RFR (S) JDK-8067480: Crash in klassItable::initialize_itable_for_interface when running vm.runtime.defmeth.StaticMethodsTest on Linux x64

[harold seigel]

Hi Lois,

These changes look good.

Harold

On 1/19/2015 4:11 PM, Lois Foltan wrote:
> Hello,
>
> Please review the following fix:
>
> Webrev:
>     http://cr.openjdk.java.net/~lfoltan/bug_jdk8067480/
>
> Bug: Crash in klassItable::initialize_itable_for_interface when 
> running vm.runtime.defmeth.StaticMethodsTest on Linux x64
>     https://bugs.openjdk.java.net/browse/JDK-8067480
>
> Summary:
> The previous fix for JDK-8033150: (invokestatic: 
> IncompatibleClassChangeError trying to invoke static method from a 
> parent in presence of conflicting defaults), made the change to 
> include overpass methods in a class' local method array even when a 
> static method is present.  An overpass method is added to the current 
> class' local method array for issues that have been encountered during 
> the walk of the default methods.  This fix allowed default method 
> processing to match method selection where statics are and should be 
> ignored. To have the static methods then later be preferred over an 
> overpass method at method and interface method resolution time, the 
> fix for JDK-8033150 introduced the concept of "skipping_overpass" 
> during method lookup.
>
> The current bug, JDK-8067480, exposes a problem with allowing both a 
> static method and an overpass method that share the same method name 
> and signature to co-exist in a class' local method array.  A class' 
> local method array is ordered based on the method name's Symbol* 
> address.  So depending on this ordering, which happened to start 
> differing between a fastdebug and product build, 
> instanceKlass::find_instance_method() was returning NULL because the 
> static method was found first and searching did not continue to find 
> the overpass method of the same name and signature.  This led to 
> consequences downstream when decisions were being made as to whither 
> or not a miranda method should be added during the class' vtable 
> initialization.  During a fastdebug build, find_instance_method() 
> found the overpass method and vtable initialization ended correctly.  
> During a product build, due to a differing sorted order of the class' 
> method array, the static method was found which caused the vtable 
> initialization to determine a miranda method was needed, overrunning 
> the vtable and actually overwriting the first slot in the itable. 
> instanceKlass::find_instance_method() must have the concept added of 
> "skipping_statics", must like the "skipping_overpass" concept. It 
> should skip a static method of the same name and signature and instead 
> of stopping, keep searching in case an overpass method of the same 
> name and signature exists as well.
>
> Tests:
>    defmeth, java/lang, java/util, hotspot jtreg - completed
>    vm.quick.testlist - in progress