On Fri, 16 May 2025 19:45:16 GMT, John R Rose <jr...@openjdk.org> wrote:
> Or just: s/, unlike the other methods// Removed mention of "the other methods". > src/java.base/share/classes/jdk/internal/vm/annotation/IntrinsicCandidate.java > line 90: > >> 88: * intrinsic.) For example, the documentation can simply say that the >> result is >> 89: * undefined if a race happens. However, race conditions must not lead >> to >> 90: * program failures or type safety breaches, as listed above. > > Maybe add a teaching paragraph: > >> Reasoning about such race conditions is difficult, but it is a necessary >> skill when working with intrinsics that can observe racing shared variables. >> One example of a tolerable race is a repeated read of a shared reference. >> This only works if the algorithm takes no action based on the first read, >> other than deciding to perform the second read; it must "forget what it saw" >> in the first read. This is why the array-mismatch intrinsics can sometimes >> report a tentative search hit (maybe using vectorized code), which can then >> be confirmed (by scalar code) as the caller makes a fresh and independent >> observation. > > (This is done when the array mismatch logic performs NaN-folding. I just > noticed that the NaN-folding code in ArraysSupport is slightly incorrect with > respect to races!) I have appened this teaching paragraph also as a blockquote inlined note after this current paragraph. ------------- PR Review Comment: https://git.openjdk.org/jdk/pull/24777#discussion_r2101197921 PR Review Comment: https://git.openjdk.org/jdk/pull/24777#discussion_r2101199974
