[PATCH] Add sign/zero extend to mips fast-isel

[reed kotler]

The statement 

  TargetSupported = ((Subtarget->getRelocationModel() == Reloc::PIC_) &&
                   (Subtarget->hasMips32r2() && (Subtarget->isABI_O32())));

is there because that is the scope of the work I have been assigned by management to do for fast-isel.
There are important customers that need exactly that and nothing more.

It's not there to reduce the testing matrix.

The scope of the work is not to worry about doing fast-isel for other old or new Mips targets or abis.

We may never want to support fast-isel for old targets. That's a decision for management to make as far as fast-isel.
Just because we support old targets in some tools does not mean that it's to be supported uniformly for all new work on llvm, like for fast-isel.

RIght now they just want was is covered by the TargetSupported list.

After that I think the plan is to add 64 bit support.

I don't see how it's difficult to add others in later.

I'm digging my heels in a bit on this patch because I think these kinds of change requests are impeding the task at hand and I'd like
to hopefully rein in the scope here and not have to revisit this issue on every patch; what other things that are beyond the scope of my work assignment
I now to need to take into account and add to my patches.

There are about 10 patches in my queue right now which when submitted will take this first cut at mips fast-isel to a high percentage of completion.

http://reviews.llvm.org/D4827