RFR:7199207 Placeholders cleanup

[Coleen Phillimore]

Karen,

In systemDictionary, why can't you throw circularity error sooner, like 
around line 726 (after you release the lock)?

811   // must throw error outside of owning lock
  812   if (throw_circularity_error) {
  813     ResourceMark rm(THREAD);
  814     THROW_MSG_0(vmSymbols::java_lang_ClassCircularityError(), name->as_C_string());
  815   }

I guess this compiles but it should be THROW_MSG_NULL() instead of 
THROW_MSG_0().   gcc is likely to be picky about things like this in the 
future.

There are some weird indentation around some of your changes, not caused 
by them, but could you clean up nearby indentation problems in 
systemDictionary?   Line 367, 352-356 (should be initialization all in 
one line).   I didn't see any others.  They are small cosmetic changes.

This change is great!   Thank you for taking the time to clean this up.  
I can see this preventing all sorts of bugs in the future!

Coleen

On 1/4/2013 3:54 PM, Karen Kinnear wrote:
> Please review:
> http://cr.openjdk.java.net/~acorn/7199207.fix2merge/webrev/
>
> bug: NPG: Crash in PlaceholderTable::verify, after a StackOverflow during class loading
> https://jbs.oracle.com/bugs/browse/JDK-7199207
>
> Thanks to Stefan Karlsson for the initial analysis and the test case.
>
> Thanks to Coleen's suggestion, I've simplified the placeholder table entry cleanup.
> Specifically the placeholder table is not used to keep the instanceKlass alive for GC during class resolution, and no
> other logic depends on the contents of the placeholder table. Therefore rather than retaining the entries for the entire
> span of resolve_from , entries are explicitly added and removed for each specific resolution action: LOAD_INSTANCE,
> LOAD_SUPER and DEFINE_CLASS (used for parallel class loading).
>
> Tests run:
> Original test case from bug (linux 32 bit client)
> regression tests on solaris/sparc 32 bit:
>    vm.sysdict.testlist
>    vm.quick.testlist
>    vm.parallel_class_loading.testlist: no flags, -XX:+AllowParallelDefineClass, -XX:+UnsyncLoadClass, -XX:+PrintSystemDictionaryAtExit
>    java.lang.instrument: jtreg
>    jli with -Xcomp
>    ctw nightly.testlist
> tests in progress on solaris/sparc 32 bit:
>    runThese -Xcomp
>    jck vm
>
> thanks,
> Karen
>
>