Limit inlining for stdlibunittest. This saves a lot of compilation time

[trentxintong]

Limit inlining for stdlibunittest. This saves a lot of compilation time for some of the stdlibunittests.

i.e. For the FixPoint benchmark, from 256s on my machine to 27s.

[trentxintong]

@gribozavr Can you please review this ?

I have some concerns.

Is this a good place to add the noinline thing to reduce the compilation time ? I am a bit worried about effectiveness/coverage of test after this noinline thing is added. Are these tests supposed to be compiled and optimized separately., i.e. do you think allowing them to be inlined into top-level function can result in better testing for the optimizer ?

[gribozavr]

@trentxintong LGTM, thank you! Could you add the attribute to the other overload of test() as well (a few lines below), and also add a comment above the attribute, something like:

This method is prohibited from inlining because inlining the test harness into the test is not interesting from the runtime performance perspective. On the contrary, it sometimes severely affects the compile time of the test code.

[trentxintong]

@gribozavr I modified your comment a bit, how does this look ?

[trentxintong]

@swift-ci Please smoke test

[gribozavr]

LGTM, thanks!