Update hardcoded flags for float and double in ArgIteratorTemplate::ComputeReturnFlags()

This fixes JIT/HardwareIntrinsics/General/Vector* tests.

Author: tomeksowi

src/coreclr/tools/aot/ILCompiler.ReadyToRun/Compiler/DependencyAnalysis/ReadyToRun/TransitionBlock.cs

@@ -314,14 +314,22 @@ public void ComputeReturnValueTreatment(CorElementType type, TypeHandle thRetTyp
                     throw new NotSupportedException();
 
                 case CorElementType.ELEMENT_TYPE_R4:
-                    if (!IsArmelABI)
+                    if (IsRiscV64 || IsLoongArch64)
+                    {
+                        fpReturnSize = (uint)FpStruct.OnlyOne | (2 << (int)FpStruct.PosSizeShift1st);
+                    }
+                    else if (!IsArmelABI)
                     {
                         fpReturnSize = sizeof(float);
                     }
                     break;
 
                 case CorElementType.ELEMENT_TYPE_R8:
-                    if (!IsArmelABI)
+                    if (IsRiscV64 || IsLoongArch64)
+                    {
+                        fpReturnSize = (uint)FpStruct.OnlyOne | (3 << (int)FpStruct.PosSizeShift1st);
+                    }
+                    else if (!IsArmelABI)
                     {
                         fpReturnSize = sizeof(double);
                     }
@@ -391,7 +399,7 @@ public void ComputeReturnValueTreatment(CorElementType type, TypeHandle thRetTyp
                                 if (IsLoongArch64)
                                     fpReturnSize = LoongArch64PassStructInRegister.GetLoongArch64PassStructInRegisterFlags(thRetType.GetRuntimeTypeHandle()) & 0xff;
                                 else if (IsRiscV64)
-                                    fpReturnSize = (uint)RiscV64PassFpStructInRegisters.GetRiscV64PassFpStructInRegistersInfo(thRetType.GetRuntimeTypeHandle()).flags & 0xff;
+                                    fpReturnSize = (uint)RiscV64PassFpStructInRegisters.GetRiscV64PassFpStructInRegistersInfo(thRetType.GetRuntimeTypeHandle()).flags;
                                 break;
 
                             }

src/coreclr/vm/callingconvention.h

@@ -1939,7 +1939,7 @@ void ArgIteratorTemplate<ARGITERATOR_BASE>::ComputeReturnFlags()
 
     case ELEMENT_TYPE_R4:
 #if defined(TARGET_LOONGARCH64) || defined(TARGET_RISCV64)
-        flags |= STRUCT_FLOAT_FIELD_ONLY_ONE << RETURN_FP_SIZE_SHIFT;
+        flags |= (FpStruct::OnlyOne | (2 << FpStruct::PosSizeShift1st)) << RETURN_FP_SIZE_SHIFT;
 #else
 #ifndef ARM_SOFTFP
         flags |= sizeof(float) << RETURN_FP_SIZE_SHIFT;
@@ -1949,7 +1949,7 @@ void ArgIteratorTemplate<ARGITERATOR_BASE>::ComputeReturnFlags()
 
     case ELEMENT_TYPE_R8:
 #if defined(TARGET_LOONGARCH64) || defined(TARGET_RISCV64)
-        flags |= (STRUCT_FLOAT_FIELD_ONLY_ONE | STRUCT_FIRST_FIELD_SIZE_IS8) << RETURN_FP_SIZE_SHIFT;
+        flags |= (FpStruct::OnlyOne | (3 << FpStruct::PosSizeShift1st)) << RETURN_FP_SIZE_SHIFT;
 #else
 #ifndef ARM_SOFTFP
         flags |= sizeof(double) << RETURN_FP_SIZE_SHIFT;
@@ -2029,7 +2029,8 @@ void ArgIteratorTemplate<ARGITERATOR_BASE>::ComputeReturnFlags()
             if  (size <= ENREGISTERED_RETURNTYPE_INTEGER_MAXSIZE)
             {
                 assert(!thValueType.IsTypeDesc());
-                flags = (MethodTable::GetRiscV64PassFpStructInRegistersInfo(thValueType).flags & 0xff) << RETURN_FP_SIZE_SHIFT;
+                FpStructInRegistersInfo info = MethodTable::GetRiscV64PassFpStructInRegistersInfo(thValueType);
+                flags |= info.flags << RETURN_FP_SIZE_SHIFT;
                 break;
             }
 #else