On Thu, 8 Jan 2026 19:24:56 GMT, Dan Heidinga <[email protected]> wrote:
>> Remove an optimization in value copying that could cause incorrect results >> with the new substitutability test method. >> >> Tested with Mach5 tier 1-3. >> >> Thank you, >> >> Fred > > Change is straight forward and correct. > > Copying this comment from jbs for context in why this is the right approach: >>The goal is to keep the default implementation of the substitutability test, >>and its companion the identity hash code method, as simple as possible. It is >>possible to make this implementation aware of the null-marker and its >>semantic, but it would make the code much more complex. Resetting a flat >>value by rewriting its whole content when it is nullified is a simple >>approach, as the code to do that is already available for values containing >>oops. > A specialized version of the substitutability test, like the one a JIT can > generate for a particular value type, can perfectly have a different approach > and use the null-marker as indicators to skip comparison of some memory > segments. Thanks @DanHeidinga @coleenp for the reviews. ------------- PR Comment: https://git.openjdk.org/valhalla/pull/1869#issuecomment-3725783318
