I ran into a case in Mips16 where I need two registers.
The problem arises from the fact that SP is not a mips16 register.
You can implicitly use it in load/store and, move it to/from a mips16 register and add small immediate values to it but that's it.
It's not in general a problem for me because there are a bunch of mips32 registers that are hard to use in mips16 so at this time, I only use them in special situations. So they are convenient for temporarily storing mips16 registers.
mips16 registers is a subset of the full mips32 register set.
so i'm guessing that I can still use the RegScavenger class for this.
I'm thinking of something [not sure if this is a correct understanding of this API]
and then I can get and set available registers???
Ideally I could use usual way to get the first register I need by implementing the virtual function for register scavenging in Mips16RegisterInfo [which I already do] and just roll my own for this one moment to get an additional register. If there are no free registers, I can save one in an unused mips32 only register.
What I need is somewhere to move SP so that I can use it in another instruction.
mov unused mips32 register, temp mips16 register; if temp is being used
mov temp mips16 register, SP
add.....temp mips16 register....
; temp is no longer needed
mov temp mips16 register, unused mip32 register ; if temp was being used
This is my main problem.