On Mon, 28 Jul 2025 01:11:26 GMT, Shaojin Wen <s...@openjdk.org> wrote:
>> I prefer to calculate an ARRAY_CHAR_SHIFT in the constant like ShortVector >> does, like this >> >> static final int ARRAY_CHAR_SHIFT >> = 31 - >> Integer.numberOfLeadingZeros(Unsafe.ARRAY_CHAR_INDEX_SCALE); >> >> Unsafe.getUnsafe().copyMemory( >> ca, >> Unsafe.ARRAY_CHAR_BASE_OFFSET + (long) off << >> ARRAY_CHAR_SHIFT, >> val, >> Unsafe.ARRAY_CHAR_BASE_OFFSET + (long) off << >> ARRAY_CHAR_SHIFT, >> (long) (end - off) << ARRAY_CHAR_SHIFT); > > String uses `<< coder` in many places. I think the following way of writing > is also good: > > Unsafe.getUnsafe().copyMemory( > ca, > Unsafe.ARRAY_CHAR_BASE_OFFSET + (long) off << String.UTF16, > val, > Unsafe.ARRAY_CHAR_BASE_OFFSET + (long) off << String.UTF16, > (long) (end - off) << String.UTF16); I agree that we can expect arrays to be laid out as a contiguous chunk of memory with the intuitively expected element size. _But..._ AFAIK this is not specified anywhere in the JVMS, although it is true that it is tacitly assumed in many low-level parts of the codebase. So, in this sense, I'm fine with your code. ------------- PR Review Comment: https://git.openjdk.org/jdk/pull/24773#discussion_r2236290641
