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

	* 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

4 files changed, 15 insertions, 6 deletions

diff --git a/ChangeLog b/ChangeLog
index ca9dce7216..eb72ea898c 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Wed Jun 27 04:20:41 2012  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* bignum.c (rb_big_pow): estimate result bit size more precisely.
+	  [ruby-core:30735][Feature #3429]
+
 Tue Jun 26 20:36:53 2012  Tanaka Akira  <akr@fsij.org>
 
 	* lib/drb/ssl.rb: generate 1024 bits RSA key instead of 512 bits.
diff --git a/bignum.c b/bignum.c
index 9c289f7a8e..8d024fe5cc 100644
--- a/bignum.c
+++ b/bignum.c
@@ -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;
diff --git a/test/ruby/test_bignum.rb b/test/ruby/test_bignum.rb
index 264c68bcf7..062d8cb4bf 100644
--- a/test/ruby/test_bignum.rb
+++ b/test/ruby/test_bignum.rb
@@ -299,6 +299,9 @@ class TestBignum < Test::Unit::TestCase
     ### rational changes the behavior of Bignum#**
     #assert_raise(TypeError) { T32**"foo" }
     assert_raise(TypeError, ArgumentError) { T32**"foo" }
+
+    feature3429 = '[ruby-core:30735]'
+    assert_instance_of(Bignum, (2 ** 7830457), feature3429)
   end
 
   def test_and
diff --git a/version.h b/version.h
index da2cac4899..68ad486f2b 100644
--- a/version.h
+++ b/version.h
@@ -1,10 +1,10 @@
 #define RUBY_VERSION "1.9.3"
-#define RUBY_PATCHLEVEL 239
+#define RUBY_PATCHLEVEL 240
 
-#define RUBY_RELEASE_DATE "2012-06-26"
+#define RUBY_RELEASE_DATE "2012-06-27"
 #define RUBY_RELEASE_YEAR 2012
 #define RUBY_RELEASE_MONTH 6
-#define RUBY_RELEASE_DAY 26
+#define RUBY_RELEASE_DAY 27
 
 #include "ruby/version.h"