Throwable types handled specially in the VM?

[David Holmes]

Hi Joe,

Joe Darcy said the following on 08/20/10 12:03:
> As part of Project Coin, try-with-resources/ARM blocks have recently 
> been integrated into JDK 7.  Part of this feature is changes to 
> java.lang.Throwable to support recording of suppressed exception 
> information (6911258 "Project Coin: Add essential API support for 
> Automatic Resource Management (ARM) blocks").  Subsequently, some more 
> changes in Throwable were necessary to fix a regression in the ability 
> to print the stack traces of specially handled OutOfMemoryErrors 
> (6973831 "NPE when printing stack trace of OOME").
> 
> Are there any other Throwable types which receive special handling or 
> creation by the VM?  If there are any, I'd like to examine them to find 
> and correct and additional issues.

All the preallocation of exceptions occurs in universe_post_init in 
universe.cpp. These are as follows

     // Setup preallocated OutOfMemoryError errors
     Universe::_out_of_memory_error_java_heap = 
k_h->allocate_permanent_instance(CHECK_false);
     Universe::_out_of_memory_error_perm_gen = 
k_h->allocate_permanent_instance(CHECK_false);
     Universe::_out_of_memory_error_array_size = 
k_h->allocate_permanent_instance(CHECK_false);
     Universe::_out_of_memory_error_gc_overhead_limit =
       k_h->allocate_permanent_instance(CHECK_false);

     // Setup preallocated NullPointerException
     // (this is currently used for a cheap & dirty solution in compiler 
exception handling)
     Universe::_null_ptr_exception_instance = 
instanceKlass::cast(k)->allocate_permanent_instance(CHECK_false);
     // Setup preallocated ArithmeticException
     // (this is currently used for a cheap & dirty solution in compiler 
exception handling)
     Universe::_arithmetic_exception_instance = 
instanceKlass::cast(k)->allocate_permanent_instance(CHECK_false);
     // Virtual Machine Error for when we get into a situation we can't 
resolve
     Universe::_virtual_machine_error_instance =
       instanceKlass::cast(k)->allocate_permanent_instance(CHECK_false);

As you're aware from 6973831 these are raw allocations that invoke no 
constructor, so all fields are implicitly set to their default (null, 0) 
values.

I can't think of any other specialized exception handling.

David