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Use builtins for overflow math if possible

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furunkel
2015-04-17 17:37:09 +02:00
parent e79afd4c74
commit 08c877699a
1 changed files with 43 additions and 0 deletions
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include/mruby/numeric.h
+43
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@@ -36,6 +36,47 @@ mrb_value mrb_num_div(mrb_state *mrb, mrb_value x, mrb_value y);
# define MRB_INT_OVERFLOW_MASK ((mrb_uint)1 << (MRB_INT_BIT - 1))
#endif
/* Idea from Potion: https://github.com/perl11/potion (MIT) */
#if (defined(__clang__) && ((__clang_major__ > 3) || (__clang_major__ == 3 && __clang_minor__ >= 4))) \
|| (defined(__GNUC__) && __GNUC__ >= 5)
static inline mrb_bool
mrb_int_add_overflow(mrb_int augend, mrb_int addend, mrb_int *sum)
{
mrb_bool of;
#ifdef MRB_INT64
long long val;
of = __builtin_saddll_overflow(augend, addend, &val) ||
#else
int val;
of = __builtin_sadd_overflow(augend, addend, &val) ||
#endif
(val > MRB_INT_MAX) || (val < MRB_INT_MIN);
*sum = (mrb_int) val;
return of;
}
static inline mrb_bool
mrb_int_sub_overflow(mrb_int minuend, mrb_int subtrahend, mrb_int *difference)
{
mrb_bool of;
#ifdef MRB_INT64
long long val;
of = __builtin_ssubll_overflow(minuend, subtrahend, &val) ||
#else
int val;
of = __builtin_ssub_overflow(minuend, subtrahend, &val) ||
#endif
(val > MRB_INT_MAX) || (val < MRB_INT_MIN);
*difference = (mrb_int) val;
return of;
}
#else
static inline mrb_bool
mrb_int_add_overflow(mrb_int augend, mrb_int addend, mrb_int *sum)
{
@@ -56,6 +97,8 @@ mrb_int_sub_overflow(mrb_int minuend, mrb_int subtrahend, mrb_int *difference)
return !!(((x ^ z) & (~y ^ z)) & MRB_INT_OVERFLOW_MASK);
}
#endif
#undef MRB_INT_OVERFLOW_MASK
#undef mrb_uint
#undef MRB_UINT_MAKE