On Mon, 14 Apr 2025 14:47:59 GMT, Per Minborg <pminb...@openjdk.org> wrote:
> This PR proposes to add the `@Stable` annotation to `j.l.String.hash` and
> `j.l.String.hashIsZero`. This means the VM can trust these fields to never
> change which enables constant folding optimizations.
>
> This PR is tested in tier1, tier2, tier3, and tier4 which all pass.
src/java.base/share/classes/java/lang/String.java line 183:
> 181: * us to avoid recalculating this.
> 182: */
> 183: @Stable
Suggestion:
// Marking hashIsZero stable is meaningless, as a read of `0` on hash blocks
// constant folding of reading hashIsZero
A compromise. A stable on the hash field is a net improvement; we can
investigate constant folding the zero hashes later.
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PR Review Comment: https://git.openjdk.org/jdk/pull/24625#discussion_r2045739565
