File:  [ELWIX - Embedded LightWeight unIX -] / embedaddon / libiconv / srclib / intprops.h
Revision 1.1.1.3 (vendor branch): download - view: text, annotated - select for diffs - revision graph
Wed Mar 17 13:38:46 2021 UTC (3 years, 3 months ago) by misho
Branches: libiconv, MAIN
CVS tags: v1_16p0, HEAD
libiconv 1.16

    1: /* intprops.h -- properties of integer types
    2: 
    3:    Copyright (C) 2001-2019 Free Software Foundation, Inc.
    4: 
    5:    This program is free software: you can redistribute it and/or modify it
    6:    under the terms of the GNU General Public License as published
    7:    by the Free Software Foundation; either version 3 of the License, or
    8:    (at your option) any later version.
    9: 
   10:    This program is distributed in the hope that it will be useful,
   11:    but WITHOUT ANY WARRANTY; without even the implied warranty of
   12:    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   13:    GNU General Public License for more details.
   14: 
   15:    You should have received a copy of the GNU General Public License
   16:    along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
   17: 
   18: /* Written by Paul Eggert.  */
   19: 
   20: #ifndef _GL_INTPROPS_H
   21: #define _GL_INTPROPS_H
   22: 
   23: #include <limits.h>
   24: 
   25: /* Return a value with the common real type of E and V and the value of V.
   26:    Do not evaluate E.  */
   27: #define _GL_INT_CONVERT(e, v) ((1 ? 0 : (e)) + (v))
   28: 
   29: /* Act like _GL_INT_CONVERT (E, -V) but work around a bug in IRIX 6.5 cc; see
   30:    <https://lists.gnu.org/r/bug-gnulib/2011-05/msg00406.html>.  */
   31: #define _GL_INT_NEGATE_CONVERT(e, v) ((1 ? 0 : (e)) - (v))
   32: 
   33: /* The extra casts in the following macros work around compiler bugs,
   34:    e.g., in Cray C 5.0.3.0.  */
   35: 
   36: /* True if the arithmetic type T is an integer type.  bool counts as
   37:    an integer.  */
   38: #define TYPE_IS_INTEGER(t) ((t) 1.5 == 1)
   39: 
   40: /* True if the real type T is signed.  */
   41: #define TYPE_SIGNED(t) (! ((t) 0 < (t) -1))
   42: 
   43: /* Return 1 if the real expression E, after promotion, has a
   44:    signed or floating type.  Do not evaluate E.  */
   45: #define EXPR_SIGNED(e) (_GL_INT_NEGATE_CONVERT (e, 1) < 0)
   46: 
   47: 
   48: /* Minimum and maximum values for integer types and expressions.  */
   49: 
   50: /* The width in bits of the integer type or expression T.
   51:    Do not evaluate T.
   52:    Padding bits are not supported; this is checked at compile-time below.  */
   53: #define TYPE_WIDTH(t) (sizeof (t) * CHAR_BIT)
   54: 
   55: /* The maximum and minimum values for the integer type T.  */
   56: #define TYPE_MINIMUM(t) ((t) ~ TYPE_MAXIMUM (t))
   57: #define TYPE_MAXIMUM(t)                                                 \
   58:   ((t) (! TYPE_SIGNED (t)                                               \
   59:         ? (t) -1                                                        \
   60:         : ((((t) 1 << (TYPE_WIDTH (t) - 2)) - 1) * 2 + 1)))
   61: 
   62: /* The maximum and minimum values for the type of the expression E,
   63:    after integer promotion.  E is not evaluated.  */
   64: #define _GL_INT_MINIMUM(e)                                              \
   65:   (EXPR_SIGNED (e)                                                      \
   66:    ? ~ _GL_SIGNED_INT_MAXIMUM (e)                                       \
   67:    : _GL_INT_CONVERT (e, 0))
   68: #define _GL_INT_MAXIMUM(e)                                              \
   69:   (EXPR_SIGNED (e)                                                      \
   70:    ? _GL_SIGNED_INT_MAXIMUM (e)                                         \
   71:    : _GL_INT_NEGATE_CONVERT (e, 1))
   72: #define _GL_SIGNED_INT_MAXIMUM(e)                                       \
   73:   (((_GL_INT_CONVERT (e, 1) << (TYPE_WIDTH ((e) + 0) - 2)) - 1) * 2 + 1)
   74: 
   75: /* Work around OpenVMS incompatibility with C99.  */
   76: #if !defined LLONG_MAX && defined __INT64_MAX
   77: # define LLONG_MAX __INT64_MAX
   78: # define LLONG_MIN __INT64_MIN
   79: #endif
   80: 
   81: /* This include file assumes that signed types are two's complement without
   82:    padding bits; the above macros have undefined behavior otherwise.
   83:    If this is a problem for you, please let us know how to fix it for your host.
   84:    This assumption is tested by the intprops-tests module.  */
   85: 
   86: /* Does the __typeof__ keyword work?  This could be done by
   87:    'configure', but for now it's easier to do it by hand.  */
   88: #if (2 <= __GNUC__ \
   89:      || (1210 <= __IBMC__ && defined __IBM__TYPEOF__) \
   90:      || (0x5110 <= __SUNPRO_C && !__STDC__))
   91: # define _GL_HAVE___TYPEOF__ 1
   92: #else
   93: # define _GL_HAVE___TYPEOF__ 0
   94: #endif
   95: 
   96: /* Return 1 if the integer type or expression T might be signed.  Return 0
   97:    if it is definitely unsigned.  This macro does not evaluate its argument,
   98:    and expands to an integer constant expression.  */
   99: #if _GL_HAVE___TYPEOF__
  100: # define _GL_SIGNED_TYPE_OR_EXPR(t) TYPE_SIGNED (__typeof__ (t))
  101: #else
  102: # define _GL_SIGNED_TYPE_OR_EXPR(t) 1
  103: #endif
  104: 
  105: /* Bound on length of the string representing an unsigned integer
  106:    value representable in B bits.  log10 (2.0) < 146/485.  The
  107:    smallest value of B where this bound is not tight is 2621.  */
  108: #define INT_BITS_STRLEN_BOUND(b) (((b) * 146 + 484) / 485)
  109: 
  110: /* Bound on length of the string representing an integer type or expression T.
  111:    Subtract 1 for the sign bit if T is signed, and then add 1 more for
  112:    a minus sign if needed.
  113: 
  114:    Because _GL_SIGNED_TYPE_OR_EXPR sometimes returns 0 when its argument is
  115:    signed, this macro may overestimate the true bound by one byte when
  116:    applied to unsigned types of size 2, 4, 16, ... bytes.  */
  117: #define INT_STRLEN_BOUND(t)                                     \
  118:   (INT_BITS_STRLEN_BOUND (TYPE_WIDTH (t) - _GL_SIGNED_TYPE_OR_EXPR (t)) \
  119:    + _GL_SIGNED_TYPE_OR_EXPR (t))
  120: 
  121: /* Bound on buffer size needed to represent an integer type or expression T,
  122:    including the terminating null.  */
  123: #define INT_BUFSIZE_BOUND(t) (INT_STRLEN_BOUND (t) + 1)
  124: 
  125: 
  126: /* Range overflow checks.
  127: 
  128:    The INT_<op>_RANGE_OVERFLOW macros return 1 if the corresponding C
  129:    operators might not yield numerically correct answers due to
  130:    arithmetic overflow.  They do not rely on undefined or
  131:    implementation-defined behavior.  Their implementations are simple
  132:    and straightforward, but they are a bit harder to use than the
  133:    INT_<op>_OVERFLOW macros described below.
  134: 
  135:    Example usage:
  136: 
  137:      long int i = ...;
  138:      long int j = ...;
  139:      if (INT_MULTIPLY_RANGE_OVERFLOW (i, j, LONG_MIN, LONG_MAX))
  140:        printf ("multiply would overflow");
  141:      else
  142:        printf ("product is %ld", i * j);
  143: 
  144:    Restrictions on *_RANGE_OVERFLOW macros:
  145: 
  146:    These macros do not check for all possible numerical problems or
  147:    undefined or unspecified behavior: they do not check for division
  148:    by zero, for bad shift counts, or for shifting negative numbers.
  149: 
  150:    These macros may evaluate their arguments zero or multiple times,
  151:    so the arguments should not have side effects.  The arithmetic
  152:    arguments (including the MIN and MAX arguments) must be of the same
  153:    integer type after the usual arithmetic conversions, and the type
  154:    must have minimum value MIN and maximum MAX.  Unsigned types should
  155:    use a zero MIN of the proper type.
  156: 
  157:    These macros are tuned for constant MIN and MAX.  For commutative
  158:    operations such as A + B, they are also tuned for constant B.  */
  159: 
  160: /* Return 1 if A + B would overflow in [MIN,MAX] arithmetic.
  161:    See above for restrictions.  */
  162: #define INT_ADD_RANGE_OVERFLOW(a, b, min, max)          \
  163:   ((b) < 0                                              \
  164:    ? (a) < (min) - (b)                                  \
  165:    : (max) - (b) < (a))
  166: 
  167: /* Return 1 if A - B would overflow in [MIN,MAX] arithmetic.
  168:    See above for restrictions.  */
  169: #define INT_SUBTRACT_RANGE_OVERFLOW(a, b, min, max)     \
  170:   ((b) < 0                                              \
  171:    ? (max) + (b) < (a)                                  \
  172:    : (a) < (min) + (b))
  173: 
  174: /* Return 1 if - A would overflow in [MIN,MAX] arithmetic.
  175:    See above for restrictions.  */
  176: #define INT_NEGATE_RANGE_OVERFLOW(a, min, max)          \
  177:   ((min) < 0                                            \
  178:    ? (a) < - (max)                                      \
  179:    : 0 < (a))
  180: 
  181: /* Return 1 if A * B would overflow in [MIN,MAX] arithmetic.
  182:    See above for restrictions.  Avoid && and || as they tickle
  183:    bugs in Sun C 5.11 2010/08/13 and other compilers; see
  184:    <https://lists.gnu.org/r/bug-gnulib/2011-05/msg00401.html>.  */
  185: #define INT_MULTIPLY_RANGE_OVERFLOW(a, b, min, max)     \
  186:   ((b) < 0                                              \
  187:    ? ((a) < 0                                           \
  188:       ? (a) < (max) / (b)                               \
  189:       : (b) == -1                                       \
  190:       ? 0                                               \
  191:       : (min) / (b) < (a))                              \
  192:    : (b) == 0                                           \
  193:    ? 0                                                  \
  194:    : ((a) < 0                                           \
  195:       ? (a) < (min) / (b)                               \
  196:       : (max) / (b) < (a)))
  197: 
  198: /* Return 1 if A / B would overflow in [MIN,MAX] arithmetic.
  199:    See above for restrictions.  Do not check for division by zero.  */
  200: #define INT_DIVIDE_RANGE_OVERFLOW(a, b, min, max)       \
  201:   ((min) < 0 && (b) == -1 && (a) < - (max))
  202: 
  203: /* Return 1 if A % B would overflow in [MIN,MAX] arithmetic.
  204:    See above for restrictions.  Do not check for division by zero.
  205:    Mathematically, % should never overflow, but on x86-like hosts
  206:    INT_MIN % -1 traps, and the C standard permits this, so treat this
  207:    as an overflow too.  */
  208: #define INT_REMAINDER_RANGE_OVERFLOW(a, b, min, max)    \
  209:   INT_DIVIDE_RANGE_OVERFLOW (a, b, min, max)
  210: 
  211: /* Return 1 if A << B would overflow in [MIN,MAX] arithmetic.
  212:    See above for restrictions.  Here, MIN and MAX are for A only, and B need
  213:    not be of the same type as the other arguments.  The C standard says that
  214:    behavior is undefined for shifts unless 0 <= B < wordwidth, and that when
  215:    A is negative then A << B has undefined behavior and A >> B has
  216:    implementation-defined behavior, but do not check these other
  217:    restrictions.  */
  218: #define INT_LEFT_SHIFT_RANGE_OVERFLOW(a, b, min, max)   \
  219:   ((a) < 0                                              \
  220:    ? (a) < (min) >> (b)                                 \
  221:    : (max) >> (b) < (a))
  222: 
  223: /* True if __builtin_add_overflow (A, B, P) works when P is non-null.  */
  224: #if 5 <= __GNUC__ && !defined __ICC
  225: # define _GL_HAS_BUILTIN_OVERFLOW 1
  226: #else
  227: # define _GL_HAS_BUILTIN_OVERFLOW 0
  228: #endif
  229: 
  230: /* True if __builtin_add_overflow_p (A, B, C) works.  */
  231: #define _GL_HAS_BUILTIN_OVERFLOW_P (7 <= __GNUC__)
  232: 
  233: /* The _GL*_OVERFLOW macros have the same restrictions as the
  234:    *_RANGE_OVERFLOW macros, except that they do not assume that operands
  235:    (e.g., A and B) have the same type as MIN and MAX.  Instead, they assume
  236:    that the result (e.g., A + B) has that type.  */
  237: #if _GL_HAS_BUILTIN_OVERFLOW_P
  238: # define _GL_ADD_OVERFLOW(a, b, min, max)                               \
  239:    __builtin_add_overflow_p (a, b, (__typeof__ ((a) + (b))) 0)
  240: # define _GL_SUBTRACT_OVERFLOW(a, b, min, max)                          \
  241:    __builtin_sub_overflow_p (a, b, (__typeof__ ((a) - (b))) 0)
  242: # define _GL_MULTIPLY_OVERFLOW(a, b, min, max)                          \
  243:    __builtin_mul_overflow_p (a, b, (__typeof__ ((a) * (b))) 0)
  244: #else
  245: # define _GL_ADD_OVERFLOW(a, b, min, max)                                \
  246:    ((min) < 0 ? INT_ADD_RANGE_OVERFLOW (a, b, min, max)                  \
  247:     : (a) < 0 ? (b) <= (a) + (b)                                         \
  248:     : (b) < 0 ? (a) <= (a) + (b)                                         \
  249:     : (a) + (b) < (b))
  250: # define _GL_SUBTRACT_OVERFLOW(a, b, min, max)                           \
  251:    ((min) < 0 ? INT_SUBTRACT_RANGE_OVERFLOW (a, b, min, max)             \
  252:     : (a) < 0 ? 1                                                        \
  253:     : (b) < 0 ? (a) - (b) <= (a)                                         \
  254:     : (a) < (b))
  255: # define _GL_MULTIPLY_OVERFLOW(a, b, min, max)                           \
  256:    (((min) == 0 && (((a) < 0 && 0 < (b)) || ((b) < 0 && 0 < (a))))       \
  257:     || INT_MULTIPLY_RANGE_OVERFLOW (a, b, min, max))
  258: #endif
  259: #define _GL_DIVIDE_OVERFLOW(a, b, min, max)                             \
  260:   ((min) < 0 ? (b) == _GL_INT_NEGATE_CONVERT (min, 1) && (a) < - (max)  \
  261:    : (a) < 0 ? (b) <= (a) + (b) - 1                                     \
  262:    : (b) < 0 && (a) + (b) <= (a))
  263: #define _GL_REMAINDER_OVERFLOW(a, b, min, max)                          \
  264:   ((min) < 0 ? (b) == _GL_INT_NEGATE_CONVERT (min, 1) && (a) < - (max)  \
  265:    : (a) < 0 ? (a) % (b) != ((max) - (b) + 1) % (b)                     \
  266:    : (b) < 0 && ! _GL_UNSIGNED_NEG_MULTIPLE (a, b, max))
  267: 
  268: /* Return a nonzero value if A is a mathematical multiple of B, where
  269:    A is unsigned, B is negative, and MAX is the maximum value of A's
  270:    type.  A's type must be the same as (A % B)'s type.  Normally (A %
  271:    -B == 0) suffices, but things get tricky if -B would overflow.  */
  272: #define _GL_UNSIGNED_NEG_MULTIPLE(a, b, max)                            \
  273:   (((b) < -_GL_SIGNED_INT_MAXIMUM (b)                                   \
  274:     ? (_GL_SIGNED_INT_MAXIMUM (b) == (max)                              \
  275:        ? (a)                                                            \
  276:        : (a) % (_GL_INT_CONVERT (a, _GL_SIGNED_INT_MAXIMUM (b)) + 1))   \
  277:     : (a) % - (b))                                                      \
  278:    == 0)
  279: 
  280: /* Check for integer overflow, and report low order bits of answer.
  281: 
  282:    The INT_<op>_OVERFLOW macros return 1 if the corresponding C operators
  283:    might not yield numerically correct answers due to arithmetic overflow.
  284:    The INT_<op>_WRAPV macros also store the low-order bits of the answer.
  285:    These macros work correctly on all known practical hosts, and do not rely
  286:    on undefined behavior due to signed arithmetic overflow.
  287: 
  288:    Example usage, assuming A and B are long int:
  289: 
  290:      if (INT_MULTIPLY_OVERFLOW (a, b))
  291:        printf ("result would overflow\n");
  292:      else
  293:        printf ("result is %ld (no overflow)\n", a * b);
  294: 
  295:    Example usage with WRAPV flavor:
  296: 
  297:      long int result;
  298:      bool overflow = INT_MULTIPLY_WRAPV (a, b, &result);
  299:      printf ("result is %ld (%s)\n", result,
  300:              overflow ? "after overflow" : "no overflow");
  301: 
  302:    Restrictions on these macros:
  303: 
  304:    These macros do not check for all possible numerical problems or
  305:    undefined or unspecified behavior: they do not check for division
  306:    by zero, for bad shift counts, or for shifting negative numbers.
  307: 
  308:    These macros may evaluate their arguments zero or multiple times, so the
  309:    arguments should not have side effects.
  310: 
  311:    The WRAPV macros are not constant expressions.  They support only
  312:    +, binary -, and *.  The result type must be signed.
  313: 
  314:    These macros are tuned for their last argument being a constant.
  315: 
  316:    Return 1 if the integer expressions A * B, A - B, -A, A * B, A / B,
  317:    A % B, and A << B would overflow, respectively.  */
  318: 
  319: #define INT_ADD_OVERFLOW(a, b) \
  320:   _GL_BINARY_OP_OVERFLOW (a, b, _GL_ADD_OVERFLOW)
  321: #define INT_SUBTRACT_OVERFLOW(a, b) \
  322:   _GL_BINARY_OP_OVERFLOW (a, b, _GL_SUBTRACT_OVERFLOW)
  323: #if _GL_HAS_BUILTIN_OVERFLOW_P
  324: # define INT_NEGATE_OVERFLOW(a) INT_SUBTRACT_OVERFLOW (0, a)
  325: #else
  326: # define INT_NEGATE_OVERFLOW(a) \
  327:    INT_NEGATE_RANGE_OVERFLOW (a, _GL_INT_MINIMUM (a), _GL_INT_MAXIMUM (a))
  328: #endif
  329: #define INT_MULTIPLY_OVERFLOW(a, b) \
  330:   _GL_BINARY_OP_OVERFLOW (a, b, _GL_MULTIPLY_OVERFLOW)
  331: #define INT_DIVIDE_OVERFLOW(a, b) \
  332:   _GL_BINARY_OP_OVERFLOW (a, b, _GL_DIVIDE_OVERFLOW)
  333: #define INT_REMAINDER_OVERFLOW(a, b) \
  334:   _GL_BINARY_OP_OVERFLOW (a, b, _GL_REMAINDER_OVERFLOW)
  335: #define INT_LEFT_SHIFT_OVERFLOW(a, b) \
  336:   INT_LEFT_SHIFT_RANGE_OVERFLOW (a, b, \
  337:                                  _GL_INT_MINIMUM (a), _GL_INT_MAXIMUM (a))
  338: 
  339: /* Return 1 if the expression A <op> B would overflow,
  340:    where OP_RESULT_OVERFLOW (A, B, MIN, MAX) does the actual test,
  341:    assuming MIN and MAX are the minimum and maximum for the result type.
  342:    Arguments should be free of side effects.  */
  343: #define _GL_BINARY_OP_OVERFLOW(a, b, op_result_overflow)        \
  344:   op_result_overflow (a, b,                                     \
  345:                       _GL_INT_MINIMUM (_GL_INT_CONVERT (a, b)), \
  346:                       _GL_INT_MAXIMUM (_GL_INT_CONVERT (a, b)))
  347: 
  348: /* Store the low-order bits of A + B, A - B, A * B, respectively, into *R.
  349:    Return 1 if the result overflows.  See above for restrictions.  */
  350: #define INT_ADD_WRAPV(a, b, r) \
  351:   _GL_INT_OP_WRAPV (a, b, r, +, __builtin_add_overflow, INT_ADD_OVERFLOW)
  352: #define INT_SUBTRACT_WRAPV(a, b, r) \
  353:   _GL_INT_OP_WRAPV (a, b, r, -, __builtin_sub_overflow, INT_SUBTRACT_OVERFLOW)
  354: #define INT_MULTIPLY_WRAPV(a, b, r) \
  355:   _GL_INT_OP_WRAPV (a, b, r, *, __builtin_mul_overflow, INT_MULTIPLY_OVERFLOW)
  356: 
  357: /* Nonzero if this compiler has GCC bug 68193 or Clang bug 25390.  See:
  358:    https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68193
  359:    https://llvm.org/bugs/show_bug.cgi?id=25390
  360:    For now, assume all versions of GCC-like compilers generate bogus
  361:    warnings for _Generic.  This matters only for older compilers that
  362:    lack __builtin_add_overflow.  */
  363: #if __GNUC__
  364: # define _GL__GENERIC_BOGUS 1
  365: #else
  366: # define _GL__GENERIC_BOGUS 0
  367: #endif
  368: 
  369: /* Store the low-order bits of A <op> B into *R, where OP specifies
  370:    the operation.  BUILTIN is the builtin operation, and OVERFLOW the
  371:    overflow predicate.  Return 1 if the result overflows.  See above
  372:    for restrictions.  */
  373: #if _GL_HAS_BUILTIN_OVERFLOW
  374: # define _GL_INT_OP_WRAPV(a, b, r, op, builtin, overflow) builtin (a, b, r)
  375: #elif 201112 <= __STDC_VERSION__ && !_GL__GENERIC_BOGUS
  376: # define _GL_INT_OP_WRAPV(a, b, r, op, builtin, overflow) \
  377:    (_Generic \
  378:     (*(r), \
  379:      signed char: \
  380:        _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned int, \
  381:                         signed char, SCHAR_MIN, SCHAR_MAX), \
  382:      short int: \
  383:        _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned int, \
  384:                         short int, SHRT_MIN, SHRT_MAX), \
  385:      int: \
  386:        _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned int, \
  387:                         int, INT_MIN, INT_MAX), \
  388:      long int: \
  389:        _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned long int, \
  390:                         long int, LONG_MIN, LONG_MAX), \
  391:      long long int: \
  392:        _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned long long int, \
  393:                         long long int, LLONG_MIN, LLONG_MAX)))
  394: #else
  395: # define _GL_INT_OP_WRAPV(a, b, r, op, builtin, overflow) \
  396:    (sizeof *(r) == sizeof (signed char) \
  397:     ? _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned int, \
  398:                        signed char, SCHAR_MIN, SCHAR_MAX) \
  399:     : sizeof *(r) == sizeof (short int) \
  400:     ? _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned int, \
  401:                        short int, SHRT_MIN, SHRT_MAX) \
  402:     : sizeof *(r) == sizeof (int) \
  403:     ? _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned int, \
  404:                        int, INT_MIN, INT_MAX) \
  405:     : _GL_INT_OP_WRAPV_LONGISH(a, b, r, op, overflow))
  406: # ifdef LLONG_MAX
  407: #  define _GL_INT_OP_WRAPV_LONGISH(a, b, r, op, overflow) \
  408:     (sizeof *(r) == sizeof (long int) \
  409:      ? _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned long int, \
  410:                         long int, LONG_MIN, LONG_MAX) \
  411:      : _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned long long int, \
  412:                         long long int, LLONG_MIN, LLONG_MAX))
  413: # else
  414: #  define _GL_INT_OP_WRAPV_LONGISH(a, b, r, op, overflow) \
  415:     _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned long int, \
  416:                      long int, LONG_MIN, LONG_MAX)
  417: # endif
  418: #endif
  419: 
  420: /* Store the low-order bits of A <op> B into *R, where the operation
  421:    is given by OP.  Use the unsigned type UT for calculation to avoid
  422:    overflow problems.  *R's type is T, with extrema TMIN and TMAX.
  423:    T must be a signed integer type.  Return 1 if the result overflows.  */
  424: #define _GL_INT_OP_CALC(a, b, r, op, overflow, ut, t, tmin, tmax) \
  425:   (sizeof ((a) op (b)) < sizeof (t) \
  426:    ? _GL_INT_OP_CALC1 ((t) (a), (t) (b), r, op, overflow, ut, t, tmin, tmax) \
  427:    : _GL_INT_OP_CALC1 (a, b, r, op, overflow, ut, t, tmin, tmax))
  428: #define _GL_INT_OP_CALC1(a, b, r, op, overflow, ut, t, tmin, tmax) \
  429:   ((overflow (a, b) \
  430:     || (EXPR_SIGNED ((a) op (b)) && ((a) op (b)) < (tmin)) \
  431:     || (tmax) < ((a) op (b))) \
  432:    ? (*(r) = _GL_INT_OP_WRAPV_VIA_UNSIGNED (a, b, op, ut, t), 1) \
  433:    : (*(r) = _GL_INT_OP_WRAPV_VIA_UNSIGNED (a, b, op, ut, t), 0))
  434: 
  435: /* Return the low-order bits of A <op> B, where the operation is given
  436:    by OP.  Use the unsigned type UT for calculation to avoid undefined
  437:    behavior on signed integer overflow, and convert the result to type T.
  438:    UT is at least as wide as T and is no narrower than unsigned int,
  439:    T is two's complement, and there is no padding or trap representations.
  440:    Assume that converting UT to T yields the low-order bits, as is
  441:    done in all known two's-complement C compilers.  E.g., see:
  442:    https://gcc.gnu.org/onlinedocs/gcc/Integers-implementation.html
  443: 
  444:    According to the C standard, converting UT to T yields an
  445:    implementation-defined result or signal for values outside T's
  446:    range.  However, code that works around this theoretical problem
  447:    runs afoul of a compiler bug in Oracle Studio 12.3 x86.  See:
  448:    https://lists.gnu.org/r/bug-gnulib/2017-04/msg00049.html
  449:    As the compiler bug is real, don't try to work around the
  450:    theoretical problem.  */
  451: 
  452: #define _GL_INT_OP_WRAPV_VIA_UNSIGNED(a, b, op, ut, t) \
  453:   ((t) ((ut) (a) op (ut) (b)))
  454: 
  455: #endif /* _GL_INTPROPS_H */

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