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Merge pull request #3154 from cremno/improve-checked-mrb_int-arithmetic-implementation

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improve checked mrb int arithmetic implementation
This commit is contained in:
Yukihiro "Matz" Matsumoto
2016-05-10 10:04:04 +09:00
parent bc715f9938 7276e84637
commit 4fd0cb61d7
1 changed files with 29 additions and 35 deletions
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include/mruby/numeric.h
+29 -35
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@@ -31,53 +31,47 @@ mrb_value mrb_fixnum_minus(mrb_state *mrb, mrb_value x, mrb_value y);
mrb_value mrb_fixnum_mul(mrb_state *mrb, mrb_value x, mrb_value y);
mrb_value mrb_num_div(mrb_state *mrb, mrb_value x, mrb_value y);
#define MRB_UINT_MAKE2(n) uint ## n ## _t
#define MRB_UINT_MAKE(n) MRB_UINT_MAKE2(n)
#define mrb_uint MRB_UINT_MAKE(MRB_INT_BIT)
#ifndef __has_builtin
#define __has_builtin(x) 0
#endif
#define MRB_INT_OVERFLOW_MASK ((mrb_uint)1 << (MRB_INT_BIT - 1 - MRB_FIXNUM_SHIFT))
#if (defined(__GNUC__) && __GNUC__ >= 5) || \
(__has_builtin(__builtin_add_overflow) && \
__has_builtin(__builtin_sub_overflow) && \
__has_builtin(__builtin_mul_overflow))
# define MRB_HAVE_TYPE_GENERIC_CHECKED_ARITHMETIC_BUILTINS
#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)
#ifdef MRB_HAVE_TYPE_GENERIC_CHECKED_ARITHMETIC_BUILTINS
#ifndef MRB_WORD_BOXING
# define WBCHK(x) 0
#else
# define WBCHK(x) !FIXABLE(x)
#endif
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;
return __builtin_add_overflow(augend, addend, sum) || WBCHK(*sum);
}
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;
return __builtin_sub_overflow(minuend, subtrahend, difference) || WBCHK(*difference);
}
#undef WBCHK
#else
#define MRB_UINT_MAKE2(n) uint ## n ## _t
#define MRB_UINT_MAKE(n) MRB_UINT_MAKE2(n)
#define mrb_uint MRB_UINT_MAKE(MRB_INT_BIT)
#define MRB_INT_OVERFLOW_MASK ((mrb_uint)1 << (MRB_INT_BIT - 1 - MRB_FIXNUM_SHIFT))
static inline mrb_bool
mrb_int_add_overflow(mrb_int augend, mrb_int addend, mrb_int *sum)
{
@@ -98,13 +92,13 @@ 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
#undef MRB_UINT_MAKE2
#endif
MRB_END_DECL
#endif /* MRUBY_NUMERIC_H */