the ISO C++ One Definition Rule.   */

#if GCC_VERSION < 3004 || !defined (__cplusplus)

/* Given X, an unsigned number, return the largest int Y such that 2**Y <= X.
   If X is 0, return -1.  */

int
floor_log2 (unsigned HOST_WIDE_INT x)
{
  int t = 0;

  if (x == 0)
    return -1;

#ifdef CLZ_HWI
  t = HOST_BITS_PER_WIDE_INT - 1 - (int) CLZ_HWI (x);
#else
  if (HOST_BITS_PER_WIDE_INT > 64)
    if (x >= (unsigned HOST_WIDE_INT) 1 << (t + 64))
      t += 64;
  if (HOST_BITS_PER_WIDE_INT > 32)
    if (x >= ((unsigned HOST_WIDE_INT) 1) << (t + 32))
      t += 32;
  if (x >= ((unsigned HOST_WIDE_INT) 1) << (t + 16))
    t += 16;
  if (x >= ((unsigned HOST_WIDE_INT) 1) << (t + 8))
    t += 8;
  if (x >= ((unsigned HOST_WIDE_INT) 1) << (t + 4))
    t += 4;
  if (x >= ((unsigned HOST_WIDE_INT) 1) << (t + 2))
    t += 2;
  if (x >= ((unsigned HOST_WIDE_INT) 1) << (t + 1))
    t += 1;
#endif

  return t;
}

/* Return the logarithm of X, base 2, considering X unsigned,
   if X is a power of 2.  Otherwise, returns -1.  */

int
exact_log2 (unsigned HOST_WIDE_INT x)
{
  if (x != (x & -x))
    return -1;
#ifdef CTZ_HWI
  return x ? CTZ_HWI (x) : -1;
#else
  return floor_log2 (x);
#endif
}

#endif /*  GCC_VERSION < 3004 || !defined (__cplusplus)  */

/* Handler for fatal signals, such as SIGSEGV.  These are transformed
   into ICE messages, which is much more user friendly.  In case the
   error printer crashes, reset the signal to prevent infinite recursion.  */

static void
crash_signal (int signo)
{
  signal (signo, SIG_DFL);

  /* If we crashed while processing an ASM statement, then be a little more
     graceful.  It's most likely the user's fault.  */
  if (this_is_asm_operands)
    {
      output_operand_lossage ("unrecoverable error");
      exit (FATAL_EXIT_CODE);
    }

  internal_error ("%s", strsignal (signo));
}

/* Arrange to dump core on error.  (The regular error message is still
   printed first, except in the case of abort().)  */

static void
setup_core_dumping (void)
{
#ifdef SIGABRT
  signal (SIGABRT, SIG_DFL);
#endif
#if defined(HAVE_SETRLIMIT)
  {
    struct rlimit rlim;
    if (getrlimit (RLIMIT_CORE, &rlim) != 0)
      fatal_error ("getting core file size maximum limit: %m");
    rlim.rlim_cur = rlim.rlim_max;
    if (setrlimit (RLIMIT_CORE, &rlim) != 0)
      fatal_error ("setting core file size limit to maximum: %m");
  }
#endif
  diagnostic_abort_on_error (global_dc);
}


/* Strip off a legitimate source ending from the input string NAME of
   length LEN.  Rather than having to know the names used by all of
   our front ends, we strip off an ending of a period followed by
   up to five characters.  (Java uses ".class".)  */

void
strip_off_ending (char *name, int len)
{
  int i;
  for (i = 2; i < 6 && len > i; i++)
    {
      if (name[len - i] == '.')
        {
          name[len - i] = '\0';
          break;
        }
    }
}

/* Output a quoted string.  */

void
output_quoted_string (FILE *asm_file, const char *string)
{
#ifdef OUTPUT_QUOTED_STRING
  OUTPUT_QUOTED_STRING (asm_file, string);
#else
  char c;

  putc ('\"', asm_file);
  while ((c = *string++) != 0)
    {
      if (ISPRINT (c))
        {
          if (c == '\"' || c == '\\')
            putc ('\\', asm_file);
          putc (c, asm_file);
        }
      else
        fprintf (asm_file, "\\%03o", (unsigned char) c);
    }
  putc ('\"', asm_file);
#endif
}

/* Output a file name in the form wanted by System V.  */

void
output_file_directive (FILE *asm_file, const char *input_name)
{
  int len;
  const char *na;

  if (input_name == NULL)
    input_name = "<stdin>";

  len = strlen (input_name);
  na = input_name + len;

  /* NA gets INPUT_NAME sans directory names.  */
  while (na > input_name)
    {
      if (IS_DIR_SEPARATOR (na[-1]))
        break;
      na--;
    }

#ifdef ASM_OUTPUT_SOURCE_FILENAME
  ASM_OUTPUT_SOURCE_FILENAME (asm_file, na);
#else
  fprintf (asm_file, "\t.file\t");
  output_quoted_string (asm_file, na);
  fputc ('\n', asm_file);
#endif
}

/* A subroutine of wrapup_global_declarations.  We've come to the end of
   the compilation unit.  All deferred variables should be undeferred,
   and all incomplete decls should be finalized.  */

void
wrapup_global_declaration_1 (tree decl)
{
  /* We're not deferring this any longer.  Assignment is conditional to
     avoid needlessly dirtying PCH pages.  */
  if (CODE_CONTAINS_STRUCT (TREE_CODE (decl), TS_DECL_WITH_VIS)
      && DECL_DEFER_OUTPUT (decl) != 0)
    DECL_DEFER_OUTPUT (decl) = 0;

  if (TREE_CODE (decl) == VAR_DECL && DECL_SIZE (decl) == 0)
    lang_hooks.finish_incomplete_decl (decl);
}

/* A subroutine of wrapup_global_declarations.  Decide whether or not DECL
   needs to be output.  Return true if it is output.  */

bool
wrapup_global_declaration_2 (tree decl)
{
  if (TREE_ASM_WRITTEN (decl) || DECL_EXTERNAL (decl))
    return false;

  /* Don't write out static consts, unless we still need them.

     We also keep static consts if not optimizing (for debugging),
     unless the user specified -fno-keep-static-consts.
     ??? They might be better written into the debug information.
     This is possible when using DWARF.

     A language processor that wants static constants to be always
     written out (even if it is not used) is responsible for
     calling rest_of_decl_compilation itself.  E.g. the C front-end
     calls rest_of_decl_compilation from finish_decl.
     One motivation for this is that is conventional in some
     environments to write things like:
     static const char rcsid[] = "... version string ...";
     intending to force the string to be in the executable.

     A language processor that would prefer to have unneeded
     static constants "optimized away" would just defer writing
     them out until here.  E.g. C++ does this, because static
     constants are often defined in header files.

     ??? A tempting alternative (for both C and C++) would be
     to force a constant to be written if and only if it is
     defined in a main file, as opposed to an include file.  */

  if (TREE_CODE (decl) == VAR_DECL && TREE_STATIC (decl))
    {
      struct cgraph_varpool_node *node;
      bool needed = true;
      node = cgraph_varpool_node (decl);

      if (node->finalized)
        needed = false;
      else if (node->alias)
        needed = false;
      else if (!cgraph_global_info_ready
               && (TREE_USED (decl)
                   || TREE_USED (DECL_ASSEMBLER_NAME (decl))))
        /* needed */;
      else if (node->needed)
        /* needed */;
      else if (DECL_COMDAT (decl))
        needed = false;
      else if (TREE_READONLY (decl) && !TREE_PUBLIC (decl)
               && (optimize || !flag_keep_static_consts
                   || DECL_ARTIFICIAL (decl)))
        needed = false;

      if (needed)
        {
          rest_of_decl_compilation (decl, 1, 1);
          return true;
        }
    }

  return false;
}

/* Do any final processing required for the declarations in VEC, of
   which there are LEN.  We write out inline functions and variables
   that have been deferred until this point, but which are required.
   Returns nonzero if anything was put out.  */

bool
wrapup_global_declarations (tree *vec, int len)
{
  bool reconsider, output_something = false;
  int i;

  for (i = 0; i < len; i++)
    wrapup_global_declaration_1 (vec[i]);

  /* Now emit any global variables or functions that we have been
     putting off.  We need to loop in case one of the things emitted
     here references another one which comes earlier in the list.  */
  do
    {
      reconsider = false;
      for (i = 0; i < len; i++)
        reconsider |= wrapup_global_declaration_2 (vec[i]);
      if (reconsider)
        output_something = true;
    }
  while (reconsider);

  return output_something;
}

/* A subroutine of check_global_declarations.  Issue appropriate warnings
   for the global declaration DECL.  */

void
check_global_declaration_1 (tree decl)
{
  /* Warn about any function declared static but not defined.  We don't
     warn about variables, because many programs have static variables
     that exist only to get some text into the object file.  */
  if (TREE_CODE (decl) == FUNCTION_DECL
      && DECL_INITIAL (decl) == 0
      && DECL_EXTERNAL (decl)
      && ! DECL_ARTIFICIAL (decl)
      && ! TREE_NO_WARNING (decl)
      && ! TREE_PUBLIC (decl)
      && (warn_unused_function
          || TREE_SYMBOL_REFERENCED (DECL_ASSEMBLER_NAME (decl))))
    {
      if (TREE_SYMBOL_REFERENCED (DECL_ASSEMBLER_NAME (decl)))
        pedwarn ("%q+F used but never defined", decl);
      else
        warning (0, "%q+F declared %<static%> but never defined", decl);
      /* This symbol is effectively an "extern" declaration now.  */
      TREE_PUBLIC (decl) = 1;
      assemble_external (decl);
    }

  /* Warn about static fns or vars defined but not used.  */
  if (((warn_unused_function && TREE_CODE (decl) == FUNCTION_DECL)
       /* We don't warn about "static const" variables because the
          "rcs_id" idiom uses that construction.  */
       || (warn_unused_variable
           && TREE_CODE (decl) == VAR_DECL && ! TREE_READONLY (decl)))
      && ! DECL_IN_SYSTEM_HEADER (decl)
      && ! TREE_USED (decl)
      /* The TREE_USED bit for file-scope decls is kept in the identifier,
         to handle multiple external decls in different scopes.  */
      && ! (DECL_NAME (decl) && TREE_USED (DECL_NAME (decl)))
      && ! DECL_EXTERNAL (decl)
      && ! TREE_PUBLIC (decl)
      /* A volatile variable might be used in some non-obvious way.  */
      && ! TREE_THIS_VOLATILE (decl)
      /* Global register variables must be declared to reserve them.  */
      && ! (TREE_CODE (decl) == VAR_DECL && DECL_REGISTER (decl))
      /* Otherwise, ask the language.  */
      && lang_hooks.decls.warn_unused_global (decl))
    warning (0, "%q+D defined but not used", decl);
}

/* Issue appropriate warnings for the global declarations in VEC (of
   which there are LEN).  */

void
check_global_declarations (tree *vec, int len)
{
  int i;

  for (i = 0; i < len; i++)
    check_global_declaration_1 (vec[i]);
}

/* Emit debugging information for all global declarations in VEC.  */

void
emit_debug_global_declarations (tree *vec, int len)
{
  int i;

  /* Avoid confusing the debug information machinery when there are errors.  */
  if (errorcount != 0 || sorrycount != 0)
    return;

  timevar_push (TV_SYMOUT);
  for (i = 0; i < len; i++)
    debug_hooks->global_decl (vec[i]);
  timevar_pop (TV_SYMOUT);
}

/* Warn about a use of an identifier which was marked deprecated.  */
void
warn_deprecated_use (tree node)
{
  if (node == 0 || !warn_deprecated_decl)
    return;

  if (DECL_P (node))
    {
      expanded_location xloc = expand_location (DECL_SOURCE_LOCATION (node));
      warning (OPT_Wdeprecated_declarations,
               "%qs is deprecated (declared at %s:%d)",
               IDENTIFIER_POINTER (DECL_NAME (node)),
               xloc.file, xloc.line);
    }
  else if (TYPE_P (node))
    {
      const char *what = NULL;
      tree decl = TYPE_STUB_DECL (node);

      if (TYPE_NAME (node))
        {
          if (TREE_CODE (TYPE_NAME (node)) == IDENTIFIER_NODE)
            what = IDENTIFIER_POINTER (TYPE_NAME (node));
          else if (TREE_CODE (TYPE_NAME (node)) == TYPE_DECL
                   && DECL_NAME (TYPE_NAME (node)))
            what = IDENTIFIER_POINTER (DECL_NAME (TYPE_NAME (node)));
        }

      if (decl)
        {
          expanded_location xloc
            = expand_location (DECL_SOURCE_LOCATION (decl));
          if (what)
            warning (OPT_Wdeprecated_declarations,
                     "%qs is deprecated (declared at %s:%d)", what,
                     xloc.file, xloc.line);
          else
            warning (OPT_Wdeprecated_declarations,
                     "type is deprecated (declared at %s:%d)",
                     xloc.file, xloc.line);
        }
      else
        {
          if (what)
            warning (OPT_Wdeprecated_declarations, "%qs is deprecated", what);
          else
            warning (OPT_Wdeprecated_declarations, "type is deprecated");
        }
    }
}

/* Save the current INPUT_LOCATION on the top entry in the
   INPUT_FILE_STACK.  Push a new entry for FILE and LINE, and set the
   INPUT_LOCATION accordingly.  */

void
#ifdef USE_MAPPED_LOCATION
push_srcloc (location_t fline)
#else
push_srcloc (const char *file, int line)
#endif
{
  struct file_stack *fs;

  gcc_assert (!input_file_stack_restored);
  if (input_file_stack_tick == (int) ((1U << INPUT_FILE_STACK_BITS) - 1))
    sorry ("GCC supports only %d input file changes", input_file_stack_tick);

  fs = XNEW (struct file_stack);
  fs->location = input_location;
  fs->next = input_file_stack;
#ifdef USE_MAPPED_LOCATION
  input_location = fline;
#else
  input_filename = file;
  input_line = line;
#endif
  input_file_stack = fs;
  input_file_stack_tick++;
  VEC_safe_push (fs_p, heap, input_file_stack_history, input_file_stack);
}

/* Pop the top entry off the stack of presently open source files.
   Restore the INPUT_LOCATION from the new topmost entry on the
   stack.  */

void
pop_srcloc (void)
{
  struct file_stack *fs;

  gcc_assert (!input_file_stack_restored);
  if (input_file_stack_tick == (int) ((1U << INPUT_FILE_STACK_BITS) - 1))
    sorry ("GCC supports only %d input file changes", input_file_stack_tick);

  fs = input_file_stack;
  input_location = fs->location;
  input_file_stack = fs->next;
  input_file_stack_tick++;
  VEC_safe_push (fs_p, heap, input_file_stack_history, input_file_stack);
}

/* Restore the input file stack to its state as of TICK, for the sake
   of diagnostics after processing the whole input.  Once this has
   been called, push_srcloc and pop_srcloc may no longer be
   called.  */
void
restore_input_file_stack (int tick)
{
  if (tick == 0)
    input_file_stack = NULL;
  else
    input_file_stack = VEC_index (fs_p, input_file_stack_history, tick - 1);
  input_file_stack_tick = tick;
  input_file_stack_restored = true;
}

/* Compile an entire translation unit.  Write a file of assembly
   output and various debugging dumps.  */

static void
compile_file (void)
{
  /* Initialize yet another pass.  */

  init_cgraph ();
  init_final (main_input_filename);
  coverage_init (aux_base_name);

  timevar_push (TV_PARSE);

  /* Call the parser, which parses the entire file (calling
     rest_of_compilation for each function).  */
  lang_hooks.parse_file (set_yydebug);

  /* In case there were missing block closers,
     get us back to the global binding level.  */
  lang_hooks.clear_binding_stack ();

  /* Compilation is now finished except for writing
     what's left of the symbol table output.  */
  timevar_pop (TV_PARSE);

  if (flag_syntax_only || errorcount || sorrycount)
    return;

  lang_hooks.decls.final_write_globals ();
  cgraph_varpool_assemble_pending_decls ();
  finish_aliases_2 ();

  /* This must occur after the loop to output deferred functions.
     Else the coverage initializer would not be emitted if all the
     functions in this compilation unit were deferred.  */
  coverage_finish ();

  /* Likewise for mudflap static object registrations.  */
  if (flag_mudflap)
    mudflap_finish_file ();

  output_shared_constant_pool ();
  output_object_blocks ();

  /* Write out any pending weak symbol declarations.  */

  weak_finish ();

  /* Do dbx symbols.  */
  timevar_push (TV_SYMOUT);

#if defined DWARF2_DEBUGGING_INFO || defined DWARF2_UNWIND_INFO
  if (dwarf2out_do_frame ())
    dwarf2out_frame_finish ();
#endif

  (*debug_hooks->finish) (main_input_filename);
  timevar_pop (TV_SYMOUT);

  /* Output some stuff at end of file if nec.  */

  dw2_output_indirect_constants ();

  /* Flush any pending external directives.  cgraph did this for
     assemble_external calls from the front end, but the RTL
     expander can also generate them.  */
  process_pending_assemble_externals ();

  /* Attach a special .ident directive to the end of the file to identify
     the version of GCC which compiled this code.  The format of the .ident
     string is patterned after the ones produced by native SVR4 compilers.  */
#ifdef IDENT_ASM_OP
  if (!flag_no_ident)
    fprintf (asm_out_file, "%s\"GCC: (GNU) %s\"\n",
             IDENT_ASM_OP, version_string);
#endif

  /* This must be at the end.  Some target ports emit end of file directives
     into the assembly file here, and hence we can not output anything to the
     assembly file after this point.  */
  targetm.asm_out.file_end ();
}

/* Parse a -d... command line switch.  */

void
decode_d_option (const char *arg)
{
  int c;

  while (*arg)
    switch (c = *arg++)
      {
      case 'A':
        flag_debug_asm = 1;
        break;
      case 'p':
        flag_print_asm_name = 1;
        break;
      case 'P':
        flag_dump_rtl_in_asm = 1;
        flag_print_asm_name = 1;
        break;
      case 'v':
        graph_dump_format = vcg;
        break;
      case 'x':
        rtl_dump_and_exit = 1;
        break;
      case 'y':
        set_yydebug = 1;
        break;
      case 'D': /* These are handled by the preprocessor.  */
      case 'I':
        break;
      case 'H':
        setup_core_dumping();
        break;

      case 'a':
      default:
        if (!enable_rtl_dump_file (c))
          warning (0, "unrecognized gcc debugging option: %c", c);
        break;
      }
}

/* Indexed by enum debug_info_type.  */
const char *const debug_type_names[] =
{
  "none", "stabs", "coff", "dwarf-2", "xcoff", "vms"
};

/* Print version information to FILE.
   Each line begins with INDENT (for the case where FILE is the
   assembler output file).  */

void
print_version (FILE *file, const char *indent)
{
  static const char fmt1[] =
#ifdef __GNUC__
    N_("%s%s%s version %s (%s)\n%s\tcompiled by GNU C version %s.\n")
#else
    N_("%s%s%s version %s (%s) compiled by CC.\n")
#endif
    ;
  static const char fmt2[] =
    N_("%s%sGGC heuristics: --param ggc-min-expand=%d --param ggc-min-heapsize=%d\n");
#ifndef __VERSION__
#define __VERSION__ "[?]"
#endif
  fprintf (file,
           file == stderr ? _(fmt1) : fmt1,
           indent, *indent != 0 ? " " : "",
           lang_hooks.name, version_string, TARGET_NAME,
           indent, __VERSION__);
  fprintf (file,
           file == stderr ? _(fmt2) : fmt2,
           indent, *indent != 0 ? " " : "",
           PARAM_VALUE (GGC_MIN_EXPAND), PARAM_VALUE (GGC_MIN_HEAPSIZE));
}

/* Print an option value and return the adjusted position in the line.
   ??? We don't handle error returns from fprintf (disk full); presumably
   other code will catch a disk full though.  */

static int
print_single_switch (FILE *file, int pos, int max,
                     const char *indent, const char *sep, const char *term,
                     const char *type, const char *name)
{
  /* The ultrix fprintf returns 0 on success, so compute the result we want
     here since we need it for the following test.  */
  int len = strlen (sep) + strlen (type) + strlen (name);

  if (pos != 0
      && pos + len > max)
    {
      fprintf (file, "%s", term);
      pos = 0;
    }
  if (pos == 0)
    {
      fprintf (file, "%s", indent);
      pos = strlen (indent);
    }
  fprintf (file, "%s%s%s", sep, type, name);
  pos += len;
  return pos;
}

/* Print active target switches to FILE.
   POS is the current cursor position and MAX is the size of a "line".
   Each line begins with INDENT and ends with TERM.
   Each switch is separated from the next by SEP.  */

static void
print_switch_values (FILE *file, int pos, int max,
                     const char *indent, const char *sep, const char *term)
{
  size_t j;
  const char **p;

  /* Fill in the -frandom-seed option, if the user didn't pass it, so
     that it can be printed below.  This helps reproducibility.  */
  randomize ();

  /* Print the options as passed.  */
  pos = print_single_switch (file, pos, max, indent, *indent ? " " : "", term,
                             _("options passed: "), "");

  for (p = &save_argv[1]; *p != NULL; p++)
    if (**p == '-')
      {
        /* Ignore these.  */
        if (strcmp (*p, "-o") == 0)
          {
            if (p[1] != NULL)
              p++;
            continue;
          }
        if (strcmp (*p, "-quiet") == 0)
          continue;
        if (strcmp (*p, "-version") == 0)
          continue;
        if ((*p)[1] == 'd')
          continue;

        pos = print_single_switch (file, pos, max, indent, sep, term, *p, "");
      }
  if (pos > 0)
    fprintf (file, "%s", term);

  /* Print the -f and -m options that have been enabled.
     We don't handle language specific options but printing argv
     should suffice.  */

  pos = print_single_switch (file, 0, max, indent, *indent ? " " : "", term,
                             _("options enabled: "), "");

  for (j = 0; j < cl_options_count; j++)
    if ((cl_options[j].flags & CL_REPORT)
        && option_enabled (j) > 0)
      pos = print_single_switch (file, pos, max, indent, sep, term,
                                 "", cl_options[j].opt_text);

  fprintf (file, "%s", term);
}

/* Open assembly code output file.  Do this even if -fsyntax-only is
   on, because then the driver will have provided the name of a
   temporary file or bit bucket for us.  NAME is the file specified on
   the command line, possibly NULL.  */
static void
init_asm_output (const char *name)
{
  if (name == NULL && asm_file_name == 0)
    asm_out_file = stdout;
  else
    {
      if (asm_file_name == 0)
        {
          int len = strlen (dump_base_name);
          char *dumpname = XNEWVEC (char, len + 6);
          memcpy (dumpname, dump_base_name, len + 1);
          strip_off_ending (dumpname, len);
          strcat (dumpname, ".s");
          asm_file_name = dumpname;
        }
      if (!strcmp (asm_file_name, "-"))
        asm_out_file = stdout;
      else
        asm_out_file = fopen (asm_file_name, "w+b");
      if (asm_out_file == 0)
        fatal_error ("can%'t open %s for writing: %m", asm_file_name);
    }

  if (!flag_syntax_only)
    {
      targetm.asm_out.file_start ();

#ifdef ASM_COMMENT_START
      if (flag_verbose_asm)
        {
          /* Print the list of options in effect.  */
          print_version (asm_out_file, ASM_COMMENT_START);
          print_switch_values (asm_out_file, 0, MAX_LINE,
                               ASM_COMMENT_START, " ", "\n");
          /* Add a blank line here so it appears in assembler output but not
             screen output.  */
          fprintf (asm_out_file, "\n");
        }
#endif
    }
}

/* Return true if the state of option OPTION should be stored in PCH files
   and checked by default_pch_valid_p.  Store the option's current state
   in STATE if so.  */

static inline bool
option_affects_pch_p (int option, struct cl_option_state *state)
{
  if ((cl_options[option].flags & CL_TARGET) == 0)
    return false;
  if (cl_options[option].flag_var == &target_flags)
    if (targetm.check_pch_target_flags)
      return false;
  return get_option_state (option, state);
}

/* Default version of get_pch_validity.
   By default, every flag difference is fatal; that will be mostly right for
   most targets, but completely right for very few.  */

void *
default_get_pch_validity (size_t *len)
{
  struct cl_option_state state;
  size_t i;
  char *result, *r;

  *len = 2;
  if (targetm.check_pch_target_flags)
    *len += sizeof (target_flags);
  for (i = 0; i < cl_options_count; i++)
    if (option_affects_pch_p (i, &state))
      *len += state.size;

  result = r = XNEWVEC (char, *len);
  r[0] = flag_pic;
  r[1] = flag_pie;
  r += 2;
  if (targetm.check_pch_target_flags)
    {
      memcpy (r, &target_flags, sizeof (target_flags));
      r += sizeof (target_flags);
    }

  for (i = 0; i < cl_options_count; i++)
    if (option_affects_pch_p (i, &state))
      {
        memcpy (r, state.data, state.size);
        r += state.size;
      }

  return result;
}

/* Return a message which says that a PCH file was created with a different
   setting of OPTION.  */

static const char *
pch_option_mismatch (const char *option)
{
  char *r;

  asprintf (&r, _("created and used with differing settings of '%s'"), option);
  if (r == NULL)
    return _("out of memory");
  return r;
}

/* Default version of pch_valid_p.  */

const char *
default_pch_valid_p (const void *data_p, size_t len)
{
  struct cl_option_state state;
  const char *data = (const char *)data_p;
  size_t i;

  /* -fpic and -fpie also usually make a PCH invalid.  */
  if (data[0] != flag_pic)
    return _("created and used with different settings of -fpic");
  if (data[1] != flag_pie)
    return _("created and used with different settings of -fpie");
  data += 2;

  /* Check target_flags.  */
  if (targetm.check_pch_target_flags)
    {
      int tf;
      const char *r;

      memcpy (&tf, data, sizeof (target_flags));
      data += sizeof (target_flags);
      len -= sizeof (target_flags);
      r = targetm.check_pch_target_flags (tf);
      if (r != NULL)
        return r;
    }

  for (i = 0; i < cl_options_count; i++)
    if (option_affects_pch_p (i, &state))
      {
        if (memcmp (data, state.data, state.size) != 0)
          return pch_option_mismatch (cl_options[i].opt_text);
        data += state.size;
        len -= state.size;
      }

  return NULL;
}

/* Default tree printer.   Handles declarations only.  */
static bool
default_tree_printer (pretty_printer * pp, text_info *text, const char *spec,
                      int precision, bool wide, bool set_locus, bool hash)
{
  tree t;

  /* FUTURE: %+x should set the locus.  */
  if (precision != 0 || wide || hash)
    return false;

  switch (*spec)
    {
    case 'D':
      t = va_arg (*text->args_ptr, tree);
      if (DECL_DEBUG_EXPR_IS_FROM (t) && DECL_DEBUG_EXPR (t))
        t = DECL_DEBUG_EXPR (t);
      break;

    case 'F':
    case 'T':
      t = va_arg (*text->args_ptr, tree);
      break;

    default:
      return false;
    }

  if (set_locus && text->locus)
    *text->locus = DECL_SOURCE_LOCATION (t);

  if (DECL_P (t))
    {
      const char *n = DECL_NAME (t)
        ? lang_hooks.decl_printable_name (t, 2)
        : "<anonymous>";
      pp_string (pp, n);
    }
  else
    dump_generic_node (pp, t, 0, 0, 0);

  return true;
}

/* Initialization of the front end environment, before command line
   options are parsed.  Signal handlers, internationalization etc.
   ARGV0 is main's argv[0].  */
static void
general_init (const char *argv0)
{
  const char *p;

  p = argv0 + strlen (argv0);
  while (p != argv0 && !IS_DIR_SEPARATOR (p[-1]))
    --p;
  progname = p;

  xmalloc_set_program_name (progname);

  hex_init ();

  /* Unlock the stdio streams.  */
  unlock_std_streams ();

  gcc_init_libintl ();

  /* Initialize the diagnostics reporting machinery, so option parsing
     can give warnings and errors.  */
  diagnostic_initialize (global_dc);
  /* Set a default printer.  Language specific initializations will
     override it later.  */
  pp_format_decoder (global_dc->printer) = &default_tree_printer;

  /* Trap fatal signals, e.g. SIGSEGV, and convert them to ICE messages.  */
#ifdef SIGSEGV
  signal (SIGSEGV, crash_signal);
#endif
#ifdef SIGILL
  signal (SIGILL, crash_signal);
#endif
#ifdef SIGBUS
  signal (SIGBUS, crash_signal);
#endif
#ifdef SIGABRT
  signal (SIGABRT, crash_signal);
#endif
#if defined SIGIOT && (!defined SIGABRT || SIGABRT != SIGIOT)
  signal (SIGIOT, crash_signal);
#endif
#ifdef SIGFPE
  signal (SIGFPE, crash_signal);
#endif

  /* Other host-specific signal setup.  */
  (*host_hooks.extra_signals)();

  /* Initialize the garbage-collector, string pools and tree type hash
     table.  */
  init_ggc ();
  init_stringpool ();
  linemap_init (&line_table);
  init_ttree ();

  /* Initialize register usage now so switches may override.  */
  init_reg_sets ();

  /* Register the language-independent parameters.  */
  add_params (lang_independent_params, LAST_PARAM);

  /* This must be done after add_params but before argument processing.  */
  init_ggc_heuristics();
  init_optimization_passes ();
}

/* Return true if the current target supports -fsection-anchors.  */

static bool
target_supports_section_anchors_p (void)
{
  if (targetm.min_anchor_offset == 0 && targetm.max_anchor_offset == 0)
    return false;

  if (targetm.asm_out.output_anchor == NULL)
    return false;

  return true;
}

/* Process the options that have been parsed.  */
static void
process_options (void)
{
  /* Just in case lang_hooks.post_options ends up calling a debug_hook.
     This can happen with incorrect pre-processed input. */
  debug_hooks = &do_nothing_debug_hooks;

  /* Allow the front end to perform consistency checks and do further
     initialization based on the command line options.  This hook also
     sets the original filename if appropriate (e.g. foo.i -> foo.c)
     so we can correctly initialize debug output.  */
  no_backend = lang_hooks.post_options (&main_input_filename);
#ifndef USE_MAPPED_LOCATION
  input_filename = main_input_filename;
#endif

#ifdef OVERRIDE_OPTIONS
  /* Some machines may reject certain combinations of options.  */
  OVERRIDE_OPTIONS;
#endif

  if (flag_section_anchors && !target_supports_section_anchors_p ())
    {
      warning (OPT_fsection_anchors,
               "this target does not support %qs", "-fsection-anchors");
      flag_section_anchors = 0;
    }

  if (flag_short_enums == 2)
    flag_short_enums = targetm.default_short_enums ();

  /* Set aux_base_name if not already set.  */
  if (aux_base_name)
    ;
  else if (main_input_filename)
    {
      char *name = xstrdup (lbasename (main_input_filename));

      strip_off_ending (name, strlen (name));
      aux_base_name = name;
    }
  else
    aux_base_name = "gccaux";

  /* Set up the align_*_log variables, defaulting them to 1 if they
     were still unset.  */
  if (align_loops <= 0) align_loops = 1;
  if (align_loops_max_skip > align_loops || !align_loops)
    align_loops_max_skip = align_loops - 1;
  align_loops_log = floor_log2 (align_loops * 2 - 1);
  if (align_jumps <= 0) align_jumps = 1;
  if (align_jumps_max_skip > align_jumps || !align_jumps)
    align_jumps_max_skip = align_jumps - 1;
  align_jumps_log = floor_log2 (align_jumps * 2 - 1);
  if (align_labels <= 0) align_labels = 1;
  align_labels_log = floor_log2 (align_labels * 2 - 1);
  if (align_labels_max_skip > align_labels || !align_labels)
    align_labels_max_skip = align_labels - 1;
  if (align_functions <= 0) align_functions = 1;
  align_functions_log = floor_log2 (align_functions * 2 - 1);

  /* Unrolling all loops implies that standard loop unrolling must also
     be done.  */
  if (flag_unroll_all_loops)
    flag_unroll_loops = 1;

  /* The loop unrolling code assumes that cse will be run after loop.
     web and rename-registers also help when run after loop unrolling.  */

  if (flag_rerun_cse_after_loop == AUTODETECT_VALUE)
    flag_rerun_cse_after_loop = flag_unroll_loops || flag_peel_loops;
  if (flag_web == AUTODETECT_VALUE)
    flag_web = flag_unroll_loops || flag_peel_loops;
  if (flag_rename_registers == AUTODETECT_VALUE)
    flag_rename_registers = flag_unroll_loops || flag_peel_loops;

  if (flag_non_call_exceptions)
    flag_asynchronous_unwind_tables = 1;
  if (flag_asynchronous_unwind_tables)
    flag_unwind_tables = 1;

  /* Disable unit-at-a-time mode for frontends not supporting callgraph
     interface.  */
  if (flag_unit_at_a_time && ! lang_hooks.callgraph.expand_function)
    flag_unit_at_a_time = 0;

  if (!flag_unit_at_a_time)
    flag_section_anchors = 0;

  if (flag_value_profile_transformations)
    flag_profile_values = 1;

  /* Warn about options that are not supported on this machine.  */
#ifndef INSN_SCHEDULING
  if (flag_schedule_insns || flag_schedule_insns_after_reload)
    warning (0, "instruction scheduling not supported on this target machine");
#endif
#ifndef DELAY_SLOTS
  if (flag_delayed_branch)
    warning (0, "this target machine does not have delayed branches");
#endif

  user_label_prefix = USER_LABEL_PREFIX;
  if (flag_leading_underscore != -1)
    {
      /* If the default prefix is more complicated than "" or "_",
         issue a warning and ignore this option.  */
      if (user_label_prefix[0] == 0 ||
          (user_label_prefix[0] == '_' && user_label_prefix[1] == 0))
        {
          user_label_prefix = flag_leading_underscore ? "_" : "";
        }
      else
        warning (0, "-f%sleading-underscore not supported on this target machine",
                 flag_leading_underscore ? "" : "no-");
    }

  /* If we are in verbose mode, write out the version and maybe all the
     option flags in use.  */
  if (version_flag)
    {
      print_version (stderr, "");
      if (! quiet_flag)
        print_switch_values (stderr, 0, MAX_LINE, "", " ", "\n");
    }

  if (flag_syntax_only)
    {
      write_symbols = NO_DEBUG;
      profile_flag = 0;
    }

  /* A lot of code assumes write_symbols == NO_DEBUG if the debugging
     level is 0.  */
  if (debug_info_level == DINFO_LEVEL_NONE)
    write_symbols = NO_DEBUG;

  /* Now we know write_symbols, set up the debug hooks based on it.
     By default we do nothing for debug output.  */
  if (PREFERRED_DEBUGGING_TYPE == NO_DEBUG)
    default_debug_hooks = &do_nothing_debug_hooks;
#if defined(DBX_DEBUGGING_INFO)
  else if (PREFERRED_DEBUGGING_TYPE == DBX_DEBUG)
    default_debug_hooks = &dbx_debug_hooks;
#endif
#if defined(XCOFF_DEBUGGING_INFO)
  else if (PREFERRED_DEBUGGING_TYPE == XCOFF_DEBUG)
    default_debug_hooks = &xcoff_debug_hooks;
#endif
#ifdef SDB_DEBUGGING_INFO
  else if (PREFERRED_DEBUGGING_TYPE == SDB_DEBUG)
    default_debug_hooks = &sdb_debug_hooks;
#endif
#ifdef DWARF2_DEBUGGING_INFO
  else if (PREFERRED_DEBUGGING_TYPE == DWARF2_DEBUG)
    default_debug_hooks = &dwarf2_debug_hooks;
#endif
#ifdef VMS_DEBUGGING_INFO
  else if (PREFERRED_DEBUGGING_TYPE == VMS_DEBUG
           || PREFERRED_DEBUGGING_TYPE == VMS_AND_DWARF2_DEBUG)
    default_debug_hooks = &vmsdbg_debug_hooks;
#endif

  if (write_symbols == NO_DEBUG)
    ;
#if defined(DBX_DEBUGGING_INFO)
  else if (write_symbols == DBX_DEBUG)
    debug_hooks = &dbx_debug_hooks;
#endif
#if defined(XCOFF_DEBUGGING_INFO)
  else if (write_symbols == XCOFF_DEBUG)
    debug_hooks = &xcoff_debug_hooks;
#endif
#ifdef SDB_DEBUGGING_INFO
  else if (write_symbols == SDB_DEBUG)
    debug_hooks = &sdb_debug_hooks;
#endif
#ifdef DWARF2_DEBUGGING_INFO
  else if (write_symbols == DWARF2_DEBUG)
    debug_hooks = &dwarf2_debug_hooks;
#endif
#ifdef VMS_DEBUGGING_INFO
  else if (write_symbols == VMS_DEBUG || write_symbols == VMS_AND_DWARF2_DEBUG)
    debug_hooks = &vmsdbg_debug_hooks;
#endif
  else
    error ("target system does not support the \"%s\" debug format",
           debug_type_names[write_symbols]);

  /* Now we know which debug output will be used so we can set
     flag_var_tracking, flag_rename_registers if the user has
     not specified them.  */
  if (debug_info_level < DINFO_LEVEL_NORMAL
      || debug_hooks->var_location == do_nothing_debug_hooks.var_location)
    {
      if (flag_var_tracking == 1)
        {
          if (debug_info_level < DINFO_LEVEL_NORMAL)
            warning (0, "variable tracking requested, but useless unless "
                     "producing debug info");
          else
            warning (0, "variable tracking requested, but not supported "
                     "by this debug format");
        }
      flag_var_tracking = 0;
    }

  if (flag_rename_registers == AUTODETECT_VALUE)
    flag_rename_registers = default_debug_hooks->var_location
                            != do_nothing_debug_hooks.var_location;

  if (flag_var_tracking == AUTODETECT_VALUE)
    flag_var_tracking = optimize >= 1;

  /* If auxiliary info generation is desired, open the output file.
     This goes in the same directory as the source file--unlike
     all the other output files.  */
  if (flag_gen_aux_info)
    {
      aux_info_file = fopen (aux_info_file_name, "w");
      if (aux_info_file == 0)
        fatal_error ("can%'t open %s: %m", aux_info_file_name);
    }

  if (! targetm.have_named_sections)
    {
      if (flag_function_sections)
        {
          warning (0, "-ffunction-sections not supported for this target");
          flag_function_sections = 0;
        }
      if (flag_data_sections)
        {
          warning (0, "-fdata-sections not supported for this target");
          flag_data_sections = 0;
        }
    }

  if (flag_function_sections && profile_flag)
    {
      warning (0, "-ffunction-sections disabled; it makes profiling impossible");
      flag_function_sections = 0;
    }

#ifndef HAVE_prefetch
  if (flag_prefetch_loop_arrays)
    {
      warning (0, "-fprefetch-loop-arrays not supported for this target");
      flag_prefetch_loop_arrays = 0;
    }
#else
  if (flag_prefetch_loop_arrays && !HAVE_prefetch)
    {
      warning (0, "-fprefetch-loop-arrays not supported for this target (try -march switches)");
      flag_prefetch_loop_arrays = 0;
    }
#endif

  /* This combination of options isn't handled for i386 targets and doesn't
     make much sense anyway, so don't allow it.  */
  if (flag_prefetch_loop_arrays && optimize_size)
    {
      warning (0, "-fprefetch-loop-arrays is not supported with -Os");
      flag_prefetch_loop_arrays = 0;
    }

#ifndef OBJECT_FORMAT_ELF
#ifndef OBJECT_FORMAT_MACHO
  if (flag_function_sections && write_symbols != NO_DEBUG)
    warning (0, "-ffunction-sections may affect debugging on some targets");
#endif
#endif

  /* The presence of IEEE signaling NaNs, implies all math can trap.  */
  if (flag_signaling_nans)
    flag_trapping_math = 1;

  /* With -fcx-limited-range, we do cheap and quick complex arithmetic.  */
  if (flag_cx_limited_range)
    flag_complex_method = 0;

  /* Targets must be able to place spill slots at lower addresses.  If the
     target already uses a soft frame pointer, the transition is trivial.  */
  if (!FRAME_GROWS_DOWNWARD && flag_stack_protect)
    {
      warning (0, "-fstack-protector not supported for this target");
      flag_stack_protect = 0;
    }
  if (!flag_stack_protect)
    warn_stack_protect = 0;

  /* ??? Unwind info is not correct around the CFG unless either a frame
     pointer is present or A_O_A is set.  Fixing this requires rewriting
     unwind info generation to be aware of the CFG and propagating states
     around edges.  */
  if (flag_unwind_tables && !ACCUMULATE_OUTGOING_ARGS
      && flag_omit_frame_pointer)
    {
      warning (0, "unwind tables currently requires a frame pointer "
               "for correctness");
      flag_omit_frame_pointer = 0;
    }
}

/* Initialize the compiler back end.  */
static void
backend_init (void)
{
  init_emit_once (debug_info_level == DINFO_LEVEL_NORMAL
                  || debug_info_level == DINFO_LEVEL_VERBOSE
#ifdef VMS_DEBUGGING_INFO
                    /* Enable line number info for traceback.  */
                    || debug_info_level > DINFO_LEVEL_NONE
#endif
                    || flag_test_coverage);

  init_rtlanal ();
  init_regs ();
  init_fake_stack_mems ();
  init_alias_once ();
  init_reload ();
  init_varasm_once ();

  /* The following initialization functions need to generate rtl, so
     provide a dummy function context for them.  */
  init_dummy_function_start ();
  init_expmed ();
  if (flag_caller_saves)
    init_caller_save ();
  expand_dummy_function_end ();
}

/* Language-dependent initialization.  Returns nonzero on success.  */
static int
lang_dependent_init (const char *name)
{
  location_t save_loc = input_location;
  if (dump_base_name == 0)
    dump_base_name = name && name[0] ? name : "gccdump";

  /* Other front-end initialization.  */
#ifdef USE_MAPPED_LOCATION
  input_location = BUILTINS_LOCATION;
#else
  input_filename = "<built-in>";
  input_line = 0;
#endif
  if (lang_hooks.init () == 0)
    return 0;
  input_location = save_loc;

  init_asm_output (name);

  /* These create various _DECL nodes, so need to be called after the
     front end is initialized.  */
  init_eh ();
  init_optabs ();

  /* The following initialization functions need to generate rtl, so
     provide a dummy function context for them.  */
  init_dummy_function_start ();
  init_expr_once ();
  expand_dummy_function_end ();

  /* If dbx symbol table desired, initialize writing it and output the
     predefined types.  */
  timevar_push (TV_SYMOUT);

#if defined DWARF2_DEBUGGING_INFO || defined DWARF2_UNWIND_INFO
  if (dwarf2out_do_frame ())
    dwarf2out_frame_init ();
#endif

  /* Now we have the correct original filename, we can initialize
     debug output.  */
  (*debug_hooks->init) (name);

  timevar_pop (TV_SYMOUT);

  return 1;
}

/* Clean up: close opened files, etc.  */

static void
finalize (void)
{
  /* Close the dump files.  */
  if (flag_gen_aux_info)
    {
      fclose (aux_info_file);
      if (errorcount)
        unlink (aux_info_file_name);
    }

  /* Close non-debugging input and output files.  Take special care to note
     whether fclose returns an error, since the pages might still be on the
     buffer chain while the file is open.  */

  if (asm_out_file)
    {
      if (ferror (asm_out_file) != 0)
        fatal_error ("error writing to %s: %m", asm_file_name);
      if (fclose (asm_out_file) != 0)
        fatal_error ("error closing %s: %m", asm_file_name);
    }

  finish_optimization_passes ();

  if (mem_report)
    {
      ggc_print_statistics ();
      stringpool_statistics ();
      dump_tree_statistics ();
      dump_rtx_statistics ();
      dump_varray_statistics ();
      dump_alloc_pool_statistics ();
      dump_ggc_loc_statistics ();
    }

  /* Free up memory for the benefit of leak detectors.  */
  free_reg_info ();

  /* Language-specific end of compilation actions.  */
  lang_hooks.finish ();
}

/* Initialize the compiler, and compile the input file.  */
static void
do_compile (void)
{
  /* Initialize timing first.  The C front ends read the main file in
     the post_options hook, and C++ does file timings.  */
  if (time_report || !quiet_flag  || flag_detailed_statistics)
    timevar_init ();
  timevar_start (TV_TOTAL);

  process_options ();

  /* Don't do any more if an error has already occurred.  */
  if (!errorcount)
    {
      /* This must be run always, because it is needed to compute the FP
         predefined macros, such as __LDBL_MAX__, for targets using non
         default FP formats.  */
      init_adjust_machine_modes ();

      /* Set up the back-end if requested.  */
      if (!no_backend)
        backend_init ();

      /* Language-dependent initialization.  Returns true on success.  */
      if (lang_dependent_init (main_input_filename))
        compile_file ();

      finalize ();
    }

  /* Stop timing and print the times.  */
  timevar_stop (TV_TOTAL);
  timevar_print (stderr);
}

/* Entry point of cc1, cc1plus, jc1, f771, etc.
   Exit code is FATAL_EXIT_CODE if can't open files or if there were
   any errors, or SUCCESS_EXIT_CODE if compilation succeeded.

   It is not safe to call this function more than once.  */

int
toplev_main (unsigned int argc, const char **argv)
{
  save_argv = argv;

  /* Initialization of GCC's environment, and diagnostics.  */
  general_init (argv[0]);

  /* Parse the options and do minimal processing; basically just
     enough to default flags appropriately.  */
  decode_options (argc, argv);

  randomize ();

  /* Exit early if we can (e.g. -help).  */
  if (!exit_after_options)
    do_compile ();

  if (errorcount || sorrycount)
    return (FATAL_EXIT_CODE);

  return (SUCCESS_EXIT_CODE);
}