[Exclusivity] Enforce exclusive access for class offsets in KeyPaths #16051
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…clusivity". This is a special @_semantics attribute that preserves exclusivity even if we are eliminating exclusivity in other parts of a module in release mode. This is done by: 1. Teaching the Access Marker Elimination pass to skip any function with the semantics tag. 2. Requiring all functions with the semantics tag to be noinline. This ensures that the SIL level inliner will not inline these functions into any callers without the protection of the semantics tag. This is enforced in IRGenPrepare and ensures that our access markers will live to IRGen time. 3. In IRGenPrepare, we convert these functions from noinline to always inline. After IRGen this then allows for the LLVM inliner to inline these trivial functions that just perform the exclusivity checks ensuring that we do not have extra calls in the fast path. This ensures that we can fix the keypaths exclusivity issue without having to enable exclusivity across the entire stdlib and deal with any of the potential performance issues therein. rdar://39335800
…ift_dumpTrackedAccesses(). This makes it easy to perform printf debugging in the debugger. I have found it to be useful in understanding programs around exclusivity quickly.
Add dynamic enforcement of exclusive access when a KeyPath directly accesses a final stored property on an instance of a class. For read-only projections, this begins and ends the access immediately. For mutable projections, this uses the ClassHolder to perform a long-term access that lasts as long as the lifetime of the ClassHolder. rdar://problem/31972680
Use begin_unpaired_access [no_nested_conflict] for
Builtin.performInstantaneousReadAccess. This can't be optimized away
and is the proper marker to use when the access scope is unknown.
Drop the requirement that
_semantics("optimize.sil.preserve_exclusivity") be @inline(never). We
actually want theses inlined into user code. Verify that the
@_semantic functions are not inlined or otherwise tampered with prior
to serialization.
Make *no* change to propagate @inline(__always) into LLVM. This no longer has
any relationship to this PR and can be investigated seperately.
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Add dynamic enforcement of exclusive access when a KeyPath directly accesses a final
stored property on an instance of a class. For read-only projections, this begins and ends
the access immediately. For mutable projections, this uses the ClassHolder to perform
a long-term access that lasts as long as the lifetime of the ClassHolder.
rdar://problem/31972680
Follow up on: @devincoughlin #15502
and: @gottesmm #16016