Function reg_32_to_opsz 

pub unsafe extern "C" fn reg_32_to_opsz(
    reg: reg_id_t,
    sz: opnd_size_t,
) -> reg_id_t

Assumes that \p reg is a DR_REG_ 32-bit register constant. If \p sz == OPSZ_2, returns the 16-bit version of \p reg. For 64-bit versions of this library, if \p sz == OPSZ_8, returns the 64-bit version of \p reg. Returns \p DR_REG_NULL when trying to get the 8-bit subregister of \p DR_REG_ESI, \p DR_REG_EDI, \p DR_REG_EBP, or \p DR_REG_ESP in 32-bit mode.

\deprecated Prefer reg_resize_to_opsz() which is more general.