RFR: 8313785: Fix -Wconversion warnings in prims code

[Dean Long]

On Fri, 4 Aug 2023 14:37:07 GMT, Coleen Phillimore <coleenp at openjdk.org> wrote:

> This patch fixes Wconversion in code in the src/hotspot/share/prims directory.  Most of the changes correct the types.  jfieldID's are created with the int offset returned by InstanceKlass::field_offset().
>      int     field_offset      (int index) const { return field(index).offset(); }
> 
> So when we get the field offset back, it's an int.
> 
> Also stackwalker passes jlong, so made that consistent.
> 
> Tested with tier1 on Oracle supported platforms.

src/hotspot/share/prims/jvm.cpp line 612:

> 610:   // as implemented in the classic virtual machine; return 0 if object is null
> 611:   return handle == nullptr ? 0 :
> 612:          checked_cast<jint>(ObjectSynchronizer::FastHashCode (THREAD, JNIHandles::resolve_non_null(handle)));

What about making FastHashCode return jint?

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PR Review Comment: https://git.openjdk.org/jdk/pull/15160#discussion_r1284876719