RFR: 8336256: memcpy short value to int local is incorrect in VtableStubs::unsafe_hash

[Amit Kumar]

On Thu, 11 Jul 2024 14:18:07 GMT, Richard Reingruber <rrich at openjdk.org> wrote:

> Make sure the local variable used as target of the `memcpy` in `VtableStubs::unsafe_hash` has the same size as `VtableStub::_index` which is the source of the `memcpy`.
> 
> With this fix we don't see the crashes reported in the JBS-issue.
> 
> JTReg tests: tier1-4 of hotspot and jdk. All of Langtools and jaxp. Renaissance Suite and SAP specific tests.
> Testing was done with fastdebug and release builds on the main platforms and also on Linux/PPC64le and AIX.

I do see crash on s390x as well: 

* For target buildtools_create_symbols_javac__the.COMPILE_CREATE_SYMBOLS_batch:
#
# A fatal error has been detected by the Java Runtime Environment:
#
#  Internal Error (/home/amit/head/jdk/src/hotspot/share/code/compiledIC.cpp:261), pid=243064, tid=243069
#  assert(is_megamorphic()) failed: sanity check
#
# JRE version: OpenJDK Runtime Environment (24.0) (fastdebug build 24-internal-adhoc.amit.jdk)
# Java VM: OpenJDK 64-Bit Server VM (fastdebug 24-internal-adhoc.amit.jdk, mixed mode, tiered, compressed oops, compressed class ptrs, g1 gc, linux-s390x)
# Problematic frame:
# V  [libjvm.so+0x6e75f2]  CompiledIC::set_to_megamorphic(CallInfo*)+0x192
#

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PR Comment: https://git.openjdk.org/jdk/pull/20137#issuecomment-2225110288