On Wed, 16 Apr 2025 05:12:28 GMT, Rémi Forax <fo...@openjdk.org> wrote:
>> 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. > > yes ! I would write > "given the current implementation of hashCode(), marking hasIsZero @Stable is > not useful for constant folding, as the field `hash` of value '0' is read > first." Yep. To be more exact, JIT anticipates a read of `hash` to be non-zero at any future point instead of trusting it to be zero when it observes `hashIsZero == 1`. ------------- PR Review Comment: https://git.openjdk.org/jdk/pull/24625#discussion_r2046111256
