The compiler with debug assertions is really slow

[Noratrieb]

The compiler compiled with debug assertions has gotten really slow recently. For example, compiling the standard library takes way longer than it used to.

This is bad, it makes it way harder to work on rustc.

[Noratrieb]

This is probably because of the recent changes to assert_unsafe_precondition. It contains a cfg(bootstrap) hack for debug_assertions() that's not inlined. Additionally, it outlines the predicate, which is super slow as well. Fixing the former is easy, fixing the latter is harder and requires adding #[inline(not_the_mir_inliner)].