On Mon, 9 Jun 2025 06:52:41 GMT, Radim Vansa <rva...@openjdk.org> wrote:
>> src/hotspot/share/utilities/packedTable.cpp line 49: >> >>> 47: assert((key & ~_key_mask) == 0, "key out of bounds"); >>> 48: assert((value & ~_value_mask) == 0, "value out of bounds: %x vs. %x >>> (%x)", value, _value_mask, ~_value_mask); >>> 49: *reinterpret_cast<uint64_t*>(data + offset) = >>> static_cast<uint64_t>(key) | (static_cast<uint64_t>(value) << _value_shift); >> >> How does this line not get a signal for unaligned write? > > From what I could find, strict alignment checking must be explicitly enabled > an aarch64. x86_64 does not require alignment either. In both cases, there > might be a performance penalty. Once I turned on hard signals for these unaligned accesses to find some performance problems (and I think I was debugging something on sparc). The OS handles these signals silently but it does/can cause performance loss. There must be a way to write this without all this C style casting with C++ syntax or a special memcpy. It would still be performant for field access even if the array was copied as a byte stream. There must be a more readable way to do this. ------------- PR Review Comment: https://git.openjdk.org/jdk/pull/24847#discussion_r2135613762
