On Tue, 8 Oct 2024 01:14:32 GMT, Chen Liang <li...@openjdk.org> wrote:
>> src/java.base/share/classes/java/util/zip/ZipUtils.java line 173:
>>
>>> 171: * The bytes are assumed to be in Intel (little-endian) byte order.
>>> 172: */
>>> 173: public static final int get16(byte[] b, int off) {
>>
>> Can JIT automatically perform MergeStore here? If JIT can automatically
>> perform MergeStore without using Unsafe, many scenarios will benefit.
>
> Unfortunately we only have merge store for writing to arrays; no merge load
> when we are reading from arrays.
Yes. As I wrote in the PR description: "An appealing alternative would be to
implement a merge load analogue to the merge store optimizations in C2." So
it's the opposite of a merge store. I recall @eme64 mentioning somewhere that
such an optimization would be possible, if we could show it to be profitable. I
think it's reasonable to do this enhancement now, then revert the `Unsafe`
stuff if/when there's a merge load optimization that beats it.
-------------
PR Review Comment: https://git.openjdk.org/jdk/pull/21377#discussion_r1791410504
