The thing I wanted for mips 16 for large literals does not seem to exist right now.
They have MipsTargetLowering::isFPImmLegal(const APFloat &Imm, EVT VT)
but not the same thing for integer literals.
For Mips16, to materialize a 32 bit literal using instructions is expensive, both in terms of the number of registers and the number of instructions.
You always want to just do a load of the constant from the local text section using a PC relative load.
I could try and add this to the target independent section if there seems to be interest in this.
I might first prototype in the Mips target area.