insns.def (opt_case_dispatch): avoid converting Infinity

Infinity cannot be written as an optimizable literal,
so it can never match a key in a CDHASH.
Avoid converting it to prevent FloatDomainError.

* insns.def (opt_case_dispatch): avoid converting Infinity
* test/ruby/test_optimization.rb (test_opt_case_dispatch_inf): new
  [ruby-dev:49423] [Bug #11804]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@53039 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 1 insertions, 1 deletions

diff --git a/insns.def b/insns.def
index 3c185bd084..df65aa8efd 100644
--- a/insns.def
+++ b/insns.def
@@ -1262,7 +1262,7 @@ opt_case_dispatch
     switch(TYPE(key)) {
       case T_FLOAT: {
 	double ival;
-	if (modf(RFLOAT_VALUE(key), &ival) == 0.0) {
+	if (modf(RFLOAT_VALUE(key), &ival) == 0.0 && !isinf(ival)) {
 	    key = FIXABLE(ival) ? LONG2FIX((long)ival) : rb_dbl2big(ival);
 	}
       }