Merge pull request #24 from ngrewe/ivar_layout

Test case for misaligned ivars.

This introduces a new failing test for the bug introduced when trying to correctly align vectors.

Test/alignTest.m

@@ -52,8 +52,36 @@ typedef int v4si __attribute__ ((vector_size (16)));
 }
 @end
 
+#if __has_attribute(objc_root_class)
+__attribute__((objc_root_class))
+#endif
+@interface StringLikeTest
+{
+  Class isa;
+  char* c_string;
+  int len;
+}
+@end
+
+@implementation StringLikeTest
++ (Class)class
+{
+  return self;
+}
+@end
+
 int main(void)
 {
 	[[Vector alloc] permute];
 	[[Foo new] check];
+
+	Ivar v_isa = class_getInstanceVariable([StringLikeTest class], "isa");
+	Ivar v_c_string = class_getInstanceVariable([StringLikeTest class], "c_string");
+	Ivar v_len = class_getInstanceVariable([StringLikeTest class], "len");
+	ptrdiff_t o_isa = ivar_getOffset(v_isa);
+	ptrdiff_t o_c_string = ivar_getOffset(v_c_string);
+	assert(o_isa == 0);
+	assert(o_c_string == sizeof(Class));
+	assert(o_isa < o_c_string);
+	assert(o_c_string < ivar_getOffset(v_len));
 }