[PATCH] D78717: [SystemZ] Implement -fstack-clash-protection

[serge via Phabricator via llvm-commits]

serge-sans-paille added a comment.



> It seems this was added in preparation for exploiting "natural probes" -- if the code can be proven to already touch all (or at least some) stack pages at least once (in this test case via the stores), then we might optimize out some of the extra probes.   But apparently this wasn't implemented in the X86 back-end in the end, and neither is it in your patch, so it doesn't make sense to have a test for it.

Correct!

> I believe this is also related to natural probes: on *Intel*, every call instruction would be a natural probe as it pushes the return address to the stack.  But on Z, the call instruction doesn't touch the stack (the called function might, but it also might not, so we cannot really rely on it).

Confirmed!


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  https://reviews.llvm.org/D78717/new/

https://reviews.llvm.org/D78717