/* intprops.h -- properties of integer types
- Copyright (C) 2001-2016 Free Software Foundation, Inc.
+ Copyright (C) 2001-2021 Free Software Foundation, Inc.
This program is free software: you can redistribute it and/or modify it
under the terms of the GNU General Public License as published
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
- along with this program. If not, see <http://www.gnu.org/licenses/>. */
+ along with this program. If not, see <https://www.gnu.org/licenses/>. */
/* Written by Paul Eggert. */
#define _GL_INTPROPS_H
#include <limits.h>
-#include <verify.h>
-#ifndef __has_builtin
-# define __has_builtin(x) 0
-#endif
-
-/* Return a value with the common real type of E and V and the value of V. */
-#define _GL_INT_CONVERT(e, v) (0 * (e) + (v))
+/* Return a value with the common real type of E and V and the value of V.
+ Do not evaluate E. */
+#define _GL_INT_CONVERT(e, v) ((1 ? 0 : (e)) + (v))
/* Act like _GL_INT_CONVERT (E, -V) but work around a bug in IRIX 6.5 cc; see
- <http://lists.gnu.org/archive/html/bug-gnulib/2011-05/msg00406.html>. */
-#define _GL_INT_NEGATE_CONVERT(e, v) (0 * (e) - (v))
+ <https://lists.gnu.org/r/bug-gnulib/2011-05/msg00406.html>. */
+#define _GL_INT_NEGATE_CONVERT(e, v) ((1 ? 0 : (e)) - (v))
/* The extra casts in the following macros work around compiler bugs,
e.g., in Cray C 5.0.3.0. */
#define TYPE_SIGNED(t) (! ((t) 0 < (t) -1))
/* Return 1 if the real expression E, after promotion, has a
- signed or floating type. */
+ signed or floating type. Do not evaluate E. */
#define EXPR_SIGNED(e) (_GL_INT_NEGATE_CONVERT (e, 1) < 0)
/* Minimum and maximum values for integer types and expressions. */
/* The width in bits of the integer type or expression T.
+ Do not evaluate T. T must not be a bit-field expression.
Padding bits are not supported; this is checked at compile-time below. */
#define TYPE_WIDTH(t) (sizeof (t) * CHAR_BIT)
: ((((t) 1 << (TYPE_WIDTH (t) - 2)) - 1) * 2 + 1)))
/* The maximum and minimum values for the type of the expression E,
- after integer promotion. E should not have side effects. */
+ after integer promotion. E is not evaluated. */
#define _GL_INT_MINIMUM(e) \
(EXPR_SIGNED (e) \
? ~ _GL_SIGNED_INT_MAXIMUM (e) \
? _GL_SIGNED_INT_MAXIMUM (e) \
: _GL_INT_NEGATE_CONVERT (e, 1))
#define _GL_SIGNED_INT_MAXIMUM(e) \
- (((_GL_INT_CONVERT (e, 1) << (TYPE_WIDTH ((e) + 0) - 2)) - 1) * 2 + 1)
+ (((_GL_INT_CONVERT (e, 1) << (TYPE_WIDTH (+ (e)) - 2)) - 1) * 2 + 1)
/* Work around OpenVMS incompatibility with C99. */
#if !defined LLONG_MAX && defined __INT64_MAX
/* This include file assumes that signed types are two's complement without
padding bits; the above macros have undefined behavior otherwise.
If this is a problem for you, please let us know how to fix it for your host.
- As a sanity check, test the assumption for some signed types that
- <limits.h> bounds. */
-verify (TYPE_MINIMUM (signed char) == SCHAR_MIN);
-verify (TYPE_MAXIMUM (signed char) == SCHAR_MAX);
-verify (TYPE_MINIMUM (short int) == SHRT_MIN);
-verify (TYPE_MAXIMUM (short int) == SHRT_MAX);
-verify (TYPE_MINIMUM (int) == INT_MIN);
-verify (TYPE_MAXIMUM (int) == INT_MAX);
-verify (TYPE_MINIMUM (long int) == LONG_MIN);
-verify (TYPE_MAXIMUM (long int) == LONG_MAX);
-#ifdef LLONG_MAX
-verify (TYPE_MINIMUM (long long int) == LLONG_MIN);
-verify (TYPE_MAXIMUM (long long int) == LLONG_MAX);
-#endif
-/* Similarly, sanity-check one ISO/IEC TS 18661-1:2014 macro if defined. */
-#ifdef UINT_WIDTH
-verify (TYPE_WIDTH (unsigned int) == UINT_WIDTH);
-#endif
+ This assumption is tested by the intprops-tests module. */
/* Does the __typeof__ keyword work? This could be done by
'configure', but for now it's easier to do it by hand. */
#if (2 <= __GNUC__ \
+ || (4 <= __clang_major__) \
|| (1210 <= __IBMC__ && defined __IBM__TYPEOF__) \
|| (0x5110 <= __SUNPRO_C && !__STDC__))
# define _GL_HAVE___TYPEOF__ 1
#endif
/* Return 1 if the integer type or expression T might be signed. Return 0
- if it is definitely unsigned. This macro does not evaluate its argument,
- and expands to an integer constant expression. */
+ if it is definitely unsigned. T must not be a bit-field expression.
+ This macro does not evaluate its argument, and expands to an
+ integer constant expression. */
#if _GL_HAVE___TYPEOF__
# define _GL_SIGNED_TYPE_OR_EXPR(t) TYPE_SIGNED (__typeof__ (t))
#else
#define INT_BITS_STRLEN_BOUND(b) (((b) * 146 + 484) / 485)
/* Bound on length of the string representing an integer type or expression T.
+ T must not be a bit-field expression.
+
Subtract 1 for the sign bit if T is signed, and then add 1 more for
a minus sign if needed.
- Because _GL_SIGNED_TYPE_OR_EXPR sometimes returns 0 when its argument is
- signed, this macro may overestimate the true bound by one byte when
+ Because _GL_SIGNED_TYPE_OR_EXPR sometimes returns 1 when its argument is
+ unsigned, this macro may overestimate the true bound by one byte when
applied to unsigned types of size 2, 4, 16, ... bytes. */
#define INT_STRLEN_BOUND(t) \
(INT_BITS_STRLEN_BOUND (TYPE_WIDTH (t) - _GL_SIGNED_TYPE_OR_EXPR (t)) \
+ _GL_SIGNED_TYPE_OR_EXPR (t))
/* Bound on buffer size needed to represent an integer type or expression T,
- including the terminating null. */
+ including the terminating null. T must not be a bit-field expression. */
#define INT_BUFSIZE_BOUND(t) (INT_STRLEN_BOUND (t) + 1)
operators might not yield numerically correct answers due to
arithmetic overflow. They do not rely on undefined or
implementation-defined behavior. Their implementations are simple
- and straightforward, but they are a bit harder to use than the
+ and straightforward, but they are harder to use and may be less
+ efficient than the INT_<op>_WRAPV, INT_<op>_OK, and
INT_<op>_OVERFLOW macros described below.
Example usage:
must have minimum value MIN and maximum MAX. Unsigned types should
use a zero MIN of the proper type.
+ Because all arguments are subject to integer promotions, these
+ macros typically do not work on types narrower than 'int'.
+
These macros are tuned for constant MIN and MAX. For commutative
operations such as A + B, they are also tuned for constant B. */
/* Return 1 if A * B would overflow in [MIN,MAX] arithmetic.
See above for restrictions. Avoid && and || as they tickle
bugs in Sun C 5.11 2010/08/13 and other compilers; see
- <http://lists.gnu.org/archive/html/bug-gnulib/2011-05/msg00401.html>. */
+ <https://lists.gnu.org/r/bug-gnulib/2011-05/msg00401.html>. */
#define INT_MULTIPLY_RANGE_OVERFLOW(a, b, min, max) \
((b) < 0 \
? ((a) < 0 \
? (a) < (min) >> (b) \
: (max) >> (b) < (a))
-/* True if __builtin_add_overflow (A, B, P) works when P is non-null. */
-#define _GL_HAS_BUILTIN_OVERFLOW \
- (5 <= __GNUC__ || __has_builtin (__builtin_add_overflow))
+/* True if __builtin_add_overflow (A, B, P) and __builtin_sub_overflow
+ (A, B, P) work when P is non-null. */
+/* __builtin_{add,sub}_overflow exists but is not reliable in GCC 5.x and 6.x,
+ see <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98269>. */
+#if 7 <= __GNUC__ && !defined __ICC
+# define _GL_HAS_BUILTIN_ADD_OVERFLOW 1
+#elif defined __has_builtin
+# define _GL_HAS_BUILTIN_ADD_OVERFLOW __has_builtin (__builtin_add_overflow)
+#else
+# define _GL_HAS_BUILTIN_ADD_OVERFLOW 0
+#endif
+
+/* True if __builtin_mul_overflow (A, B, P) works when P is non-null. */
+#ifdef __clang__
+/* Work around Clang bug <https://bugs.llvm.org/show_bug.cgi?id=16404>. */
+# define _GL_HAS_BUILTIN_MUL_OVERFLOW 0
+#else
+# define _GL_HAS_BUILTIN_MUL_OVERFLOW _GL_HAS_BUILTIN_ADD_OVERFLOW
+#endif
-/* True if __builtin_add_overflow_p (A, B, C) works. */
-#define _GL_HAS_BUILTIN_OVERFLOW_P \
- (7 <= __GNUC__ || __has_builtin (__builtin_add_overflow_p))
+/* True if __builtin_add_overflow_p (A, B, C) works, and similarly for
+ __builtin_sub_overflow_p and __builtin_mul_overflow_p. */
+#if defined __clang__ || defined __ICC
+/* Clang 11 lacks __builtin_mul_overflow_p, and even if it did it
+ would presumably run afoul of Clang bug 16404. ICC 2021.1's
+ __builtin_add_overflow_p etc. are not treated as integral constant
+ expressions even when all arguments are. */
+# define _GL_HAS_BUILTIN_OVERFLOW_P 0
+#elif defined __has_builtin
+# define _GL_HAS_BUILTIN_OVERFLOW_P __has_builtin (__builtin_mul_overflow_p)
+#else
+# define _GL_HAS_BUILTIN_OVERFLOW_P (7 <= __GNUC__)
+#endif
/* The _GL*_OVERFLOW macros have the same restrictions as the
*_RANGE_OVERFLOW macros, except that they do not assume that operands
The INT_<op>_OVERFLOW macros return 1 if the corresponding C operators
might not yield numerically correct answers due to arithmetic overflow.
- The INT_<op>_WRAPV macros also store the low-order bits of the answer.
+ The INT_<op>_WRAPV macros compute the low-order bits of the sum,
+ difference, and product of two C integers, and return 1 if these
+ low-order bits are not numerically correct.
These macros work correctly on all known practical hosts, and do not rely
on undefined behavior due to signed arithmetic overflow.
arguments should not have side effects.
The WRAPV macros are not constant expressions. They support only
- +, binary -, and *. The result type must be signed.
+ +, binary -, and *.
- These macros are tuned for their last argument being a constant.
+ Because the WRAPV macros convert the result, they report overflow
+ in different circumstances than the OVERFLOW macros do. For
+ example, in the typical case with 16-bit 'short' and 32-bit 'int',
+ if A, B and R are all of type 'short' then INT_ADD_OVERFLOW (A, B)
+ returns false because the addition cannot overflow after A and B
+ are converted to 'int', whereas INT_ADD_WRAPV (A, B, &R) returns
+ true or false depending on whether the sum fits into 'short'.
+
+ These macros are tuned for their last input argument being a constant.
Return 1 if the integer expressions A * B, A - B, -A, A * B, A / B,
A % B, and A << B would overflow, respectively. */
Arguments should be free of side effects. */
#define _GL_BINARY_OP_OVERFLOW(a, b, op_result_overflow) \
op_result_overflow (a, b, \
- _GL_INT_MINIMUM (0 * (b) + (a)), \
- _GL_INT_MAXIMUM (0 * (b) + (a)))
+ _GL_INT_MINIMUM (_GL_INT_CONVERT (a, b)), \
+ _GL_INT_MAXIMUM (_GL_INT_CONVERT (a, b)))
/* Store the low-order bits of A + B, A - B, A * B, respectively, into *R.
Return 1 if the result overflows. See above for restrictions. */
-#define INT_ADD_WRAPV(a, b, r) \
- _GL_INT_OP_WRAPV (a, b, r, +, __builtin_add_overflow, INT_ADD_OVERFLOW)
-#define INT_SUBTRACT_WRAPV(a, b, r) \
- _GL_INT_OP_WRAPV (a, b, r, -, __builtin_sub_overflow, INT_SUBTRACT_OVERFLOW)
-#define INT_MULTIPLY_WRAPV(a, b, r) \
- _GL_INT_OP_WRAPV (a, b, r, *, __builtin_mul_overflow, INT_MULTIPLY_OVERFLOW)
+#if _GL_HAS_BUILTIN_ADD_OVERFLOW
+# define INT_ADD_WRAPV(a, b, r) __builtin_add_overflow (a, b, r)
+# define INT_SUBTRACT_WRAPV(a, b, r) __builtin_sub_overflow (a, b, r)
+#else
+# define INT_ADD_WRAPV(a, b, r) \
+ _GL_INT_OP_WRAPV (a, b, r, +, _GL_INT_ADD_RANGE_OVERFLOW)
+# define INT_SUBTRACT_WRAPV(a, b, r) \
+ _GL_INT_OP_WRAPV (a, b, r, -, _GL_INT_SUBTRACT_RANGE_OVERFLOW)
+#endif
+#if _GL_HAS_BUILTIN_MUL_OVERFLOW
+# if ((9 < __GNUC__ + (3 <= __GNUC_MINOR__) \
+ || (__GNUC__ == 8 && 4 <= __GNUC_MINOR__)) \
+ && !defined __ICC)
+# define INT_MULTIPLY_WRAPV(a, b, r) __builtin_mul_overflow (a, b, r)
+# else
+ /* Work around GCC bug 91450. */
+# define INT_MULTIPLY_WRAPV(a, b, r) \
+ ((!_GL_SIGNED_TYPE_OR_EXPR (*(r)) && EXPR_SIGNED (a) && EXPR_SIGNED (b) \
+ && _GL_INT_MULTIPLY_RANGE_OVERFLOW (a, b, 0, (__typeof__ (*(r))) -1)) \
+ ? ((void) __builtin_mul_overflow (a, b, r), 1) \
+ : __builtin_mul_overflow (a, b, r))
+# endif
+#else
+# define INT_MULTIPLY_WRAPV(a, b, r) \
+ _GL_INT_OP_WRAPV (a, b, r, *, _GL_INT_MULTIPLY_RANGE_OVERFLOW)
+#endif
/* Nonzero if this compiler has GCC bug 68193 or Clang bug 25390. See:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68193
https://llvm.org/bugs/show_bug.cgi?id=25390
For now, assume all versions of GCC-like compilers generate bogus
- warnings for _Generic. This matters only for older compilers that
- lack __builtin_add_overflow. */
-#if __GNUC__
+ warnings for _Generic. This matters only for compilers that
+ lack relevant builtins. */
+#if __GNUC__ || defined __clang__
# define _GL__GENERIC_BOGUS 1
#else
# define _GL__GENERIC_BOGUS 0
#endif
/* Store the low-order bits of A <op> B into *R, where OP specifies
- the operation. BUILTIN is the builtin operation, and OVERFLOW the
- overflow predicate. Return 1 if the result overflows. See above
- for restrictions. */
-#if _GL_HAS_BUILTIN_OVERFLOW
-# define _GL_INT_OP_WRAPV(a, b, r, op, builtin, overflow) builtin (a, b, r)
-#elif 201112 <= __STDC_VERSION__ && !_GL__GENERIC_BOGUS
-# define _GL_INT_OP_WRAPV(a, b, r, op, builtin, overflow) \
+ the operation and OVERFLOW the overflow predicate. Return 1 if the
+ result overflows. See above for restrictions. */
+#if 201112 <= __STDC_VERSION__ && !_GL__GENERIC_BOGUS
+# define _GL_INT_OP_WRAPV(a, b, r, op, overflow) \
(_Generic \
(*(r), \
signed char: \
- _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned char, \
+ _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned int, \
signed char, SCHAR_MIN, SCHAR_MAX), \
+ unsigned char: \
+ _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned int, \
+ unsigned char, 0, UCHAR_MAX), \
short int: \
- _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned short int, \
+ _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned int, \
short int, SHRT_MIN, SHRT_MAX), \
+ unsigned short int: \
+ _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned int, \
+ unsigned short int, 0, USHRT_MAX), \
int: \
_GL_INT_OP_CALC (a, b, r, op, overflow, unsigned int, \
int, INT_MIN, INT_MAX), \
+ unsigned int: \
+ _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned int, \
+ unsigned int, 0, UINT_MAX), \
long int: \
_GL_INT_OP_CALC (a, b, r, op, overflow, unsigned long int, \
long int, LONG_MIN, LONG_MAX), \
+ unsigned long int: \
+ _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned long int, \
+ unsigned long int, 0, ULONG_MAX), \
long long int: \
_GL_INT_OP_CALC (a, b, r, op, overflow, unsigned long long int, \
- long long int, LLONG_MIN, LLONG_MAX)))
+ long long int, LLONG_MIN, LLONG_MAX), \
+ unsigned long long int: \
+ _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned long long int, \
+ unsigned long long int, 0, ULLONG_MAX)))
#else
-# define _GL_INT_OP_WRAPV(a, b, r, op, builtin, overflow) \
+/* Store the low-order bits of A <op> B into *R, where OP specifies
+ the operation and OVERFLOW the overflow predicate. If *R is
+ signed, its type is ST with bounds SMIN..SMAX; otherwise its type
+ is UT with bounds U..UMAX. ST and UT are narrower than int.
+ Return 1 if the result overflows. See above for restrictions. */
+# if _GL_HAVE___TYPEOF__
+# define _GL_INT_OP_WRAPV_SMALLISH(a,b,r,op,overflow,st,smin,smax,ut,umax) \
+ (TYPE_SIGNED (__typeof__ (*(r))) \
+ ? _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned int, st, smin, smax) \
+ : _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned int, ut, 0, umax))
+# else
+# define _GL_INT_OP_WRAPV_SMALLISH(a,b,r,op,overflow,st,smin,smax,ut,umax) \
+ (overflow (a, b, smin, smax) \
+ ? (overflow (a, b, 0, umax) \
+ ? (*(r) = _GL_INT_OP_WRAPV_VIA_UNSIGNED (a,b,op,unsigned,st), 1) \
+ : (*(r) = _GL_INT_OP_WRAPV_VIA_UNSIGNED (a,b,op,unsigned,st)) < 0) \
+ : (overflow (a, b, 0, umax) \
+ ? (*(r) = _GL_INT_OP_WRAPV_VIA_UNSIGNED (a,b,op,unsigned,st)) >= 0 \
+ : (*(r) = _GL_INT_OP_WRAPV_VIA_UNSIGNED (a,b,op,unsigned,st), 0)))
+# endif
+
+# define _GL_INT_OP_WRAPV(a, b, r, op, overflow) \
(sizeof *(r) == sizeof (signed char) \
- ? _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned char, \
- signed char, SCHAR_MIN, SCHAR_MAX) \
+ ? _GL_INT_OP_WRAPV_SMALLISH (a, b, r, op, overflow, \
+ signed char, SCHAR_MIN, SCHAR_MAX, \
+ unsigned char, UCHAR_MAX) \
: sizeof *(r) == sizeof (short int) \
- ? _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned short int, \
- short int, SHRT_MIN, SHRT_MAX) \
+ ? _GL_INT_OP_WRAPV_SMALLISH (a, b, r, op, overflow, \
+ short int, SHRT_MIN, SHRT_MAX, \
+ unsigned short int, USHRT_MAX) \
: sizeof *(r) == sizeof (int) \
- ? _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned int, \
- int, INT_MIN, INT_MAX) \
+ ? (EXPR_SIGNED (*(r)) \
+ ? _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned int, \
+ int, INT_MIN, INT_MAX) \
+ : _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned int, \
+ unsigned int, 0, UINT_MAX)) \
: _GL_INT_OP_WRAPV_LONGISH(a, b, r, op, overflow))
# ifdef LLONG_MAX
# define _GL_INT_OP_WRAPV_LONGISH(a, b, r, op, overflow) \
(sizeof *(r) == sizeof (long int) \
- ? _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned long int, \
- long int, LONG_MIN, LONG_MAX) \
- : _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned long long int, \
- long long int, LLONG_MIN, LLONG_MAX))
+ ? (EXPR_SIGNED (*(r)) \
+ ? _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned long int, \
+ long int, LONG_MIN, LONG_MAX) \
+ : _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned long int, \
+ unsigned long int, 0, ULONG_MAX)) \
+ : (EXPR_SIGNED (*(r)) \
+ ? _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned long long int, \
+ long long int, LLONG_MIN, LLONG_MAX) \
+ : _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned long long int, \
+ unsigned long long int, 0, ULLONG_MAX)))
# else
# define _GL_INT_OP_WRAPV_LONGISH(a, b, r, op, overflow) \
- _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned long int, \
- long int, LONG_MIN, LONG_MAX)
+ (EXPR_SIGNED (*(r)) \
+ ? _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned long int, \
+ long int, LONG_MIN, LONG_MAX) \
+ : _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned long int, \
+ unsigned long int, 0, ULONG_MAX))
# endif
#endif
/* Store the low-order bits of A <op> B into *R, where the operation
is given by OP. Use the unsigned type UT for calculation to avoid
- overflow problems. *R's type is T, with extremal values TMIN and
- TMAX. T must be a signed integer type. Return 1 if the result
- overflows. */
+ overflow problems. *R's type is T, with extrema TMIN and TMAX.
+ T must be a signed integer type. Return 1 if the result overflows. */
#define _GL_INT_OP_CALC(a, b, r, op, overflow, ut, t, tmin, tmax) \
- (sizeof ((a) op (b)) < sizeof (t) \
- ? _GL_INT_OP_CALC1 ((t) (a), (t) (b), r, op, overflow, ut, t, tmin, tmax) \
- : _GL_INT_OP_CALC1 (a, b, r, op, overflow, ut, t, tmin, tmax))
-#define _GL_INT_OP_CALC1(a, b, r, op, overflow, ut, t, tmin, tmax) \
- ((overflow (a, b) \
- || (EXPR_SIGNED ((a) op (b)) && ((a) op (b)) < (tmin)) \
- || (tmax) < ((a) op (b))) \
- ? (*(r) = _GL_INT_OP_WRAPV_VIA_UNSIGNED (a, b, op, ut, t, tmin, tmax), 1) \
- : (*(r) = _GL_INT_OP_WRAPV_VIA_UNSIGNED (a, b, op, ut, t, tmin, tmax), 0))
-
-/* Return A <op> B, where the operation is given by OP. Use the
- unsigned type UT for calculation to avoid overflow problems.
- Convert the result to type T without overflow by subtracting TMIN
- from large values before converting, and adding it afterwards.
- Compilers can optimize all the operations except OP. */
-#define _GL_INT_OP_WRAPV_VIA_UNSIGNED(a, b, op, ut, t, tmin, tmax) \
- (((ut) (a) op (ut) (b)) <= (tmax) \
- ? (t) ((ut) (a) op (ut) (b)) \
- : ((t) (((ut) (a) op (ut) (b)) - (tmin)) + (tmin)))
+ (overflow (a, b, tmin, tmax) \
+ ? (*(r) = _GL_INT_OP_WRAPV_VIA_UNSIGNED (a, b, op, ut, t), 1) \
+ : (*(r) = _GL_INT_OP_WRAPV_VIA_UNSIGNED (a, b, op, ut, t), 0))
+
+/* Return the low-order bits of A <op> B, where the operation is given
+ by OP. Use the unsigned type UT for calculation to avoid undefined
+ behavior on signed integer overflow, and convert the result to type T.
+ UT is at least as wide as T and is no narrower than unsigned int,
+ T is two's complement, and there is no padding or trap representations.
+ Assume that converting UT to T yields the low-order bits, as is
+ done in all known two's-complement C compilers. E.g., see:
+ https://gcc.gnu.org/onlinedocs/gcc/Integers-implementation.html
+
+ According to the C standard, converting UT to T yields an
+ implementation-defined result or signal for values outside T's
+ range. However, code that works around this theoretical problem
+ runs afoul of a compiler bug in Oracle Studio 12.3 x86. See:
+ https://lists.gnu.org/r/bug-gnulib/2017-04/msg00049.html
+ As the compiler bug is real, don't try to work around the
+ theoretical problem. */
+
+#define _GL_INT_OP_WRAPV_VIA_UNSIGNED(a, b, op, ut, t) \
+ ((t) ((ut) (a) op (ut) (b)))
+
+/* Return true if the numeric values A + B, A - B, A * B fall outside
+ the range TMIN..TMAX. Arguments should be integer expressions
+ without side effects. TMIN should be signed and nonpositive.
+ TMAX should be positive, and should be signed unless TMIN is zero. */
+#define _GL_INT_ADD_RANGE_OVERFLOW(a, b, tmin, tmax) \
+ ((b) < 0 \
+ ? (((tmin) \
+ ? ((EXPR_SIGNED (_GL_INT_CONVERT (a, (tmin) - (b))) || (b) < (tmin)) \
+ && (a) < (tmin) - (b)) \
+ : (a) <= -1 - (b)) \
+ || ((EXPR_SIGNED (a) ? 0 <= (a) : (tmax) < (a)) && (tmax) < (a) + (b))) \
+ : (a) < 0 \
+ ? (((tmin) \
+ ? ((EXPR_SIGNED (_GL_INT_CONVERT (b, (tmin) - (a))) || (a) < (tmin)) \
+ && (b) < (tmin) - (a)) \
+ : (b) <= -1 - (a)) \
+ || ((EXPR_SIGNED (_GL_INT_CONVERT (a, b)) || (tmax) < (b)) \
+ && (tmax) < (a) + (b))) \
+ : (tmax) < (b) || (tmax) - (b) < (a))
+#define _GL_INT_SUBTRACT_RANGE_OVERFLOW(a, b, tmin, tmax) \
+ (((a) < 0) == ((b) < 0) \
+ ? ((a) < (b) \
+ ? !(tmin) || -1 - (tmin) < (b) - (a) - 1 \
+ : (tmax) < (a) - (b)) \
+ : (a) < 0 \
+ ? ((!EXPR_SIGNED (_GL_INT_CONVERT ((a) - (tmin), b)) && (a) - (tmin) < 0) \
+ || (a) - (tmin) < (b)) \
+ : ((! (EXPR_SIGNED (_GL_INT_CONVERT (tmax, b)) \
+ && EXPR_SIGNED (_GL_INT_CONVERT ((tmax) + (b), a))) \
+ && (tmax) <= -1 - (b)) \
+ || (tmax) + (b) < (a)))
+#define _GL_INT_MULTIPLY_RANGE_OVERFLOW(a, b, tmin, tmax) \
+ ((b) < 0 \
+ ? ((a) < 0 \
+ ? (EXPR_SIGNED (_GL_INT_CONVERT (tmax, b)) \
+ ? (a) < (tmax) / (b) \
+ : ((INT_NEGATE_OVERFLOW (b) \
+ ? _GL_INT_CONVERT (b, tmax) >> (TYPE_WIDTH (+ (b)) - 1) \
+ : (tmax) / -(b)) \
+ <= -1 - (a))) \
+ : INT_NEGATE_OVERFLOW (_GL_INT_CONVERT (b, tmin)) && (b) == -1 \
+ ? (EXPR_SIGNED (a) \
+ ? 0 < (a) + (tmin) \
+ : 0 < (a) && -1 - (tmin) < (a) - 1) \
+ : (tmin) / (b) < (a)) \
+ : (b) == 0 \
+ ? 0 \
+ : ((a) < 0 \
+ ? (INT_NEGATE_OVERFLOW (_GL_INT_CONVERT (a, tmin)) && (a) == -1 \
+ ? (EXPR_SIGNED (b) ? 0 < (b) + (tmin) : -1 - (tmin) < (b) - 1) \
+ : (tmin) / (a) < (b)) \
+ : (tmax) / (b) < (a)))
+
+/* The following macros compute A + B, A - B, and A * B, respectively.
+ If no overflow occurs, they set *R to the result and return 1;
+ otherwise, they return 0 and may modify *R.
+
+ Example usage:
+
+ long int result;
+ if (INT_ADD_OK (a, b, &result))
+ printf ("result is %ld\n", result);
+ else
+ printf ("overflow\n");
+
+ A, B, and *R should be integers; they need not be the same type,
+ and they need not be all signed or all unsigned.
+
+ These macros work correctly on all known practical hosts, and do not rely
+ on undefined behavior due to signed arithmetic overflow.
+
+ These macros are not constant expressions.
+
+ These macros may evaluate their arguments zero or multiple times, so the
+ arguments should not have side effects.
+
+ These macros are tuned for B being a constant. */
+
+#define INT_ADD_OK(a, b, r) ! INT_ADD_WRAPV (a, b, r)
+#define INT_SUBTRACT_OK(a, b, r) ! INT_SUBTRACT_WRAPV (a, b, r)
+#define INT_MULTIPLY_OK(a, b, r) ! INT_MULTIPLY_WRAPV (a, b, r)
#endif /* _GL_INTPROPS_H */