The comment seems no longer valid, the functions technically check for
non-pseudo registers, like zmmh. Which is a valid use case.
/* Types for i386-specific registers. */
extern struct type *i387_ext_type (struct gdbarch *gdbarch);
-/* Checks of different pseudo-registers. */
+/* Checks of different registers. */
extern int i386_byte_regnum_p (struct gdbarch *gdbarch, int regnum);
extern int i386_word_regnum_p (struct gdbarch *gdbarch, int regnum);
extern int i386_dword_regnum_p (struct gdbarch *gdbarch, int regnum);