* improvements and fixes in tcg8086.a_load_reg_reg and .a_load_ref_reg:
  o When expanding from a OS_8 to a 16-bit or 32-bit tcgsize, use the R_SUBH
    subregister to initialize the high 16 bits of the register to zero. This
    generates shorter and faster code, without increasing register
    interferences, because R_SUBH has the same register constraints on i8086 as
    R_SUBL, which is already used on the same imaginary register.
  o After performing operations on the 8-bit subparts of a register that was
    initially 16-bit, call makeregsize(OS_16) to notify the register allocator
    that the register is once again 16-bit.



git-svn-id: http://svn.freepascal.org/svn/fpc/trunk@26328 3ad0048d-3df7-0310-abae-a5850022a9f2