[PATCH] D68720: Support -fstack-clash-protection for x86

[serge via Phabricator via cfe-commits]

serge-sans-paille added a comment.

Some benchmark / instrumentation report: due to the way memory moves are ordered in the entry block, there tend to be relatively few free probes between two stack growth within a function, and a large number after the last stack growth.

When recompiling llc, I only get 18 free probes between stack growth, and a large amount (several thousands) after the last stack growth.
When recompiling cpython, I only get 4 free probes between stack growth.

This may be improved by rescheduling instructions / changing stack object layout but that's probably not worth the effort (there's not that much functions with stack space > a page)


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  https://reviews.llvm.org/D68720/new/

https://reviews.llvm.org/D68720