On Sat, 18 Feb 2023 23:26:08 GMT, Claes Redestad <redes...@openjdk.org> wrote:
> When encoding Strings to US-ASCII we can speed up the happy path > significantly by using `StringCoding.countPositives` as a speculative check > for whether there are any chars that needs to be replaced by `'?'`. Once a > non-ASCII char is encountered we fall back to the slow loop and replace as > needed. > > An alternative could be unrolling or using a byte array VarHandle, as > show-cased by Brett Okken here: > https://mail.openjdk.org/pipermail/core-libs-dev/2023-February/100573.html > Having to replace chars with `?` is essentially an encoding error so it might > be safe to assume this case is exceptional in practice. Baseline: Benchmark (charsetName) Mode Cnt Score Error Units StringEncode.encodeAsciiLong US-ASCII avgt 5 26626,025 ± 448,307 ns/op StringEncode.encodeAsciiShort US-ASCII avgt 5 33,336 ± 2,032 ns/op Patch: Benchmark (charsetName) Mode Cnt Score Error Units StringEncode.encodeAsciiLong US-ASCII avgt 5 5492,985 ± 40,066 ns/op StringEncode.encodeAsciiShort US-ASCII avgt 5 28,545 ± 4,883 ns/op ------------- PR: https://git.openjdk.org/jdk/pull/12640
