[14] RFR(XS): 8231058: VerifyOops crashes with assert(_offset >= 0) failed: offset for non comment?

[Tobias Hartmann]

Hi,

please review the following patch:
https://bugs.openjdk.java.net/browse/JDK-8231058
http://cr.openjdk.java.net/~thartmann/8231058/webrev.00/

I've accidentally broke CodeStrings::find_last with my patch for JDK-8224624 [1] but didn't notice
because the failure only triggers with -XX:+VerifyOops and apparently we don't have any tests that
execute with that flag.

The problem is that CodeString::offset() should only be called for comments. I've modified the
condition accordingly. I've verified that the behavior is now equivalent to before JDK-8224624.

Thanks,
Tobias

[1] https://bugs.openjdk.java.net/browse/JDK-8224624
http://cr.openjdk.java.net/~thartmann/8224624/webrev.00/src/hotspot/share/asm/codeBuffer.cpp.sdiff.html