diff causing a infinite loop in the optimizer

gistfile1.txt

diff --git a/src/core/IO/Handle.pm b/src/core/IO/Handle.pm
index 1baf95b..215b3ef 100644
--- a/src/core/IO/Handle.pm
+++ b/src/core/IO/Handle.pm
@@ -154,6 +154,17 @@ my class IO::Handle does IO {
         $c;
     }
 
+    method !readcharsfh(int $chars) {
+#?if jvm
+        my Buf $buf := Buf.new;   # nqp::readcharsfh doesn't work on the JVM
+        nqp::readfh($!PIO, $buf, $chars); # optimize for ASCII
+        nqp::unbox_s($buf.decode);
+#?endif
+#?if !jvm
+        nqp::readcharsfh($!PIO, $chars); # optimize for ASCII
+#?endif
+    }
+
     proto method words (|) { * }
     multi method words(IO::Handle:D: :$close) {
         X::NYI.new(feature => "'words' without closing the file handle").throw
@@ -167,7 +178,7 @@ my class IO::Handle does IO {
 
             submethod BUILD(\handle, $!close) {
                 $!handle := handle;
-                $!str = self!readcharsfh();
+                $!str = $!handle!readcharsfh(65536);
                 $!pos = nqp::findnotcclass(
                   nqp::const::CCLASS_WHITESPACE, $!str, 0, nqp::chars($!str));
                 self
@@ -175,21 +186,11 @@ my class IO::Handle does IO {
             method new(\handle, \close) {
                 nqp::create(self).BUILD(handle, close);
             }
-            method !readcharsfh() {
-                my Mu $PIO := nqp::getattr($!handle, IO::Handle, '$!PIO');
-#?if jvm
-                my Buf $buf := Buf.new;   # nqp::readcharsfh doesn't work on the JVM
-                nqp::readfh($PIO, $buf, 65536); # optimize for ASCII
-                nqp::unbox_s($buf.decode);
-#?endif
-#?if !jvm
-                nqp::readcharsfh($PIO, 65536); # optimize for ASCII
-#?endif
-            }
             method !next-chunk(\chars) {
                 $!str = $!pos < chars
-                  ?? nqp::concat(nqp::substr($!str,$!pos),self!readcharsfh)
-                  !! self!readcharsfh;
+                  ?? nqp::concat(
+                       nqp::substr($!str,$!pos),$!handle!readcharsfh(65536))
+                  !! $!handle!readcharsfh(65536);
                 chars = nqp::chars($!str);
                 $!pos = chars
                   ?? nqp::findnotcclass(
@@ -479,10 +480,10 @@ my class IO::Handle does IO {
         else {
             supply {
                 my int $chars = $size;
-                my str $str = nqp::readcharsfh($!PIO,$chars);
+                my str $str = self!readcharsfh($chars);
                 while nqp::chars($str) {
                     emit nqp::p6box_s($str);
-                    $str = nqp::readcharsfh($!PIO,$chars);
+                    $str = self!readcharsfh($chars);
                 }
             }
         }