[Async CC] Added conveniences to retrieve arguments.

lib/IRGen/GenCall.cpp

@@ -273,6 +273,27 @@ static llvm::Value *getAsyncTask(IRGenFunction &IGF) {
   return llvm::Constant::getNullValue(IGF.IGM.SwiftTaskPtrTy);
 }
 
+llvm::Value *IRGenFunction::getAsyncTask() {
+  assert(isAsync());
+  auto *value = CurFn->getArg((unsigned)AsyncFunctionArgumentIndex::Task);
+  assert(value->getType() == IGM.SwiftTaskPtrTy);
+  return value;
+}
+
+llvm::Value *IRGenFunction::getAsyncExecutor() {
+  assert(isAsync());
+  auto *value = CurFn->getArg((unsigned)AsyncFunctionArgumentIndex::Executor);
+  assert(value->getType() == IGM.SwiftExecutorPtrTy);
+  return value;
+}
+
+llvm::Value *IRGenFunction::getAsyncContext() {
+  assert(isAsync());
+  auto *value = CurFn->getArg((unsigned)AsyncFunctionArgumentIndex::Context);
+  assert(value->getType() == IGM.SwiftContextPtrTy);
+  return value;
+}
+
 llvm::Type *ExplosionSchema::getScalarResultType(IRGenModule &IGM) const {
   if (size() == 0) {
     return IGM.VoidTy;

lib/IRGen/GenCall.h

@@ -340,6 +340,11 @@ namespace irgen {
                          CanSILFunctionType coroutineType,
                          Explosion &yieldedValues);
 
+  enum class AsyncFunctionArgumentIndex : unsigned {
+    Task = 0,
+    Executor = 1,
+    Context = 2,
+  };
 } // end namespace irgen
 } // end namespace swift
 

lib/IRGen/IRGenFunction.h

@@ -83,7 +83,7 @@ class IRGenFunction {
                 OptimizationMode Mode = OptimizationMode::NotSet,
                 const SILDebugScope *DbgScope = nullptr,
                 Optional<SILLocation> DbgLoc = None);
-  ~IRGenFunction();
+  virtual ~IRGenFunction();
 
   void unimplemented(SourceLoc Loc, StringRef Message);
 
@@ -127,7 +127,11 @@ class IRGenFunction {
     assert(handle != nullptr && "setting a null handle");
     CoroutineHandle = handle;
   }
-
+
+  virtual llvm::Value *getAsyncTask();
+  virtual llvm::Value *getAsyncExecutor();
+  virtual llvm::Value *getAsyncContext();
+
 private:
   void emitPrologue();
   void emitEpilogue();

lib/IRGen/IRGenSIL.cpp

@@ -852,7 +852,43 @@ class IRGenSILFunction :
       }
     }
   }
-
+
+  llvm::Value *getAsyncTask() override {
+    // FIXME: (1) Remove this override, (2) mark the IRGenFunction::getAsyncTask
+    //        declaration as non-virtual, and (3) mark IRGenFunction's
+    //        destructor non-virtual once Task.runDetached is available.
+    //        rdar://problem/70597390*/
+    if (CurSILFn->getLoweredFunctionType()->getRepresentation() ==
+        SILFunctionTypeRepresentation::CFunctionPointer) {
+      return llvm::Constant::getNullValue(IGM.SwiftTaskPtrTy);
+    }
+    return IRGenFunction::getAsyncTask();
+  }
+
+  llvm::Value *getAsyncExecutor() override {
+    // FIXME: (1) Remove this override, (2) mark the
+    //        IRGenFunction::getAsyncExecutor declaration as non-virtual, and
+    //        (3) mark IRGenFunction's destructor non-virtual once
+    //        Task.runDetached is available.  rdar://problem/70597390*/
+    if (CurSILFn->getLoweredFunctionType()->getRepresentation() ==
+        SILFunctionTypeRepresentation::CFunctionPointer) {
+      return llvm::Constant::getNullValue(IGM.SwiftExecutorPtrTy);
+    }
+    return IRGenFunction::getAsyncExecutor();
+  }
+
+  llvm::Value *getAsyncContext() override {
+    // FIXME: (1) Remove this override, (2) mark the
+    //        IRGenFunction::getAsyncContext declaration as non-virtual, and
+    //        (3) mark IRGenFunction's destructor non-virtual once
+    //        Task.runDetached is available.  rdar://problem/70597390*/
+    if (CurSILFn->getLoweredFunctionType()->getRepresentation() ==
+        SILFunctionTypeRepresentation::CFunctionPointer) {
+      return llvm::Constant::getNullValue(IGM.SwiftContextPtrTy);
+    }
+    return IRGenFunction::getAsyncContext();
+  }
+
   //===--------------------------------------------------------------------===//
   // SIL instruction lowering
   //===--------------------------------------------------------------------===//
@@ -3179,7 +3215,7 @@ static void emitReturnInst(IRGenSILFunction &IGF,
     assert(!IGF.IndirectReturn.isValid() &&
            "Formally direct results should stay direct results for async "
            "functions");
-    llvm::Value *context = IGF.CurFn->getArg(2);
+    llvm::Value *context = IGF.getAsyncContext();
     auto layout = getAsyncContextLayout(IGF);
 
     Address dataAddr = layout.emitCastTo(IGF, context);