[foreign-memaccess+abi] RFR: 8300201: When storing MemoryAddress.ofLong(0x0000000080000000L), MemorySegment.get is not equal to MemorySegment.set because of the expanded sign [v2]

[Maurizio Cimadamore]

On Mon, 23 Jan 2023 17:47:40 GMT, Per Minborg <pminborg at openjdk.org> wrote:

>> This PR proposes to normalize the upper 32-bit to zero on 32-bit systems.
>
> Per Minborg has updated the pull request incrementally with two additional commits since the last revision:
> 
>  - Update comments for 32-bit platforms
>  - Update src/java.base/share/classes/java/lang/foreign/MemorySegment.java
>    
>    Co-authored-by: Maurizio Cimadamore <54672762+mcimadamore at users.noreply.github.com>

src/java.base/share/classes/java/lang/foreign/MemorySegment.java line 1071:

> 1069:      * <p>
> 1070:      * On 32-bit platforms, the given address value will be normalized such that the
> 1071:      * upper 32 bits of the {@link MemorySegment#address() address} of returned memory segment

Ah - late to the party. Is "upper bits" correct here? E.g. doesn't it depend on endianness? Perhaps use "most-significant bits?"

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PR: https://git.openjdk.org/panama-foreign/pull/774