RFR: 8323582: C2 SuperWord AlignVector: misaligned vector memory access with unaligned native memory

[Emanuel Peter]

On Tue, 18 Feb 2025 09:57:29 GMT, Roland Westrelin <roland at openjdk.org> wrote:

> > That one is more tricky. Because what if the loop somehow gets folded away? How would we catch that?

>There is code that removes the OuterStripMinedLoop if the CountedLoop goes away and also, if I recall correctly, logic that verifies no ``OuterStripMinedLoopis left behind without aCountedLoop` so it's probably possible. Question is whether we want that or not. Seems like quite a bit of extra complexity.

Hmm ok, I see. I wonder how bad it is to leave the slow-loop there until after loop-opts. I mean it was already created, and it now has no loop-opts performed on it (it is stalled), so it just sits there like dead code. So I'm not sure there is really a performance benefit to kill it already a little earlier. Maybe a very small one?

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PR Comment: https://git.openjdk.org/jdk/pull/22016#issuecomment-2665161507