To make it possible to change the implementation of
_stdlib_isOSVersionAtLeast(), remove the @inlinable attribute from it.
Since it is currently inlinable and calls the helper function
_swift_stdlib_operatingSystemVersion(), we’ll have to keep the
helper around as ABI.
This change causes a minor pessimization where the LLVM optimizer can no
longer reason that, for example, a successful check for 10.12 availability
means that a later check for 10.11 will always succeed. I don't expect this
pessimization to be a problem, but if needed we could write a custom SIL
optimizer pass to claw back the performance.
<rdar://problem/59447474>
This tells the compiler that repeated calls to this function will always generate the same result, which allows the optimizer to coalesce multiple calls, hoist calls out of loops, and other such nice things.
rdar://problem/20690429
This disables inlinability of _stdlib_isOSVersionAtLeast. I don't see
value in making it inlinable as long as _swift_stdlib_operatingSystemVersion is
opaque.
rdar://41849700
