[arm] fix stack alignment for structs (mono#7691)

fixes mono#7449

Author: lewurm

mono/mini/mini-arm.c

@@ -1524,7 +1524,7 @@ get_call_info (MonoMemPool *mp, MonoMethodSignature *sig)
 			ainfo->storage = RegTypeStructByVal;
 			ainfo->struct_size = size;
 			ainfo->align = align;
-			/* FIXME: align stack_size if needed */
+
 			if (eabi_supported) {
 				if (align >= 8 && (gr & 1))
 					gr ++;
@@ -1542,9 +1542,8 @@ get_call_info (MonoMemPool *mp, MonoMethodSignature *sig)
 				gr += n_in_regs;
 				nwords -= n_in_regs;
 			}
-			if (sig->call_convention == MONO_CALL_VARARG)
-				/* This matches the alignment in mono_ArgIterator_IntGetNextArg () */
-				stack_size = ALIGN_TO (stack_size, align);
+			stack_size = ALIGN_TO (stack_size, align);
+
 			ainfo->offset = stack_size;
 			/*g_print ("offset for arg %d at %d\n", n, stack_size);*/
 			stack_size += nwords * sizeof (gpointer);

mono/tests/libtest.c

@@ -280,6 +280,25 @@ mono_return_nested_float (void)
 	return f;
 }
 
+struct Scalar4 {
+	double val[4];
+};
+
+struct Rect {
+	int x;
+	int y;
+	int width;
+	int height;
+};
+
+LIBTEST_API char * STDCALL
+mono_return_struct_4_double (void *ptr, struct Rect rect, struct Scalar4 sc4, int a, int b, int c)
+{
+	char *buffer = (char *) malloc (1024 * sizeof (char));
+	sprintf (buffer, "sc4 = {%.1f, %.1f, %.1f, %.1f }, a=%x, b=%x, c=%x\n", (float) sc4.val [0], (float) sc4.val [1], (float) sc4.val [2], (float) sc4.val [3], a, b, c);
+	return buffer;
+}
+
 LIBTEST_API int STDCALL  
 mono_test_many_int_arguments (int a, int b, int c, int d, int e,
 							  int f, int g, int h, int i, int j);

mono/tests/pinvoke11.cs

@@ -60,6 +60,39 @@ public struct NestedFloat {
 	public float f4;
 }
 
+[Serializable]
+[StructLayout(LayoutKind.Sequential)]
+public struct Rectangle
+{
+	public int X;
+	public int Y;
+	public int Width;
+	public int Height;
+
+	public Rectangle(int x, int y, int width, int height)
+	{
+		X = x;
+		Y = y;
+		Width = width;
+		Height = height;
+	}
+}
+
+[Serializable]
+public struct Scalar4 {
+	public double Val0;
+	public double Val1;
+	public double Val2;
+	public double Val3;
+
+	public Scalar4 (double v0, double v1, double v2, double v3) {
+		Val0 = v0;
+		Val1 = v1;
+		Val2 = v2;
+		Val3 = v3;
+	}
+}
+
 public class Test
 {
 	[DllImport ("libtest")]
@@ -89,6 +122,10 @@ public class Test
 	[DllImport ("libtest", EntryPoint="mono_return_nested_float")]
 	public static extern NestedFloat mono_return_nested_float ();
 
+	[DllImport("libtest", EntryPoint="mono_return_struct_4_double")]
+	[return: MarshalAs(UnmanagedType.LPStr)]
+	public static extern string mono_return_struct_4_double (IntPtr ptr, Rectangle rect, Scalar4 sc4, int a, int b, int c);
+
         static int Main()
         {
 		if (mono_return_int (5) != 5)
@@ -159,6 +196,14 @@ static int Main()
 		if (f.fi.f1 != 1.0)
 			return 12;
 
+		Rectangle rect = new Rectangle (10, 10, 100, 20);
+		Scalar4 sc4 = new Scalar4 (32, 64, 128, 256);
+		var sc4_ret = mono_return_struct_4_double (IntPtr.Zero, rect, sc4, 0x1337, 0x1234, 0x9876);
+		if (sc4_ret != "sc4 = {32.0, 64.0, 128.0, 256.0 }, a=1337, b=1234, c=9876\n") {
+			Console.WriteLine ("sc4_ret = " + sc4_ret);
+			return 13;
+		}
+
 		return 0;
         }
 }