643 lines
28 KiB
C
643 lines
28 KiB
C
/* intprops.h -- properties of integer types
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Copyright (C) 2001-2022 Free Software Foundation, Inc.
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This program is free software: you can redistribute it and/or modify it
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under the terms of the GNU Lesser General Public License as published
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by the Free Software Foundation; either version 2.1 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with this program. If not, see <https://www.gnu.org/licenses/>. */
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#ifndef _GL_INTPROPS_H
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#define _GL_INTPROPS_H
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#include <limits.h>
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/* Return a value with the common real type of E and V and the value of V.
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Do not evaluate E. */
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#define _GL_INT_CONVERT(e, v) ((1 ? 0 : (e)) + (v))
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/* Act like _GL_INT_CONVERT (E, -V) but work around a bug in IRIX 6.5 cc; see
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<https://lists.gnu.org/r/bug-gnulib/2011-05/msg00406.html>. */
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#define _GL_INT_NEGATE_CONVERT(e, v) ((1 ? 0 : (e)) - (v))
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/* The extra casts in the following macros work around compiler bugs,
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e.g., in Cray C 5.0.3.0. */
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/* True if the arithmetic type T is an integer type. bool counts as
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an integer. */
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#define TYPE_IS_INTEGER(t) ((t) 1.5 == 1)
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/* True if the real type T is signed. */
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#define TYPE_SIGNED(t) (! ((t) 0 < (t) -1))
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/* Return 1 if the real expression E, after promotion, has a
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signed or floating type. Do not evaluate E. */
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#define EXPR_SIGNED(e) (_GL_INT_NEGATE_CONVERT (e, 1) < 0)
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/* Minimum and maximum values for integer types and expressions. */
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/* The width in bits of the integer type or expression T.
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Do not evaluate T. T must not be a bit-field expression.
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Padding bits are not supported; this is checked at compile-time below. */
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#define TYPE_WIDTH(t) (sizeof (t) * CHAR_BIT)
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/* The maximum and minimum values for the integer type T. */
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#define TYPE_MINIMUM(t) ((t) ~ TYPE_MAXIMUM (t))
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#define TYPE_MAXIMUM(t) \
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((t) (! TYPE_SIGNED (t) \
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? (t) -1 \
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: ((((t) 1 << (TYPE_WIDTH (t) - 2)) - 1) * 2 + 1)))
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/* The maximum and minimum values for the type of the expression E,
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after integer promotion. E is not evaluated. */
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#define _GL_INT_MINIMUM(e) \
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(EXPR_SIGNED (e) \
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? ~ _GL_SIGNED_INT_MAXIMUM (e) \
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: _GL_INT_CONVERT (e, 0))
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#define _GL_INT_MAXIMUM(e) \
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(EXPR_SIGNED (e) \
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? _GL_SIGNED_INT_MAXIMUM (e) \
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: _GL_INT_NEGATE_CONVERT (e, 1))
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#define _GL_SIGNED_INT_MAXIMUM(e) \
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(((_GL_INT_CONVERT (e, 1) << (TYPE_WIDTH (+ (e)) - 2)) - 1) * 2 + 1)
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/* Work around OpenVMS incompatibility with C99. */
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#if !defined LLONG_MAX && defined __INT64_MAX
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# define LLONG_MAX __INT64_MAX
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# define LLONG_MIN __INT64_MIN
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#endif
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/* This include file assumes that signed types are two's complement without
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padding bits; the above macros have undefined behavior otherwise.
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If this is a problem for you, please let us know how to fix it for your host.
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This assumption is tested by the intprops-tests module. */
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/* Does the __typeof__ keyword work? This could be done by
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'configure', but for now it's easier to do it by hand. */
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#if (2 <= __GNUC__ \
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|| (4 <= __clang_major__) \
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|| (1210 <= __IBMC__ && defined __IBM__TYPEOF__) \
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|| (0x5110 <= __SUNPRO_C && !__STDC__))
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# define _GL_HAVE___TYPEOF__ 1
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#else
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# define _GL_HAVE___TYPEOF__ 0
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#endif
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/* Return 1 if the integer type or expression T might be signed. Return 0
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if it is definitely unsigned. T must not be a bit-field expression.
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This macro does not evaluate its argument, and expands to an
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integer constant expression. */
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#if _GL_HAVE___TYPEOF__
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# define _GL_SIGNED_TYPE_OR_EXPR(t) TYPE_SIGNED (__typeof__ (t))
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#else
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# define _GL_SIGNED_TYPE_OR_EXPR(t) 1
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#endif
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/* Bound on length of the string representing an unsigned integer
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value representable in B bits. log10 (2.0) < 146/485. The
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smallest value of B where this bound is not tight is 2621. */
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#define INT_BITS_STRLEN_BOUND(b) (((b) * 146 + 484) / 485)
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/* Bound on length of the string representing an integer type or expression T.
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T must not be a bit-field expression.
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Subtract 1 for the sign bit if T is signed, and then add 1 more for
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a minus sign if needed.
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Because _GL_SIGNED_TYPE_OR_EXPR sometimes returns 1 when its argument is
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unsigned, this macro may overestimate the true bound by one byte when
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applied to unsigned types of size 2, 4, 16, ... bytes. */
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#define INT_STRLEN_BOUND(t) \
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(INT_BITS_STRLEN_BOUND (TYPE_WIDTH (t) - _GL_SIGNED_TYPE_OR_EXPR (t)) \
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+ _GL_SIGNED_TYPE_OR_EXPR (t))
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/* Bound on buffer size needed to represent an integer type or expression T,
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including the terminating null. T must not be a bit-field expression. */
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#define INT_BUFSIZE_BOUND(t) (INT_STRLEN_BOUND (t) + 1)
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/* Range overflow checks.
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The INT_<op>_RANGE_OVERFLOW macros return 1 if the corresponding C
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operators might not yield numerically correct answers due to
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arithmetic overflow. They do not rely on undefined or
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implementation-defined behavior. Their implementations are simple
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and straightforward, but they are harder to use and may be less
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efficient than the INT_<op>_WRAPV, INT_<op>_OK, and
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INT_<op>_OVERFLOW macros described below.
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Example usage:
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long int i = ...;
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long int j = ...;
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if (INT_MULTIPLY_RANGE_OVERFLOW (i, j, LONG_MIN, LONG_MAX))
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printf ("multiply would overflow");
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else
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printf ("product is %ld", i * j);
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Restrictions on *_RANGE_OVERFLOW macros:
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These macros do not check for all possible numerical problems or
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undefined or unspecified behavior: they do not check for division
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by zero, for bad shift counts, or for shifting negative numbers.
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These macros may evaluate their arguments zero or multiple times,
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so the arguments should not have side effects. The arithmetic
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arguments (including the MIN and MAX arguments) must be of the same
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integer type after the usual arithmetic conversions, and the type
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must have minimum value MIN and maximum MAX. Unsigned types should
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use a zero MIN of the proper type.
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Because all arguments are subject to integer promotions, these
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macros typically do not work on types narrower than 'int'.
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These macros are tuned for constant MIN and MAX. For commutative
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operations such as A + B, they are also tuned for constant B. */
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/* Return 1 if A + B would overflow in [MIN,MAX] arithmetic.
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See above for restrictions. */
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#define INT_ADD_RANGE_OVERFLOW(a, b, min, max) \
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((b) < 0 \
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? (a) < (min) - (b) \
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: (max) - (b) < (a))
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/* Return 1 if A - B would overflow in [MIN,MAX] arithmetic.
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See above for restrictions. */
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#define INT_SUBTRACT_RANGE_OVERFLOW(a, b, min, max) \
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((b) < 0 \
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? (max) + (b) < (a) \
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: (a) < (min) + (b))
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/* Return 1 if - A would overflow in [MIN,MAX] arithmetic.
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See above for restrictions. */
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#define INT_NEGATE_RANGE_OVERFLOW(a, min, max) \
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((min) < 0 \
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? (a) < - (max) \
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: 0 < (a))
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/* Return 1 if A * B would overflow in [MIN,MAX] arithmetic.
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See above for restrictions. Avoid && and || as they tickle
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bugs in Sun C 5.11 2010/08/13 and other compilers; see
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<https://lists.gnu.org/r/bug-gnulib/2011-05/msg00401.html>. */
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#define INT_MULTIPLY_RANGE_OVERFLOW(a, b, min, max) \
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((b) < 0 \
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? ((a) < 0 \
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? (a) < (max) / (b) \
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: (b) == -1 \
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? 0 \
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: (min) / (b) < (a)) \
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: (b) == 0 \
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? 0 \
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: ((a) < 0 \
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? (a) < (min) / (b) \
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: (max) / (b) < (a)))
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/* Return 1 if A / B would overflow in [MIN,MAX] arithmetic.
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See above for restrictions. Do not check for division by zero. */
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#define INT_DIVIDE_RANGE_OVERFLOW(a, b, min, max) \
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((min) < 0 && (b) == -1 && (a) < - (max))
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/* Return 1 if A % B would overflow in [MIN,MAX] arithmetic.
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See above for restrictions. Do not check for division by zero.
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Mathematically, % should never overflow, but on x86-like hosts
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INT_MIN % -1 traps, and the C standard permits this, so treat this
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as an overflow too. */
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#define INT_REMAINDER_RANGE_OVERFLOW(a, b, min, max) \
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INT_DIVIDE_RANGE_OVERFLOW (a, b, min, max)
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/* Return 1 if A << B would overflow in [MIN,MAX] arithmetic.
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See above for restrictions. Here, MIN and MAX are for A only, and B need
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not be of the same type as the other arguments. The C standard says that
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behavior is undefined for shifts unless 0 <= B < wordwidth, and that when
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A is negative then A << B has undefined behavior and A >> B has
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implementation-defined behavior, but do not check these other
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restrictions. */
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#define INT_LEFT_SHIFT_RANGE_OVERFLOW(a, b, min, max) \
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((a) < 0 \
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? (a) < (min) >> (b) \
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: (max) >> (b) < (a))
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/* True if __builtin_add_overflow (A, B, P) and __builtin_sub_overflow
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(A, B, P) work when P is non-null. */
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#ifdef __EDG__
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/* EDG-based compilers like nvc 22.1 cannot add 64-bit signed to unsigned
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<https://bugs.gnu.org/53256>. */
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# define _GL_HAS_BUILTIN_ADD_OVERFLOW 0
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#elif defined __has_builtin
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# define _GL_HAS_BUILTIN_ADD_OVERFLOW __has_builtin (__builtin_add_overflow)
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/* __builtin_{add,sub}_overflow exists but is not reliable in GCC 5.x and 6.x,
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see <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98269>. */
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#elif 7 <= __GNUC__
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# define _GL_HAS_BUILTIN_ADD_OVERFLOW 1
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#else
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# define _GL_HAS_BUILTIN_ADD_OVERFLOW 0
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#endif
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/* True if __builtin_mul_overflow (A, B, P) works when P is non-null. */
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#if defined __clang_major__ && __clang_major__ < 14
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/* Work around Clang bug <https://bugs.llvm.org/show_bug.cgi?id=16404>. */
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# define _GL_HAS_BUILTIN_MUL_OVERFLOW 0
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#else
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# define _GL_HAS_BUILTIN_MUL_OVERFLOW _GL_HAS_BUILTIN_ADD_OVERFLOW
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#endif
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/* True if __builtin_add_overflow_p (A, B, C) works, and similarly for
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__builtin_sub_overflow_p and __builtin_mul_overflow_p. */
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#ifdef __EDG__
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/* In EDG-based compilers like ICC 2021.3 and earlier,
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__builtin_add_overflow_p etc. are not treated as integral constant
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expressions even when all arguments are. */
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# define _GL_HAS_BUILTIN_OVERFLOW_P 0
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#elif defined __has_builtin
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# define _GL_HAS_BUILTIN_OVERFLOW_P __has_builtin (__builtin_mul_overflow_p)
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#else
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# define _GL_HAS_BUILTIN_OVERFLOW_P (7 <= __GNUC__)
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#endif
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/* The _GL*_OVERFLOW macros have the same restrictions as the
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*_RANGE_OVERFLOW macros, except that they do not assume that operands
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(e.g., A and B) have the same type as MIN and MAX. Instead, they assume
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that the result (e.g., A + B) has that type. */
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#if _GL_HAS_BUILTIN_OVERFLOW_P
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# define _GL_ADD_OVERFLOW(a, b, min, max) \
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__builtin_add_overflow_p (a, b, (__typeof__ ((a) + (b))) 0)
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# define _GL_SUBTRACT_OVERFLOW(a, b, min, max) \
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__builtin_sub_overflow_p (a, b, (__typeof__ ((a) - (b))) 0)
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# define _GL_MULTIPLY_OVERFLOW(a, b, min, max) \
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__builtin_mul_overflow_p (a, b, (__typeof__ ((a) * (b))) 0)
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#else
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# define _GL_ADD_OVERFLOW(a, b, min, max) \
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((min) < 0 ? INT_ADD_RANGE_OVERFLOW (a, b, min, max) \
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: (a) < 0 ? (b) <= (a) + (b) \
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: (b) < 0 ? (a) <= (a) + (b) \
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: (a) + (b) < (b))
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# define _GL_SUBTRACT_OVERFLOW(a, b, min, max) \
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((min) < 0 ? INT_SUBTRACT_RANGE_OVERFLOW (a, b, min, max) \
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: (a) < 0 ? 1 \
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: (b) < 0 ? (a) - (b) <= (a) \
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: (a) < (b))
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# define _GL_MULTIPLY_OVERFLOW(a, b, min, max) \
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(((min) == 0 && (((a) < 0 && 0 < (b)) || ((b) < 0 && 0 < (a)))) \
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|| INT_MULTIPLY_RANGE_OVERFLOW (a, b, min, max))
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#endif
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#define _GL_DIVIDE_OVERFLOW(a, b, min, max) \
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((min) < 0 ? (b) == _GL_INT_NEGATE_CONVERT (min, 1) && (a) < - (max) \
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: (a) < 0 ? (b) <= (a) + (b) - 1 \
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: (b) < 0 && (a) + (b) <= (a))
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#define _GL_REMAINDER_OVERFLOW(a, b, min, max) \
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((min) < 0 ? (b) == _GL_INT_NEGATE_CONVERT (min, 1) && (a) < - (max) \
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: (a) < 0 ? (a) % (b) != ((max) - (b) + 1) % (b) \
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: (b) < 0 && ! _GL_UNSIGNED_NEG_MULTIPLE (a, b, max))
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/* Return a nonzero value if A is a mathematical multiple of B, where
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A is unsigned, B is negative, and MAX is the maximum value of A's
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type. A's type must be the same as (A % B)'s type. Normally (A %
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-B == 0) suffices, but things get tricky if -B would overflow. */
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#define _GL_UNSIGNED_NEG_MULTIPLE(a, b, max) \
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(((b) < -_GL_SIGNED_INT_MAXIMUM (b) \
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? (_GL_SIGNED_INT_MAXIMUM (b) == (max) \
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? (a) \
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: (a) % (_GL_INT_CONVERT (a, _GL_SIGNED_INT_MAXIMUM (b)) + 1)) \
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: (a) % - (b)) \
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== 0)
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/* Check for integer overflow, and report low order bits of answer.
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The INT_<op>_OVERFLOW macros return 1 if the corresponding C operators
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might not yield numerically correct answers due to arithmetic overflow.
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The INT_<op>_WRAPV macros compute the low-order bits of the sum,
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difference, and product of two C integers, and return 1 if these
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low-order bits are not numerically correct.
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These macros work correctly on all known practical hosts, and do not rely
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on undefined behavior due to signed arithmetic overflow.
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Example usage, assuming A and B are long int:
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if (INT_MULTIPLY_OVERFLOW (a, b))
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printf ("result would overflow\n");
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else
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printf ("result is %ld (no overflow)\n", a * b);
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Example usage with WRAPV flavor:
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long int result;
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bool overflow = INT_MULTIPLY_WRAPV (a, b, &result);
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printf ("result is %ld (%s)\n", result,
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overflow ? "after overflow" : "no overflow");
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Restrictions on these macros:
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These macros do not check for all possible numerical problems or
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undefined or unspecified behavior: they do not check for division
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by zero, for bad shift counts, or for shifting negative numbers.
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These macros may evaluate their arguments zero or multiple times, so the
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arguments should not have side effects.
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The WRAPV macros are not constant expressions. They support only
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+, binary -, and *.
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Because the WRAPV macros convert the result, they report overflow
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in different circumstances than the OVERFLOW macros do. For
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example, in the typical case with 16-bit 'short' and 32-bit 'int',
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if A, B and R are all of type 'short' then INT_ADD_OVERFLOW (A, B)
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returns false because the addition cannot overflow after A and B
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are converted to 'int', whereas INT_ADD_WRAPV (A, B, &R) returns
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true or false depending on whether the sum fits into 'short'.
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These macros are tuned for their last input argument being a constant.
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Return 1 if the integer expressions A * B, A - B, -A, A * B, A / B,
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A % B, and A << B would overflow, respectively. */
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#define INT_ADD_OVERFLOW(a, b) \
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_GL_BINARY_OP_OVERFLOW (a, b, _GL_ADD_OVERFLOW)
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#define INT_SUBTRACT_OVERFLOW(a, b) \
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_GL_BINARY_OP_OVERFLOW (a, b, _GL_SUBTRACT_OVERFLOW)
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#if _GL_HAS_BUILTIN_OVERFLOW_P
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# define INT_NEGATE_OVERFLOW(a) INT_SUBTRACT_OVERFLOW (0, a)
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#else
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# define INT_NEGATE_OVERFLOW(a) \
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INT_NEGATE_RANGE_OVERFLOW (a, _GL_INT_MINIMUM (a), _GL_INT_MAXIMUM (a))
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#endif
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#define INT_MULTIPLY_OVERFLOW(a, b) \
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_GL_BINARY_OP_OVERFLOW (a, b, _GL_MULTIPLY_OVERFLOW)
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#define INT_DIVIDE_OVERFLOW(a, b) \
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_GL_BINARY_OP_OVERFLOW (a, b, _GL_DIVIDE_OVERFLOW)
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#define INT_REMAINDER_OVERFLOW(a, b) \
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_GL_BINARY_OP_OVERFLOW (a, b, _GL_REMAINDER_OVERFLOW)
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#define INT_LEFT_SHIFT_OVERFLOW(a, b) \
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INT_LEFT_SHIFT_RANGE_OVERFLOW (a, b, \
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_GL_INT_MINIMUM (a), _GL_INT_MAXIMUM (a))
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/* Return 1 if the expression A <op> B would overflow,
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where OP_RESULT_OVERFLOW (A, B, MIN, MAX) does the actual test,
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assuming MIN and MAX are the minimum and maximum for the result type.
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Arguments should be free of side effects. */
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#define _GL_BINARY_OP_OVERFLOW(a, b, op_result_overflow) \
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op_result_overflow (a, b, \
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_GL_INT_MINIMUM (_GL_INT_CONVERT (a, b)), \
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_GL_INT_MAXIMUM (_GL_INT_CONVERT (a, b)))
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/* Store the low-order bits of A + B, A - B, A * B, respectively, into *R.
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Return 1 if the result overflows. See above for restrictions. */
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#if _GL_HAS_BUILTIN_ADD_OVERFLOW
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# define INT_ADD_WRAPV(a, b, r) __builtin_add_overflow (a, b, r)
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# define INT_SUBTRACT_WRAPV(a, b, r) __builtin_sub_overflow (a, b, r)
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#else
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# define INT_ADD_WRAPV(a, b, r) \
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_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 */
|