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merge revision(s) 35081: [Backport #6605]

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* bignum.c (rb_big_pow): estimate result bit size more precisely.
	  [ruby-core:30735][Feature #3429]


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_1_9_3@36226 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
This commit is contained in:
naruse 2012-06-26 19:21:02 +00:00
parent 0659c5351e
commit 49dbacf73e
4 changed files with 15 additions and 6 deletions
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7
bignum.c
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@ -3079,10 +3079,11 @@ rb_big_pow(VALUE x, VALUE y)
else {
VALUE z = 0;
SIGNED_VALUE mask;
const long BIGLEN_LIMIT = 1024*1024 / SIZEOF_BDIGITS;
const long xlen = RBIGNUM_LEN(x) - 1;
const long xbits = ffs(RBIGNUM_DIGITS(x)[xlen]) + SIZEOF_BDIGITS*BITSPERDIG*xlen;
const long BIGLEN_LIMIT = BITSPERDIG*1024*1024;
if ((RBIGNUM_LEN(x) > BIGLEN_LIMIT) ||
(RBIGNUM_LEN(x) > BIGLEN_LIMIT / yy)) {
if ((xbits > BIGLEN_LIMIT) || (xbits * yy > BIGLEN_LIMIT)) {
rb_warn("in a**b, b may be too big");
d = (double)yy;
break;