This resolves minor inefficiency in the fast-path for decoding latin-1 chars from UTF-8. I also took the opportunity to refactor the StringDecode microbenchmark to align with recent changes to the StringEncode micro.
The inefficiency is that this test is quite branchy: `if ((b1 == (byte)0xc2 || b1 == (byte)0xc3) && ...` Since the two constant bytes differ only on the lowest bit this can be transformed to this, saving us a branch: `if ((b1 & 0xfe) == 0xc2 && ...` This provides a small speed-up on microbenchmarks where the input can be internally encoded as latin1: Benchmark (charsetName) Mode Cnt Score Error Units StringDecode.decodeLatin1LongStart UTF-8 avgt 50 2283.591 ± 12.332 ns/op StringDecode.decodeLatin1LongStart UTF-8 avgt 50 2165.984 ± 13.136 ns/op ------------- Commit messages: - 8280124: Reduce branches decoding latin-1 chars from UTF-8 encoded bytes - Align StringDecode microbenchmark with StringEncode Changes: https://git.openjdk.java.net/jdk/pull/7122/files Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=7122&range=00 Issue: https://bugs.openjdk.java.net/browse/JDK-8280124 Stats: 139 lines in 2 files changed: 93 ins; 34 del; 12 mod Patch: https://git.openjdk.java.net/jdk/pull/7122.diff Fetch: git fetch https://git.openjdk.java.net/jdk pull/7122/head:pull/7122 PR: https://git.openjdk.java.net/jdk/pull/7122
