[IRGen][wasm] Disable manual indirection for coroutine yielding results

lib/IRGen/GenCall.cpp

@@ -867,22 +867,26 @@ void SignatureExpansion::expandCoroutineResult(bool forContinuation) {
   }
 
   // Find the maximal sequence of the component types that we can
-  // convince the ABI to pass directly.
+  // convince the ABI to pass directly if the target supports
+  // directly returning at least two pointers.
   // When counting components, ignore the continuation pointer.
   unsigned numDirectComponents = components.size() - 1;
   SmallVector<llvm::Type*, 8> overflowTypes;
-  while (clang::CodeGen::swiftcall::
-                shouldPassIndirectly(IGM.ClangCodeGen->CGM(), components,
-                                     /*asReturnValue*/ true)) {
-    // If we added a pointer to the end of components, remove it.
-    if (!overflowTypes.empty()) components.pop_back();
-
-    // Remove the last component and add it as an overflow type.
-    overflowTypes.push_back(components.pop_back_val());
-    --numDirectComponents;
-
-    // Add a pointer to the end of components.
-    components.push_back(IGM.Int8PtrTy);
+  if (IGM.TargetInfo.SupportsDirectReturningAtLeastTwoPointers) {
+    while (clang::CodeGen::swiftcall::shouldPassIndirectly(
+        IGM.ClangCodeGen->CGM(), components,
+        /*asReturnValue*/ true)) {
+      // If we added a pointer to the end of components, remove it.
+      if (!overflowTypes.empty())
+        components.pop_back();
+
+      // Remove the last component and add it as an overflow type.
+      overflowTypes.push_back(components.pop_back_val());
+      --numDirectComponents;
+
+      // Add a pointer to the end of components.
+      components.push_back(IGM.Int8PtrTy);
+    }
   }
 
   // We'd better have been able to pass at least two pointers.

lib/IRGen/SwiftTargetInfo.cpp

@@ -17,12 +17,13 @@
 
 #include "SwiftTargetInfo.h"
 #include "IRGenModule.h"
-#include "llvm/TargetParser/Triple.h"
-#include "llvm/IR/DataLayout.h"
 #include "swift/ABI/System.h"
 #include "swift/AST/ASTContext.h"
 #include "swift/AST/IRGenOptions.h"
 #include "swift/Basic/Platform.h"
+#include "clang/CodeGen/SwiftCallingConv.h"
+#include "llvm/IR/DataLayout.h"
+#include "llvm/TargetParser/Triple.h"
 
 using namespace swift;
 using namespace irgen;
@@ -186,6 +187,11 @@ static void configureWasm32(IRGenModule &IGM, const llvm::Triple &triple,
                             SwiftTargetInfo &target) {
   target.LeastValidPointerValue =
     SWIFT_ABI_WASM32_LEAST_VALID_POINTER;
+
+  target.SupportsDirectReturningAtLeastTwoPointers =
+      clang::CodeGen::swiftcall::shouldPassIndirectly(IGM.getClangCGM(),
+                                                      {IGM.PtrTy, IGM.PtrTy},
+                                                      /*asReturnValue*/ true);
 }
 
 /// Configure a default target.

lib/IRGen/SwiftTargetInfo.h

@@ -115,6 +115,9 @@ class SwiftTargetInfo {
   bool SwiftRetainIgnoresNegativeValues = false;
 
   bool UsableSwiftAsyncContextAddrIntrinsic = false;
+
+  /// True if the target supports directly returning at least two pointers.
+  bool SupportsDirectReturningAtLeastTwoPointers = true;
 };
 
 }