X86::getConstantFromPool attempts to extract the Constant data structure from a MachineInstr but currently bails if it finds a non-zero displacement/offset as it can be difficult to extract Constant elements from offset data.

X86FixupVectorConstantsPass and asm comments would really benefit from supporting offset cases if they can still extract the constant element data, so providing an opt-in variant of X86::getConstantFromPool would be very useful.