diff options
Diffstat (limited to 'lib/gllib/intprops.h')
| -rw-r--r-- | lib/gllib/intprops.h | 266 |
1 files changed, 202 insertions, 64 deletions
diff --git a/lib/gllib/intprops.h b/lib/gllib/intprops.h index 6936ad5..eb06b69 100644 --- a/lib/gllib/intprops.h +++ b/lib/gllib/intprops.h @@ -1,10 +1,10 @@ /* intprops.h -- properties of integer types - Copyright (C) 2001-2005, 2009-2014 Free Software Foundation, Inc. + Copyright (C) 2001-2017 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 + 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, @@ -21,9 +21,9 @@ #define _GL_INTPROPS_H #include <limits.h> +#include <verify.h> -/* Return an integer value, converted to the same type as the integer - expression E after integer type promotion. V is the unconverted value. */ +/* Return a value with the common real type of E and V and the value of V. */ #define _GL_INT_CONVERT(e, v) (0 * (e) + (v)) /* Act like _GL_INT_CONVERT (E, -V) but work around a bug in IRIX 6.5 cc; see @@ -37,59 +37,72 @@ an integer. */ #define TYPE_IS_INTEGER(t) ((t) 1.5 == 1) -/* True if negative values of the signed integer type T use two's - complement, ones' complement, or signed magnitude representation, - respectively. Much GNU code assumes two's complement, but some - people like to be portable to all possible C hosts. */ -#define TYPE_TWOS_COMPLEMENT(t) ((t) ~ (t) 0 == (t) -1) -#define TYPE_ONES_COMPLEMENT(t) ((t) ~ (t) 0 == 0) -#define TYPE_SIGNED_MAGNITUDE(t) ((t) ~ (t) 0 < (t) -1) - -/* True if the signed integer expression E uses two's complement. */ -#define _GL_INT_TWOS_COMPLEMENT(e) (~ _GL_INT_CONVERT (e, 0) == -1) - -/* True if the arithmetic type T is signed. */ +/* True if the real type T is signed. */ #define TYPE_SIGNED(t) (! ((t) 0 < (t) -1)) -/* Return 1 if the integer expression E, after integer promotion, has - a signed type. */ -#define _GL_INT_SIGNED(e) (_GL_INT_NEGATE_CONVERT (e, 1) < 0) +/* Return 1 if the real expression E, after promotion, has a + signed or floating type. */ +#define EXPR_SIGNED(e) (_GL_INT_NEGATE_CONVERT (e, 1) < 0) -/* Minimum and maximum values for integer types and expressions. These - macros have undefined behavior if T is signed and has padding bits. - If this is a problem for you, please let us know how to fix it for - your host. */ +/* Minimum and maximum values for integer types and expressions. */ + +/* The width in bits of the integer type or expression T. + 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_SIGNED (t) \ - ? (t) 0 \ - : TYPE_SIGNED_MAGNITUDE (t) \ - ? ~ (t) 0 \ - : ~ TYPE_MAXIMUM (t))) +#define TYPE_MINIMUM(t) ((t) ~ TYPE_MAXIMUM (t)) #define TYPE_MAXIMUM(t) \ ((t) (! TYPE_SIGNED (t) \ ? (t) -1 \ - : ((((t) 1 << (sizeof (t) * CHAR_BIT - 2)) - 1) * 2 + 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 should not have side effects. */ #define _GL_INT_MINIMUM(e) \ - (_GL_INT_SIGNED (e) \ - ? - _GL_INT_TWOS_COMPLEMENT (e) - _GL_SIGNED_INT_MAXIMUM (e) \ + (EXPR_SIGNED (e) \ + ? ~ _GL_SIGNED_INT_MAXIMUM (e) \ : _GL_INT_CONVERT (e, 0)) #define _GL_INT_MAXIMUM(e) \ - (_GL_INT_SIGNED (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) << (sizeof ((e) + 0) * CHAR_BIT - 2)) - 1) * 2 + 1) + (((_GL_INT_CONVERT (e, 1) << (TYPE_WIDTH ((e) + 0) - 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. + As a sanity check, test the assumption for some signed types that + <limits.h> bounds. */ +verify (TYPE_MINIMUM (signed char) == SCHAR_MIN); +verify (TYPE_MAXIMUM (signed char) == SCHAR_MAX); +verify (TYPE_MINIMUM (short int) == SHRT_MIN); +verify (TYPE_MAXIMUM (short int) == SHRT_MAX); +verify (TYPE_MINIMUM (int) == INT_MIN); +verify (TYPE_MAXIMUM (int) == INT_MAX); +verify (TYPE_MINIMUM (long int) == LONG_MIN); +verify (TYPE_MAXIMUM (long int) == LONG_MAX); +#ifdef LLONG_MAX +verify (TYPE_MINIMUM (long long int) == LLONG_MIN); +verify (TYPE_MAXIMUM (long long int) == LLONG_MAX); +#endif +/* Similarly, sanity-check one ISO/IEC TS 18661-1:2014 macro if defined. */ +#ifdef UINT_WIDTH +verify (TYPE_WIDTH (unsigned int) == UINT_WIDTH); +#endif -/* Return 1 if the __typeof__ keyword works. This could be done by +/* 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__ || defined __IBM__TYPEOF__ \ +#if (2 <= __GNUC__ \ + || (1210 <= __IBMC__ && defined __IBM__TYPEOF__) \ || (0x5110 <= __SUNPRO_C && !__STDC__)) # define _GL_HAVE___TYPEOF__ 1 #else @@ -118,8 +131,7 @@ signed, 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 (sizeof (t) * CHAR_BIT \ - - _GL_SIGNED_TYPE_OR_EXPR (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, @@ -224,24 +236,38 @@ ? (a) < (min) >> (b) \ : (max) >> (b) < (a)) +/* True if __builtin_add_overflow (A, B, P) works when P is non-null. */ +#define _GL_HAS_BUILTIN_OVERFLOW (5 <= __GNUC__) + +/* True if __builtin_add_overflow_p (A, B, C) works. */ +#define _GL_HAS_BUILTIN_OVERFLOW_P (7 <= __GNUC__) /* 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. */ -#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)) +#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 \ @@ -263,22 +289,29 @@ : (a) % - (b)) \ == 0) - -/* Integer overflow checks. +/* 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. - They work correctly on all known practical hosts, and do not rely + The INT_<op>_WRAPV macros also store the low-order bits of the answer. + These macros work correctly on all known practical hosts, and do not rely on undefined behavior due to signed arithmetic overflow. - Example usage: + Example usage, assuming A and B are long int: - long int i = ...; - long int j = ...; - if (INT_MULTIPLY_OVERFLOW (i, j)) - printf ("multiply would overflow"); + if (INT_MULTIPLY_OVERFLOW (a, b)) + printf ("result would overflow\n"); else - printf ("product is %ld", i * j); + 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 @@ -287,6 +320,9 @@ 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 *. The result type must be signed. + These macros are tuned for their last argument being a constant. Return 1 if the integer expressions A * B, A - B, -A, A * B, A / B, @@ -296,8 +332,12 @@ _GL_BINARY_OP_OVERFLOW (a, b, _GL_ADD_OVERFLOW) #define INT_SUBTRACT_OVERFLOW(a, b) \ _GL_BINARY_OP_OVERFLOW (a, b, _GL_SUBTRACT_OVERFLOW) -#define INT_NEGATE_OVERFLOW(a) \ - INT_NEGATE_RANGE_OVERFLOW (a, _GL_INT_MINIMUM (a), _GL_INT_MAXIMUM (a)) +#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) \ @@ -317,4 +357,102 @@ _GL_INT_MINIMUM (0 * (b) + (a)), \ _GL_INT_MAXIMUM (0 * (b) + (a))) +/* Store the low-order bits of A + B, A - B, A * B, respectively, into *R. + Return 1 if the result overflows. See above for restrictions. */ +#define INT_ADD_WRAPV(a, b, r) \ + _GL_INT_OP_WRAPV (a, b, r, +, __builtin_add_overflow, INT_ADD_OVERFLOW) +#define INT_SUBTRACT_WRAPV(a, b, r) \ + _GL_INT_OP_WRAPV (a, b, r, -, __builtin_sub_overflow, INT_SUBTRACT_OVERFLOW) +#define INT_MULTIPLY_WRAPV(a, b, r) \ + _GL_INT_OP_WRAPV (a, b, r, *, __builtin_mul_overflow, INT_MULTIPLY_OVERFLOW) + +/* Nonzero if this compiler has GCC bug 68193 or Clang bug 25390. See: + https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68193 + https://llvm.org/bugs/show_bug.cgi?id=25390 + For now, assume all versions of GCC-like compilers generate bogus + warnings for _Generic. This matters only for older compilers that + lack __builtin_add_overflow. */ +#if __GNUC__ +# define _GL__GENERIC_BOGUS 1 +#else +# define _GL__GENERIC_BOGUS 0 +#endif + +/* Store the low-order bits of A <op> B into *R, where OP specifies + the operation. BUILTIN is the builtin operation, and OVERFLOW the + overflow predicate. Return 1 if the result overflows. See above + for restrictions. */ +#if _GL_HAS_BUILTIN_OVERFLOW +# define _GL_INT_OP_WRAPV(a, b, r, op, builtin, overflow) builtin (a, b, r) +#elif 201112 <= __STDC_VERSION__ && !_GL__GENERIC_BOGUS +# define _GL_INT_OP_WRAPV(a, b, r, op, builtin, overflow) \ + (_Generic \ + (*(r), \ + signed char: \ + _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned char, \ + signed char, SCHAR_MIN, SCHAR_MAX), \ + short int: \ + _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned short int, \ + short int, SHRT_MIN, SHRT_MAX), \ + int: \ + _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned int, \ + int, INT_MIN, INT_MAX), \ + long int: \ + _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned long int, \ + long int, LONG_MIN, LONG_MAX), \ + long long int: \ + _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned long long int, \ + long long int, LLONG_MIN, LLONG_MAX))) +#else +# define _GL_INT_OP_WRAPV(a, b, r, op, builtin, overflow) \ + (sizeof *(r) == sizeof (signed char) \ + ? _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned char, \ + signed char, SCHAR_MIN, SCHAR_MAX) \ + : sizeof *(r) == sizeof (short int) \ + ? _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned short int, \ + short int, SHRT_MIN, SHRT_MAX) \ + : sizeof *(r) == sizeof (int) \ + ? _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned int, \ + int, INT_MIN, INT_MAX) \ + : _GL_INT_OP_WRAPV_LONGISH(a, b, r, op, overflow)) +# ifdef LLONG_MAX +# define _GL_INT_OP_WRAPV_LONGISH(a, b, r, op, overflow) \ + (sizeof *(r) == sizeof (long int) \ + ? _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned long int, \ + long int, LONG_MIN, LONG_MAX) \ + : _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned long long int, \ + long long int, LLONG_MIN, LLONG_MAX)) +# else +# define _GL_INT_OP_WRAPV_LONGISH(a, b, r, op, overflow) \ + _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned long int, \ + long int, LONG_MIN, LONG_MAX) +# endif +#endif + +/* Store the low-order bits of A <op> B into *R, where the operation + is given by OP. Use the unsigned type UT for calculation to avoid + overflow problems. *R's type is T, with extremal values TMIN and + TMAX. T must be a signed integer type. Return 1 if the result + overflows. */ +#define _GL_INT_OP_CALC(a, b, r, op, overflow, ut, t, tmin, tmax) \ + (sizeof ((a) op (b)) < sizeof (t) \ + ? _GL_INT_OP_CALC1 ((t) (a), (t) (b), r, op, overflow, ut, t, tmin, tmax) \ + : _GL_INT_OP_CALC1 (a, b, r, op, overflow, ut, t, tmin, tmax)) +#define _GL_INT_OP_CALC1(a, b, r, op, overflow, ut, t, tmin, tmax) \ + ((overflow (a, b) \ + || (EXPR_SIGNED ((a) op (b)) && ((a) op (b)) < (tmin)) \ + || (tmax) < ((a) op (b))) \ + ? (*(r) = _GL_INT_OP_WRAPV_VIA_UNSIGNED (a, b, op, ut, t, tmin, tmax), 1) \ + : (*(r) = _GL_INT_OP_WRAPV_VIA_UNSIGNED (a, b, op, ut, t, tmin, tmax), 0)) + +/* Return A <op> B, where the operation is given by OP. Use the + unsigned type UT for calculation to avoid overflow problems. + Convert the result to type T without overflow by subtracting TMIN + from large values before converting, and adding it afterwards. + Compilers can optimize all the operations except OP. */ +#define _GL_INT_OP_WRAPV_VIA_UNSIGNED(a, b, op, ut, t, tmin, tmax) \ + (((ut) (a) op (ut) (b)) <= (tmax) \ + ? (t) ((ut) (a) op (ut) (b)) \ + : ((t) (((ut) (a) op (ut) (b)) - (tmin)) + (tmin))) + #endif /* _GL_INTPROPS_H */ |