Do not allow DEF signedness to become mixed due to propagation of USE operand signedness within an RTL.

Infer signedness from opcodes; suppress overflow and underflow checks on small values from condition codes.

Removed --no-undefined flag from link step, as this flag is generally unsupported, and seems unneeded.

Reduce SMPInstr memory by pulling disasm text into a global shared object, produced on demand per address.