Merge pull request #36079 from rjmccall/thread-local-task-state

Progress towards storing task/executor state in thread-local storage

Author: rjmccall

include/swift/ABI/Task.h

@@ -80,8 +80,17 @@ class alignas(2 * alignof(void*)) Job {
     return Flags.getPriority();
   }
 
-  /// Run this job.
-  void run(ExecutorRef currentExecutor);
+  /// Given that we've fully established the job context in the current
+  /// thread, actually start running this job.  To establish the context
+  /// correctly, call swift_job_run or runJobInExecutorContext.
+  void runInFullyEstablishedContext(ExecutorRef currentExecutor);
+
+  /// Given that we've fully established the job context in the
+  /// current thread, and that the job is a simple (non-task) job,
+  /// actually start running this job.
+  void runSimpleInFullyEstablishedContext(ExecutorRef currentExecutor) {
+    RunJob(this, currentExecutor);
+  }
 };
 
 // The compiler will eventually assume these.
@@ -173,7 +182,11 @@ class AsyncTask : public HeapObject, public Job {
     assert(flags.isAsyncTask());
   }
 
-  void run(ExecutorRef currentExecutor) {
+  /// Given that we've already fully established the job context
+  /// in the current thread, start running this task.  To establish
+  /// the job context correctly, call swift_job_run or
+  /// runInExecutorContext.
+  void runInFullyEstablishedContext(ExecutorRef currentExecutor) {
     ResumeTask(this, currentExecutor, ResumeContext);
   }
 
@@ -860,6 +873,10 @@ class AsyncTask : public HeapObject, public Job {
     /// Destroy the storage associated with the future.
     void destroy();
 
+    const Metadata *getResultType() const {
+      return resultType;
+    }
+
     /// Retrieve a pointer to the storage of result.
     OpaqueValue *getStoragePtr() {
       return reinterpret_cast<OpaqueValue *>(
@@ -941,11 +958,11 @@ static_assert(sizeof(AsyncTask) == 12 * sizeof(void*),
 static_assert(alignof(AsyncTask) == 2 * alignof(void*),
               "AsyncTask alignment is wrong");
 
-inline void Job::run(ExecutorRef currentExecutor) {
+inline void Job::runInFullyEstablishedContext(ExecutorRef currentExecutor) {
   if (auto task = dyn_cast<AsyncTask>(this))
-    task->run(currentExecutor);
+    task->runInFullyEstablishedContext(currentExecutor);
   else
-    RunJob(this, currentExecutor);
+    runSimpleInFullyEstablishedContext(currentExecutor);
 }
 
 /// An asynchronous context within a task.  Generally contexts are

include/swift/Runtime/Concurrency.h

@@ -117,37 +117,36 @@ SWIFT_EXPORT_FROM(swift_Concurrency) SWIFT_CC(swift)
 JobPriority
 swift_task_escalate(AsyncTask *task, JobPriority newPriority);
 
-/// The result of waiting for a task future.
-struct TaskFutureWaitResult {
-  /// Whether the storage represents the error result vs. the successful
-  /// result.
-  bool hadErrorResult;
-
-  /// Storage for the result of the future.
-  ///
-  /// When the future completed normally, this is a pointer to the storage
-  /// of the result value, which lives inside the future task itself.
-  ///
-  /// When the future completed by throwing an error, this is the error
-  /// object itself.
-  OpaqueValue *storage;
-};
-
 using TaskFutureWaitSignature =
-  AsyncSignature<TaskFutureWaitResult(AsyncTask *), /*throws*/ false>;
+  AsyncSignature<void(AsyncTask *, OpaqueValue *), /*throws*/ false>;
 
-/// Wait for a future task to complete.
+/// Wait for a non-throwing future task to complete.
 ///
 /// This can be called from any thread. Its Swift signature is
 ///
 /// \code
-/// func swift_task_future_wait(on task: Builtin.NativeObject) async
-///     -> TaskFutureWaitResult
+/// func swift_task_future_wait(on task: _owned Builtin.NativeObject) async
+///     -> Success
 /// \endcode
 SWIFT_EXPORT_FROM(swift_Concurrency) SWIFT_CC(swiftasync)
 TaskFutureWaitSignature::FunctionType
 swift_task_future_wait;
 
+using TaskFutureWaitThrowingSignature =
+  AsyncSignature<void(AsyncTask *, OpaqueValue *), /*throws*/ true>;
+
+/// Wait for a potentially-throwing future task to complete.
+///
+/// This can be called from any thread. Its Swift signature is
+///
+/// \code
+/// func swift_task_future_wait_throwing(on task: _owned Builtin.NativeObject)
+///    async throws -> Success
+/// \endcode
+SWIFT_EXPORT_FROM(swift_Concurrency) SWIFT_CC(swiftasync)
+TaskFutureWaitThrowingSignature::FunctionType
+swift_task_future_wait_throwing;
+
 /// Wait for a readyQueue of a Channel to become non empty.
 ///
 /// This can be called from any thread. Its Swift signature is
@@ -422,6 +421,16 @@ void swift_continuation_logFailedCheck(const char *message);
 /// Otherwise it uses dispatchMain.
 SWIFT_EXPORT_FROM(swift_Concurrency) SWIFT_CC(swift)
 void swift_task_asyncMainDrainQueue();
+
+/// Establish that the current thread is running as the given
+/// executor, then run a job.
+SWIFT_EXPORT_FROM(swift_Concurrency) SWIFT_CC(swift)
+void swift_job_run(Job *job, ExecutorRef executor);
+
+/// Return the current thread's active task reference.
+SWIFT_EXPORT_FROM(swift_Concurrency) SWIFT_CC(swift)
+AsyncTask *swift_task_getCurrent(void);
+
 }
 
 #endif

include/swift/Runtime/Error.h

@@ -0,0 +1,95 @@
+//===--- Error.h - Swift Runtime ABI for error values -----------*- C++ -*-===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2014 - 2017 Apple Inc. and the Swift project authors
+// Licensed under Apache License v2.0 with Runtime Library Exception
+//
+// See https://swift.org/LICENSE.txt for license information
+// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
+//
+//===----------------------------------------------------------------------===//
+//
+// Swift runtime support for working with error values.
+//
+// The ABI here is quite different in ObjC and non-ObjC modes.
+// In ObjC mode, SwiftError is closely related to the NSError class:
+// native errors are boxed as a subclass of NSError, but non-native
+// errors may simply be NSError objects directly from Objective-C.
+// In non-ObjC mode, SwiftError boxes are always native.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef SWIFT_RUNTIME_ERROR_H
+#define SWIFT_RUNTIME_ERROR_H
+
+#include "swift/Runtime/HeapObject.h"
+#include "swift/Runtime/Metadata.h"
+
+namespace swift {
+
+struct SwiftError;
+
+/// Allocate a catchable error object.
+///
+/// If value is nonnull, it should point to a value of \c type, which will be
+/// copied (or taken if \c isTake is true) into the newly-allocated error box.
+/// If value is null, the box's contents will be left uninitialized, and
+/// \c isTake should be false.
+SWIFT_CC(swift) SWIFT_RUNTIME_STDLIB_API
+BoxPair swift_allocError(const Metadata *type,
+                         const WitnessTable *errorConformance,
+                         OpaqueValue *value, bool isTake);
+
+/// Deallocate an error object whose contained object has already been
+/// destroyed.
+SWIFT_RUNTIME_STDLIB_API
+void swift_deallocError(SwiftError *error, const Metadata *type);
+
+struct ErrorValueResult {
+  const OpaqueValue *value;
+  const Metadata *type;
+  const WitnessTable *errorConformance;
+};
+
+/// Extract a pointer to the value, the type metadata, and the Error
+/// protocol witness from an error object.
+///
+/// The "scratch" pointer should point to an uninitialized word-sized
+/// temporary buffer. The implementation may write a reference to itself to
+/// that buffer if the error object is a toll-free-bridged NSError instead of
+/// a native Swift error, in which case the object itself is the "boxed" value.
+SWIFT_RUNTIME_STDLIB_API
+void swift_getErrorValue(const SwiftError *errorObject,
+                         void **scratch,
+                         ErrorValueResult *out);
+
+/// Called when throwing an error.  Serves as a breakpoint hook
+/// for debuggers.
+SWIFT_CC(swift)
+SWIFT_RUNTIME_STDLIB_API void
+swift_willThrow(SWIFT_CONTEXT void *unused,
+                SWIFT_ERROR_RESULT SwiftError **object);
+
+/// Called when an error is thrown out of the top level of a script.
+SWIFT_CC(swift)
+SWIFT_RUNTIME_STDLIB_API SWIFT_NORETURN void
+swift_errorInMain(SwiftError *object);
+
+/// Called when the try! operator fails.
+SWIFT_CC(swift)
+SWIFT_RUNTIME_STDLIB_API SWIFT_NORETURN void
+swift_unexpectedError(SwiftError *object, OpaqueValue *filenameStart,
+                      long filenameLength, bool isAscii, unsigned long line);
+
+/// Retain an error box.
+SWIFT_RUNTIME_STDLIB_API
+SwiftError *swift_errorRetain(SwiftError *object);
+
+/// Release an error box.
+SWIFT_RUNTIME_STDLIB_API
+void swift_errorRelease(SwiftError *object);
+
+} // end namespace swift
+
+#endif

lib/IRGen/Callee.h

@@ -125,28 +125,76 @@ namespace irgen {
   /// A function pointer value.
   class FunctionPointer {
   public:
-    struct KindTy {
-      enum class Value {
-        Function,
-        AsyncFunctionPointer,
-      };
-      static const Value Function = Value::Function;
-      static const Value AsyncFunctionPointer = Value::AsyncFunctionPointer;
-      Value value;
-      KindTy(Value value) : value(value) {}
-      KindTy(CanSILFunctionType fnType)
-          : value(fnType->isAsync() ? Value::AsyncFunctionPointer
-                                    : Value::Function) {}
-      friend bool operator==(const KindTy &lhs, const KindTy &rhs) {
+    enum class BasicKind {
+      Function,
+      AsyncFunctionPointer
+    };
+
+    enum class SpecialKind {
+      TaskFutureWait,
+      TaskFutureWaitThrowing,
+      TaskGroupWaitNext,
+    };
+
+    class Kind {
+      static constexpr unsigned SpecialOffset = 2;
+      unsigned value;
+    public:
+      static constexpr BasicKind Function =
+        BasicKind::Function;
+      static constexpr BasicKind AsyncFunctionPointer =
+        BasicKind::AsyncFunctionPointer;
+
+      Kind(BasicKind kind) : value(unsigned(kind)) {}
+      Kind(SpecialKind kind) : value(unsigned(kind) + SpecialOffset) {}
+      Kind(CanSILFunctionType fnType)
+        : Kind(fnType->isAsync() ? BasicKind::AsyncFunctionPointer
+                                 : BasicKind::Function) {}
+
+      BasicKind getBasicKind() const {
+        return value < SpecialOffset ? BasicKind(value) : BasicKind::Function;
+      }
+      bool isAsyncFunctionPointer() const {
+        return value == unsigned(BasicKind::AsyncFunctionPointer);
+      }
+
+      bool isSpecial() const {
+        return value >= SpecialOffset;
+      }
+      SpecialKind getSpecialKind() const {
+        assert(isSpecial());
+        return SpecialKind(value - SpecialOffset);
+      }
+
+      /// Should we suppress the generic signature from the given function?
+      ///
+      /// This is a micro-optimization we apply to certain special functions
+      /// that we know don't need generics.
+      bool suppressGenerics() const {
+        if (!isSpecial()) return false;
+
+        switch (getSpecialKind()) {
+        case SpecialKind::TaskFutureWait:
+        case SpecialKind::TaskFutureWaitThrowing:
+          // We suppress generics from these as a code-size optimization
+          // because the runtime can recover the success type from the
+          // future.
+          return true;
+        case SpecialKind::TaskGroupWaitNext:
+          return false;
+        }
+      }
+
+      friend bool operator==(Kind lhs, Kind rhs) {
         return lhs.value == rhs.value;
       }
-      friend bool operator!=(const KindTy &lhs, const KindTy &rhs) {
+      friend bool operator!=(Kind lhs, Kind rhs) {
         return !(lhs == rhs);
       }
     };
 
   private:
-    KindTy Kind;
+    Kind kind;
 
     /// The actual pointer, either to the function or to its descriptor.
     llvm::Value *Value;
@@ -155,34 +203,29 @@ namespace irgen {
 
     Signature Sig;
 
-    bool isFunctionPointerWithoutContext = false;
-
   public:
     /// Construct a FunctionPointer for an arbitrary pointer value.
     /// We may add more arguments to this; try to use the other
     /// constructors/factories if possible.
-    explicit FunctionPointer(KindTy kind, llvm::Value *value,
+    explicit FunctionPointer(Kind kind, llvm::Value *value,
                              PointerAuthInfo authInfo,
-                             const Signature &signature,
-                             bool isWithoutCtxt = false)
-        : Kind(kind), Value(value), AuthInfo(authInfo), Sig(signature),
-          isFunctionPointerWithoutContext(isWithoutCtxt) {
+                             const Signature &signature)
+        : kind(kind), Value(value), AuthInfo(authInfo), Sig(signature) {
       // The function pointer should have function type.
       assert(value->getType()->getPointerElementType()->isFunctionTy());
       // TODO: maybe assert similarity to signature.getType()?
     }
 
     // Temporary only!
-    explicit FunctionPointer(KindTy kind, llvm::Value *value,
-                             const Signature &signature,
-                             bool isWithoutCtxt = false)
-        : FunctionPointer(kind, value, PointerAuthInfo(), signature, isWithoutCtxt) {}
+    explicit FunctionPointer(Kind kind, llvm::Value *value,
+                             const Signature &signature)
+      : FunctionPointer(kind, value, PointerAuthInfo(), signature) {}
 
     static FunctionPointer forDirect(IRGenModule &IGM,
                                      llvm::Constant *value,
                                      CanSILFunctionType fnType);
 
-    static FunctionPointer forDirect(KindTy kind, llvm::Constant *value,
+    static FunctionPointer forDirect(Kind kind, llvm::Constant *value,
                                      const Signature &signature) {
       return FunctionPointer(kind, value, PointerAuthInfo(), signature);
     }
@@ -197,7 +240,8 @@ namespace irgen {
       return (isa<llvm::Constant>(Value) && AuthInfo.isConstant());
     }
 
-    KindTy getKind() const { return Kind; }
+    Kind getKind() const { return kind; }
+    BasicKind getBasicKind() const { return kind.getBasicKind(); }
 
     /// Given that this value is known to have been constructed from a direct
     /// function,  Return the name of that function.
@@ -250,7 +294,11 @@ namespace irgen {
     FunctionPointer getAsFunction(IRGenFunction &IGF) const;
 
     bool useStaticContextSize() const {
-      return isFunctionPointerWithoutContext;
+      return !kind.isAsyncFunctionPointer();
+    }
+
+    bool suppressGenerics() const {
+      return kind.suppressGenerics();
     }
   };
 
@@ -315,6 +363,10 @@ namespace irgen {
       return Fn.getSignature();
     }
 
+    bool suppressGenerics() const {
+      return Fn.suppressGenerics();
+    }
+
     /// If this callee has a value for the Swift context slot, return
     /// it; otherwise return non-null.
     llvm::Value *getSwiftContext() const;