The code that saves/restores the exclusivity checks for tasks was
newly introduced into the runtime. Clone that code into the back-
deployed version of the runtime.
Some notes:
1. Even though I refactored out AccessSet/Access from Exclusivity.cpp ->
ExclusivityPrivate.h, I left the actual implementations of insert/remove in
Exclusivity.cpp to allow for the most aggressive optimization for use in
Exclusivity.cpp without exposing a bunch of internal details to other parts of
the runtime. Smaller routines like getHead() and manipulating the linked list
directly I left as methods that can be used by other parts of the runtime. I am
going to use these methods to enable backwards deployment of exclusivity support
for concurrency.
2. I moved function replacements out of the Exclusivity header/cpp files since
it has nothing to do with Exclusivity beyond taking advantage of the TLS context
that we are already using.
The implemented semantics are that:
1. Tasks have separate exclusivity access sets.
2. Any synchronous context that creates tasks will have its exclusive access set
merged into the Tasks while the Task is running.
rdar://80492364
dynamic-replacement runtime functions.
The recent change of how we do dynamic replacements added 2 new runtime
functions. This patch adds those functions to the Compatibility50 static
archive.
This will allow backward deployment to a swift 5.0 runtime.
Patch by Erik Eckstein with a modification to call the standard
libraries implementation (marked as weak) when it is available.
This ensures we can change the implementation in the future and are not
ABI locked.
rdar://problem/51601233
Instead of a thunk insert the dispatch into the original function.
If the original function should be executed the prolog just jumps to the "real" code in the function. Otherwise the replacement function is called.
There is one little complication here: when the replacement function calls the original function, the original function should not dispatch to the replacement again.
To pass this information, we use a flag in thread local storage.
The setting and reading of the flag is done in two new runtime functions.
rdar://problem/51043781
This is yet another waypoint on the path towards the final
generic-metadata design. The immediate goal is to make the
pattern a private implementation detail and to give the runtime
more visibility into the allocation and caching of generic types.
