@@ -111,8 +111,8 @@
Subtract 1 for the sign bit if T is signed, and then add 1 more for
a minus sign if needed.
- Because _GL_SIGNED_TYPE_OR_EXPR sometimes returns 0 when its argument is
- signed, this macro may overestimate the true bound by one byte when
+ Because _GL_SIGNED_TYPE_OR_EXPR sometimes returns 1 when its argument is
+ unsigned, this macro may overestimate the true bound by one byte when
applied to unsigned types of size 2, 4, 16, ... bytes. */
#define INT_STRLEN_BOUND(t) \
(INT_BITS_STRLEN_BOUND (TYPE_WIDTH (t) - _GL_SIGNED_TYPE_OR_EXPR (t)) \
@@ -220,14 +220,26 @@
? (a) < (min) >> (b) \
: (max) >> (b) < (a))
-/* True if __builtin_add_overflow (A, B, P) works when P is non-null. */
+/* True if __builtin_add_overflow (A, B, P) and __builtin_sub_overflow
+ (A, B, P) work when P is non-null. */
#if 5 <= __GNUC__ && !defined __ICC
-# define _GL_HAS_BUILTIN_OVERFLOW 1
+# 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_OVERFLOW 0
+# define _GL_HAS_BUILTIN_ADD_OVERFLOW 0
#endif
-/* True if __builtin_add_overflow_p (A, B, C) works. */
+/* 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_mul_overflow_p and __builtin_mul_overflow_p. */
#define _GL_HAS_BUILTIN_OVERFLOW_P (7 <= __GNUC__)
/* The _GL*_OVERFLOW macros have the same restrictions as the
@@ -281,7 +293,9 @@
The INT_<op>_OVERFLOW macros return 1 if the corresponding C operators
might not yield numerically correct answers due to arithmetic overflow.
- The INT_<op>_WRAPV macros also store the low-order bits of the answer.
+ The INT_<op>_WRAPV macros compute the low-order bits of the sum,
+ difference, and product of two C integers, and return 1 if these
+ low-order bits are not numerically correct.
These macros work correctly on all known practical hosts, and do not rely
on undefined behavior due to signed arithmetic overflow.
@@ -309,9 +323,11 @@
arguments should not have side effects.
The WRAPV macros are not constant expressions. They support only
- +, binary -, and *. The result type must be signed.
+ +, binary -, and *. 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 argument being a constant.
+ 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. */
@@ -347,19 +363,33 @@
/* Store the low-order bits of A + B, A - B, A * B, respectively, into *R.
Return 1 if the result overflows. See above for restrictions. */
-#define INT_ADD_WRAPV(a, b, r) \
- _GL_INT_OP_WRAPV (a, b, r, +, __builtin_add_overflow, INT_ADD_OVERFLOW)
-#define INT_SUBTRACT_WRAPV(a, b, r) \
- _GL_INT_OP_WRAPV (a, b, r, -, __builtin_sub_overflow, INT_SUBTRACT_OVERFLOW)
-#define INT_MULTIPLY_WRAPV(a, b, r) \
- _GL_INT_OP_WRAPV (a, b, r, *, __builtin_mul_overflow, INT_MULTIPLY_OVERFLOW)
+#if _GL_HAS_BUILTIN_ADD_OVERFLOW
+# define INT_ADD_WRAPV(a, b, r) __builtin_add_overflow (a, b, r)
+# define INT_SUBTRACT_WRAPV(a, b, r) __builtin_sub_overflow (a, b, r)
+#else
+# define INT_ADD_WRAPV(a, b, r) \
+ _GL_INT_OP_WRAPV (a, b, r, +, _GL_INT_ADD_RANGE_OVERFLOW)
+# define INT_SUBTRACT_WRAPV(a, b, r) \
+ _GL_INT_OP_WRAPV (a, b, r, -, _GL_INT_SUBTRACT_RANGE_OVERFLOW)
+#endif
+#if _GL_HAS_BUILTIN_MUL_OVERFLOW
+/* 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))
+#else
+# define INT_MULTIPLY_WRAPV(a, b, r) \
+ _GL_INT_OP_WRAPV (a, b, r, *, _GL_INT_MULTIPLY_RANGE_OVERFLOW)
+#endif
/* Nonzero if this compiler has GCC bug 68193 or Clang bug 25390. See:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68193
https://llvm.org/bugs/show_bug.cgi?id=25390
For now, assume all versions of GCC-like compilers generate bogus
- warnings for _Generic. This matters only for older compilers that
- lack __builtin_add_overflow. */
+ warnings for _Generic. This matters only for compilers that
+ lack relevant builtins. */
#if __GNUC__
# define _GL__GENERIC_BOGUS 1
#else
@@ -367,53 +397,100 @@
#endif
/* Store the low-order bits of A <op> B into *R, where OP specifies
- the operation. BUILTIN is the builtin operation, and OVERFLOW the
- overflow predicate. Return 1 if the result overflows. See above
- for restrictions. */
-#if _GL_HAS_BUILTIN_OVERFLOW
-# define _GL_INT_OP_WRAPV(a, b, r, op, builtin, overflow) builtin (a, b, r)
-#elif 201112 <= __STDC_VERSION__ && !_GL__GENERIC_BOGUS
-# define _GL_INT_OP_WRAPV(a, b, r, op, builtin, overflow) \
+ the operation and OVERFLOW the overflow predicate. Return 1 if the
+ result overflows. See above for restrictions. */
+#if 201112 <= __STDC_VERSION__ && !_GL__GENERIC_BOGUS
+# define _GL_INT_OP_WRAPV(a, b, r, op, overflow) \
(_Generic \
(*(r), \
signed char: \
_GL_INT_OP_CALC (a, b, r, op, overflow, unsigned 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)))
+ long long int, LLONG_MIN, LLONG_MAX), \
+ unsigned long long int: \
+ _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned long long int, \
+ unsigned long long int, 0, ULLONG_MAX)))
#else
-# define _GL_INT_OP_WRAPV(a, b, r, op, builtin, overflow) \
+/* Store the low-order bits of A <op> B into *R, where OP specifies
+ the operation and OVERFLOW the overflow predicate. If *R is
+ signed, its type is ST with bounds SMIN..SMAX; otherwise its type
+ is UT with bounds U..UMAX. ST and UT are narrower than int.
+ Return 1 if the result overflows. See above for restrictions. */
+# if _GL_HAVE___TYPEOF__
+# define _GL_INT_OP_WRAPV_SMALLISH(a,b,r,op,overflow,st,smin,smax,ut,umax) \
+ (TYPE_SIGNED (__typeof__ (*(r))) \
+ ? _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned int, st, smin, smax) \
+ : _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned int, ut, 0, umax))
+# else
+# define _GL_INT_OP_WRAPV_SMALLISH(a,b,r,op,overflow,st,smin,smax,ut,umax) \
+ (overflow (a, b, smin, smax) \
+ ? (overflow (a, b, 0, umax) \
+ ? (*(r) = _GL_INT_OP_WRAPV_VIA_UNSIGNED (a,b,op,unsigned,st), 1) \
+ : (*(r) = _GL_INT_OP_WRAPV_VIA_UNSIGNED (a,b,op,unsigned,st)) < 0) \
+ : (overflow (a, b, 0, umax) \
+ ? (*(r) = _GL_INT_OP_WRAPV_VIA_UNSIGNED (a,b,op,unsigned,st)) >= 0 \
+ : (*(r) = _GL_INT_OP_WRAPV_VIA_UNSIGNED (a,b,op,unsigned,st), 0)))
+# endif
+
+# define _GL_INT_OP_WRAPV(a, b, r, op, overflow) \
(sizeof *(r) == sizeof (signed char) \
- ? _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned int, \
- signed char, SCHAR_MIN, SCHAR_MAX) \
+ ? _GL_INT_OP_WRAPV_SMALLISH (a, b, r, op, overflow, \
+ signed char, SCHAR_MIN, SCHAR_MAX, \
+ unsigned char, UCHAR_MAX) \
: sizeof *(r) == sizeof (short int) \
- ? _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned int, \
- short int, SHRT_MIN, SHRT_MAX) \
+ ? _GL_INT_OP_WRAPV_SMALLISH (a, b, r, op, overflow, \
+ short int, SHRT_MIN, SHRT_MAX, \
+ unsigned short int, USHRT_MAX) \
: sizeof *(r) == sizeof (int) \
- ? _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned int, \
- int, INT_MIN, INT_MAX) \
+ ? (EXPR_SIGNED (*(r)) \
+ ? _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned int, \
+ int, INT_MIN, INT_MAX) \
+ : _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned int, \
+ unsigned int, 0, UINT_MAX)) \
: _GL_INT_OP_WRAPV_LONGISH(a, b, r, op, overflow))
# ifdef LLONG_MAX
# define _GL_INT_OP_WRAPV_LONGISH(a, b, r, op, overflow) \
(sizeof *(r) == sizeof (long int) \
- ? _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned long int, \
- long int, LONG_MIN, LONG_MAX) \
- : _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned long long int, \
- long long int, LLONG_MIN, LLONG_MAX))
+ ? (EXPR_SIGNED (*(r)) \
+ ? _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned long int, \
+ long int, LONG_MIN, LONG_MAX) \
+ : _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned long int, \
+ unsigned long int, 0, ULONG_MAX)) \
+ : (EXPR_SIGNED (*(r)) \
+ ? _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned long long int, \
+ long long int, LLONG_MIN, LLONG_MAX) \
+ : _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned long long int, \
+ unsigned long long int, 0, ULLONG_MAX)))
# else
# define _GL_INT_OP_WRAPV_LONGISH(a, b, r, op, overflow) \
- _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned long int, \
- long int, LONG_MIN, LONG_MAX)
+ (EXPR_SIGNED (*(r)) \
+ ? _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned long int, \
+ long int, LONG_MIN, LONG_MAX) \
+ : _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned long int, \
+ unsigned long int, 0, ULONG_MAX))
# endif
#endif
@@ -422,13 +499,7 @@
overflow problems. *R's type is T, with extrema TMIN and TMAX.
T must be a signed integer type. Return 1 if the result overflows. */
#define _GL_INT_OP_CALC(a, b, r, op, overflow, ut, t, tmin, tmax) \
- (sizeof ((a) op (b)) < sizeof (t) \
- ? _GL_INT_OP_CALC1 ((t) (a), (t) (b), r, op, overflow, ut, t, tmin, tmax) \
- : _GL_INT_OP_CALC1 (a, b, r, op, overflow, ut, t, tmin, tmax))
-#define _GL_INT_OP_CALC1(a, b, r, op, overflow, ut, t, tmin, tmax) \
- ((overflow (a, b) \
- || (EXPR_SIGNED ((a) op (b)) && ((a) op (b)) < (tmin)) \
- || (tmax) < ((a) op (b))) \
+ (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))
@@ -452,4 +523,57 @@
#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)))
+
#endif /* _GL_INTPROPS_H */