RFR: 8247909: Improve PrimitiveConversions::cast using C++14

[David Holmes]

Hi Kim,

On 13/09/2020 5:37 pm, Kim Barrett wrote:
> Please review this reimplementation of PrimitiveConversions::cast,
> using facilities from C++14.  In particular, conversions involving
> only integral values or integral and enum values are now constexpr.
> Also using <type_traits> rather than HotSpot work-alikes.
> 
> Had to update zForwardingEntry.hpp because of a class no longer being
> implicitly included.  Improved a friend declaration while in the
> vicinity.

Can't comment on C++ specifics but all the changes seem reasonable to me.

Thanks,
David

> Testing
> mach5 tier1
> 
> -------------
> 
> Commit messages:
>   - Reimpliment PC::cast, with some cases now constexpr.
> 
> Changes: https://git.openjdk.java.net/jdk/pull/143/files
>   Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=143&range=00
>    Issue: https://bugs.openjdk.java.net/browse/JDK-8247909
>    Stats: 237 lines in 3 files changed: 111 ins; 110 del; 16 mod
>    Patch: https://git.openjdk.java.net/jdk/pull/143.diff
>    Fetch: git fetch https://git.openjdk.java.net/jdk pull/143/head:pull/143
> 
> PR: https://git.openjdk.java.net/jdk/pull/143
>