Swift uses rt_swift_* functions to call the Swift runtime without using dyld's stubs. These functions are renamed to swift_rt_* to reduce namespace pollution.
rdar://28706212
MetadataCache's allocator into it.
The major functional change here is that MetadataCache will now use
the slab allocator for tree nodes, but I also switched the Hashable
conformances cache to use ConcurrentMap directly instead of a
Lazy<ConcurrentMap<>>.
Previously, these were all using MetadataCache. MetadataCache is a
more heavyweight structure which acquires a lock before building the
metadata. This is appropriate if building the metadata is very
expensive or might have semantic side-effects which cannot be rolled
back. It's also useful when there's a risk of re-entrance, since it
can diagnose such things instead of simply dead-locking or infinitely
recursing. However, it's necessary for structural cases like tuple
and function types, and instead we can just use ConcurrentMap, which
does a compare-and-swap to publish the constructed metadata and
potentially destroys it if another thread successfully won the race.
This is an optimization which we could not previously attempt.
As part of this, fix tuple metadata uniquing to consider the label
string correctly. This exposes a bug where the runtime demangling
of tuple metadata nodes doesn't preserve labels; fix this as well.
Previously, these were all using MetadataCache. MetadataCache is a
more heavyweight structure which acquires a lock before building the
metadata. This is appropriate if building the metadata is very
expensive or might have semantic side-effects which cannot be rolled
back. It's also useful when there's a risk of re-entrance, since it
can diagnose such things instead of simply dead-locking or infinitely
recursing. However, it's necessary for structural cases like tuple
and function types, and instead we can just use ConcurrentMap, which
does a compare-and-swap to publish the constructed metadata and
potentially destroys it if another thread successfully won the race.
This is an optimization which we could not previously attempt.
As part of this, fix tuple metadata uniquing to consider the label
string correctly. This exposes a bug where the runtime demangling
of tuple metadata nodes doesn't preserve labels; fix this as well.
When getting a mirror child that is a class existential, there
may be witness tables for the protocol composition to copy. Don't
just take the address of a class instance pointer from the stack -
make a temporary existential-like before calling into the Mirror
constructor.
This now correctly covers reflecting weak optional class types, and weak
optional class existential types, along with fixing a stack buffer
overflow reported by the Address Sanitizer (thanks, ASan!).
Tests were also updated to check for the validity of the child's data.
rdar://problem/27348445
This makes it a bit easier to diagnose unexpected boxing problems in the debugger, by allowing `po [value _swiftTypeName]` to work, instead of forcing users to know how to call `swift_getTypeName` from lldb themselves.
I apologize in advance to @jrose-apple, who is not a fan
of this fix ;-)
In unoptimized builds, the convenience initializers on
DispatchQueue allocate and immediately deallocate an
instance of OS_dispatch_queue prior to calling the
C function that returns the "real" instance.
This is because we don't have a way to write user-defined
factory initializers yet; convenience initializers still
have an 'initializing' entry point that takes an existing
instance, which we have no choice but to throw away.
Unfortunately, when we perform the fake allocation, we
look up class metadata by calling the wrong Swift runtime
function, causing a crash when we send +allocWithZone:.
Fix this so that the metadata is accessed via a lookup
from the Objective-C runtime, instead of making a totally
fake 'foreign metadata' object -- it looks like there was
code for this already, it just wasn't used in all cases.
While getting metadata for a runtime-only class should be
rare, this feels like a real bug fix, to me.
Second, we would ultimately free the fake object by sending
-release, however OS_dispatch_queue has an override of
-dealloc which doesn't like to be called with a completely
uninitialized instance.
Here, I'm going to drop all pretense of sanity. The patch
just changes IRGen to lower the dealloc_partial_ref instruction
as a call to the object_dispose() Objective-C runtime function
when the class in question is a runtime-only class. This
frees the object without running -dealloc, which *happens*
to work for OS_dispatch_queue.
Fixes <rdar://problem/27226313>.
There were places were RelativeDirectPointers were copied using bitwise copies, which is semantically wrong. This patch makes sure it cannot happen anymore.
This adds an explicit cast of the atomic type to the contained type prior to
comparing it to nullptr. This is generally unnecessary, however, the Windows
C++ library (msvcprt) from Visual Studio 2014 (WinSDK 10.0.10586.0) has
extensions which makes the conversion ambiguous. Simply cast the value on all
targets.
In order to reduce the duplication of the type, create a local typedef for the
constant runtime-uniqued metadata pointer type.
`WIN32_LEAN_AND_MEAN` prevents "rarely-used" headers from being pulled in. This
significantly reduced preprocessor pressure, speeding up compile. It also
reduces the amount of cruft pulled in by the Windows.h.
`NOMINMAX` ensures that the `min` and `max` macros are not defined. These
macros collide with the use of `min` and `max` from C++ in certain cases: e.g.
`std::limits<T>`.
This patch is for libswiftCore.lib, linking with the library set of Visual Studio 2015. Clang with the option -fms-extension is used to build this port.
This is the approved subpatch of a large patch.
Part 1: Generic SIL Boxes always have instatiated metadata with kind
HeapGenericLocalVariable, which includes a metadata pointer for the
boxed type.
Part 2, after this, is to provide some kind of outgoing pointer map for
fixed heap boxes, whose metadata may be shared among different but
destructor-compatible types.
rdar://problem/26240419
This adds various MetadataReader methods to support closure layout:
- Reading generic arguments from metadata
- Reading parent metadata
- Reading capture descriptor from heap metadata
To a large extent, this is not currently taken advantage of, because
SILGen always wraps address-only captures in SIL box types.
Tests are in the next patch.
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.
It has been fairly easy to cause the runtime to crash on multithreaded read-read access to weak references (e.g. https://bugs.swift.org/browse/SR-192). Although weak references are value types, they can get elevated to the heap in multiple ways, such as when captured by a closure or when used as a property in a class object instance. In such cases, race conditions involving weak references could cause the runtime to perform to multiple decrement operations of the unowned reference count for a single increment; this eventually causes early deallocation, leading to use-after-free, modify-after-free and double-free errors.
This commit changes the weak reference operations to use a spinlock rather than assuming thread-exclusive access, when appropriate.
With this change, the crasher discussed in SR-192 no longer encounters crashes due to modify-after-free or double-free errors.
