Properly mark stack slot for struct return as lvalue

Author: dnadlinger

gen/tocall.cpp

@@ -806,6 +806,8 @@ DValue* DtoCallFunction(Loc& loc, Type* resulttype, DValue* fnval, Expressions*
         (returnTy == Tstruct && !isaPointer(retllval)) ||
         (returnTy == Tsarray && isaArray(retllval));
 
+    bool retValIsAlloca = false;
+
     // Ignore ABI for intrinsics
     if (!intrinsic && !retinptr)
     {
@@ -817,6 +819,7 @@ DValue* DtoCallFunction(Loc& loc, Type* resulttype, DValue* fnval, Expressions*
             LLValue* mem = DtoRawAlloca(DtoType(dReturnType), 0);
             irFty.getRet(dReturnType, &dretval, mem);
             retllval = mem;
+            retValIsAlloca = true;
             storeReturnValueOnStack = false;
         }
         else
@@ -834,6 +837,7 @@ DValue* DtoCallFunction(Loc& loc, Type* resulttype, DValue* fnval, Expressions*
         LLValue* mem = DtoRawAlloca(retllval->getType(), 0);
         DtoStore(retllval, mem);
         retllval = mem;
+        retValIsAlloca = true;
     }
 
     // repaint the type if necessary
@@ -967,7 +971,7 @@ DValue* DtoCallFunction(Loc& loc, Type* resulttype, DValue* fnval, Expressions*
     // if we are returning through a pointer arg
     // or if we are returning a reference
     // make sure we provide a lvalue back!
-    if (retinptr || (tf->isref && returnTy != Tvoid))
+    if (retinptr || (tf->isref && returnTy != Tvoid) || retValIsAlloca)
         return new DVarValue(resulttype, retllval);
 
     return new DImValue(resulttype, retllval);