[SILGen] Pass storage block type and callee info to async completion handler generator

Instead of relying on `continuationType` for information, let's
take it from the source.

Author: xedin

lib/SILGen/ResultPlan.cpp

@@ -767,9 +767,9 @@ class ForeignAsyncInitializationPlan final : public ResultPlan {
                            {continuation});
 
     // Stash it in a buffer for a block object.
-    auto blockStorageTy = SILType::getPrimitiveAddressType(
-        SILBlockStorageType::get(continuationTy));
-    auto blockStorage = SGF.emitTemporaryAllocation(loc, blockStorageTy);
+    auto blockStorageTy = SILBlockStorageType::get(continuationTy);
+    auto blockStorage = SGF.emitTemporaryAllocation(
+        loc, SILType::getPrimitiveAddressType(blockStorageTy));
     auto continuationAddr = SGF.B.createProjectBlockStorage(loc, blockStorage);
     SGF.B.createStore(loc, wrappedContinuation, continuationAddr,
                       StoreOwnershipQualifier::Trivial);
@@ -796,11 +796,10 @@ class ForeignAsyncInitializationPlan final : public ResultPlan {
         SGF.SGM.getOrCreateForeignAsyncCompletionHandlerImplFunction(
             cast<SILFunctionType>(
                 impFnTy->mapTypeOutOfContext()->getReducedType(sig)),
-            continuationTy->mapTypeOutOfContext()->getReducedType(sig),
-            origFormalType, sig, *calleeTypeInfo.foreign.async,
-            calleeTypeInfo.foreign.error);
+            blockStorageTy->mapTypeOutOfContext()->getReducedType(sig),
+            origFormalType, sig, calleeTypeInfo);
     auto impRef = SGF.B.createFunctionRef(loc, impl);
-    
+
     // Initialize the block object for the completion handler.
     SILValue block = SGF.B.createInitBlockStorageHeader(loc, blockStorage,
                           impRef, SILType::getPrimitiveObjectType(impFnTy),

lib/SILGen/SILGen.h

@@ -32,6 +32,7 @@ namespace swift {
 namespace Lowering {
   class TypeConverter;
   class SILGenFunction;
+  class CalleeTypeInfo;
 
 /// An enum to indicate whether a protocol method requirement is satisfied by
 /// a free function, as for an operator requirement.
@@ -182,10 +183,9 @@ class LLVM_LIBRARY_VISIBILITY SILGenModule : public ASTVisitor<SILGenModule> {
   /// implementation function for an ObjC API that was imported
   /// as `async` in Swift.
   SILFunction *getOrCreateForeignAsyncCompletionHandlerImplFunction(
-      CanSILFunctionType blockType, CanType continuationTy,
+      CanSILFunctionType blockType, CanType blockStorageType,
       AbstractionPattern origFormalType, CanGenericSignature sig,
-      ForeignAsyncConvention convention,
-      llvm::Optional<ForeignErrorConvention> foreignError);
+      CalleeTypeInfo &calleeInfo);
 
   /// Determine whether the given class has any instance variables that
   /// need to be destroyed.

lib/SILGen/SILGenThunk.cpp

@@ -20,6 +20,7 @@
 //
 //===----------------------------------------------------------------------===//
 
+#include "Callee.h"
 #include "ManagedValue.h"
 #include "SILGenFunction.h"
 #include "SILGenFunctionBuilder.h"
@@ -198,12 +199,12 @@ static const clang::Type *prependParameterType(
 }
 
 SILFunction *SILGenModule::getOrCreateForeignAsyncCompletionHandlerImplFunction(
-    CanSILFunctionType blockType, CanType continuationTy,
+    CanSILFunctionType blockType, CanType blockStorageType,
     AbstractionPattern origFormalType, CanGenericSignature sig,
-    ForeignAsyncConvention convention,
-    llvm::Optional<ForeignErrorConvention> foreignError) {
-  // Extract the result and error types from the continuation type.
-  auto resumeType = cast<BoundGenericType>(continuationTy).getGenericArgs()[0];
+    CalleeTypeInfo &calleeInfo) {
+  auto convention = *calleeInfo.foreign.async;
+  auto resumeType =
+      calleeInfo.substResultType->mapTypeOutOfContext()->getReducedType(sig);
 
   CanAnyFunctionType completionHandlerOrigTy = [&]() {
     auto completionHandlerOrigTy =
@@ -236,18 +237,17 @@ SILFunction *SILGenModule::getOrCreateForeignAsyncCompletionHandlerImplFunction(
   // block buffer. The block storage holds the continuation we feed the
   // result values into.
   SmallVector<SILParameterInfo, 4> implArgs;
-  auto blockStorageTy = SILBlockStorageType::get(continuationTy);
-  implArgs.push_back(SILParameterInfo(blockStorageTy,
-                                ParameterConvention::Indirect_InoutAliasable));
-  
+  implArgs.push_back(SILParameterInfo(
+      blockStorageType, ParameterConvention::Indirect_InoutAliasable));
+
   std::copy(blockType->getParameters().begin(),
             blockType->getParameters().end(),
             std::back_inserter(implArgs));
 
   auto newClangTy = prependParameterType(
       getASTContext(),
       blockType->getClangTypeInfo().getType(),
-      getASTContext().getClangTypeForIRGen(blockStorageTy));
+      getASTContext().getClangTypeForIRGen(blockStorageType));
 
   auto implTy = SILFunctionType::get(
       sig,
@@ -384,7 +384,7 @@ SILFunction *SILGenModule::getOrCreateForeignAsyncCompletionHandlerImplFunction(
         errorScope.pop();
         SGF.B.createBranch(loc, returnBB);
         SGF.B.emitBlock(noneErrorBB);
-      } else if (foreignError) {
+      } else if (auto foreignError = calleeInfo.foreign.error) {
         resumeIntrinsic = getResumeUnsafeThrowingContinuation();
       } else {
         resumeIntrinsic = getResumeUnsafeContinuation();