[llvm] r178438 - Cleanup PPC(64) i32 -> float/double conversion

[Bill Schmidt]

On Mon, 2013-04-01 at 10:08 -0500, Bill Schmidt wrote:
> On Sun, 2013-03-31 at 09:50 -0500, Hal Finkel wrote:

> > 
> > Hrmm... does the pattern associated with EXTSW_32_64 match anything in practice? Maybe we could declare the sign-extension to be Promote and just define the 64-bit quantity (the use in CTRLoops could likely be handled the same way: some kind of subregister insertion and then the 64-bit version)? Would you care to investigate?
> 
> Sure, I'll look into it (as a low priority item).  Just wanted to make
> sure there wasn't something obvious I missed before messing with it.
> 

Just a follow-up to this:  I took a look at this but didn't get
anywhere.  It seems to be a necessary artifact of using subregisters.
We can't match on sext_inreg without having a full i64 quantity on the
right side (treated as an i32), so anything that looks like an i32
needing to be extended to an i64 needs a different pattern.

Bill