Use objc_msgSend_stret2_np when returning a non-trivial data type on woa64

Author: hmelder

clang/lib/CodeGen/CGCall.cpp

@@ -1585,6 +1585,11 @@ bool CodeGenModule::ReturnTypeUsesSRet(const CGFunctionInfo &FI) {
   return RI.isIndirect() || (RI.isInAlloca() && RI.getInAllocaSRet());
 }
 
+bool CodeGenModule::ReturnTypeHasInReg(const CGFunctionInfo &FI) {
+  const auto &RI = FI.getReturnInfo();
+  return RI.getInReg();
+}
+
 bool CodeGenModule::ReturnSlotInterferesWithArgs(const CGFunctionInfo &FI) {
   return ReturnTypeUsesSRet(FI) &&
          getTargetCodeGenInfo().doesReturnSlotInterfereWithArgs();

clang/lib/CodeGen/CGObjCGNU.cpp

@@ -2911,12 +2911,25 @@ CGObjCGNU::GenerateMessageSend(CodeGenFunction &CGF,
                                       "objc_msgSend_fpret")
                 .getCallee();
       } else if (CGM.ReturnTypeUsesSRet(MSI.CallInfo)) {
+        StringRef name = "objc_msgSend_stret";
+
+        // The address of the memory block is be passed in x8 for POD type,
+        // or in x0 for non-POD type (marked as inreg).
+        bool shouldCheckForInReg =
+            CGM.getContext()
+                .getTargetInfo()
+                .getTriple()
+                .isWindowsMSVCEnvironment() &&
+            CGM.getContext().getTargetInfo().getTriple().isAArch64();
+        if (shouldCheckForInReg && CGM.ReturnTypeHasInReg(MSI.CallInfo)) {
+          name = "objc_msgSend_stret2_np";
+        }
+
         // The actual types here don't matter - we're going to bitcast the
         // function anyway
-        imp =
-            CGM.CreateRuntimeFunction(llvm::FunctionType::get(IdTy, IdTy, true),
-                                      "objc_msgSend_stret")
-                .getCallee();
+        CGM.CreateRuntimeFunction(llvm::FunctionType::get(IdTy, IdTy, true),
+                                  name)
+            .getCallee();
       } else {
         imp = CGM.CreateRuntimeFunction(
                      llvm::FunctionType::get(IdTy, IdTy, true), "objc_msgSend")

clang/lib/CodeGen/CodeGenModule.h

@@ -1241,6 +1241,9 @@ class CodeGenModule : public CodeGenTypeCache {
   /// Return true iff the given type uses 'sret' when used as a return type.
   bool ReturnTypeUsesSRet(const CGFunctionInfo &FI);
 
+  /// Return true iff the given type has `inreg` set.
+  bool ReturnTypeHasInReg(const CGFunctionInfo &FI);
+
   /// Return true iff the given type uses an argument slot when 'sret' is used
   /// as a return type.
   bool ReturnSlotInterferesWithArgs(const CGFunctionInfo &FI);