[Bug target/105930] [12/13 Regression] Excessive stack spill generation on 32-bit x86

torvalds@linux-foundation.org gcc-bugzilla@gcc.gnu.org
Mon Jun 13 18:31:22 GMT 2022


--- Comment #14 from Linus Torvalds <torvalds@linux-foundation.org> ---
(In reply to Samuel Neves from comment #13)
> Something simple like this -- https://godbolt.org/z/61orYdjK7 -- already
> exhibits the effect. 


That's a much better test-case. I think you should attach it to the gcc
bugzilla, I don't know how long godbolt remembers those links.

But godbolt here is good for another thing: select clang-14 as the compiler,
and you realize how even gcc-11 is actually doing a really really bad job.

And I'm not saying that to shame anybody: I think it's more a sign that maybe
the issue is actually much deeper, and that the problem already exists in
gcc-11, but some small perturbation then just makes an already existing problem
much worse in gcc-12.

So that commit I bisected to is probably almost entirely unrelated, and it is
just the thing that turns up the bad behavior to 11.

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