[Bug middle-end/87220] -fstack-check produces inefficient and wrong tests

[bugdal at aerifal dot cx]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87220

--- Comment #6 from Rich Felker <bugdal at aerifal dot cx> ---
Eric, even accepting the purpose in 1, what I described in 2 seems like a bug.
If it needs an extra page past what's actually used, it needs to make one probe
in the last-used page to ensure it doesn't jump a guard page.

Anyway, I'll accept that this feature just isn't useful for what I wanted it
for, but I agree with Alexander that it should be clearly documented that not
only is it not intended for this purpose, but it fails to perform this purpose
at all and can even introduce new jump-the-guard-page conditions that would not
have been present without the option.