Routine to aid in setting things up for gen().
Look for common subexpression.
Can handle indirection operators, but not if they're common subs.
Input:
e -> elem where we get some of the data from
cs -> partially filled code to add
op = opcode
reg = reg field of (mod reg r/m)
offset = data to be added to Voffset field
keepmsk = mask of registers we must not destroy
desmsk = mask of registers destroyed by executing the instruction
Routine to aid in setting things up for gen(). Look for common subexpression. Can handle indirection operators, but not if they're common subs. Input: e -> elem where we get some of the data from cs -> partially filled code to add op = opcode reg = reg field of (mod reg r/m) offset = data to be added to Voffset field keepmsk = mask of registers we must not destroy desmsk = mask of registers destroyed by executing the instruction