http://mail.openjdk.java.net/pipermail/hotspot-compiler-dev/2012-May/007689.html

Krystal Mok wrote:

Hi all,

Could I get some reviews for this patch, please?
https://gist.github.com/2710000#file_count_compiled_calls.patch

Description:

C2 may crash when compiling methods with -XX:+CountCompiledCalls turned on.
The cause is in Parse::count_compiled_calls(), where it made a TypeInstPtr
from a ciMethod:

const TypeInstPtr* addr_type = TypeInstPtr::make(method());

Since the klass of a ciMethod is a ciMethodKlass, which isn't a
ciInstanceKlass, an assertion is hit later in
Compile::flatten_alias_type(), where it's expecting a TypeInstPtr to have a
ciInstanceKlass:

ciInstanceKlass *k = to->klass()->as_instance_klass();

An example of the crash is available here: https://gist.github.com/2710000
In the example, I started a Groovy shell with -XX:+CountCompiledCalls set,
and it crashed quickly when compiling java.lang.String.charAt().

The fix is to use TypeOopPtr::make_from_constant(method()) instead
of TypeInstPtr::make(method()).
I did check the hg history, and looks like it's been like this since
duke at 0.Wonder if there's any history behind this.

Note that this fix may have to be changed again when methodOopDesc's are
moved out of PermGen.

Regards,
Kris