Instead of generating stuff like this:

        mov %ECX, %EAX
        add %ECX, 32768
        mov %SI, WORD PTR [2*%ECX + l13_prev]

Generate this:

        mov %SI, WORD PTR [2*%ECX + l13_prev + 65536]

This occurs when you have a GEP instruction where an index is
"something + imm".

llvm-svn: 19472