We need to be able to locate `swift-backtrace` relative to the current
location of the runtime library.
This needs to work:
* In a Swift build directory.
* On Darwin, where we're installed in /usr/lib/swift and /usr/libexec/swift.
* On Linux, where we're in /usr/lib/swift/linux and /usr/libexec/swift/linux.
* On Windows, where we may be in a flat directory layout (because of limitations
of Windows DLL lookups).
rdar://103071801
Moved all the threading code to one place. Added explicit support for
Darwin, Linux, Pthreads, C11 threads and Win32 threads, including new
implementations of Once for Linux, Pthreads, C11 and Win32.
rdar://90776105
Moved all the threading code to one place. Added explicit support for
Darwin, Linux, Pthreads, C11 threads and Win32 threads, including new
implementations of Once for Linux, Pthreads, C11 and Win32.
rdar://90776105
Fill out the metadata for Job to have a Dispatch-compatible vtable. When available, use the dispatch_enqueue_onto_queue_4Swift to enqueue Jobs directly onto queues. Otherwise, keep using dispatch_async_f as we have been.
rdar://75227953
There are a few environment variables used to enable debugging options in the
runtime, and we'll likely add more over time. These are implemented with
scattered getenv() calls at the point of use. This is inefficient, as most/all
OSes have to do a linear scan of the environment for each call. It's also not
discoverable, since the only way to find these variables is to inspect the
source.
This commit places all of these variables in a central location.
stdlib/public/runtime/EnvironmentVariables.def defines all of the debug
variables including their name, type, default value, and a help string. On OSes
which make an `environ` array available, the entire array is scanned in a single
pass the first time any debug variable is requested. By quickly rejecting
variables that do not start with `SWIFT_`, we optimize for the common case where
no debug variables are set. We also have a fallback to repeated `getenv()` calls
when a full scan is not possible.
Setting `SWIFT_HELP=YES` will print out all available debug variables along with
a brief description of what they do.
