On Wed, 21 May 2025 21:28:07 GMT, Chen Liang <li...@openjdk.org> wrote:
>> 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. This unnecessary detail goes will beyond the description of the annotation and is more of a design doc for VM implementation so this is not really the best place for it. ------------- PR Review Comment: https://git.openjdk.org/jdk/pull/24777#discussion_r2101204688
