/* intprops.h -- properties of integer types | |

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 | |

by the Free Software Foundation; either version 3 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 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 <https://www.gnu.org/licenses/>. */ | |

/* Written by Paul Eggert. */ | |

#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 a bit harder to use than the | |

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. | |

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. */ | |

/* __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, 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 | |

(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. | |

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 __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 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 */ |