[Async CC] Added task and executor args.

The previous stage of bringup only had async functions taking a single
argument: the async context.  The next stage will involve the task and
executor.  Here, arguments are added for those values.  To begin with,
null is always passed for these values.

Author: nate-chandler

lib/IRGen/GenCall.cpp

@@ -690,9 +690,12 @@ void SignatureExpansion::expandCoroutineContinuationParameters() {
 }
 
 void SignatureExpansion::addAsyncParameters() {
+  // using TaskContinuationFunction =
+  //   SWIFT_CC(swift)
+  //   void (AsyncTask *, ExecutorRef, AsyncContext *);
+  ParamIRTypes.push_back(IGM.SwiftTaskPtrTy);
+  ParamIRTypes.push_back(IGM.SwiftExecutorPtrTy);
   ParamIRTypes.push_back(IGM.SwiftContextPtrTy);
-  // TODO: Add actor.
-  // TODO: Add task.
   if (FnType->getRepresentation() == SILFunctionTypeRepresentation::Thick) {
     IGM.addSwiftSelfAttributes(Attrs, ParamIRTypes.size());
     ParamIRTypes.push_back(IGM.RefCountedPtrTy);
@@ -2141,6 +2144,9 @@ class AsyncCallEmission final : public CallEmission {
   void setArgs(Explosion &llArgs, bool isOutlined,
                WitnessMetadata *witnessMetadata) override {
     Explosion asyncExplosion;
+    asyncExplosion.add(llvm::Constant::getNullValue(IGF.IGM.SwiftTaskPtrTy));
+    asyncExplosion.add(
+        llvm::Constant::getNullValue(IGF.IGM.SwiftExecutorPtrTy));
     asyncExplosion.add(contextBuffer.getAddress());
     if (getCallee().getRepresentation() ==
         SILFunctionTypeRepresentation::Thick) {

lib/IRGen/GenFunc.cpp

@@ -1014,6 +1014,8 @@ class AsyncPartialApplicationForwarderEmission
     : public PartialApplicationForwarderEmission {
   using super = PartialApplicationForwarderEmission;
   AsyncContextLayout layout;
+  llvm::Value *task;
+  llvm::Value *executor;
   llvm::Value *contextBuffer;
   Size contextSize;
   Address context;
@@ -1067,6 +1069,8 @@ class AsyncPartialApplicationForwarderEmission
             substType, outType, subs, layout, conventions),
         layout(getAsyncContextLayout(subIGF, origType, substType, subs)),
         currentArgumentIndex(outType->getNumParameters()) {
+    task = origParams.claimNext();
+    executor = origParams.claimNext();
     contextBuffer = origParams.claimNext();
     heapContextBuffer = origParams.claimNext();
   }
@@ -1223,6 +1227,9 @@ class AsyncPartialApplicationForwarderEmission
   }
   llvm::CallInst *createCall(FunctionPointer &fnPtr) override {
     Explosion asyncExplosion;
+    asyncExplosion.add(llvm::Constant::getNullValue(subIGF.IGM.SwiftTaskPtrTy));
+    asyncExplosion.add(
+        llvm::Constant::getNullValue(subIGF.IGM.SwiftExecutorPtrTy));
     asyncExplosion.add(contextBuffer);
     if (dynamicFunction &&
         dynamicFunction->kind == DynamicFunction::Kind::PartialApply) {

lib/IRGen/IRGenModule.cpp

@@ -589,8 +589,10 @@ IRGenModule::IRGenModule(IRGenerator &irgen,
 
   SwiftContextTy = createStructType(*this, "swift.context", {});
   SwiftTaskTy = createStructType(*this, "swift.task", {});
+  SwiftExecutorTy = createStructType(*this, "swift.executor", {});
   SwiftContextPtrTy = SwiftContextTy->getPointerTo(DefaultAS);
   SwiftTaskPtrTy = SwiftTaskTy->getPointerTo(DefaultAS);
+  SwiftExecutorPtrTy = SwiftExecutorTy->getPointerTo(DefaultAS);
 
   DifferentiabilityWitnessTy = createStructType(
       *this, "swift.differentiability_witness", {Int8PtrTy, Int8PtrTy});

lib/IRGen/IRGenModule.h

@@ -725,8 +725,10 @@ class IRGenModule {
 
   llvm::StructType *SwiftContextTy;
   llvm::StructType *SwiftTaskTy;
+  llvm::StructType *SwiftExecutorTy;
   llvm::PointerType *SwiftContextPtrTy;
   llvm::PointerType *SwiftTaskPtrTy;
+  llvm::PointerType *SwiftExecutorPtrTy;
 
   llvm::StructType *DifferentiabilityWitnessTy; // { i8*, i8* }
 

lib/IRGen/IRGenSIL.cpp

@@ -1231,6 +1231,8 @@ class SyncNativeCCEntryPointArgumentEmission final
 class AsyncNativeCCEntryPointArgumentEmission final
     : public NativeCCEntryPointArgumentEmission,
       public AsyncEntryPointArgumentEmission {
+  llvm::Value *task;
+  llvm::Value *executor;
   llvm::Value *context;
   /*const*/ AsyncContextLayout layout;
   const Address dataAddr;
@@ -1253,6 +1255,7 @@ class AsyncNativeCCEntryPointArgumentEmission final
                                           SILBasicBlock &entry,
                                           Explosion &allParamValues)
       : AsyncEntryPointArgumentEmission(IGF, entry, allParamValues),
+        task(allParamValues.claimNext()), executor(allParamValues.claimNext()),
         context(allParamValues.claimNext()), layout(getAsyncContextLayout(IGF)),
         dataAddr(layout.emitCastTo(IGF, context)){};
 
@@ -3176,8 +3179,7 @@ static void emitReturnInst(IRGenSILFunction &IGF,
     assert(!IGF.IndirectReturn.isValid() &&
            "Formally direct results should stay direct results for async "
            "functions");
-    Explosion parameters = IGF.collectParameters();
-    llvm::Value *context = parameters.claimNext();
+    llvm::Value *context = IGF.CurFn->getArg(2);
     auto layout = getAsyncContextLayout(IGF);
 
     Address dataAddr = layout.emitCastTo(IGF, context);