RFR(S): 8232980: Cleanup initialization of function pointers into java.base from classloader.cpp

[Langer, Christoph]

Hi,

please help reviewing a cleanup patch to classLoader.cpp.

The methods load_zip_library() and load_jimage_library() can be cleaned up a little bit. In my patch, I also extracted the initialization of the one symbol coming from libjava to a new method load_java_library(). However, I'm not fully sure on whether it would be nicer to have all these 3 methods consolidated into one. What do you think?

In my patch I check for all needed symbols since it's all coming from the JDK and we can assume consistency. Should there be a problem in resolving some symbol, then VM initialization should fail.

Furthermore, I'm wondering, whether to use guarantee or vm_exit_during_initialization for the NULL checks of the resolved symbols. Currently we have both but I think we should use one consistent approach. I  think vm_exit_during_initialization would be the best fit. Opinions?

Bug: https://bugs.openjdk.java.net/browse/JDK-8232980
Webrev: http://cr.openjdk.java.net/~clanger/webrevs/8232980.0/

Thanks
Christoph