Daily bump.

[official-gcc.git] / gcc / gimple-ssa-sprintf.c

/* Copyright (C) 2016-2017 Free Software Foundation, Inc.
   Contributed by Martin Sebor <msebor@redhat.com>.

This file is part of GCC.

GCC is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free
Software Foundation; either version 3, or (at your option) any later
version.

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

You should have received a copy of the GNU General Public License
along with GCC; see the file COPYING3.  If not see
<http://www.gnu.org/licenses/>.  */

/* This file implements the printf-return-value pass.  The pass does
   two things: 1) it analyzes calls to formatted output functions like
   sprintf looking for possible buffer overflows and calls to bounded
   functions like snprintf for early truncation (and under the control
   of the -Wformat-length option issues warnings), and 2) under the
   control of the -fprintf-return-value option it folds the return
   value of safe calls into constants, making it possible to eliminate
   code that depends on the value of those constants.

   For all functions (bounded or not) the pass uses the size of the
   destination object.  That means that it will diagnose calls to
   snprintf not on the basis of the size specified by the function's
   second argument but rathger on the basis of the size the first
   argument points to (if possible).  For bound-checking built-ins
   like __builtin___snprintf_chk the pass uses the size typically
   determined by __builtin_object_size and passed to the built-in
   by the Glibc inline wrapper.

   The pass handles all forms standard sprintf format directives,
   including character, integer, floating point, pointer, and strings,
   with the standard C flags, widths, and precisions.  For integers
   and strings it computes the length of output itself.  For floating
   point it uses MPFR to fornmat known constants with up and down
   rounding and uses the resulting range of output lengths.  For
   strings it uses the length of string literals and the sizes of
   character arrays that a character pointer may point to as a bound
   on the longest string.  */

#include "config.h"
#include "system.h"
#include "coretypes.h"
#include "backend.h"
#include "tree.h"
#include "gimple.h"
#include "tree-pass.h"
#include "ssa.h"
#include "gimple-fold.h"
#include "gimple-pretty-print.h"
#include "diagnostic-core.h"
#include "fold-const.h"
#include "gimple-iterator.h"
#include "tree-ssa.h"
#include "tree-object-size.h"
#include "params.h"
#include "tree-cfg.h"
#include "tree-ssa-propagate.h"
#include "calls.h"
#include "cfgloop.h"
#include "intl.h"

#include "builtins.h"
#include "stor-layout.h"

#include "realmpfr.h"
#include "target.h"

#include "cpplib.h"
#include "input.h"
#include "toplev.h"
#include "substring-locations.h"
#include "diagnostic.h"

/* The likely worst case value of MB_LEN_MAX for the target, large enough
   for UTF-8.  Ideally, this would be obtained by a target hook if it were
   to be used for optimization but it's good enough as is for warnings.  */
#define target_mb_len_max()   6

/* The maximum number of bytes a single non-string directive can result
   in.  This is the result of printf("%.*Lf", INT_MAX, -LDBL_MAX) for
   LDBL_MAX_10_EXP of 4932.  */
#define IEEE_MAX_10_EXP    4932
#define target_dir_max()   (target_int_max () + IEEE_MAX_10_EXP + 2)

namespace {

const pass_data pass_data_sprintf_length = {
  GIMPLE_PASS,             // pass type
  "printf-return-value",   // pass name
  OPTGROUP_NONE,           // optinfo_flags
  TV_NONE,                 // tv_id
  PROP_cfg,                // properties_required
  0,                       // properties_provided
  0,                       // properties_destroyed
  0,                       // properties_start
  0,                       // properties_finish
};

/* Set to the warning level for the current function which is equal
   either to warn_format_trunc for bounded functions or to
   warn_format_overflow otherwise.  */

static int warn_level;

struct format_result;

class pass_sprintf_length : public gimple_opt_pass
{
  bool fold_return_value;

public:
  pass_sprintf_length (gcc::context *ctxt)
    : gimple_opt_pass (pass_data_sprintf_length, ctxt),
    fold_return_value (false)
  { }

  opt_pass * clone () { return new pass_sprintf_length (m_ctxt); }

  virtual bool gate (function *);

  virtual unsigned int execute (function *);

  void set_pass_param (unsigned int n, bool param)
    {
      gcc_assert (n == 0);
      fold_return_value = param;
    }

  bool handle_gimple_call (gimple_stmt_iterator *);

  struct call_info;
  bool compute_format_length (call_info &, format_result *);
};

bool
pass_sprintf_length::gate (function *)
{
  /* Run the pass iff -Warn-format-overflow or -Warn-format-truncation
     is specified and either not optimizing and the pass is being invoked
     early, or when optimizing and the pass is being invoked during
     optimization (i.e., "late").  */
  return ((warn_format_overflow > 0
           || warn_format_trunc > 0
           || flag_printf_return_value)
          && (optimize > 0) == fold_return_value);
}

/* The minimum, maximum, likely, and unlikely maximum number of bytes
   of output either a formatting function or an individual directive
   can result in.  */

struct result_range
{
  /* The absolute minimum number of bytes.  The result of a successful
     conversion is guaranteed to be no less than this.  (An erroneous
     conversion can be indicated by MIN > HOST_WIDE_INT_MAX.)  */
  unsigned HOST_WIDE_INT min;
  /* The likely maximum result that is used in diagnostics.  In most
     cases MAX is the same as the worst case UNLIKELY result.  */
  unsigned HOST_WIDE_INT max;
  /* The likely result used to trigger diagnostics.  For conversions
     that result in a range of bytes [MIN, MAX], LIKELY is somewhere
     in that range.  */
  unsigned HOST_WIDE_INT likely;
  /* In rare cases (e.g., for nultibyte characters) UNLIKELY gives
     the worst cases maximum result of a directive.  In most cases
     UNLIKELY == MAX.  UNLIKELY is used to control the return value
     optimization but not in diagnostics.  */
  unsigned HOST_WIDE_INT unlikely;
};

/* The result of a call to a formatted function.  */

struct format_result
{
  /* Range of characters written by the formatted function.
     Setting the minimum to HOST_WIDE_INT_MAX disables all
     length tracking for the remainder of the format string.  */
  result_range range;

  /* True when the range above is obtained from known values of
     directive arguments, or bounds on the amount of output such
     as width and precision, and not the result of  heuristics that
     depend on warning levels.  It's used to issue stricter diagnostics
     in cases where strings of unknown lengths are bounded by the arrays
     they are determined to refer to.  KNOWNRANGE must not be used for
     the return value optimization.  */
  bool knownrange;

  /* True if no individual directive resulted in more than 4095 bytes
     of output (the total NUMBER_CHARS_{MIN,MAX} might be greater).
     Implementations are not required to handle directives that produce
     more than 4K bytes (leading to undefined behavior) and so when one
     is found it disables the return value optimization.  */
  bool under4k;

  /* True when a floating point directive has been seen in the format
     string.  */
  bool floating;

  /* True when an intermediate result has caused a warning.  Used to
     avoid issuing duplicate warnings while finishing the processing
     of a call.  WARNED also disables the return value optimization.  */
  bool warned;

  /* Preincrement the number of output characters by 1.  */
  format_result& operator++ ()
  {
    return *this += 1;
  }

  /* Postincrement the number of output characters by 1.  */
  format_result operator++ (int)
  {
    format_result prev (*this);
    *this += 1;
    return prev;
  }

  /* Increment the number of output characters by N.  */
  format_result& operator+= (unsigned HOST_WIDE_INT);
};

format_result&
format_result::operator+= (unsigned HOST_WIDE_INT n)
{
  gcc_assert (n < HOST_WIDE_INT_MAX);

  if (range.min < HOST_WIDE_INT_MAX)
    range.min += n;

  if (range.max < HOST_WIDE_INT_MAX)
    range.max += n;

  if (range.likely < HOST_WIDE_INT_MAX)
    range.likely += n;

  if (range.unlikely < HOST_WIDE_INT_MAX)
    range.unlikely += n;

  return *this;
}

/* Return the value of INT_MIN for the target.  */

static inline HOST_WIDE_INT
target_int_min ()
{
  return tree_to_shwi (TYPE_MIN_VALUE (integer_type_node));
}

/* Return the value of INT_MAX for the target.  */

static inline unsigned HOST_WIDE_INT
target_int_max ()
{
  return tree_to_uhwi (TYPE_MAX_VALUE (integer_type_node));
}

/* Return the value of SIZE_MAX for the target.  */

static inline unsigned HOST_WIDE_INT
target_size_max ()
{
  return tree_to_uhwi (TYPE_MAX_VALUE (size_type_node));
}

/* Return the constant initial value of DECL if available or DECL
   otherwise.  Same as the synonymous function in c/c-typeck.c.  */

static tree
decl_constant_value (tree decl)
{
  if (/* Don't change a variable array bound or initial value to a constant
         in a place where a variable is invalid.  Note that DECL_INITIAL
         isn't valid for a PARM_DECL.  */
      current_function_decl != 0
      && TREE_CODE (decl) != PARM_DECL
      && !TREE_THIS_VOLATILE (decl)
      && TREE_READONLY (decl)
      && DECL_INITIAL (decl) != 0
      && TREE_CODE (DECL_INITIAL (decl)) != ERROR_MARK
      /* This is invalid if initial value is not constant.
         If it has either a function call, a memory reference,
         or a variable, then re-evaluating it could give different results.  */
      && TREE_CONSTANT (DECL_INITIAL (decl))
      /* Check for cases where this is sub-optimal, even though valid.  */
      && TREE_CODE (DECL_INITIAL (decl)) != CONSTRUCTOR)
    return DECL_INITIAL (decl);
  return decl;
}

/* Given FORMAT, set *PLOC to the source location of the format string
   and return the format string if it is known or null otherwise.  */

static const char*
get_format_string (tree format, location_t *ploc)
{
  if (VAR_P (format))
    {
      /* Pull out a constant value if the front end didn't.  */
      format = decl_constant_value (format);
      STRIP_NOPS (format);
    }

  if (integer_zerop (format))
    {
      /* FIXME: Diagnose null format string if it hasn't been diagnosed
         by -Wformat (the latter diagnoses only nul pointer constants,
         this pass can do better).  */
      return NULL;
    }

  HOST_WIDE_INT offset = 0;

  if (TREE_CODE (format) == POINTER_PLUS_EXPR)
    {
      tree arg0 = TREE_OPERAND (format, 0);
      tree arg1 = TREE_OPERAND (format, 1);
      STRIP_NOPS (arg0);
      STRIP_NOPS (arg1);

      if (TREE_CODE (arg1) != INTEGER_CST)
        return NULL;

      format = arg0;

      /* POINTER_PLUS_EXPR offsets are to be interpreted signed.  */
      if (!cst_and_fits_in_hwi (arg1))
        return NULL;

      offset = int_cst_value (arg1);
    }

  if (TREE_CODE (format) != ADDR_EXPR)
    return NULL;

  *ploc = EXPR_LOC_OR_LOC (format, input_location);

  format = TREE_OPERAND (format, 0);

  if (TREE_CODE (format) == ARRAY_REF
      && tree_fits_shwi_p (TREE_OPERAND (format, 1))
      && (offset += tree_to_shwi (TREE_OPERAND (format, 1))) >= 0)
    format = TREE_OPERAND (format, 0);

  if (offset < 0)
    return NULL;

  tree array_init;
  tree array_size = NULL_TREE;

  if (VAR_P (format)
      && TREE_CODE (TREE_TYPE (format)) == ARRAY_TYPE
      && (array_init = decl_constant_value (format)) != format
      && TREE_CODE (array_init) == STRING_CST)
    {
      /* Extract the string constant initializer.  Note that this may
         include a trailing NUL character that is not in the array (e.g.
         const char a[3] = "foo";).  */
      array_size = DECL_SIZE_UNIT (format);
      format = array_init;
    }

  if (TREE_CODE (format) != STRING_CST)
    return NULL;

  if (TYPE_MAIN_VARIANT (TREE_TYPE (TREE_TYPE (format))) != char_type_node)
    {
      /* Wide format string.  */
      return NULL;
    }

  const char *fmtstr = TREE_STRING_POINTER (format);
  unsigned fmtlen = TREE_STRING_LENGTH (format);

  if (array_size)
    {
      /* Variable length arrays can't be initialized.  */
      gcc_assert (TREE_CODE (array_size) == INTEGER_CST);

      if (tree_fits_shwi_p (array_size))
        {
          HOST_WIDE_INT array_size_value = tree_to_shwi (array_size);
          if (array_size_value > 0
              && array_size_value == (int) array_size_value
              && fmtlen > array_size_value)
            fmtlen = array_size_value;
        }
    }
  if (offset)
    {
      if (offset >= fmtlen)
        return NULL;

      fmtstr += offset;
      fmtlen -= offset;
    }

  if (fmtlen < 1 || fmtstr[--fmtlen] != 0)
    {
      /* FIXME: Diagnose an unterminated format string if it hasn't been
         diagnosed by -Wformat.  Similarly to a null format pointer,
         -Wformay diagnoses only nul pointer constants, this pass can
         do better).  */
      return NULL;
    }

  return fmtstr;
}

/* The format_warning_at_substring function is not used here in a way
   that makes using attribute format viable.  Suppress the warning.  */

#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wsuggest-attribute=format"

/* For convenience and brevity.  */

static bool
  (* const fmtwarn) (const substring_loc &, const source_range *,
                     const char *, int, const char *, ...)
  = format_warning_at_substring;

/* Format length modifiers.  */

enum format_lengths
{
  FMT_LEN_none,
  FMT_LEN_hh,    // char argument
  FMT_LEN_h,     // short
  FMT_LEN_l,     // long
  FMT_LEN_ll,    // long long
  FMT_LEN_L,     // long double (and GNU long long)
  FMT_LEN_z,     // size_t
  FMT_LEN_t,     // ptrdiff_t
  FMT_LEN_j      // intmax_t
};


/* Description of the result of conversion either of a single directive
   or the whole format string.  */

struct fmtresult
{
  /* Construct a FMTRESULT object with all counters initialized
     to MIN.  KNOWNRANGE is set when MIN is valid.  */
  fmtresult (unsigned HOST_WIDE_INT min = HOST_WIDE_INT_MAX)
  : argmin (), argmax (),
    knownrange (min < HOST_WIDE_INT_MAX),
    nullp ()
  {
    range.min = min;
    range.max = min;
    range.likely = min;
    range.unlikely = min;
  }

  /* Construct a FMTRESULT object with MIN, MAX, and LIKELY counters.
     KNOWNRANGE is set when both MIN and MAX are valid.   */
  fmtresult (unsigned HOST_WIDE_INT min, unsigned HOST_WIDE_INT max,
             unsigned HOST_WIDE_INT likely = HOST_WIDE_INT_MAX)
  : argmin (), argmax (),
    knownrange (min < HOST_WIDE_INT_MAX && max < HOST_WIDE_INT_MAX),
    nullp ()
  {
    range.min = min;
    range.max = max;
    range.likely = max < likely ? min : likely;
    range.unlikely = max;
  }

  /* Adjust result upward to reflect the RANGE of values the specified
     width or precision is known to be in.  */
  fmtresult& adjust_for_width_or_precision (const HOST_WIDE_INT[2],
                                            tree = NULL_TREE,
                                            unsigned = 0, unsigned = 0);

  /* Return the maximum number of decimal digits a value of TYPE
     formats as on output.  */
  static unsigned type_max_digits (tree, int);

  /* The range a directive's argument is in.  */
  tree argmin, argmax;

  /* The minimum and maximum number of bytes that a directive
     results in on output for an argument in the range above.  */
  result_range range;

  /* True when the range above is obtained from a known value of
     a directive's argument or its bounds and not the result of
     heuristics that depend on warning levels.  */
  bool knownrange;

  /* True when the argument is a null pointer.  */
  bool nullp;
};

/* Adjust result upward to reflect the range ADJUST of values the
   specified width or precision is known to be in.  When non-null,
   TYPE denotes the type of the directive whose result is being
   adjusted, BASE gives the base of the directive (octal, decimal,
   or hex), and ADJ denotes the additional adjustment to the LIKELY
   counter that may need to be added when ADJUST is a range.  */

fmtresult&
fmtresult::adjust_for_width_or_precision (const HOST_WIDE_INT adjust[2],
                                          tree type /* = NULL_TREE */,
                                          unsigned base /* = 0 */,
                                          unsigned adj /* = 0 */)
{
  bool minadjusted = false;

  /* Adjust the minimum and likely counters.  */
  if (adjust[0] >= 0)
    {
      if (range.min < (unsigned HOST_WIDE_INT)adjust[0])
        {
          range.min = adjust[0];
          minadjusted = true;
        }

      /* Adjust the likely counter.  */
      if (range.likely < range.min)
        range.likely = range.min;
    }
  else if (adjust[0] == target_int_min ()
           && (unsigned HOST_WIDE_INT)adjust[1] == target_int_max ())
    knownrange = false;

  /* Adjust the maximum counter.  */
  if (adjust[1] > 0)
    {
      if (range.max < (unsigned HOST_WIDE_INT)adjust[1])
        {
          range.max = adjust[1];

          /* Set KNOWNRANGE if both the minimum and maximum have been
             adjusted.  Otherwise leave it at what it was before.  */
          knownrange = minadjusted;
        }
    }

  if (warn_level > 1 && type)
    {
      /* For large non-constant width or precision whose range spans
         the maximum number of digits produced by the directive for
         any argument, set the likely number of bytes to be at most
         the number digits plus other adjustment determined by the
         caller (one for sign or two for the hexadecimal "0x"
         prefix).  */
      unsigned dirdigs = type_max_digits (type, base);
      if (adjust[0] < dirdigs && dirdigs < adjust[1]
          && range.likely < dirdigs)
        range.likely = dirdigs + adj;
    }
  else if (range.likely < (range.min ? range.min : 1))
    {
      /* Conservatively, set LIKELY to at least MIN but no less than
         1 unless MAX is zero.  */
      range.likely = (range.min
                      ? range.min
                      : range.max && (range.max < HOST_WIDE_INT_MAX
                                      || warn_level > 1) ? 1 : 0);
    }

  /* Finally adjust the unlikely counter to be at least as large as
     the maximum.  */
  if (range.unlikely < range.max)
    range.unlikely = range.max;

  return *this;
}

/* Return the maximum number of digits a value of TYPE formats in
   BASE on output, not counting base prefix .  */

unsigned
fmtresult::type_max_digits (tree type, int base)
{
  unsigned prec = TYPE_PRECISION (type);
  if (base == 8)
    return (prec + 2) / 3;

  if (base == 16)
    return prec / 4;

  /* Decimal approximation: yields 3, 5, 10, and 20 for precision
     of 8, 16, 32, and 64 bits.  */
  return prec * 301 / 1000 + 1;
}

static bool
get_int_range (tree, tree, HOST_WIDE_INT *, HOST_WIDE_INT *,
               bool, HOST_WIDE_INT);

/* Description of a format directive.  A directive is either a plain
   string or a conversion specification that starts with '%'.  */

struct directive
{
  /* The 1-based directive number (for debugging).  */
  unsigned dirno;

  /* The first character of the directive and its length.  */
  const char *beg;
  size_t len;

  /* A bitmap of flags, one for each character.  */
  unsigned flags[256 / sizeof (int)];

  /* The range of values of the specified width, or -1 if not specified.  */
  HOST_WIDE_INT width[2];
  /* The range of values of the specified precision, or -1 if not
     specified.  */
  HOST_WIDE_INT prec[2];

  /* Length modifier.  */
  format_lengths modifier;

  /* Format specifier character.  */
  char specifier;

  /* The argument of the directive or null when the directive doesn't
     take one or when none is available (such as for vararg functions).  */
  tree arg;

  /* Format conversion function that given a directive and an argument
     returns the formatting result.  */
  fmtresult (*fmtfunc) (const directive &, tree);

  /* Return True when a the format flag CHR has been used.  */
  bool get_flag (char chr) const
  {
    unsigned char c = chr & 0xff;
    return (flags[c / (CHAR_BIT * sizeof *flags)]
            & (1U << (c % (CHAR_BIT * sizeof *flags))));
  }

  /* Make a record of the format flag CHR having been used.  */
  void set_flag (char chr)
  {
    unsigned char c = chr & 0xff;
    flags[c / (CHAR_BIT * sizeof *flags)]
      |= (1U << (c % (CHAR_BIT * sizeof *flags)));
  }

  /* Reset the format flag CHR.  */
  void clear_flag (char chr)
  {
    unsigned char c = chr & 0xff;
    flags[c / (CHAR_BIT * sizeof *flags)]
      &= ~(1U << (c % (CHAR_BIT * sizeof *flags)));
  }

  /* Set both bounds of the width range to VAL.  */
  void set_width (HOST_WIDE_INT val)
  {
    width[0] = width[1] = val;
  }

  /* Set the width range according to ARG, with both bounds being
     no less than 0.  For a constant ARG set both bounds to its value
     or 0, whichever is greater.  For a non-constant ARG in some range
     set width to its range adjusting each bound to -1 if it's less.
     For an indeterminate ARG set width to [0, INT_MAX].  */
  void set_width (tree arg)
  {
    get_int_range (arg, integer_type_node, width, width + 1, true, 0);
  }

  /* Set both bounds of the precision range to VAL.  */
  void set_precision (HOST_WIDE_INT val)
  {
    prec[0] = prec[1] = val;
  }

  /* Set the precision range according to ARG, with both bounds being
     no less than -1.  For a constant ARG set both bounds to its value
     or -1 whichever is greater.  For a non-constant ARG in some range
     set precision to its range adjusting each bound to -1 if it's less.
     For an indeterminate ARG set precision to [-1, INT_MAX].  */
  void set_precision (tree arg)
  {
    get_int_range (arg, integer_type_node, prec, prec + 1, false, -1);
  }

  /* Return true if both width and precision are known to be
     either constant or in some range, false otherwise.  */
  bool known_width_and_precision () const
  {
    return ((width[1] < 0
             || (unsigned HOST_WIDE_INT)width[1] <= target_int_max ())
            && (prec[1] < 0
                || (unsigned HOST_WIDE_INT)prec[1] < target_int_max ()));
  }
};

/* Return the logarithm of X in BASE.  */

static int
ilog (unsigned HOST_WIDE_INT x, int base)
{
  int res = 0;
  do
    {
      ++res;
      x /= base;
    } while (x);
  return res;
}

/* Return the number of bytes resulting from converting into a string
   the INTEGER_CST tree node X in BASE with a minimum of PREC digits.
   PLUS indicates whether 1 for a plus sign should be added for positive
   numbers, and PREFIX whether the length of an octal ('O') or hexadecimal
   ('0x') prefix should be added for nonzero numbers.  Return -1 if X cannot
   be represented.  */

static HOST_WIDE_INT
tree_digits (tree x, int base, HOST_WIDE_INT prec, bool plus, bool prefix)
{
  unsigned HOST_WIDE_INT absval;

  HOST_WIDE_INT res;

  if (TYPE_UNSIGNED (TREE_TYPE (x)))
    {
      if (tree_fits_uhwi_p (x))
        {
          absval = tree_to_uhwi (x);
          res = plus;
        }
      else
        return -1;
    }
  else
    {
      if (tree_fits_shwi_p (x))
        {
          HOST_WIDE_INT i = tree_to_shwi (x);
         if (HOST_WIDE_INT_MIN == i)
           {
             /* Avoid undefined behavior due to negating a minimum.  */
             absval = HOST_WIDE_INT_MAX;
             res = 1;
           }
         else if (i < 0)
           {
             absval = -i;
             res = 1;
           }
         else
           {
             absval = i;
             res = plus;
           }
        }
      else
        return -1;
    }

  int ndigs = ilog (absval, base);

  res += prec < ndigs ? ndigs : prec;

  /* Adjust a non-zero value for the base prefix, either hexadecimal,
     or, unless precision has resulted in a leading zero, also octal.  */
  if (prefix && absval && (base == 16 || prec <= ndigs))
    {
      if (base == 8)
        res += 1;
      else if (base == 16)
        res += 2;
    }

  return res;
}

/* Given the formatting result described by RES and NAVAIL, the number
   of available in the destination, return the range of bytes remaining
   in the destination.  */

static inline result_range
bytes_remaining (unsigned HOST_WIDE_INT navail, const format_result &res)
{
  result_range range;

  if (HOST_WIDE_INT_MAX <= navail)
    {
      range.min = range.max = range.likely = range.unlikely = navail;
      return range;
    }

  /* The lower bound of the available range is the available size
     minus the maximum output size, and the upper bound is the size
     minus the minimum.  */
  range.max = res.range.min < navail ? navail - res.range.min : 0;

  range.likely = res.range.likely < navail ? navail - res.range.likely : 0;

  if (res.range.max < HOST_WIDE_INT_MAX)
    range.min = res.range.max < navail ? navail - res.range.max : 0;
  else
    range.min = range.likely;

  range.unlikely = (res.range.unlikely < navail
                    ? navail - res.range.unlikely : 0);

  return range;
}

/* Description of a call to a formatted function.  */

struct pass_sprintf_length::call_info
{
  /* Function call statement.  */
  gimple *callstmt;

  /* Function called.  */
  tree func;

  /* Called built-in function code.  */
  built_in_function fncode;

  /* Format argument and format string extracted from it.  */
  tree format;
  const char *fmtstr;

  /* The location of the format argument.  */
  location_t fmtloc;

  /* The destination object size for __builtin___xxx_chk functions
     typically determined by __builtin_object_size, or -1 if unknown.  */
  unsigned HOST_WIDE_INT objsize;

  /* Number of the first variable argument.  */
  unsigned HOST_WIDE_INT argidx;

  /* True for functions like snprintf that specify the size of
     the destination, false for others like sprintf that don't.  */
  bool bounded;

  /* True for bounded functions like snprintf that specify a zero-size
     buffer as a request to compute the size of output without actually
     writing any.  NOWRITE is cleared in response to the %n directive
     which has side-effects similar to writing output.  */
  bool nowrite;

  /* Return true if the called function's return value is used.  */
  bool retval_used () const
  {
    return gimple_get_lhs (callstmt);
  }

  /* Return the warning option corresponding to the called function.  */
  int warnopt () const
  {
    return bounded ? OPT_Wformat_truncation_ : OPT_Wformat_overflow_;
  }
};

/* Return the result of formatting a no-op directive (such as '%n').  */

static fmtresult
format_none (const directive &, tree)
{
  fmtresult res (0);
  return res;
}

/* Return the result of formatting the '%%' directive.  */

static fmtresult
format_percent (const directive &, tree)
{
  fmtresult res (1);
  return res;
}


/* Compute intmax_type_node and uintmax_type_node similarly to how
   tree.c builds size_type_node.  */

static void
build_intmax_type_nodes (tree *pintmax, tree *puintmax)
{
  if (strcmp (UINTMAX_TYPE, "unsigned int") == 0)
    {
      *pintmax = integer_type_node;
      *puintmax = unsigned_type_node;
    }
  else if (strcmp (UINTMAX_TYPE, "long unsigned int") == 0)
    {
      *pintmax = long_integer_type_node;
      *puintmax = long_unsigned_type_node;
    }
  else if (strcmp (UINTMAX_TYPE, "long long unsigned int") == 0)
    {
      *pintmax = long_long_integer_type_node;
      *puintmax = long_long_unsigned_type_node;
    }
  else
    {
      for (int i = 0; i < NUM_INT_N_ENTS; i++)
        if (int_n_enabled_p[i])
          {
            char name[50];
            sprintf (name, "__int%d unsigned", int_n_data[i].bitsize);

            if (strcmp (name, UINTMAX_TYPE) == 0)
              {
                *pintmax = int_n_trees[i].signed_type;
                *puintmax = int_n_trees[i].unsigned_type;
                return;
              }
          }
      gcc_unreachable ();
    }
}

/* Determine the range [*PMIN, *PMAX] that the expression ARG of TYPE
   is in.  Return true when the range is a subrange of that of TYPE.
   Whn ARG is null it is as if it had the full range of TYPE.
   When ABSOLUTE is true the range reflects the absolute value of
   the argument.  When ABSOLUTE is false, negative bounds of
   the determined range are replaced with NEGBOUND.  */

static bool
get_int_range (tree arg, tree type, HOST_WIDE_INT *pmin, HOST_WIDE_INT *pmax,
               bool absolute, HOST_WIDE_INT negbound)
{
  bool knownrange = false;

  if (!arg)
    {
      *pmin = (TYPE_UNSIGNED (type)
               ? tree_to_uhwi (TYPE_MIN_VALUE (type))
               : tree_to_shwi (TYPE_MIN_VALUE (type)));
      *pmax = tree_to_uhwi (TYPE_MAX_VALUE (type));
    }
  else if (TREE_CODE (arg) == INTEGER_CST)
    {
      /* For a constant argument return its value adjusted as specified
         by NEGATIVE and NEGBOUND and return true to indicate that the
         result is known.  */
      *pmin = tree_fits_shwi_p (arg) ? tree_to_shwi (arg) : tree_to_uhwi (arg);
      *pmax = *pmin;
      knownrange = true;
    }
  else
    {
      /* True if the argument's range cannot be determined.  */
      bool unknown = true;

      type = TREE_TYPE (arg);

      if (TREE_CODE (arg) == SSA_NAME
          && TREE_CODE (type) == INTEGER_TYPE)
        {
          /* Try to determine the range of values of the integer argument.  */
          wide_int min, max;
          enum value_range_type range_type = get_range_info (arg, &min, &max);
          if (range_type == VR_RANGE)
            {
              HOST_WIDE_INT type_min
                = (TYPE_UNSIGNED (type)
                   ? tree_to_uhwi (TYPE_MIN_VALUE (type))
                   : tree_to_shwi (TYPE_MIN_VALUE (type)));

              HOST_WIDE_INT type_max = tree_to_uhwi (TYPE_MAX_VALUE (type));

              *pmin = min.to_shwi ();
              *pmax = max.to_shwi ();

              /* Return true if the adjusted range is a subrange of
                 the full range of the argument's type.  */
              knownrange = type_min < *pmin || *pmax < type_max;

              unknown = false;
            }
        }

      /* Handle an argument with an unknown range as if none had been
         provided.  */
      if (unknown)
        return get_int_range (NULL_TREE, type, pmin, pmax, absolute, negbound);
    }

  /* Adjust each bound as specified by ABSOLUTE and NEGBOUND.  */
  if (absolute)
    {
      if (*pmin < 0)
        {
          if (*pmin == *pmax)
            *pmin = *pmax = -*pmin;
          else
            {
              HOST_WIDE_INT tmp = -*pmin;
              *pmin = 0;
              if (*pmax < tmp)
                *pmax = tmp;
            }
        }
    }
  else if (*pmin < negbound)
    *pmin = negbound;

  return knownrange;
}

/* With the range [*ARGMIN, *ARGMAX] of an integer directive's actual
   argument, due to the conversion from either *ARGMIN or *ARGMAX to
   the type of the directive's formal argument it's possible for both
   to result in the same number of bytes or a range of bytes that's
   less than the number of bytes that would result from formatting
   some other value in the range [*ARGMIN, *ARGMAX].  This can be
   determined by checking for the actual argument being in the range
   of the type of the directive.  If it isn't it must be assumed to
   take on the full range of the directive's type.
   Return true when the range has been adjusted to the full range
   of DIRTYPE, and false otherwise.  */

static bool
adjust_range_for_overflow (tree dirtype, tree *argmin, tree *argmax)
{
  tree argtype = TREE_TYPE (*argmin);
  unsigned argprec = TYPE_PRECISION (argtype);
  unsigned dirprec = TYPE_PRECISION (dirtype);

  /* If the actual argument and the directive's argument have the same
     precision and sign there can be no overflow and so there is nothing
     to adjust.  */
  if (argprec == dirprec && TYPE_SIGN (argtype) == TYPE_SIGN (dirtype))
    return false;

  /* The logic below was inspired/lifted from the CONVERT_EXPR_CODE_P
     branch in the extract_range_from_unary_expr function in tree-vrp.c.  */

  if (TREE_CODE (*argmin) == INTEGER_CST
      && TREE_CODE (*argmax) == INTEGER_CST
      && (dirprec >= argprec
          || integer_zerop (int_const_binop (RSHIFT_EXPR,
                                             int_const_binop (MINUS_EXPR,
                                                              *argmax,
                                                              *argmin),
                                             size_int (dirprec)))))
    {
      *argmin = force_fit_type (dirtype, wi::to_widest (*argmin), 0, false);
      *argmax = force_fit_type (dirtype, wi::to_widest (*argmax), 0, false);

      /* If *ARGMIN is still less than *ARGMAX the conversion above
         is safe.  Otherwise, it has overflowed and would be unsafe.  */
      if (tree_int_cst_le (*argmin, *argmax))
        return false;
    }

  *argmin = TYPE_MIN_VALUE (dirtype);
  *argmax = TYPE_MAX_VALUE (dirtype);
  return true;
}

/* Return a range representing the minimum and maximum number of bytes
   that the format directive DIR will output for any argument given
   the WIDTH and PRECISION (extracted from DIR).  This function is
   used when the directive argument or its value isn't known.  */

static fmtresult
format_integer (const directive &dir, tree arg)
{
  tree intmax_type_node;
  tree uintmax_type_node;

  /* Base to format the number in.  */
  int base;

  /* True when a conversion is preceded by a prefix indicating the base
     of the argument (octal or hexadecimal).  */
  bool maybebase = dir.get_flag ('#');

  /* True when a signed conversion is preceded by a sign or space.  */
  bool maybesign = false;

  /* True for signed conversions (i.e., 'd' and 'i').  */
  bool sign = false;

  switch (dir.specifier)
    {
    case 'd':
    case 'i':
      /* Space and '+' are  only meaningful for signed conversions.  */
      maybesign = dir.get_flag (' ') | dir.get_flag ('+');
      sign = true;
      base = 10;
      break;
    case 'u':
      base = 10;
      break;
    case 'o':
      base = 8;
      break;
    case 'X':
    case 'x':
      base = 16;
      break;
    default:
      gcc_unreachable ();
    }

  /* The type of the "formal" argument expected by the directive.  */
  tree dirtype = NULL_TREE;

  /* Determine the expected type of the argument from the length
     modifier.  */
  switch (dir.modifier)
    {
    case FMT_LEN_none:
      if (dir.specifier == 'p')
        dirtype = ptr_type_node;
      else
        dirtype = sign ? integer_type_node : unsigned_type_node;
      break;

    case FMT_LEN_h:
      dirtype = sign ? short_integer_type_node : short_unsigned_type_node;
      break;

    case FMT_LEN_hh:
      dirtype = sign ? signed_char_type_node : unsigned_char_type_node;
      break;

    case FMT_LEN_l:
      dirtype = sign ? long_integer_type_node : long_unsigned_type_node;
      break;

    case FMT_LEN_L:
    case FMT_LEN_ll:
      dirtype = (sign
                 ? long_long_integer_type_node
                 : long_long_unsigned_type_node);
      break;

    case FMT_LEN_z:
      dirtype = signed_or_unsigned_type_for (!sign, size_type_node);
      break;

    case FMT_LEN_t:
      dirtype = signed_or_unsigned_type_for (!sign, ptrdiff_type_node);
      break;

    case FMT_LEN_j:
      build_intmax_type_nodes (&intmax_type_node, &uintmax_type_node);
      dirtype = sign ? intmax_type_node : uintmax_type_node;
      break;

    default:
      return fmtresult ();
    }

  /* The type of the argument to the directive, either deduced from
     the actual non-constant argument if one is known, or from
     the directive itself when none has been provided because it's
     a va_list.  */
  tree argtype = NULL_TREE;

  if (!arg)
    {
      /* When the argument has not been provided, use the type of
         the directive's argument as an approximation.  This will
         result in false positives for directives like %i with
         arguments with smaller precision (such as short or char).  */
      argtype = dirtype;
    }
  else if (TREE_CODE (arg) == INTEGER_CST)
    {
      /* When a constant argument has been provided use its value
         rather than type to determine the length of the output.  */
      fmtresult res;

      if ((dir.prec[0] <= 0 && dir.prec[1] >= 0) && integer_zerop (arg))
        {
          /* As a special case, a precision of zero with a zero argument
             results in zero bytes except in base 8 when the '#' flag is
             specified, and for signed conversions in base 8 and 10 when
             either the space or '+' flag has been specified and it results
             in just one byte (with width having the normal effect).  This
             must extend to the case of a specified precision with
             an unknown value because it can be zero.  */
          res.range.min = ((base == 8 && dir.get_flag ('#')) || maybesign);
          if (res.range.min == 0 && dir.prec[0] != dir.prec[1])
            {
              res.range.max = 1;
              res.range.likely = 1;
            }
          else
            {
              res.range.max = res.range.min;
              res.range.likely = res.range.min;
            }
        }
      else
        {
          /* Convert the argument to the type of the directive.  */
          arg = fold_convert (dirtype, arg);

          res.range.min = tree_digits (arg, base, dir.prec[0],
                                       maybesign, maybebase);
          if (dir.prec[0] == dir.prec[1])
            res.range.max = res.range.min;
          else
            res.range.max = tree_digits (arg, base, dir.prec[1],
                                         maybesign, maybebase);
          res.range.likely = res.range.min;
        }

      res.range.unlikely = res.range.max;

      /* Bump up the counters if WIDTH is greater than LEN.  */
      res.adjust_for_width_or_precision (dir.width, dirtype, base,
                                         (sign | maybebase) + (base == 16));
      /* Bump up the counters again if PRECision is greater still.  */
      res.adjust_for_width_or_precision (dir.prec, dirtype, base,
                                         (sign | maybebase) + (base == 16));

      return res;
    }
  else if (TREE_CODE (TREE_TYPE (arg)) == INTEGER_TYPE
           || TREE_CODE (TREE_TYPE (arg)) == POINTER_TYPE)
    /* Determine the type of the provided non-constant argument.  */
    argtype = TREE_TYPE (arg);
  else
    /* Don't bother with invalid arguments since they likely would
       have already been diagnosed, and disable any further checking
       of the format string by returning [-1, -1].  */
    return fmtresult ();

  fmtresult res;

  /* Using either the range the non-constant argument is in, or its
     type (either "formal" or actual), create a range of values that
     constrain the length of output given the warning level.  */
  tree argmin = NULL_TREE;
  tree argmax = NULL_TREE;

  if (arg
      && TREE_CODE (arg) == SSA_NAME
      && TREE_CODE (argtype) == INTEGER_TYPE)
    {
      /* Try to determine the range of values of the integer argument
         (range information is not available for pointers).  */
      wide_int min, max;
      enum value_range_type range_type = get_range_info (arg, &min, &max);
      if (range_type == VR_RANGE)
        {
          argmin = wide_int_to_tree (argtype, min);
          argmax = wide_int_to_tree (argtype, max);

          /* Set KNOWNRANGE if the argument is in a known subrange
             of the directive's type and neither width nor precision
             is unknown.  (KNOWNRANGE may be reset below).  */
          res.knownrange
            = ((!tree_int_cst_equal (TYPE_MIN_VALUE (dirtype), argmin)
                || !tree_int_cst_equal (TYPE_MAX_VALUE (dirtype), argmax))
               && dir.known_width_and_precision ());

          res.argmin = argmin;
          res.argmax = argmax;
        }
      else if (range_type == VR_ANTI_RANGE)
        {
          /* Handle anti-ranges if/when bug 71690 is resolved.  */
        }
      else if (range_type == VR_VARYING)
        {
          /* The argument here may be the result of promoting the actual
             argument to int.  Try to determine the type of the actual
             argument before promotion and narrow down its range that
             way.  */
          gimple *def = SSA_NAME_DEF_STMT (arg);
          if (is_gimple_assign (def))
            {
              tree_code code = gimple_assign_rhs_code (def);
              if (code == INTEGER_CST)
                {
                  arg = gimple_assign_rhs1 (def);
                  return format_integer (dir, arg);
                }

              if (code == NOP_EXPR)
                {
                  tree type = TREE_TYPE (gimple_assign_rhs1 (def));
                  if (TREE_CODE (type) == INTEGER_TYPE
                      || TREE_CODE (type) == POINTER_TYPE)
                    argtype = type;
                }
            }
        }
    }

  if (!argmin)
    {
      if (TREE_CODE (argtype) == POINTER_TYPE)
        {
          argmin = build_int_cst (pointer_sized_int_node, 0);
          argmax = build_all_ones_cst (pointer_sized_int_node);
        }
      else
        {
          argmin = TYPE_MIN_VALUE (argtype);
          argmax = TYPE_MAX_VALUE (argtype);
        }
    }

  /* Clear KNOWNRANGE if the range has been adjusted to the maximum
     of the directive.  If it has been cleared then since ARGMIN and/or
     ARGMAX have been adjusted also adjust the corresponding ARGMIN and
     ARGMAX in the result to include in diagnostics.  */
  if (adjust_range_for_overflow (dirtype, &argmin, &argmax))
    {
      res.knownrange = false;
      res.argmin = argmin;
      res.argmax = argmax;
    }

  /* Recursively compute the minimum and maximum from the known range.  */
  if (TYPE_UNSIGNED (dirtype) || tree_int_cst_sgn (argmin) >= 0)
    {
      /* For unsigned conversions/directives or signed when
         the minimum is positive, use the minimum and maximum to compute
         the shortest and longest output, respectively.  */
      res.range.min = format_integer (dir, argmin).range.min;
      res.range.max = format_integer (dir, argmax).range.max;
    }
  else if (tree_int_cst_sgn (argmax) < 0)
    {
      /* For signed conversions/directives if maximum is negative,
         use the minimum as the longest output and maximum as the
         shortest output.  */
      res.range.min = format_integer (dir, argmax).range.min;
      res.range.max = format_integer (dir, argmin).range.max;
    }
  else
    {
      /* Otherwise, 0 is inside of the range and minimum negative.  Use 0
         as the shortest output and for the longest output compute the
         length of the output of both minimum and maximum and pick the
         longer.  */
      unsigned HOST_WIDE_INT max1 = format_integer (dir, argmin).range.max;
      unsigned HOST_WIDE_INT max2 = format_integer (dir, argmax).range.max;
      res.range.min = format_integer (dir, integer_zero_node).range.min;
      res.range.max = MAX (max1, max2);
    }

  /* If the range is known, use the maximum as the likely length.  */
  if (res.knownrange)
    res.range.likely = res.range.max;
  else
    {
      /* Otherwise, use the minimum.  Except for the case where for %#x or
         %#o the minimum is just for a single value in the range (0) and
         for all other values it is something longer, like 0x1 or 01.
          Use the length for value 1 in that case instead as the likely
          length.  */
      res.range.likely = res.range.min;
      if (maybebase
          && base != 10
          && (tree_int_cst_sgn (argmin) < 0 || tree_int_cst_sgn (argmax) > 0))
        {
          if (res.range.min == 1)
            res.range.likely += base == 8 ? 1 : 2;
          else if (res.range.min == 2
                   && base == 16
                   && (dir.width[0] == 2 || dir.prec[0] == 2))
            ++res.range.likely;
        }
    }

  res.range.unlikely = res.range.max;
  res.adjust_for_width_or_precision (dir.width, dirtype, base,
                                     (sign | maybebase) + (base == 16));
  res.adjust_for_width_or_precision (dir.prec, dirtype, base,
                                     (sign | maybebase) + (base == 16));

  return res;
}

/* Return the number of bytes that a format directive consisting of FLAGS,
   PRECision, format SPECification, and MPFR rounding specifier RNDSPEC,
   would result for argument X under ideal conditions (i.e., if PREC
   weren't excessive).  MPFR 3.1 allocates large amounts of memory for
   values of PREC with large magnitude and can fail (see MPFR bug #21056).
   This function works around those problems.  */

static unsigned HOST_WIDE_INT
get_mpfr_format_length (mpfr_ptr x, const char *flags, HOST_WIDE_INT prec,
                        char spec, char rndspec)
{
  char fmtstr[40];

  HOST_WIDE_INT len = strlen (flags);

  fmtstr[0] = '%';
  memcpy (fmtstr + 1, flags, len);
  memcpy (fmtstr + 1 + len, ".*R", 3);
  fmtstr[len + 4] = rndspec;
  fmtstr[len + 5] = spec;
  fmtstr[len + 6] = '\0';

  spec = TOUPPER (spec);
  if (spec == 'E' || spec == 'F')
    {
      /* For %e, specify the precision explicitly since mpfr_sprintf
         does its own thing just to be different (see MPFR bug 21088).  */
      if (prec < 0)
        prec = 6;
    }
  else
    {
      /* Avoid passing negative precisions with larger magnitude to MPFR
         to avoid exposing its bugs.  (A negative precision is supposed
         to be ignored.)  */
      if (prec < 0)
        prec = -1;
    }

  HOST_WIDE_INT p = prec;

  if (spec == 'G' && !strchr (flags, '#'))
    {
      /* For G/g without the pound flag, precision gives the maximum number
         of significant digits which is bounded by LDBL_MAX_10_EXP, or, for
         a 128 bit IEEE extended precision, 4932.  Using twice as much here
         should be more than sufficient for any real format.  */
      if ((IEEE_MAX_10_EXP * 2) < prec)
        prec = IEEE_MAX_10_EXP * 2;
      p = prec;
    }
  else
    {
      /* Cap precision arbitrarily at 1KB and add the difference
         (if any) to the MPFR result.  */
      if (prec > 1024)
        p = 1024;
    }

  len = mpfr_snprintf (NULL, 0, fmtstr, (int)p, x);

  /* Handle the unlikely (impossible?) error by returning more than
     the maximum dictated by the function's return type.  */
  if (len < 0)
    return target_dir_max () + 1;

  /* Adjust the return value by the difference.  */
  if (p < prec)
    len += prec - p;

  return len;
}

/* Return the number of bytes to format using the format specifier
   SPEC and the precision PREC the largest value in the real floating
   TYPE.  */

static unsigned HOST_WIDE_INT
format_floating_max (tree type, char spec, HOST_WIDE_INT prec)
{
  machine_mode mode = TYPE_MODE (type);

  /* IBM Extended mode.  */
  if (MODE_COMPOSITE_P (mode))
    mode = DFmode;

  /* Get the real type format desription for the target.  */
  const real_format *rfmt = REAL_MODE_FORMAT (mode);
  REAL_VALUE_TYPE rv;

  real_maxval (&rv, 0, mode);

  /* Convert the GCC real value representation with the precision
     of the real type to the mpfr_t format with the GCC default
     round-to-nearest mode.  */
  mpfr_t x;
  mpfr_init2 (x, rfmt->p);
  mpfr_from_real (x, &rv, GMP_RNDN);

  /* Return a value one greater to account for the leading minus sign.  */
  unsigned HOST_WIDE_INT r
    = 1 + get_mpfr_format_length (x, "", prec, spec, 'D');
  mpfr_clear (x);
  return r;
}

/* Return a range representing the minimum and maximum number of bytes
   that the directive DIR will output for any argument.  PREC gives
   the adjusted precision range to account for negative precisions
   meaning the default 6.  This function is used when the directive
   argument or its value isn't known.  */

static fmtresult
format_floating (const directive &dir, const HOST_WIDE_INT prec[2])
{
  tree type;

  switch (dir.modifier)
    {
    case FMT_LEN_l:
    case FMT_LEN_none:
      type = double_type_node;
      break;

    case FMT_LEN_L:
      type = long_double_type_node;
      break;

    case FMT_LEN_ll:
      type = long_double_type_node;
      break;

    default:
      return fmtresult ();
    }

  /* The minimum and maximum number of bytes produced by the directive.  */
  fmtresult res;

  /* The minimum output as determined by flags.  It's always at least 1.
     When plus or space are set the output is preceded by either a sign
     or a space.  */
  unsigned flagmin = (1 /* for the first digit */
                      + (dir.get_flag ('+') | dir.get_flag (' ')));

  /* When the pound flag is set the decimal point is included in output
     regardless of precision.  Whether or not a decimal point is included
     otherwise depends on the specification and precision.  */
  bool radix = dir.get_flag ('#');

  switch (dir.specifier)
    {
    case 'A':
    case 'a':
      {
        HOST_WIDE_INT minprec = 6 + !radix /* decimal point */;
        if (dir.prec[0] <= 0)
          minprec = 0;
        else if (dir.prec[0] > 0)
          minprec = dir.prec[0] + !radix /* decimal point */;

        res.range.min = (2 /* 0x */
                         + flagmin
                         + radix
                         + minprec
                         + 3 /* p+0 */);

        res.range.max = format_floating_max (type, 'a', prec[1]);
        res.range.likely = res.range.min;

        /* The unlikely maximum accounts for the longest multibyte
           decimal point character.  */
        res.range.unlikely = res.range.max;
        if (dir.prec[1] > 0)
          res.range.unlikely += target_mb_len_max () - 1;

        break;
      }

    case 'E':
    case 'e':
      {
        /* Minimum output attributable to precision and, when it's
           non-zero, decimal point.  */
        HOST_WIDE_INT minprec = prec[0] ? prec[0] + !radix : 0;

        /* The minimum output is "[-+]1.234567e+00" regardless
           of the value of the actual argument.  */
        res.range.min = (flagmin
                         + radix
                         + minprec
                         + 2 /* e+ */ + 2);

        res.range.max = format_floating_max (type, 'e', prec[1]);
        res.range.likely = res.range.min;

        /* The unlikely maximum accounts for the longest multibyte
           decimal point character.  */
        if (dir.prec[0] != dir.prec[1]
            || dir.prec[0] == -1 || dir.prec[0] > 0)
          res.range.unlikely = res.range.max + target_mb_len_max () -1;
        else
          res.range.unlikely = res.range.max;
        break;
      }

    case 'F':
    case 'f':
      {
        /* Minimum output attributable to precision and, when it's non-zero,
           decimal point.  */
        HOST_WIDE_INT minprec = prec[0] ? prec[0] + !radix : 0;

        /* The lower bound when precision isn't specified is 8 bytes
           ("1.23456" since precision is taken to be 6).  When precision
           is zero, the lower bound is 1 byte (e.g., "1").  Otherwise,
           when precision is greater than zero, then the lower bound
           is 2 plus precision (plus flags).  */
        res.range.min = flagmin + radix + minprec;

        /* Compute the upper bound for -TYPE_MAX.  */
        res.range.max = format_floating_max (type, 'f', prec[1]);

        /* The minimum output with unknown precision is a single byte
           (e.g., "0") but the more likely output is 3 bytes ("0.0").  */
        if (dir.prec[0] < 0 && dir.prec[1] > 0)
          res.range.likely = 3;
        else
          res.range.likely = res.range.min;

        /* The unlikely maximum accounts for the longest multibyte
           decimal point character.  */
        if (dir.prec[0] != dir.prec[1]
            || dir.prec[0] == -1 || dir.prec[0] > 0)
          res.range.unlikely = res.range.max + target_mb_len_max () - 1;
        break;
      }

    case 'G':
    case 'g':
      {
        /* The %g output depends on precision and the exponent of
           the argument.  Since the value of the argument isn't known
           the lower bound on the range of bytes (not counting flags
           or width) is 1 plus radix (i.e., either "0" or "0." for
           "%g" and "%#g", respectively, with a zero argument).  */
        res.range.min = flagmin + radix;

        char spec = 'g';
        HOST_WIDE_INT maxprec = dir.prec[1];
        if (radix && maxprec)
          {
            /* When the pound flag (radix) is set, trailing zeros aren't
               trimmed and so the longest output is the same as for %e,
               except with precision minus 1 (as specified in C11).  */
            spec = 'e';
            if (maxprec > 0)
              --maxprec;
            else if (maxprec < 0)
              maxprec = 5;
          }
        else
          maxprec = prec[1];

        res.range.max = format_floating_max (type, spec, maxprec);

        /* The likely output is either the maximum computed above
           minus 1 (assuming the maximum is positive) when precision
           is known (or unspecified), or the same minimum as for %e
           (which is computed for a non-negative argument).  Unlike
           for the other specifiers above the likely output isn't
           the minimum because for %g that's 1 which is unlikely.  */
        if (dir.prec[1] < 0
            || (unsigned HOST_WIDE_INT)dir.prec[1] < target_int_max ())
          res.range.likely = res.range.max - 1;
        else
          {
            HOST_WIDE_INT minprec = 6 + !radix /* decimal point */;
            res.range.likely = (flagmin
                                + radix
                                + minprec
                                + 2 /* e+ */ + 2);
          }

        /* The unlikely maximum accounts for the longest multibyte
           decimal point character.  */
        res.range.unlikely = res.range.max + target_mb_len_max () - 1;
        break;
      }

    default:
      return fmtresult ();
    }

  /* Bump up the byte counters if WIDTH is greater.  */
  res.adjust_for_width_or_precision (dir.width);
  return res;
}

/* Return a range representing the minimum and maximum number of bytes
   that the directive DIR will write on output for the floating argument
   ARG.  */

static fmtresult
format_floating (const directive &dir, tree arg)
{
  HOST_WIDE_INT prec[] = { dir.prec[0], dir.prec[1] };

  /* For an indeterminate precision the lower bound must be assumed
     to be zero.  */
  if (TOUPPER (dir.specifier) == 'A')
    {
      /* Get the number of fractional decimal digits needed to represent
         the argument without a loss of accuracy.  */
      tree type = arg ? TREE_TYPE (arg) :
        (dir.modifier == FMT_LEN_L || dir.modifier == FMT_LEN_ll
         ? long_double_type_node : double_type_node);

      unsigned fmtprec
        = REAL_MODE_FORMAT (TYPE_MODE (type))->p;

      /* The precision of the IEEE 754 double format is 53.
         The precision of all other GCC binary double formats
         is 56 or less.  */
      unsigned maxprec = fmtprec <= 56 ? 13 : 15;

      /* For %a, leave the minimum precision unspecified to let
         MFPR trim trailing zeros (as it and many other systems
         including Glibc happen to do) and set the maximum
         precision to reflect what it would be with trailing zeros
         present (as Solaris and derived systems do).  */
      if (dir.prec[1] < 0)
        {
          /* Both bounds are negative implies that precision has
             not been specified.  */
          prec[0] = maxprec;
          prec[1] = -1;
        }
      else if (dir.prec[0] < 0)
        {
          /* With a negative lower bound and a non-negative upper
             bound set the minimum precision to zero and the maximum
             to the greater of the maximum precision (i.e., with
             trailing zeros present) and the specified upper bound.  */
          prec[0] = 0;
          prec[1] = dir.prec[1] < maxprec ? maxprec : dir.prec[1];
        }
    }
  else if (dir.prec[0] < 0)
    {
      if (dir.prec[1] < 0)
        {
          /* A precision in a strictly negative range is ignored and
             the default of 6 is used instead.  */
          prec[0] = prec[1] = 6;
        }
      else
        {
          /* For a precision in a partly negative range, the lower bound
             must be assumed to be zero and the new upper bound is the
             greater of 6 (the default precision used when the specified
             precision is negative) and the upper bound of the specified
             range.  */
          prec[0] = 0;
          prec[1] = dir.prec[1] < 6 ? 6 : dir.prec[1];
        }
    }

  if (!arg || TREE_CODE (arg) != REAL_CST)
    return format_floating (dir, prec);

  /* The minimum and maximum number of bytes produced by the directive.  */
  fmtresult res;

  /* Get the real type format desription for the target.  */
  const REAL_VALUE_TYPE *rvp = TREE_REAL_CST_PTR (arg);
  const real_format *rfmt = REAL_MODE_FORMAT (TYPE_MODE (TREE_TYPE (arg)));

  char fmtstr [40];
  char *pfmt = fmtstr;

  /* Append flags.  */
  for (const char *pf = "-+ #0"; *pf; ++pf)
    if (dir.get_flag (*pf))
      *pfmt++ = *pf;

  *pfmt = '\0';

  {
    /* Set up an array to easily iterate over.  */
    unsigned HOST_WIDE_INT* const minmax[] = {
      &res.range.min, &res.range.max
    };

    for (int i = 0; i != sizeof minmax / sizeof *minmax; ++i)
      {
        /* Convert the GCC real value representation with the precision
           of the real type to the mpfr_t format rounding down in the
           first iteration that computes the minimm and up in the second
           that computes the maximum.  This order is arbibtrary because
           rounding in either direction can result in longer output.  */
        mpfr_t mpfrval;
        mpfr_init2 (mpfrval, rfmt->p);
        mpfr_from_real (mpfrval, rvp, i ? GMP_RNDU : GMP_RNDD);

        /* Use the MPFR rounding specifier to round down in the first
           iteration and then up.  In most but not all cases this will
           result in the same number of bytes.  */
        char rndspec = "DU"[i];

        /* Format it and store the result in the corresponding member
           of the result struct.  */
        *minmax[i] = get_mpfr_format_length (mpfrval, fmtstr, prec[i],
                                             dir.specifier, rndspec);
        mpfr_clear (mpfrval);
      }
  }

  /* Make sure the minimum is less than the maximum (MPFR rounding
     in the call to mpfr_snprintf can result in the reverse.  */
  if (res.range.max < res.range.min)
    {
      unsigned HOST_WIDE_INT tmp = res.range.min;
      res.range.min = res.range.max;
      res.range.max = tmp;
    }

  /* The range is known unless either width or precision is unknown.  */
  res.knownrange = dir.known_width_and_precision ();

  /* For the same floating point constant, unless width or precision
     is unknown, use the longer output as the likely maximum since
     with round to nearest either is equally likely.  Otheriwse, when
     precision is unknown, use the greater of the minimum and 3 as
     the likely output (for "0.0" since zero precision is unlikely).  */
  if (res.knownrange)
    res.range.likely = res.range.max;
  else if (res.range.min < 3
           && dir.prec[0] < 0
           && (unsigned HOST_WIDE_INT)dir.prec[1] == target_int_max ())
    res.range.likely = 3;
  else
    res.range.likely = res.range.min;

  res.range.unlikely = res.range.max;

  if (res.range.max > 2 && (prec[0] != 0 || prec[1] != 0))
    {
      /* Unless the precision is zero output longer than 2 bytes may
         include the decimal point which must be a single character
         up to MB_LEN_MAX in length.  This is overly conservative
         since in some conversions some constants result in no decimal
         point (e.g., in %g).  */
      res.range.unlikely += target_mb_len_max () - 1;
    }

  res.adjust_for_width_or_precision (dir.width);
  return res;
}

/* Return a FMTRESULT struct set to the lengths of the shortest and longest
   strings referenced by the expression STR, or (-1, -1) when not known.
   Used by the format_string function below.  */

static fmtresult
get_string_length (tree str)
{
  if (!str)
    return fmtresult ();

  if (tree slen = c_strlen (str, 1))
    {
      /* Simply return the length of the string.  */
      fmtresult res (tree_to_shwi (slen));
      return res;
    }

  /* Determine the length of the shortest and longest string referenced
     by STR.  Strings of unknown lengths are bounded by the sizes of
     arrays that subexpressions of STR may refer to.  Pointers that
     aren't known to point any such arrays result in LENRANGE[1] set
     to SIZE_MAX.  */
  tree lenrange[2];
  bool flexarray = get_range_strlen (str, lenrange);

  if (lenrange [0] || lenrange [1])
    {
      HOST_WIDE_INT min
        = (tree_fits_uhwi_p (lenrange[0])
           ? tree_to_uhwi (lenrange[0])
           : 0);

      HOST_WIDE_INT max
        = (tree_fits_uhwi_p (lenrange[1])
           ? tree_to_uhwi (lenrange[1])
           : HOST_WIDE_INT_M1U);

      /* get_range_strlen() returns the target value of SIZE_MAX for
         strings of unknown length.  Bump it up to HOST_WIDE_INT_M1U
         which may be bigger.  */
      if ((unsigned HOST_WIDE_INT)min == target_size_max ())
        min = HOST_WIDE_INT_M1U;
      if ((unsigned HOST_WIDE_INT)max == target_size_max ())
        max = HOST_WIDE_INT_M1U;

      fmtresult res (min, max);

      /* Set RES.KNOWNRANGE to true if and only if all strings referenced
         by STR are known to be bounded (though not necessarily by their
         actual length but perhaps by their maximum possible length).  */
      if (res.range.max < target_int_max ())
        {
          res.knownrange = true;
          /* When the the length of the longest string is known and not
             excessive use it as the likely length of the string(s).  */
          res.range.likely = res.range.max;
        }
      else
        {
          /* When the upper bound is unknown (it can be zero or excessive)
             set the likely length to the greater of 1 and the length of
             the shortest string and reset the lower bound to zero.  */
          res.range.likely = res.range.min ? res.range.min : warn_level > 1;
          res.range.min = 0;
        }

      /* If the range of string length has been estimated from the size
         of an array at the end of a struct assume that it's longer than
         the array bound says it is in case it's used as a poor man's
         flexible array member, such as in struct S { char a[4]; };  */
      res.range.unlikely = flexarray ? HOST_WIDE_INT_MAX : res.range.max;

      return res;
    }

  return get_string_length (NULL_TREE);
}

/* Return the minimum and maximum number of characters formatted
   by the '%c' format directives and its wide character form for
   the argument ARG.  ARG can be null (for functions such as
   vsprinf).  */

static fmtresult
format_character (const directive &dir, tree arg)
{
  fmtresult res;

  res.knownrange = true;

  if (dir.modifier == FMT_LEN_l)
    {
      /* A wide character can result in as few as zero bytes.  */
      res.range.min = 0;

      HOST_WIDE_INT min, max;
      if (get_int_range (arg, integer_type_node, &min, &max, false, 0))
        {
          if (min == 0 && max == 0)
            {
              /* The NUL wide character results in no bytes.  */
              res.range.max = 0;
              res.range.likely = 0;
              res.range.unlikely = 0;
            }
          else if (min > 0 && min < 128)
            {
              /* A wide character in the ASCII range most likely results
                 in a single byte, and only unlikely in up to MB_LEN_MAX.  */
              res.range.max = 1;
              res.range.likely = 1;
              res.range.unlikely = target_mb_len_max ();
            }
          else
            {
              /* A wide character outside the ASCII range likely results
                 in up to two bytes, and only unlikely in up to MB_LEN_MAX.  */
              res.range.max = target_mb_len_max ();
              res.range.likely = 2;
              res.range.unlikely = res.range.max;
            }
        }
      else
        {
          /* An unknown wide character is treated the same as a wide
             character outside the ASCII range.  */
          res.range.max = target_mb_len_max ();
          res.range.likely = 2;
          res.range.unlikely = res.range.max;
        }
    }
  else
    {
      /* A plain '%c' directive.  Its ouput is exactly 1.  */
      res.range.min = res.range.max = 1;
      res.range.likely = res.range.unlikely = 1;
      res.knownrange = true;
    }

  /* Bump up the byte counters if WIDTH is greater.  */
  return res.adjust_for_width_or_precision (dir.width);
}

/* Return the minimum and maximum number of characters formatted
   by the '%s' format directive and its wide character form for
   the argument ARG.  ARG can be null (for functions such as
   vsprinf).  */

static fmtresult
format_string (const directive &dir, tree arg)
{
  fmtresult res;

  /* Compute the range the argument's length can be in.  */
  fmtresult slen = get_string_length (arg);
  if (slen.range.min == slen.range.max
      && slen.range.min < HOST_WIDE_INT_MAX)
    {
      /* The argument is either a string constant or it refers
         to one of a number of strings of the same length.  */

      /* A '%s' directive with a string argument with constant length.  */
      res.range = slen.range;

      if (dir.modifier == FMT_LEN_l)
        {
          /* In the worst case the length of output of a wide string S
             is bounded by MB_LEN_MAX * wcslen (S).  */
          res.range.max *= target_mb_len_max ();
          res.range.unlikely = res.range.max;
          /* It's likely that the the total length is not more that
             2 * wcslen (S).*/
          res.range.likely = res.range.min * 2;

          if (dir.prec[1] >= 0
              && (unsigned HOST_WIDE_INT)dir.prec[1] < res.range.max)
            {
              res.range.max = dir.prec[1];
              res.range.likely = dir.prec[1];
              res.range.unlikely = dir.prec[1];
            }

          if (dir.prec[0] < 0 && dir.prec[1] > -1)
            res.range.min = 0;
          else if (dir.prec[0] >= 0)
            res.range.likely = dir.prec[0];

          /* Even a non-empty wide character string need not convert into
             any bytes.  */
          res.range.min = 0;
        }
      else
        {
          res.knownrange = true;

          if (dir.prec[0] < 0 && dir.prec[1] > -1)
            res.range.min = 0;
          else if ((unsigned HOST_WIDE_INT)dir.prec[0] < res.range.min)
            res.range.min = dir.prec[0];

          if ((unsigned HOST_WIDE_INT)dir.prec[1] < res.range.max)
            {
              res.range.max = dir.prec[1];
              res.range.likely = dir.prec[1];
              res.range.unlikely = dir.prec[1];
            }
        }
    }
  else if (arg && integer_zerop (arg))
    {
      /* Handle null pointer argument.  */

      fmtresult res (0);
      res.nullp = true;
      return res;
    }
  else
    {
      /* For a '%s' and '%ls' directive with a non-constant string (either
         one of a number of strings of known length or an unknown string)
         the minimum number of characters is lesser of PRECISION[0] and
         the length of the shortest known string or zero, and the maximum
         is the lessser of the length of the longest known string or
         PTRDIFF_MAX and PRECISION[1].  The likely length is either
         the minimum at level 1 and the greater of the minimum and 1
         at level 2.  This result is adjust upward for width (if it's
         specified).  */

      if (dir.modifier == FMT_LEN_l)
        {
          /* A wide character converts to as few as zero bytes.  */
          slen.range.min = 0;
          if (slen.range.max < target_int_max ())
            slen.range.max *= target_mb_len_max ();

          if (slen.range.likely < target_int_max ())
            slen.range.likely *= 2;

          if (slen.range.likely < target_int_max ())
            slen.range.unlikely *= target_mb_len_max ();
        }

      res.range = slen.range;

      if (dir.prec[0] >= 0)
        {
          /* Adjust the minimum to zero if the string length is unknown,
             or at most the lower bound of the precision otherwise.  */
          if (slen.range.min >= target_int_max ())
            res.range.min = 0;
          else if ((unsigned HOST_WIDE_INT)dir.prec[0] < slen.range.min)
            res.range.min = dir.prec[0];

          /* Make both maxima no greater than the upper bound of precision.  */
          if ((unsigned HOST_WIDE_INT)dir.prec[1] < slen.range.max
              || slen.range.max >= target_int_max ())
            {
              res.range.max = dir.prec[1];
              res.range.unlikely = dir.prec[1];
            }

          /* If precision is constant, set the likely counter to the lesser
             of it and the maximum string length.  Otherwise, if the lower
             bound of precision is greater than zero, set the likely counter
             to the minimum.  Otherwise set it to zero or one based on
             the warning level.  */
          if (dir.prec[0] == dir.prec[1])
            res.range.likely
              = ((unsigned HOST_WIDE_INT)dir.prec[0] < slen.range.max
                 ? dir.prec[0] : slen.range.max);
          else if (dir.prec[0] > 0)
            res.range.likely = res.range.min;
          else
            res.range.likely = warn_level > 1;
        }
      else if (dir.prec[1] >= 0)
        {
          res.range.min = 0;
          if ((unsigned HOST_WIDE_INT)dir.prec[1] < slen.range.max)
            res.range.max = dir.prec[1];
          res.range.likely = dir.prec[1] ? warn_level > 1 : 0;
        }
      else if (slen.range.min >= target_int_max ())
        {
          res.range.min = 0;
          res.range.max = HOST_WIDE_INT_MAX;
          /* At level 1 strings of unknown length are assumed to be
             empty, while at level 1 they are assumed to be one byte
             long.  */
          res.range.likely = warn_level > 1;
        }
      else
        {
          /* A string of unknown length unconstrained by precision is
             assumed to be empty at level 1 and just one character long
             at higher levels.  */
          if (res.range.likely >= target_int_max ())
            res.range.likely = warn_level > 1;
        }

      res.range.unlikely = res.range.max;
    }

  /* Bump up the byte counters if WIDTH is greater.  */
  return res.adjust_for_width_or_precision (dir.width);
}

/* Format plain string (part of the format string itself).  */

static fmtresult
format_plain (const directive &dir, tree)
{
  fmtresult res (dir.len);
  return res;
}

/* Return true if the RESULT of a directive in a call describe by INFO
   should be diagnosed given the AVAILable space in the destination.  */

static bool
should_warn_p (const pass_sprintf_length::call_info &info,
               const result_range &avail, const result_range &result)
{
  if (result.max <= avail.min)
    {
      /* The least amount of space remaining in the destination is big
         enough for the longest output.  */
      return false;
    }

  if (info.bounded)
    {
      if (warn_format_trunc == 1 && result.min <= avail.max
          && info.retval_used ())
        {
          /* The likely amount of space remaining in the destination is big
             enough for the least output and the return value is used.  */
          return false;
        }

      if (warn_format_trunc == 1 && result.likely <= avail.likely
          && !info.retval_used ())
        {
          /* The likely amount of space remaining in the destination is big
             enough for the likely output and the return value is unused.  */
          return false;
        }

      if (warn_format_trunc == 2
          && result.likely <= avail.min
          && (result.max <= avail.min
              || result.max > HOST_WIDE_INT_MAX))
        {
          /* The minimum amount of space remaining in the destination is big
             enough for the longest output.  */
          return false;
        }
    }
  else
    {
      if (warn_level == 1 && result.likely <= avail.likely)
        {
          /* The likely amount of space remaining in the destination is big
             enough for the likely output.  */
          return false;
        }

      if (warn_level == 2
          && result.likely <= avail.min
          && (result.max <= avail.min
              || result.max > HOST_WIDE_INT_MAX))
        {
          /* The minimum amount of space remaining in the destination is big
             enough for the longest output.  */
          return false;
        }
    }

  return true;
}

/* At format string location describe by DIRLOC in a call described
   by INFO, issue a warning for a directive DIR whose output may be
   in excess of the available space AVAIL_RANGE in the destination
   given the formatting result FMTRES.  This function does nothing
   except decide whether to issue a warning for a possible write
   past the end or truncation and, if so, format the warning.
   Return true if a warning has been issued.  */

static bool
maybe_warn (substring_loc &dirloc, source_range *pargrange,
            const pass_sprintf_length::call_info &info,
            const result_range &avail_range, const result_range &res,
            const directive &dir)
{
  if (!should_warn_p (info, avail_range, res))
    return false;

  /* A warning will definitely be issued below.  */

  /* The maximum byte count to reference in the warning.  Larger counts
     imply that the upper bound is unknown (and could be anywhere between
     RES.MIN + 1 and SIZE_MAX / 2) are printed as "N or more bytes" rather
     than "between N and X" where X is some huge number.  */
  unsigned HOST_WIDE_INT maxbytes = target_dir_max ();

  /* True when there is enough room in the destination for the least
     amount of a directive's output but not enough for its likely or
     maximum output.  */
  bool maybe = (res.min <= avail_range.max
                && (avail_range.min < res.likely
                    || (res.max < HOST_WIDE_INT_MAX
                        && avail_range.min < res.max)));

  if (avail_range.min == avail_range.max)
    {
      /* The size of the destination region is exact.  */
      unsigned HOST_WIDE_INT navail = avail_range.max;

      if (*dir.beg != '%')
        {
          /* For plain character directives (i.e., the format string itself)
             but not others, point the caret at the first character that's
             past the end of the destination.  */
          dirloc.set_caret_index (dirloc.get_caret_idx () + navail);
        }

      if (*dir.beg == '\0')
        {
          /* This is the terminating nul.  */
          gcc_assert (res.min == 1 && res.min == res.max);

          const char *fmtstr
            = (info.bounded
               ? (maybe
                  ? G_("%qE output may be truncated before the last format "
                       "character")
                  : G_("%qE output truncated before the last format character"))
               : (maybe
                  ? G_("%qE may write a terminating nul past the end "
                       "of the destination")
                  : G_("%qE writing a terminating nul past the end "
                       "of the destination")));

          return fmtwarn (dirloc, NULL, NULL, info.warnopt (), fmtstr,
                          info.func);
        }

      if (res.min == res.max)
        {
          const char* fmtstr
            = (res.min == 1
               ? (info.bounded
                  ? (maybe
                     ? G_("%<%.*s%> directive output may be truncated writing "
                          "%wu byte into a region of size %wu")
                     : G_("%<%.*s%> directive output truncated writing "
                          "%wu byte into a region of size %wu"))
                  : G_("%<%.*s%> directive writing %wu byte "
                       "into a region of size %wu"))
               : (info.bounded
                  ? (maybe
                     ? G_("%<%.*s%> directive output may be truncated writing "
                          "%wu bytes into a region of size %wu")
                     : G_("%<%.*s%> directive output truncated writing "
                          "%wu bytes into a region of size %wu"))
                  : G_("%<%.*s%> directive writing %wu bytes "
                       "into a region of size %wu")));
          return fmtwarn (dirloc, pargrange, NULL,
                          info.warnopt (), fmtstr,
                          dir.len, dir.beg, res.min,
                          navail);
        }

      if (res.min == 0 && res.max < maxbytes)
        {
          const char* fmtstr
            = (info.bounded
               ? (maybe
                  ? G_("%<%.*s%> directive output may be truncated writing "
                       "up to %wu bytes into a region of size %wu")
                  : G_("%<%.*s%> directive output truncated writing "
                       "up to %wu bytes into a region of size %wu"))
               : G_("%<%.*s%> directive writing up to %wu bytes "
                    "into a region of size %wu"));
          return fmtwarn (dirloc, pargrange, NULL,
                          info.warnopt (), fmtstr,
                          dir.len, dir.beg,
                          res.max, navail);
        }

      if (res.min == 0 && maxbytes <= res.max)
        {
          /* This is a special case to avoid issuing the potentially
             confusing warning:
               writing 0 or more bytes into a region of size 0.  */
          const char* fmtstr
            = (info.bounded
               ? (maybe
                  ? G_("%<%.*s%> directive output may be truncated writing "
                       "likely %wu or more bytes into a region of size %wu")
                  : G_("%<%.*s%> directive output truncated writing "
                       "likely %wu or more bytes into a region of size %wu"))
               : G_("%<%.*s%> directive writing likely %wu or more bytes "
                    "into a region of size %wu"));
          return fmtwarn (dirloc, pargrange, NULL,
                          info.warnopt (), fmtstr,
                          dir.len, dir.beg,
                          res.likely, navail);
        }

      if (res.max < maxbytes)
        {
          const char* fmtstr
            = (info.bounded
               ? (maybe
                  ? G_("%<%.*s%> directive output may be truncated writing "
                       "between %wu and %wu bytes into a region of size %wu")
                  : G_("%<%.*s%> directive output truncated writing "
                       "between %wu and %wu bytes into a region of size %wu"))
               : G_("%<%.*s%> directive writing between %wu and "
                    "%wu bytes into a region of size %wu"));
          return fmtwarn (dirloc, pargrange, NULL,
                          info.warnopt (), fmtstr,
                          dir.len, dir.beg,
                          res.min, res.max,
                          navail);
        }

      const char* fmtstr
        = (info.bounded
           ? (maybe
              ? G_("%<%.*s%> directive output may be truncated writing "
                   "%wu or more bytes into a region of size %wu")
              : G_("%<%.*s%> directive output truncated writing "
                   "%wu or more bytes into a region of size %wu"))
           : G_("%<%.*s%> directive writing %wu or more bytes "
                "into a region of size %wu"));
      return fmtwarn (dirloc, pargrange, NULL,
                      info.warnopt (), fmtstr,
                      dir.len, dir.beg,
                      res.min, navail);
    }

  /* The size of the destination region is a range.  */

  if (*dir.beg != '%')
    {
      unsigned HOST_WIDE_INT navail = avail_range.max;

      /* For plain character directives (i.e., the format string itself)
         but not others, point the caret at the first character that's
         past the end of the destination.  */
      dirloc.set_caret_index (dirloc.get_caret_idx () + navail);
    }

  if (*dir.beg == '\0')
    {
      gcc_assert (res.min == 1 && res.min == res.max);

      const char *fmtstr
        = (info.bounded
           ? (maybe
              ? G_("%qE output may be truncated before the last format "
                   "character")
              : G_("%qE output truncated before the last format character"))
           : (maybe
              ? G_("%qE may write a terminating nul past the end "
                   "of the destination")
              : G_("%qE writing a terminating nul past the end "
                   "of the destination")));

      return fmtwarn (dirloc, NULL, NULL, info.warnopt (), fmtstr,
                      info.func);
    }

  if (res.min == res.max)
    {
      const char* fmtstr
        = (res.min == 1
           ? (info.bounded
              ? (maybe
                 ? G_("%<%.*s%> directive output may be truncated writing "
                      "%wu byte into a region of size between %wu and %wu")
                 : G_("%<%.*s%> directive output truncated writing "
                      "%wu byte into a region of size between %wu and %wu"))
              : G_("%<%.*s%> directive writing %wu byte "
                   "into a region of size between %wu and %wu"))
           : (info.bounded
              ? (maybe
                 ? G_("%<%.*s%> directive output may be truncated writing "
                      "%wu bytes into a region of size between %wu and %wu")
                 : G_("%<%.*s%> directive output truncated writing "
                      "%wu bytes into a region of size between %wu and %wu"))
              : G_("%<%.*s%> directive writing %wu bytes "
                   "into a region of size between %wu and %wu")));

      return fmtwarn (dirloc, pargrange, NULL,
                      info.warnopt (), fmtstr,
                      dir.len, dir.beg, res.min,
                      avail_range.min, avail_range.max);
    }

  if (res.min == 0 && res.max < maxbytes)
    {
      const char* fmtstr
        = (info.bounded
           ? (maybe
              ? G_("%<%.*s%> directive output may be truncated writing "
                   "up to %wu bytes into a region of size between "
                   "%wu and %wu")
              : G_("%<%.*s%> directive output truncated writing "
                   "up to %wu bytes into a region of size between "
                   "%wu and %wu"))
           : G_("%<%.*s%> directive writing up to %wu bytes "
                "into a region of size between %wu and %wu"));
      return fmtwarn (dirloc, pargrange, NULL,
                      info.warnopt (), fmtstr,
                      dir.len, dir.beg, res.max,
                      avail_range.min, avail_range.max);
    }

  if (res.min == 0 && maxbytes <= res.max)
    {
      /* This is a special case to avoid issuing the potentially confusing
         warning:
           writing 0 or more bytes into a region of size between 0 and N.  */
      const char* fmtstr
        = (info.bounded
           ? (maybe
              ? G_("%<%.*s%> directive output may be truncated writing "
                   "likely %wu or more bytes into a region of size between "
                   "%wu and %wu")
              : G_("%<%.*s%> directive output truncated writing likely "
                   "%wu or more bytes into a region of size between "
                   "%wu and %wu"))
           : G_("%<%.*s%> directive writing likely %wu or more bytes "
                "into a region of size between %wu and %wu"));
      return fmtwarn (dirloc, pargrange, NULL,
                      info.warnopt (), fmtstr,
                      dir.len, dir.beg, res.likely,
                      avail_range.min, avail_range.max);
    }

  if (res.max < maxbytes)
    {
      const char* fmtstr
        = (info.bounded
           ? (maybe
              ? G_("%<%.*s%> directive output may be truncated writing "
                   "between %wu and %wu bytes into a region of size "
                   "between %wu and %wu")
              : G_("%<%.*s%> directive output truncated writing "
                   "between %wu and %wu bytes into a region of size "
                   "between %wu and %wu"))
           : G_("%<%.*s%> directive writing between %wu and "
                "%wu bytes into a region of size between %wu and %wu"));
      return fmtwarn (dirloc, pargrange, NULL,
                      info.warnopt (), fmtstr,
                      dir.len, dir.beg,
                      res.min, res.max,
                      avail_range.min, avail_range.max);
    }

  const char* fmtstr
    = (info.bounded
       ? (maybe
          ? G_("%<%.*s%> directive output may be truncated writing "
               "%wu or more bytes into a region of size between "
               "%wu and %wu")
          : G_("%<%.*s%> directive output truncated writing "
               "%wu or more bytes into a region of size between "
               "%wu and %wu"))
       : G_("%<%.*s%> directive writing %wu or more bytes "
            "into a region of size between %wu and %wu"));
  return fmtwarn (dirloc, pargrange, NULL,
                  info.warnopt (), fmtstr,
                  dir.len, dir.beg,
                  res.min,
                  avail_range.min, avail_range.max);
}

/* Compute the length of the output resulting from the directive DIR
   in a call described by INFO and update the overall result of the call
   in *RES.  Return true if the directive has been handled.  */

static bool
format_directive (const pass_sprintf_length::call_info &info,
                  format_result *res, const directive &dir)
{
  /* Offset of the beginning of the directive from the beginning
     of the format string.  */
  size_t offset = dir.beg - info.fmtstr;
  size_t start = offset;
  size_t length = offset + dir.len - !!dir.len;

  /* Create a location for the whole directive from the % to the format
     specifier.  */
  substring_loc dirloc (info.fmtloc, TREE_TYPE (info.format),
                        offset, start, length);

  /* Also create a location range for the argument if possible.
     This doesn't work for integer literals or function calls.  */
  source_range argrange;
  source_range *pargrange;
  if (dir.arg && CAN_HAVE_LOCATION_P (dir.arg))
    {
      argrange = EXPR_LOCATION_RANGE (dir.arg);
      pargrange = &argrange;
    }
  else
    pargrange = NULL;

  /* Bail when there is no function to compute the output length,
     or when minimum length checking has been disabled.   */
  if (!dir.fmtfunc || res->range.min >= HOST_WIDE_INT_MAX)
    return false;

  /* Compute the range of lengths of the formatted output.  */
  fmtresult fmtres = dir.fmtfunc (dir, dir.arg);

  /* Record whether the output of all directives is known to be
     bounded by some maximum, implying that their arguments are
     either known exactly or determined to be in a known range
     or, for strings, limited by the upper bounds of the arrays
     they refer to.  */
  res->knownrange &= fmtres.knownrange;

  if (!fmtres.knownrange)
    {
      /* Only when the range is known, check it against the host value
         of INT_MAX + (the number of bytes of the "%.*Lf" directive with
         INT_MAX precision, which is the longest possible output of any
         single directive).  That's the largest valid byte count (though
         not valid call to a printf-like function because it can never
         return such a count).  Otherwise, the range doesn't correspond
         to known values of the argument.  */
      if (fmtres.range.max > target_dir_max ())
        {
          /* Normalize the MAX counter to avoid having to deal with it
             later.  The counter can be less than HOST_WIDE_INT_M1U
             when compiling for an ILP32 target on an LP64 host.  */
          fmtres.range.max = HOST_WIDE_INT_M1U;
          /* Disable exact and maximum length checking after a failure
             to determine the maximum number of characters (for example
             for wide characters or wide character strings) but continue
             tracking the minimum number of characters.  */
          res->range.max = HOST_WIDE_INT_M1U;
        }

      if (fmtres.range.min > target_dir_max ())
        {
          /* Disable exact length checking after a failure to determine
             even the minimum number of characters (it shouldn't happen
             except in an error) but keep tracking the minimum and maximum
             number of characters.  */
          return true;
        }
    }

  int dirlen = dir.len;

  if (fmtres.nullp)
    {
      fmtwarn (dirloc, pargrange, NULL, info.warnopt (),
               "%<%.*s%> directive argument is null",
               dirlen, dir.beg);

      /* Don't bother processing the rest of the format string.  */
      res->warned = true;
      res->range.min = HOST_WIDE_INT_M1U;
      res->range.max = HOST_WIDE_INT_M1U;
      return false;
    }

  /* Compute the number of available bytes in the destination.  There
     must always be at least one byte of space for the terminating
     NUL that's appended after the format string has been processed.  */
  result_range avail_range = bytes_remaining (info.objsize, *res);

  bool warned = res->warned;

  if (!warned)
    warned = maybe_warn (dirloc, pargrange, info, avail_range,
                         fmtres.range, dir);

  /* Bump up the total maximum if it isn't too big.  */
  if (res->range.max < HOST_WIDE_INT_MAX
      && fmtres.range.max < HOST_WIDE_INT_MAX)
    res->range.max += fmtres.range.max;

  /* Raise the total unlikely maximum by the larger of the maximum
     and the unlikely maximum.  */
  unsigned HOST_WIDE_INT save = res->range.unlikely;
  if (fmtres.range.max < fmtres.range.unlikely)
    res->range.unlikely += fmtres.range.unlikely;
  else
    res->range.unlikely += fmtres.range.max;

  if (res->range.unlikely < save)
    res->range.unlikely = HOST_WIDE_INT_M1U;

  res->range.min += fmtres.range.min;
  res->range.likely += fmtres.range.likely;

  /* Has the minimum directive output length exceeded the maximum
     of 4095 bytes required to be supported?  */
  bool minunder4k = fmtres.range.min < 4096;
  bool maxunder4k = fmtres.range.max < 4096;
  /* Clear UNDER4K in the overall result if the maximum has exceeded
     the 4k (this is necessary to avoid the return valuye optimization
     that may not be safe in the maximum case).  */
  if (!maxunder4k)
    res->under4k = false;

  if (!warned
      /* Only warn at level 2.  */
      && 1 < warn_level
      && (!minunder4k
          || (!maxunder4k && fmtres.range.max < HOST_WIDE_INT_MAX)))
    {
      /* The directive output may be longer than the maximum required
         to be handled by an implementation according to 7.21.6.1, p15
         of C11.  Warn on this only at level 2 but remember this and
         prevent folding the return value when done.  This allows for
         the possibility of the actual libc call failing due to ENOMEM
         (like Glibc does under some conditions).  */

      if (fmtres.range.min == fmtres.range.max)
        warned = fmtwarn (dirloc, pargrange, NULL,
                          info.warnopt (),
                          "%<%.*s%> directive output of %wu bytes exceeds "
                          "minimum required size of 4095",
                          dirlen, dir.beg, fmtres.range.min);
      else
        {
          const char *fmtstr
            = (minunder4k
               ? G_("%<%.*s%> directive output between %wu and %wu "
                    "bytes may exceed minimum required size of 4095")
               : G_("%<%.*s%> directive output between %wu and %wu "
                    "bytes exceeds minimum required size of 4095"));

          warned = fmtwarn (dirloc, pargrange, NULL,
                            info.warnopt (), fmtstr,
                            dirlen, dir.beg,
                            fmtres.range.min, fmtres.range.max);
        }
    }

  /* Has the likely and maximum directive output exceeded INT_MAX?  */
  bool likelyximax = *dir.beg && res->range.likely > target_int_max ();
  /* Don't consider the maximum to be in excess when it's the result
     of a string of unknown length (i.e., whose maximum has been set
     to be greater than or equal to HOST_WIDE_INT_MAX.  */
  bool maxximax = (*dir.beg
                   && res->range.max > target_int_max ()
                   && res->range.max < HOST_WIDE_INT_MAX);

  if (!warned
      /* Warn for the likely output size at level 1.  */
      && (likelyximax
          /* But only warn for the maximum at level 2.  */
          || (1 < warn_level
              && maxximax
              && fmtres.range.max < HOST_WIDE_INT_MAX)))
    {
      /* The directive output causes the total length of output
         to exceed INT_MAX bytes.  */

      if (fmtres.range.min == fmtres.range.max)
        warned = fmtwarn (dirloc, pargrange, NULL, info.warnopt (),
                          "%<%.*s%> directive output of %wu bytes causes "
                          "result to exceed %<INT_MAX%>",
                          dirlen, dir.beg, fmtres.range.min);
      else
        {
          const char *fmtstr
            = (fmtres.range.min > target_int_max ()
               ? G_ ("%<%.*s%> directive output between %wu and %wu "
                     "bytes causes result to exceed %<INT_MAX%>")
               : G_ ("%<%.*s%> directive output between %wu and %wu "
                     "bytes may cause result to exceed %<INT_MAX%>"));
          warned = fmtwarn (dirloc, pargrange, NULL,
                            info.warnopt (), fmtstr,
                            dirlen, dir.beg,
                            fmtres.range.min, fmtres.range.max);
        }
    }

  if (warned && fmtres.range.min < fmtres.range.likely
      && fmtres.range.likely < fmtres.range.max)
    {
      inform (info.fmtloc,
              (1 == fmtres.range.likely
               ? G_("assuming directive output of %wu byte")
               : G_("assuming directive output of %wu bytes")),
              fmtres.range.likely);
    }

  if (warned && fmtres.argmin)
    {
      if (fmtres.argmin == fmtres.argmax)
        inform (info.fmtloc, "directive argument %qE", fmtres.argmin);
      else if (fmtres.knownrange)
        inform (info.fmtloc, "directive argument in the range [%E, %E]",
                fmtres.argmin, fmtres.argmax);
      else
        inform (info.fmtloc,
                "using the range [%E, %E] for directive argument",
                fmtres.argmin, fmtres.argmax);
    }

  res->warned |= warned;

  if (!dir.beg[0] && res->warned && info.objsize < HOST_WIDE_INT_MAX)
    {
      /* If a warning has been issued for buffer overflow or truncation
         (but not otherwise) help the user figure out how big a buffer
         they need.  */

      location_t callloc = gimple_location (info.callstmt);

      unsigned HOST_WIDE_INT min = res->range.min;
      unsigned HOST_WIDE_INT max = res->range.max;

      if (min == max)
        inform (callloc,
                (min == 1
                 ? G_("%qE output %wu byte into a destination of size %wu")
                 : G_("%qE output %wu bytes into a destination of size %wu")),
                info.func, min, info.objsize);
      else if (max < HOST_WIDE_INT_MAX)
        inform (callloc,
                "%qE output between %wu and %wu bytes into "
                "a destination of size %wu",
                info.func, min, max, info.objsize);
      else if (min < res->range.likely && res->range.likely < max)
        inform (callloc,
                "%qE output %wu or more bytes (assuming %wu) into "
                "a destination of size %wu",
                info.func, min, res->range.likely, info.objsize);
      else
        inform (callloc,
                "%qE output %wu or more bytes into a destination of size %wu",
                info.func, min, info.objsize);
    }

  if (dump_file && *dir.beg)
    {
      fprintf (dump_file, "    Result: %lli, %lli, %lli, %lli "
               "(%lli, %lli, %lli, %lli)\n",
               (long long)fmtres.range.min,
               (long long)fmtres.range.likely,
               (long long)fmtres.range.max,
               (long long)fmtres.range.unlikely,
               (long long)res->range.min,
               (long long)res->range.likely,
               (long long)res->range.max,
               (long long)res->range.unlikely);
    }

  return true;
}

#pragma GCC diagnostic pop

/* Parse a format directive in function call described by INFO starting
   at STR and populate DIR structure.  Bump up *ARGNO by the number of
   arguments extracted for the directive.  Return the length of
   the directive.  */

static size_t
parse_directive (pass_sprintf_length::call_info &info,
                 directive &dir, format_result *res,
                 const char *str, unsigned *argno)
{
  const char *pcnt = strchr (str, '%');
  dir.beg = str;

  if (size_t len = pcnt ? pcnt - str : *str ? strlen (str) : 1)
    {
      /* This directive is either a plain string or the terminating nul
         (which isn't really a directive but it simplifies things to
         handle it as if it were).  */
      dir.len = len;
      dir.fmtfunc = format_plain;

      if (dump_file)
        {
          fprintf (dump_file, "  Directive %u at offset %llu: \"%.*s\", "
                   "length = %llu\n",
                   dir.dirno,
                   (unsigned long long)(size_t)(dir.beg - info.fmtstr),
                   (int)dir.len, dir.beg, (unsigned long long)dir.len);
        }

      return len - !*str;
    }

  const char *pf = pcnt + 1;

    /* POSIX numbered argument index or zero when none.  */
  unsigned dollar = 0;

  /* With and precision.  -1 when not specified, HOST_WIDE_INT_MIN
     when given by a va_list argument, and a non-negative value
     when specified in the format string itself.  */
  HOST_WIDE_INT width = -1;
  HOST_WIDE_INT precision = -1;

  /* Width specified via the asterisk.  Need not be INTEGER_CST.
     For vararg functions set to void_node.  */
  tree star_width = NULL_TREE;

  /* Width specified via the asterisk.  Need not be INTEGER_CST.
     For vararg functions set to void_node.  */
  tree star_precision = NULL_TREE;

  if (ISDIGIT (*pf))
    {
      /* This could be either a POSIX positional argument, the '0'
         flag, or a width, depending on what follows.  Store it as
         width and sort it out later after the next character has
         been seen.  */
      char *end;
      width = strtol (pf, &end, 10);
      pf = end;
    }
  else if ('*' == *pf)
    {
      /* Similarly to the block above, this could be either a POSIX
         positional argument or a width, depending on what follows.  */
      if (*argno < gimple_call_num_args (info.callstmt))
        star_width = gimple_call_arg (info.callstmt, (*argno)++);
      else
        star_width = void_node;
      ++pf;
    }

  if (*pf == '$')
    {
      /* Handle the POSIX dollar sign which references the 1-based
         positional argument number.  */
      if (width != -1)
        dollar = width + info.argidx;
      else if (star_width
               && TREE_CODE (star_width) == INTEGER_CST)
        dollar = width + tree_to_shwi (star_width);

      /* Bail when the numbered argument is out of range (it will
         have already been diagnosed by -Wformat).  */
      if (dollar == 0
          || dollar == info.argidx
          || dollar > gimple_call_num_args (info.callstmt))
        return false;

      --dollar;

      star_width = NULL_TREE;
      width = -1;
      ++pf;
    }

  if (dollar || !star_width)
    {
      if (width != -1)
        {
          if (width == 0)
            {
              /* The '0' that has been interpreted as a width above is
                 actually a flag.  Reset HAVE_WIDTH, set the '0' flag,
                 and continue processing other flags.  */
              width = -1;
              dir.set_flag ('0');
            }
          else if (!dollar)
            {
              /* (Non-zero) width has been seen.  The next character
                 is either a period or a digit.  */
              goto start_precision;
            }
        }
      /* When either '$' has been seen, or width has not been seen,
         the next field is the optional flags followed by an optional
         width.  */
      for ( ; ; ) {
        switch (*pf)
          {
          case ' ':
          case '0':
          case '+':
          case '-':
          case '#':
            dir.set_flag (*pf++);
            break;

          default:
            goto start_width;
          }
      }

    start_width:
      if (ISDIGIT (*pf))
        {
          char *end;
          width = strtol (pf, &end, 10);
          pf = end;
        }
      else if ('*' == *pf)
        {
          if (*argno < gimple_call_num_args (info.callstmt))
            star_width = gimple_call_arg (info.callstmt, (*argno)++);
          else
            {
              /* This is (likely) a va_list.  It could also be an invalid
                 call with insufficient arguments.  */
              star_width = void_node;
            }
          ++pf;
        }
      else if ('\'' == *pf)
        {
          /* The POSIX apostrophe indicating a numeric grouping
             in the current locale.  Even though it's possible to
             estimate the upper bound on the size of the output
             based on the number of digits it probably isn't worth
             continuing.  */
          return 0;
        }
    }

 start_precision:
  if ('.' == *pf)
    {
      ++pf;

      if (ISDIGIT (*pf))
        {
          char *end;
          precision = strtol (pf, &end, 10);
          pf = end;
        }
      else if ('*' == *pf)
        {
          if (*argno < gimple_call_num_args (info.callstmt))
            star_precision = gimple_call_arg (info.callstmt, (*argno)++);
          else
            {
              /* This is (likely) a va_list.  It could also be an invalid
                 call with insufficient arguments.  */
              star_precision = void_node;
            }
          ++pf;
        }
      else
        {
          /* The decimal precision or the asterisk are optional.
             When neither is dirified it's taken to be zero.  */
          precision = 0;
        }
    }

  switch (*pf)
    {
    case 'h':
      if (pf[1] == 'h')
        {
          ++pf;
          dir.modifier = FMT_LEN_hh;
        }
      else
        dir.modifier = FMT_LEN_h;
      ++pf;
      break;

    case 'j':
      dir.modifier = FMT_LEN_j;
      ++pf;
      break;

    case 'L':
      dir.modifier = FMT_LEN_L;
      ++pf;
      break;

    case 'l':
      if (pf[1] == 'l')
        {
          ++pf;
          dir.modifier = FMT_LEN_ll;
        }
      else
        dir.modifier = FMT_LEN_l;
      ++pf;
      break;

    case 't':
      dir.modifier = FMT_LEN_t;
      ++pf;
      break;

    case 'z':
      dir.modifier = FMT_LEN_z;
      ++pf;
      break;
    }

  switch (*pf)
    {
      /* Handle a sole '%' character the same as "%%" but since it's
         undefined prevent the result from being folded.  */
    case '\0':
      --pf;
      res->range.min = res->range.max = HOST_WIDE_INT_M1U;
      /* FALLTHRU */
    case '%':
      dir.fmtfunc = format_percent;
      break;

    case 'a':
    case 'A':
    case 'e':
    case 'E':
    case 'f':
    case 'F':
    case 'g':
    case 'G':
      res->floating = true;
      dir.fmtfunc = format_floating;
      break;

    case 'd':
    case 'i':
    case 'o':
    case 'u':
    case 'x':
    case 'X':
      dir.fmtfunc = format_integer;
      break;

    case 'p':
      /* The %p output is implementation-defined.  It's possible
         to determine this format but due to extensions (edirially
         those of the Linux kernel -- see bug 78512) the first %p
         in the format string disables any further processing.  */
      return false;

    case 'n':
      /* %n has side-effects even when nothing is actually printed to
         any buffer.  */
      info.nowrite = false;
      dir.fmtfunc = format_none;
      break;

    case 'c':
      dir.fmtfunc = format_character;
      break;

    case 'S':
    case 's':
      dir.fmtfunc = format_string;
      break;

    default:
      /* Unknown conversion specification.  */
      return 0;
    }

  dir.specifier = *pf++;

  if (star_width)
    {
      if (TREE_CODE (TREE_TYPE (star_width)) == INTEGER_TYPE)
        dir.set_width (star_width);
      else
        {
          /* Width specified by a va_list takes on the range [0, -INT_MIN]
             (width is the absolute value of that specified).  */
          dir.width[0] = 0;
          dir.width[1] = target_int_max () + 1;
        }
    }
  else
    dir.set_width (width);

  if (star_precision)
    {
      if (TREE_CODE (TREE_TYPE (star_precision)) == INTEGER_TYPE)
        dir.set_precision (star_precision);
      else
        {
          /* Precision specified by a va_list takes on the range [-1, INT_MAX]
             (unlike width, negative precision is ignored).  */
          dir.prec[0] = -1;
          dir.prec[1] = target_int_max ();
        }
    }
  else
    dir.set_precision (precision);

  /* Extract the argument if the directive takes one and if it's
     available (e.g., the function doesn't take a va_list).  Treat
     missing arguments the same as va_list, even though they will
     have likely already been diagnosed by -Wformat.  */
  if (dir.specifier != '%'
      && *argno < gimple_call_num_args (info.callstmt))
    dir.arg = gimple_call_arg (info.callstmt, dollar ? dollar : (*argno)++);

  /* Return the length of the format directive.  */
  dir.len = pf - pcnt;

  if (dump_file)
    {
      fprintf (dump_file, "  Directive %u at offset %llu: \"%.*s\"",
               dir.dirno, (unsigned long long)(size_t)(dir.beg - info.fmtstr),
               (int)dir.len, dir.beg);
      if (star_width)
        {
          if (dir.width[0] == dir.width[1])
            fprintf (dump_file, ", width = %lli", (long long)dir.width[0]);
          else
            fprintf (dump_file, ", width in range [%lli, %lli]",
                     (long long)dir.width[0], (long long)dir.width[1]);
        }

      if (star_precision)
        {
          if (dir.prec[0] == dir.prec[1])
            fprintf (dump_file, ", precision = %lli", (long long)dir.prec[0]);
          else
            fprintf (dump_file, ", precision in range [%lli, %lli]",
                     (long long)dir.prec[0], (long long)dir.prec[1]);
        }
      fputc ('\n', dump_file);
    }

  return dir.len;
}

/* Compute the length of the output resulting from the call to a formatted
   output function described by INFO and store the result of the call in
   *RES.  Issue warnings for detected past the end writes.  Return true
   if the complete format string has been processed and *RES can be relied
   on, false otherwise (e.g., when a unknown or unhandled directive was seen
   that caused the processing to be terminated early).  */

bool
pass_sprintf_length::compute_format_length (call_info &info,
                                            format_result *res)
{
  if (dump_file)
    {
      location_t callloc = gimple_location (info.callstmt);
      fprintf (dump_file, "%s:%i: ",
               LOCATION_FILE (callloc), LOCATION_LINE (callloc));
      print_generic_expr (dump_file, info.func, dump_flags);

      fprintf (dump_file, ": objsize = %llu, fmtstr = \"%s\"\n",
               (unsigned long long)info.objsize, info.fmtstr);
    }

  /* Reset the minimum and maximum byte counters.  */
  res->range.min = res->range.max = 0;

  /* No directive has been seen yet so the length of output is bounded
     by the known range [0, 0] (with no conversion producing more than
     4K bytes) until determined otherwise.  */
  res->knownrange = true;
  res->under4k = true;
  res->floating = false;
  res->warned = false;

  /* 1-based directive counter.  */
  unsigned dirno = 1;

  /* The variadic argument counter.  */
  unsigned argno = info.argidx;

  for (const char *pf = info.fmtstr; ; ++dirno)
    {
      directive dir = directive ();
      dir.dirno = dirno;

      size_t n = parse_directive (info, dir, res, pf, &argno);

      /* Return failure if the format function fails.  */
      if (!format_directive (info, res, dir))
        return false;

      /* Return success the directive is zero bytes long and it's
         the last think in the format string (i.e., it's the terminating
         nul, which isn't really a directive but handling it as one makes
         things simpler).  */
      if (!n)
        return *pf == '\0';

      pf += n;
    }

  /* The complete format string was processed (with or without warnings).  */
  return true;
}

/* Return the size of the object referenced by the expression DEST if
   available, or -1 otherwise.  */

static unsigned HOST_WIDE_INT
get_destination_size (tree dest)
{
  /* Initialize object size info before trying to compute it.  */
  init_object_sizes ();

  /* Use __builtin_object_size to determine the size of the destination
     object.  When optimizing, determine the smallest object (such as
     a member array as opposed to the whole enclosing object), otherwise
     use type-zero object size to determine the size of the enclosing
     object (the function fails without optimization in this type).  */
  int ost = optimize > 0;
  unsigned HOST_WIDE_INT size;
  if (compute_builtin_object_size (dest, ost, &size))
    return size;

  return HOST_WIDE_INT_M1U;
}

/* Given a suitable result RES of a call to a formatted output function
   described by INFO, substitute the result for the return value of
   the call.  The result is suitable if the number of bytes it represents
   is known and exact.  A result that isn't suitable for substitution may
   have its range set to the range of return values, if that is known.
   Return true if the call is removed and gsi_next should not be performed
   in the caller.  */

static bool
try_substitute_return_value (gimple_stmt_iterator *gsi,
                             const pass_sprintf_length::call_info &info,
                             const format_result &res)
{
  tree lhs = gimple_get_lhs (info.callstmt);

  /* Set to true when the entire call has been removed.  */
  bool removed = false;

  /* The minimum return value.  */
  unsigned HOST_WIDE_INT minretval = res.range.min;

  /* The maximum return value is in most cases bounded by RES.RANGE.MAX
     but in cases involving multibyte characters could be as large as
     RES.RANGE.UNLIKELY.  */
  unsigned HOST_WIDE_INT maxretval
    = res.range.unlikely < res.range.max ? res.range.max : res.range.unlikely;

  /* Adjust the number of bytes which includes the terminating nul
     to reflect the return value of the function which does not.
     Because the valid range of the function is [INT_MIN, INT_MAX],
     a valid range before the adjustment below is [0, INT_MAX + 1]
     (the functions only return negative values on error or undefined
     behavior).  */
  if (minretval <= target_int_max () + 1)
    --minretval;
  if (maxretval <= target_int_max () + 1)
    --maxretval;

  /* Avoid the return value optimization when the behavior of the call
     is undefined either because any directive may have produced 4K or
     more of output, or the return value exceeds INT_MAX, or because
     the output overflows the destination object (but leave it enabled
     when the function is bounded because then the behavior is well-
     defined).  */
  if (res.under4k
      && minretval == maxretval
      && (info.bounded || minretval < info.objsize)
      && minretval <= target_int_max ()
      /* Not prepared to handle possibly throwing calls here; they shouldn't
         appear in non-artificial testcases, except when the __*_chk routines
         are badly declared.  */
      && !stmt_ends_bb_p (info.callstmt))
    {
      tree cst = build_int_cst (integer_type_node, minretval);

      if (lhs == NULL_TREE
          && info.nowrite)
        {
          /* Remove the call to the bounded function with a zero size
             (e.g., snprintf(0, 0, "%i", 123)) if there is no lhs.  */
          unlink_stmt_vdef (info.callstmt);
          gsi_remove (gsi, true);
          removed = true;
        }
      else if (info.nowrite)
        {
          /* Replace the call to the bounded function with a zero size
             (e.g., snprintf(0, 0, "%i", 123) with the constant result
             of the function.  */
          if (!update_call_from_tree (gsi, cst))
            gimplify_and_update_call_from_tree (gsi, cst);
          gimple *callstmt = gsi_stmt (*gsi);
          update_stmt (callstmt);
        }
      else if (lhs)
        {
          /* Replace the left-hand side of the call with the constant
             result of the formatted function.  */
          gimple_call_set_lhs (info.callstmt, NULL_TREE);
          gimple *g = gimple_build_assign (lhs, cst);
          gsi_insert_after (gsi, g, GSI_NEW_STMT);
          update_stmt (info.callstmt);
        }

      if (dump_file)
        {
          if (removed)
            fprintf (dump_file, "  Removing call statement.");
          else
            {
              fprintf (dump_file, "  Substituting ");
              print_generic_expr (dump_file, cst, dump_flags);
              fprintf (dump_file, " for %s.\n",
                       info.nowrite ? "statement" : "return value");
            }
        }
    }
  else if (lhs)
    {
      bool setrange = false;

      if ((info.bounded || maxretval < info.objsize)
          && res.under4k
          && (minretval < target_int_max ()
              && maxretval < target_int_max ()))
        {
          /* If the result is in a valid range bounded by the size of
             the destination set it so that it can be used for subsequent
             optimizations.  */
          int prec = TYPE_PRECISION (integer_type_node);

          wide_int min = wi::shwi (minretval, prec);
          wide_int max = wi::shwi (maxretval, prec);
          set_range_info (lhs, VR_RANGE, min, max);

          setrange = true;
        }

      if (dump_file)
        {
          const char *inbounds
            = (minretval < info.objsize
               ? (maxretval < info.objsize
                  ? "in" : "potentially out-of")
               : "out-of");

          const char *what = setrange ? "Setting" : "Discarding";
          if (minretval != maxretval)
            fprintf (dump_file,
                     "  %s %s-bounds return value range [%llu, %llu].\n",
                     what, inbounds,
                     (unsigned long long)minretval,
                     (unsigned long long)maxretval);
          else
            fprintf (dump_file, "  %s %s-bounds return value %llu.\n",
                     what, inbounds, (unsigned long long)minretval);
        }
    }

  if (dump_file)
    fputc ('\n', dump_file);

  return removed;
}

/* Determine if a GIMPLE CALL is to one of the sprintf-like built-in
   functions and if so, handle it.  Return true if the call is removed
   and gsi_next should not be performed in the caller.  */

bool
pass_sprintf_length::handle_gimple_call (gimple_stmt_iterator *gsi)
{
  call_info info = call_info ();

  info.callstmt = gsi_stmt (*gsi);
  if (!gimple_call_builtin_p (info.callstmt, BUILT_IN_NORMAL))
    return false;

  info.func = gimple_call_fndecl (info.callstmt);
  info.fncode = DECL_FUNCTION_CODE (info.func);

  /* The size of the destination as in snprintf(dest, size, ...).  */
  unsigned HOST_WIDE_INT dstsize = HOST_WIDE_INT_M1U;

  /* The size of the destination determined by __builtin_object_size.  */
  unsigned HOST_WIDE_INT objsize = HOST_WIDE_INT_M1U;

  /* Buffer size argument number (snprintf and vsnprintf).  */
  unsigned HOST_WIDE_INT idx_dstsize = HOST_WIDE_INT_M1U;

  /* Object size argument number (snprintf_chk and vsnprintf_chk).  */
  unsigned HOST_WIDE_INT idx_objsize = HOST_WIDE_INT_M1U;

  /* Format string argument number (valid for all functions).  */
  unsigned idx_format;

  switch (info.fncode)
    {
    case BUILT_IN_SPRINTF:
      // Signature:
      //   __builtin_sprintf (dst, format, ...)
      idx_format = 1;
      info.argidx = 2;
      break;

    case BUILT_IN_SPRINTF_CHK:
      // Signature:
      //   __builtin___sprintf_chk (dst, ost, objsize, format, ...)
      idx_objsize = 2;
      idx_format = 3;
      info.argidx = 4;
      break;

    case BUILT_IN_SNPRINTF:
      // Signature:
      //   __builtin_snprintf (dst, size, format, ...)
      idx_dstsize = 1;
      idx_format = 2;
      info.argidx = 3;
      info.bounded = true;
      break;

    case BUILT_IN_SNPRINTF_CHK:
      // Signature:
      //   __builtin___snprintf_chk (dst, size, ost, objsize, format, ...)
      idx_dstsize = 1;
      idx_objsize = 3;
      idx_format = 4;
      info.argidx = 5;
      info.bounded = true;
      break;

    case BUILT_IN_VSNPRINTF:
      // Signature:
      //   __builtin_vsprintf (dst, size, format, va)
      idx_dstsize = 1;
      idx_format = 2;
      info.argidx = -1;
      info.bounded = true;
      break;

    case BUILT_IN_VSNPRINTF_CHK:
      // Signature:
      //   __builtin___vsnprintf_chk (dst, size, ost, objsize, format, va)
      idx_dstsize = 1;
      idx_objsize = 3;
      idx_format = 4;
      info.argidx = -1;
      info.bounded = true;
      break;

    case BUILT_IN_VSPRINTF:
      // Signature:
      //   __builtin_vsprintf (dst, format, va)
      idx_format = 1;
      info.argidx = -1;
      break;

    case BUILT_IN_VSPRINTF_CHK:
      // Signature:
      //   __builtin___vsprintf_chk (dst, ost, objsize, format, va)
      idx_format = 3;
      idx_objsize = 2;
      info.argidx = -1;
      break;

    default:
      return false;
    }

  /* Set the global warning level for this function.  */
  warn_level = info.bounded ? warn_format_trunc : warn_format_overflow;

  /* The first argument is a pointer to the destination.  */
  tree dstptr = gimple_call_arg (info.callstmt, 0);

  info.format = gimple_call_arg (info.callstmt, idx_format);

  /* True when the destination size is constant as opposed to the lower
     or upper bound of a range.  */
  bool dstsize_cst_p = true;

  if (idx_dstsize == HOST_WIDE_INT_M1U)
    {
      /* For non-bounded functions like sprintf, determine the size
         of the destination from the object or pointer passed to it
         as the first argument.  */
      dstsize = get_destination_size (dstptr);
    }
  else if (tree size = gimple_call_arg (info.callstmt, idx_dstsize))
    {
      /* For bounded functions try to get the size argument.  */

      if (TREE_CODE (size) == INTEGER_CST)
        {
          dstsize = tree_to_uhwi (size);
          /* No object can be larger than SIZE_MAX bytes (half the address
             space) on the target.
             The functions are defined only for output of at most INT_MAX
             bytes.  Specifying a bound in excess of that limit effectively
             defeats the bounds checking (and on some implementations such
             as Solaris cause the function to fail with EINVAL).  */
          if (dstsize > target_size_max () / 2)
            {
              /* Avoid warning if -Wstringop-overflow is specified since
                 it also warns for the same thing though only for the
                 checking built-ins.  */
              if ((idx_objsize == HOST_WIDE_INT_M1U
                   || !warn_stringop_overflow))
                warning_at (gimple_location (info.callstmt), info.warnopt (),
                            "specified bound %wu exceeds maximum object size "
                            "%wu",
                            dstsize, target_size_max () / 2);
            }
          else if (dstsize > target_int_max ())
            warning_at (gimple_location (info.callstmt), info.warnopt (),
                        "specified bound %wu exceeds %<INT_MAX %>",
                        dstsize);
        }
      else if (TREE_CODE (size) == SSA_NAME)
        {
          /* Try to determine the range of values of the argument
             and use the greater of the two at level 1 and the smaller
             of them at level 2.  */
          wide_int min, max;
          enum value_range_type range_type
            = get_range_info (size, &min, &max);
          if (range_type == VR_RANGE)
            {
              dstsize
                = (warn_level < 2
                   ? wi::fits_uhwi_p (max) ? max.to_uhwi () : max.to_shwi ()
                   : wi::fits_uhwi_p (min) ? min.to_uhwi () : min.to_shwi ());
            }

          /* The destination size is not constant.  If the function is
             bounded (e.g., snprintf) a lower bound of zero doesn't
             necessarily imply it can be eliminated.  */
          dstsize_cst_p = false;
        }
    }

  if (idx_objsize != HOST_WIDE_INT_M1U)
    if (tree size = gimple_call_arg (info.callstmt, idx_objsize))
      if (tree_fits_uhwi_p (size))
        objsize = tree_to_uhwi (size);

  if (info.bounded && !dstsize)
    {
      /* As a special case, when the explicitly specified destination
         size argument (to a bounded function like snprintf) is zero
         it is a request to determine the number of bytes on output
         without actually producing any.  Pretend the size is
         unlimited in this case.  */
      info.objsize = HOST_WIDE_INT_MAX;
      info.nowrite = dstsize_cst_p;
    }
  else
    {
      /* For calls to non-bounded functions or to those of bounded
         functions with a non-zero size, warn if the destination
         pointer is null.  */
      if (integer_zerop (dstptr))
        {
          /* This is diagnosed with -Wformat only when the null is a constant
             pointer.  The warning here diagnoses instances where the pointer
             is not constant.  */
          location_t loc = gimple_location (info.callstmt);
          warning_at (EXPR_LOC_OR_LOC (dstptr, loc),
                      info.warnopt (), "null destination pointer");
          return false;
        }

      /* Set the object size to the smaller of the two arguments
         of both have been specified and they're not equal.  */
      info.objsize = dstsize < objsize ? dstsize : objsize;

      if (info.bounded
          && dstsize < target_size_max () / 2 && objsize < dstsize
          /* Avoid warning if -Wstringop-overflow is specified since
             it also warns for the same thing though only for the
             checking built-ins.  */
          && (idx_objsize == HOST_WIDE_INT_M1U
              || !warn_stringop_overflow))
        {
          warning_at (gimple_location (info.callstmt), info.warnopt (),
                      "specified bound %wu exceeds the size %wu "
                      "of the destination object", dstsize, objsize);
        }
    }

  if (integer_zerop (info.format))
    {
      /* This is diagnosed with -Wformat only when the null is a constant
         pointer.  The warning here diagnoses instances where the pointer
         is not constant.  */
      location_t loc = gimple_location (info.callstmt);
      warning_at (EXPR_LOC_OR_LOC (info.format, loc),
                  info.warnopt (), "null format string");
      return false;
    }

  info.fmtstr = get_format_string (info.format, &info.fmtloc);
  if (!info.fmtstr)
    return false;

  /* The result is the number of bytes output by the formatted function,
     including the terminating NUL.  */
  format_result res = format_result ();

  bool success = compute_format_length (info, &res);

  /* When optimizing and the printf return value optimization is enabled,
     attempt to substitute the computed result for the return value of
     the call.  Avoid this optimization when -frounding-math is in effect
     and the format string contains a floating point directive.  */
  if (success
      && optimize > 0
      && flag_printf_return_value
      && (!flag_rounding_math || !res.floating))
    return try_substitute_return_value (gsi, info, res);

  return false;
}

/* Execute the pass for function FUN.  */

unsigned int
pass_sprintf_length::execute (function *fun)
{
  basic_block bb;
  FOR_EACH_BB_FN (bb, fun)
    {
      for (gimple_stmt_iterator si = gsi_start_bb (bb); !gsi_end_p (si); )
        {
          /* Iterate over statements, looking for function calls.  */
          gimple *stmt = gsi_stmt (si);

          if (is_gimple_call (stmt) && handle_gimple_call (&si))
            /* If handle_gimple_call returns true, the iterator is
               already pointing to the next statement.  */
            continue;

          gsi_next (&si);
        }
    }

  /* Clean up object size info.  */
  fini_object_sizes ();

  return 0;
}

}   /* Unnamed namespace.  */

/* Return a pointer to a pass object newly constructed from the context
   CTXT.  */

gimple_opt_pass *
make_pass_sprintf_length (gcc::context *ctxt)
{
  return new pass_sprintf_length (ctxt);
}