Only perform the disp32->disp8 addressing mode optimization on valid instructions (bug 543440 r=dvander+)
Only perform the disp32->disp8 addressing mode optimization on valid instructions (bug 543440 r=dvander+)

RIP-relative addressing uses mod 00 "disp32" encoding, but mod_disp32() assumes
all instructions passed in can be optimized to disp8 encoding if the actual
displacement is 8-bit.  This is invalid for mode 00 modes, including RIP addressing.

mod_disp32() can still do the right thing in the other arm of its branch; this
patch removes the assert and tightens the check for the disp8 case.

pnkfelix/tamarin-redux,pfgenyun/tamarin-redux,pnkfelix/tamarin-redux,pfgenyun/tamarin-redux,pfgenyun/tamarin-redux,pnkfelix/tamarin-redux,pnkfelix/tamarin-redux,pfgenyun/tamarin-redux,pnkfelix/tamarin-redux,pfgenyun/tamarin-redux,pfgenyun/tamarin-redux,pfgenyun/tamarin-redux,pnkfelix/tamarin-redux,pnkfelix/tamarin-redux,pfgenyun/tamarin-redux