_swift_stdlib_getHardwareConcurrency's declaration isn't a proper prototype:
it's missing `void` inside the brackets.
Found while compiling the stdlib to WebAssembly, which fails with:
Functions with 'no-prototype' attribute must take varargs: _swift_stdlib_getHardwareConcurrency
This shouldn't impact existing platforms.
This fixes the Windows platform, where the aligned allocation path is
not malloc-compatible. It won't have any observable difference on
Darwin or Linux, aside from manually allocated memory on Linux now
being consistently 16-byte aligned (heap objects will still be 8-byte
aligned on Linux).
It is unfortunate that we can't guarantee Swift-allocated memory via
Unsafe*Pointer is malloc compatible on Windows. It would have been
nice for that to be a cross platform guarantee since it's normal to
allocate in C and deallocate in Swift or vice-versa. Now we have to
tell developers to always use _aligned_malloc/_aligned_free when
transitioning between Swift/C if they expect their code to work on
Windows.
Even though this fix isn't required today on Darwin/Linux, it makes
good sense to guarantee that the allocation/deallocation paths are
consistent.
This is done by specifying a constant that stdlib can use to round up
alignment, _swift_MinAllocationAlignment. The runtime asserts that
this constant is greater than MALLOC_ALIGN_MASK for all platforms.
This way, manually allocated buffers will always use the aligned
allocation path. If users specify an alignment less than m
round up so users don't need
to pass the same alignment to deallocate the buffer). This constant
does not need to be ABI.
Alternatives are:
1. Require users of Unsafe*Pointer to specify the same alignment
during deallocation. This is obviously madness.
2. Introduce new runtime entry points:
swift_alignedAlloc/swift_alignedDealloc, introduce corresponding
new builtins, and have Unsafe*Pointer always call those. This would
make the runtime API a little more obvious but would introduce
complexity in other areas of the compiler and it doesn't have any
other significant benefit. Less than 16-byte alignment of manually
allocated buffers on Linux is a non-goal.
The general rule here is that something needs to be SWIFT_CC(swift)
if it's just declared in Swift code using _silgen_name, as opposed to
importing something via a header.
Of course, SWIFT_CC(swift) expands to nothing by default for now, and
I haven't made an effort yet to add the indirect-result / context
parameter ABI attributes. This is just a best-effort first pass.
I also took the opportunity to shift a few files to just implement
their shims header and to demote a few things to be private stdlib
interfaces.
- Add RuntimeTarget template This will allow for converting between
metadata structures for native host and remote target architectures.
- Create InProcess and External templates for stored pointers
Add a few more types to abstract pointer access in the runtime
structures but keep native in-process pointer access the same as that
with a plain old pointer type.
There is now a notion of a "stored pointer", which is just the raw value
of the pointer, and the actual pointer type, which is used for loads.
Decoupling these allows us to fork the behavior when looking at metadata
in an external process, but keep things the same for the in-process
case.
There are two basic "runtime targets" that you can use to work with
metadata:
InProcess: Defines the pointer to be trivially a T* and stored as a
uintptr_t. A Metadata * is exactly as it was before, but defined via
AbstractMetadata<InProcess>.
External: A template that requires a target to specify its pointer size.
ExternalPointer: An opaque pointer in another address space that can't
(and shouldn't) be indirected with operator* or operator->. The memory
reader will fetch the data explicitly.
...and explicitly mark symbols we export, either for use by executables or for runtime-stdlib interaction. Until the stdlib supports resilience we have to allow programs to link to these SPI symbols.
Getting a superclass, instance extents, and whether a class is native-refcounted are all useful type API. De-underscore these functions and give them a consistent `swift[_objc]_class*` naming scheme.
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
