> 1. I can see the standard algorithms (bigblock, linearscan -- good
> choice for
> the JIT and for general use as well, and the other algorithms). Is
> it possible
> to pre-allocate registers in your linearscan (or in another
> allocation engine)
> for specific source-level or (better) intermediate code (bitcode)
Yes that's done at instruction selection time. If you specify an
instruction definition must go to a physical register, the selector
and scheduler will take care of it. Same for instructions that require
its operands that must be in fixed registers.
You mean a temporary defined in an instruction. OK, that is what i basically
need here. Is it guaranteed to "live" in the physical register for the entire
program (or at least for a single function, which would trivially work for
> 2. Which are the new register allocation algorithms currently under
> design? Do
> they support preallocation of registers (it is different to "fixing"
> a register
> in GCC parlance)?
I know of a number of allocators in development. They are not yet made
available to the public yet. Perhaps their authors can chime in.
Fernando has a lot of work going on, and his UCLA page looks very interesting.
Fernando, is your SSA-based regalloc usable as of now; is it in an SVN repo?
Further, do you allow register "fixing" (in the sense of pre-allocated a
register for its entire lifetime, or for the entire program)?