RFR: 8282241: Invalid generic signature for redefined classes [v2]

[Alex Menkov]

> JDK-8238048 (fixed in jdk15) moved major_version, minor_version, generic_signature_index and source_file_name_index from InstanceKlass to ConstantPool.
> We still have some incorrect code in CP merge during class redefinition.
> 
> rewrite_cp_refs(scratch_class) updates generic_signature_index and source_file_name_index in the scratch_cp, so we need to copy the attributes (merge_cp->copy_fields(scratch_cp())) after rewrite_cp_refs.
> 
> In redefine_single_class we don't need to copy source_file_name_index because it's a CP property and we swap CPs. So this copying actually sets the value from old class.
> 
> tested:
> - test/jdk/java/lang/instrument
> - test/hotspot/jtreg/serviceability/jvmti/RedefineClasses
> - test/hotspot/jtreg/vmTestbase/nsk/jvmti/RedefineClasses
> - test/hotspot/jtreg/vmTestbase/nsk/jvmti/RetransformClasses

Alex Menkov has updated the pull request incrementally with one additional commit since the last revision:

  Reworked the test

-------------

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/7676/files
  - new: https://git.openjdk.java.net/jdk/pull/7676/files/8c6d55c5..c51b82d7

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=7676&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=7676&range=00-01

  Stats: 429 lines in 2 files changed: 196 ins; 233 del; 0 mod
  Patch: https://git.openjdk.java.net/jdk/pull/7676.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/7676/head:pull/7676

PR: https://git.openjdk.java.net/jdk/pull/7676