RFR (S): 8211394: CHECK_ must be used in the rhs of an assignment statement within a block

[David Holmes]

Bug: https://bugs.openjdk.java.net/browse/JDK-8211394
webrev: http://cr.openjdk.java.net/~dholmes/8211394/webrev/

If a CHECK_ macro is used on a function call that is part of a return 
statement i.e.

return foo(CHECK_NULL);

then it expands into an unreachable if-statement that checks the 
exception state:

return foo();
if (EXCEPTION_OCCURRED)
   return NULL;

This is obviously a programming error, but unfortunately not something 
our often pedantic compilers complain about.

There are two ways to fix:

1. Convert to assignment:

T* t = foo(CHECK_NULL);
return t;

2. If the method is local and its exception behaviour easily discernible 
and matches the expected behaviour, then change CHECK_ to THREAD

return foo(THREAD);

Both fixes are applied as appropriate. As per the bug report I also 
revisited an earlier fix in this area - JDK-8062808 - and made adjustments.

Thanks,
David