| /* intprops.h -- properties of integer types |
| |
| Copyright (C) 2001-2022 Free Software Foundation, Inc. |
| |
| This program is free software: you can redistribute it and/or modify it |
| under the terms of the GNU Lesser General Public License as published |
| by the Free Software Foundation; either version 2.1 of the License, or |
| (at your option) any later version. |
| |
| This program is distributed in the hope that it will be useful, |
| but WITHOUT ANY WARRANTY; without even the implied warranty of |
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| GNU Lesser General Public License for more details. |
| |
| You should have received a copy of the GNU Lesser General Public License |
| along with this program. If not, see <https://www.gnu.org/licenses/>. */ |
| |
| |
| #ifndef _GL_INTPROPS_H |
| #define _GL_INTPROPS_H |
| |
| #include <limits.h> |
| |
| /* 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 |
| <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. */ |
| |
| /* True if the arithmetic type T is an integer type. bool counts as |
| an integer. */ |
| #define TYPE_IS_INTEGER(t) ((t) 1.5 == 1) |
| |
| /* True if the real type T is signed. */ |
| #define TYPE_SIGNED(t) (! ((t) 0 < (t) -1)) |
| |
| /* Return 1 if the real expression E, after promotion, has a |
| 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) |
| |
| /* The maximum and minimum values for the integer type T. */ |
| #define TYPE_MINIMUM(t) ((t) ~ TYPE_MAXIMUM (t)) |
| #define TYPE_MAXIMUM(t) \ |
| ((t) (! TYPE_SIGNED (t) \ |
| ? (t) -1 \ |
| : ((((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 is not evaluated. */ |
| #define _GL_INT_MINIMUM(e) \ |
| (EXPR_SIGNED (e) \ |
| ? ~ _GL_SIGNED_INT_MAXIMUM (e) \ |
| : _GL_INT_CONVERT (e, 0)) |
| #define _GL_INT_MAXIMUM(e) \ |
| (EXPR_SIGNED (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)) - 2)) - 1) * 2 + 1) |
| |
| /* Work around OpenVMS incompatibility with C99. */ |
| #if !defined LLONG_MAX && defined __INT64_MAX |
| # define LLONG_MAX __INT64_MAX |
| # define LLONG_MIN __INT64_MIN |
| #endif |
| |
| /* 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. |
| 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 |
| #else |
| # define _GL_HAVE___TYPEOF__ 0 |
| #endif |
| |
| /* Return 1 if the integer type or expression T might be signed. Return 0 |
| 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 _GL_SIGNED_TYPE_OR_EXPR(t) 1 |
| #endif |
| |
| /* Bound on length of the string representing an unsigned integer |
| value representable in B bits. log10 (2.0) < 146/485. The |
| smallest value of B where this bound is not tight is 2621. */ |
| #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 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. T must not be a bit-field expression. */ |
| #define INT_BUFSIZE_BOUND(t) (INT_STRLEN_BOUND (t) + 1) |
| |
| |
| /* Range overflow checks. |
| |
| The INT_<op>_RANGE_OVERFLOW macros return 1 if the corresponding C |
| 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 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: |
| |
| long int i = ...; |
| long int j = ...; |
| if (INT_MULTIPLY_RANGE_OVERFLOW (i, j, LONG_MIN, LONG_MAX)) |
| printf ("multiply would overflow"); |
| else |
| printf ("product is %ld", i * j); |
| |
| Restrictions on *_RANGE_OVERFLOW macros: |
| |
| These macros do not check for all possible numerical problems or |
| undefined or unspecified behavior: they do not check for division |
| by zero, for bad shift counts, or for shifting negative numbers. |
| |
| These macros may evaluate their arguments zero or multiple times, |
| so the arguments should not have side effects. The arithmetic |
| arguments (including the MIN and MAX arguments) must be of the same |
| integer type after the usual arithmetic conversions, and the type |
| 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. */ |
| #define INT_ADD_RANGE_OVERFLOW(a, b, min, max) \ |
| ((b) < 0 \ |
| ? (a) < (min) - (b) \ |
| : (max) - (b) < (a)) |
| |
| /* Return 1 if A - B would overflow in [MIN,MAX] arithmetic. |
| See above for restrictions. */ |
| #define INT_SUBTRACT_RANGE_OVERFLOW(a, b, min, max) \ |
| ((b) < 0 \ |
| ? (max) + (b) < (a) \ |
| : (a) < (min) + (b)) |
| |
| /* Return 1 if - A would overflow in [MIN,MAX] arithmetic. |
| See above for restrictions. */ |
| #define INT_NEGATE_RANGE_OVERFLOW(a, min, max) \ |
| ((min) < 0 \ |
| ? (a) < - (max) \ |
| : 0 < (a)) |
| |
| /* 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 |
| <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) < (max) / (b) \ |
| : (b) == -1 \ |
| ? 0 \ |
| : (min) / (b) < (a)) \ |
| : (b) == 0 \ |
| ? 0 \ |
| : ((a) < 0 \ |
| ? (a) < (min) / (b) \ |
| : (max) / (b) < (a))) |
| |
| /* Return 1 if A / B would overflow in [MIN,MAX] arithmetic. |
| See above for restrictions. Do not check for division by zero. */ |
| #define INT_DIVIDE_RANGE_OVERFLOW(a, b, min, max) \ |
| ((min) < 0 && (b) == -1 && (a) < - (max)) |
| |
| /* Return 1 if A % B would overflow in [MIN,MAX] arithmetic. |
| See above for restrictions. Do not check for division by zero. |
| Mathematically, % should never overflow, but on x86-like hosts |
| INT_MIN % -1 traps, and the C standard permits this, so treat this |
| as an overflow too. */ |
| #define INT_REMAINDER_RANGE_OVERFLOW(a, b, min, max) \ |
| INT_DIVIDE_RANGE_OVERFLOW (a, b, min, max) |
| |
| /* Return 1 if A << B would overflow in [MIN,MAX] arithmetic. |
| See above for restrictions. Here, MIN and MAX are for A only, and B need |
| not be of the same type as the other arguments. The C standard says that |
| behavior is undefined for shifts unless 0 <= B < wordwidth, and that when |
| A is negative then A << B has undefined behavior and A >> B has |
| implementation-defined behavior, but do not check these other |
| restrictions. */ |
| #define INT_LEFT_SHIFT_RANGE_OVERFLOW(a, b, min, max) \ |
| ((a) < 0 \ |
| ? (a) < (min) >> (b) \ |
| : (max) >> (b) < (a)) |
| |
| /* True if __builtin_add_overflow (A, B, P) and __builtin_sub_overflow |
| (A, B, P) work when P is non-null. */ |
| #ifdef __EDG__ |
| /* EDG-based compilers like nvc 22.1 cannot add 64-bit signed to unsigned |
| <https://bugs.gnu.org/53256>. */ |
| # define _GL_HAS_BUILTIN_ADD_OVERFLOW 0 |
| #elif defined __has_builtin |
| # define _GL_HAS_BUILTIN_ADD_OVERFLOW __has_builtin (__builtin_add_overflow) |
| /* __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>. */ |
| #elif 7 <= __GNUC__ |
| # define _GL_HAS_BUILTIN_ADD_OVERFLOW 1 |
| #else |
| # define _GL_HAS_BUILTIN_ADD_OVERFLOW 0 |
| #endif |
| |
| /* True if __builtin_mul_overflow (A, B, P) works when P is non-null. */ |
| #if defined __clang_major__ && __clang_major__ < 14 |
| /* 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, and similarly for |
| __builtin_sub_overflow_p and __builtin_mul_overflow_p. */ |
| #ifdef __EDG__ |
| /* In EDG-based compilers like ICC 2021.3 and earlier, |
| __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 |
| (e.g., A and B) have the same type as MIN and MAX. Instead, they assume |
| that the result (e.g., A + B) has that type. */ |
| #if _GL_HAS_BUILTIN_OVERFLOW_P |
| # define _GL_ADD_OVERFLOW(a, b, min, max) \ |
| __builtin_add_overflow_p (a, b, (__typeof__ ((a) + (b))) 0) |
| # define _GL_SUBTRACT_OVERFLOW(a, b, min, max) \ |
| __builtin_sub_overflow_p (a, b, (__typeof__ ((a) - (b))) 0) |
| # define _GL_MULTIPLY_OVERFLOW(a, b, min, max) \ |
| __builtin_mul_overflow_p (a, b, (__typeof__ ((a) * (b))) 0) |
| #else |
| # define _GL_ADD_OVERFLOW(a, b, min, max) \ |
| ((min) < 0 ? INT_ADD_RANGE_OVERFLOW (a, b, min, max) \ |
| : (a) < 0 ? (b) <= (a) + (b) \ |
| : (b) < 0 ? (a) <= (a) + (b) \ |
| : (a) + (b) < (b)) |
| # define _GL_SUBTRACT_OVERFLOW(a, b, min, max) \ |
| ((min) < 0 ? INT_SUBTRACT_RANGE_OVERFLOW (a, b, min, max) \ |
| : (a) < 0 ? 1 \ |
| : (b) < 0 ? (a) - (b) <= (a) \ |
| : (a) < (b)) |
| # define _GL_MULTIPLY_OVERFLOW(a, b, min, max) \ |
| (((min) == 0 && (((a) < 0 && 0 < (b)) || ((b) < 0 && 0 < (a)))) \ |
| || INT_MULTIPLY_RANGE_OVERFLOW (a, b, min, max)) |
| #endif |
| #define _GL_DIVIDE_OVERFLOW(a, b, min, max) \ |
| ((min) < 0 ? (b) == _GL_INT_NEGATE_CONVERT (min, 1) && (a) < - (max) \ |
| : (a) < 0 ? (b) <= (a) + (b) - 1 \ |
| : (b) < 0 && (a) + (b) <= (a)) |
| #define _GL_REMAINDER_OVERFLOW(a, b, min, max) \ |
| ((min) < 0 ? (b) == _GL_INT_NEGATE_CONVERT (min, 1) && (a) < - (max) \ |
| : (a) < 0 ? (a) % (b) != ((max) - (b) + 1) % (b) \ |
| : (b) < 0 && ! _GL_UNSIGNED_NEG_MULTIPLE (a, b, max)) |
| |
| /* Return a nonzero value if A is a mathematical multiple of B, where |
| A is unsigned, B is negative, and MAX is the maximum value of A's |
| type. A's type must be the same as (A % B)'s type. Normally (A % |
| -B == 0) suffices, but things get tricky if -B would overflow. */ |
| #define _GL_UNSIGNED_NEG_MULTIPLE(a, b, max) \ |
| (((b) < -_GL_SIGNED_INT_MAXIMUM (b) \ |
| ? (_GL_SIGNED_INT_MAXIMUM (b) == (max) \ |
| ? (a) \ |
| : (a) % (_GL_INT_CONVERT (a, _GL_SIGNED_INT_MAXIMUM (b)) + 1)) \ |
| : (a) % - (b)) \ |
| == 0) |
| |
| /* Check for integer overflow, and report low order bits of answer. |
| |
| 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 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. |
| |
| Example usage, assuming A and B are long int: |
| |
| if (INT_MULTIPLY_OVERFLOW (a, b)) |
| printf ("result would overflow\n"); |
| else |
| printf ("result is %ld (no overflow)\n", a * b); |
| |
| Example usage with WRAPV flavor: |
| |
| long int result; |
| bool overflow = INT_MULTIPLY_WRAPV (a, b, &result); |
| printf ("result is %ld (%s)\n", result, |
| overflow ? "after overflow" : "no overflow"); |
| |
| Restrictions on these macros: |
| |
| These macros do not check for all possible numerical problems or |
| undefined or unspecified behavior: they do not check for division |
| by zero, for bad shift counts, or for shifting negative numbers. |
| |
| These macros may evaluate their arguments zero or multiple times, so the |
| arguments should not have side effects. |
| |
| The WRAPV macros are not constant expressions. They support only |
| +, binary -, and *. |
| |
| 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. */ |
| |
| #define INT_ADD_OVERFLOW(a, b) \ |
| _GL_BINARY_OP_OVERFLOW (a, b, _GL_ADD_OVERFLOW) |
| #define INT_SUBTRACT_OVERFLOW(a, b) \ |
| _GL_BINARY_OP_OVERFLOW (a, b, _GL_SUBTRACT_OVERFLOW) |
| #if _GL_HAS_BUILTIN_OVERFLOW_P |
| # define INT_NEGATE_OVERFLOW(a) INT_SUBTRACT_OVERFLOW (0, a) |
| #else |
| # define INT_NEGATE_OVERFLOW(a) \ |
| INT_NEGATE_RANGE_OVERFLOW (a, _GL_INT_MINIMUM (a), _GL_INT_MAXIMUM (a)) |
| #endif |
| #define INT_MULTIPLY_OVERFLOW(a, b) \ |
| _GL_BINARY_OP_OVERFLOW (a, b, _GL_MULTIPLY_OVERFLOW) |
| #define INT_DIVIDE_OVERFLOW(a, b) \ |
| _GL_BINARY_OP_OVERFLOW (a, b, _GL_DIVIDE_OVERFLOW) |
| #define INT_REMAINDER_OVERFLOW(a, b) \ |
| _GL_BINARY_OP_OVERFLOW (a, b, _GL_REMAINDER_OVERFLOW) |
| #define INT_LEFT_SHIFT_OVERFLOW(a, b) \ |
| INT_LEFT_SHIFT_RANGE_OVERFLOW (a, b, \ |
| _GL_INT_MINIMUM (a), _GL_INT_MAXIMUM (a)) |
| |
| /* Return 1 if the expression A <op> B would overflow, |
| where OP_RESULT_OVERFLOW (A, B, MIN, MAX) does the actual test, |
| assuming MIN and MAX are the minimum and maximum for the result type. |
| 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 (_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. */ |
| #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 __EDG__) |
| # 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 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 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 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 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), \ |
| 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 |
| /* 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_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_WRAPV_SMALLISH (a, b, r, op, overflow, \ |
| short int, SHRT_MIN, SHRT_MAX, \ |
| unsigned short int, USHRT_MAX) \ |
| : sizeof *(r) == sizeof (int) \ |
| ? (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) \ |
| ? (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) \ |
| (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 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) \ |
| (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 */ |
