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* numeric.c (int_pow): overflow detection using FIT_SQRT_LONG().

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[ruby-dev:31215]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@12778 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
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matz 2007-07-13 17:29:24 +00:00
parent 2a5c48a54d
commit b13b3e624b
2 changed files with 11 additions and 6 deletions
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5
ChangeLog
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@ -1,3 +1,8 @@
Sat Jul 14 02:27:43 2007 Yukihiro Matsumoto <matz@ruby-lang.org>
* numeric.c (int_pow): overflow detection using FIT_SQRT_LONG().
[ruby-dev:31215]
Sat Jul 14 02:05:53 2007 Yukihiro Matsumoto <matz@ruby-lang.org> Sat Jul 14 02:05:53 2007 Yukihiro Matsumoto <matz@ruby-lang.org>
* insns.def (opt_div): LONG2FIX() may not work for corner cases, * insns.def (opt_div): LONG2FIX() may not work for corner cases,

12
numeric.c
View File

@ -2046,6 +2046,10 @@ fix_minus(VALUE x, VALUE y)
* result. * result.
*/ */
#define SQRT_LONG_MAX ((SIGNED_VALUE)1<<((SIZEOF_VALUE*CHAR_BIT-1)/2))
/*tests if N*N would overflow*/
#define FIT_SQRT_LONG(n) (((n)<SQRT_LONG_MAX)&&((n)>=-SQRT_LONG_MAX))
static VALUE static VALUE
fix_mul(VALUE x, VALUE y) fix_mul(VALUE x, VALUE y)
{ {
@ -2070,9 +2074,6 @@ fix_mul(VALUE x, VALUE y)
if (FIXABLE(d)) return LONG2FIX(d); if (FIXABLE(d)) return LONG2FIX(d);
return rb_ll2inum(d); return rb_ll2inum(d);
#else #else
# define SQRT_LONG_MAX ((SIGNED_VALUE)1<<((SIZEOF_VALUE*CHAR_BIT-1)/2))
/*tests if N*N would overflow*/
# define FIT_SQRT_LONG(n) (((n)<SQRT_LONG_MAX)&&((n)>=-SQRT_LONG_MAX))
if (FIT_SQRT_LONG(a) && FIT_SQRT_LONG(b)) if (FIT_SQRT_LONG(a) && FIT_SQRT_LONG(b))
return LONG2FIX(a*b); return LONG2FIX(a*b);
c = a * b; c = a * b;
@ -2288,15 +2289,14 @@ int_pow(long x, unsigned long y)
y &= ~1; y &= ~1;
do { do {
while (y % 2 == 0) { while (y % 2 == 0) {
long x2 = x * x; if (!FIT_SQRT_LONG(x)) {
if (x2 < x || !POSFIXABLE(x2)) {
VALUE v; VALUE v;
bignum: bignum:
v = rb_big_pow(rb_int2big(x), LONG2NUM(y)); v = rb_big_pow(rb_int2big(x), LONG2NUM(y));
if (z != 1) v = rb_big_mul(rb_int2big(neg ? -z : z), v); if (z != 1) v = rb_big_mul(rb_int2big(neg ? -z : z), v);
return v; return v;
} }
x = x2; x = x * x;
y >>= 1; y >>= 1;
} }
{ {