Update Context docs

Author: CodaFi

Sources/LLVM/Context.swift

@@ -0,0 +1,62 @@
+#if SWIFT_PACKAGE
+import cllvm
+#endif
+
+/// A `Context` is an LLVM compilation session environment.
+///
+/// A `Context` is a container for the global state of an execution of the
+/// LLVM environment and tooling.  It contains independent copies of global and
+/// module-level entities like types, metadata attachments, and constants.
+///
+/// An LLVM context is needed for interacting with LLVM in a concurrent
+/// environment. Because a context maintains state independent of any other
+/// context, it is recommended that each thread of execution be assigned a unique
+/// context.  LLVM's core infrastructure and API provides no locking guarantees
+/// and no atomicity guarantees.
+public class Context {
+  internal let llvm: LLVMContextRef
+  private let ownsContext: Bool
+
+  /// Retrieves the global context instance.
+  ///
+  /// The global context is an particularly convenient instance managed by LLVM
+  /// itself.  It is the default context provided for any operations that
+  /// require it.
+  ///
+  /// - WARNING: Failure to specify the correct context in concurrent
+  ///   environments can lead to data corruption.  In general, it is always
+  ///   recommended that each thread of execution attempting to access the LLVM
+  ///   API have its own `Context` instance, rather than rely on this global
+  ///   context.
+  public static let global = Context(llvm: LLVMGetGlobalContext()!)
+
+  /// Creates a new `Context` object.
+  public init() {
+    llvm = LLVMContextCreate()
+    ownsContext = true
+  }
+
+  /// Creates a `Context` object from an `LLVMContextRef` object.
+  public init(llvm: LLVMContextRef, ownsContext: Bool = false) {
+    self.llvm = llvm
+    self.ownsContext = ownsContext
+  }
+
+  /// Returns whether the given context is set to discard all value names.
+  ///
+  /// If true, only the names of GlobalValue objects will be available in
+  /// the IR.  This can be used to save memory and processing time, especially
+  /// in release environments.
+  public var discardValueNames: Bool {
+    get { return LLVMContextShouldDiscardValueNames(self.llvm) != 0 }
+    set { LLVMContextSetDiscardValueNames(self.llvm, newValue.llvm) }
+  }
+
+  /// Deinitialize this value and dispose of its resources.
+  deinit {
+    guard self.ownsContext else {
+      return
+    }
+    LLVMContextDispose(self.llvm)
+  }
+}