This has a couple benefits:
- Since metadata allocations are already guarded by a lock, the allocator doesn't require synchronization, and can be much much simpler and a little faster than malloc.
- By bypassing malloc, we also avoid tools like 'heap' prying into our metadata cache and misrepresenting cache entries keyed on classes as live objects, fixing rdar://problem/20562886.
In my unscientific local tests, this appeared to give a small across-the-board improvement to Onone performance in the perf test suite, though not far enough from noise for me to declare that definitively. Fixing the bug is the bigger point here.
Swift SVN r27856
We have enough flag bits on function types now to warrant stashing an extra word in the metadata key alongside the arguments and results, so add one, and pack the number of arguments, function convention, and 'throws' bit in there. This lets us merge the separate metadata caches for thick/thin/block/C functions into one, saving a bit of runtime memory, and simplifying a bunch of repetitive code in the runtime and IRGen.
This also fixes a subtle bug we had where the runtime getFunctionTypeMetadata function expected the result argument to be passed in the arguments array, but IRGen was passing it as a separate argument, which would have caused function type metadata to fail to be uniqued by result type.
Swift SVN r27651
Previously some parts of the compiler referred to them as "fields",
and most referred to them as "elements". Use the more generic 'elements'
nomenclature because that's what we refer to other things in the compiler
(e.g. the elements of a bracestmt).
At the same time, make the API better by providing "getElement" consistently
and using it, instead of getElements()[i].
NFC.
Swift SVN r26894
Add a 'mayTakeValue' function, which returns true if we're allowed to take the value from an existential container (assuming we own the existential container value). This is true for class and opaque existential containers, but not for boxed existentials, where multiple owners may share references to the boxed value. Also add a 'deinitExistentialContainer' function to do any cleanup that must happen after the value has been consumed out of an existential container. Fix up an off-by-one indirection level in the SwiftError implementations of the existing existential container methods.
Swift SVN r26561
Teach ExistentialTypeMetadata how to project out the value pointer, type metadata, and protocol witness table from ErrorType containers. NFC yet; the dynamic casting and reflection machinery needs further work to correctly handle ErrorType boxes.
Swift SVN r26509
If an existential type for a special protocol (not a composition) is instantiated, carry the special protocol identifier from that protocol to the existential, allowing us to easily recognize existentials with unique runtime characteristics.
Swift SVN r26436
The standard library has grown significantly, and we need a new
directory structure that clearly reflects the role of the APIs, and
allows future growth.
See stdlib/{public,internal,private}/README.txt for more information.
Swift SVN r25876
