Merge remote-tracking branch 'savannah/master' into HEAD

1 files changed, 46 insertions, 4 deletions

diff --git a/lib/intprops.h b/lib/intprops.h
index b27f2eea056..bc2107c9295 100644
--- a/lib/intprops.h
+++ b/lib/intprops.h
@@ -226,7 +226,9 @@
 
 /* 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
+/* __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)
@@ -244,7 +246,17 @@
 
 /* True if __builtin_add_overflow_p (A, B, C) works, and similarly for
    __builtin_sub_overflow_p and __builtin_mul_overflow_p.  */
-#define _GL_HAS_BUILTIN_OVERFLOW_P (7 <= __GNUC__)
+#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
@@ -377,8 +389,9 @@
    _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__))
+# 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.  */
@@ -585,4 +598,33 @@
          : (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 */