SUBREG questions

[Joern Rennecke]

> So, this means, that a (set (subreg:SI ...)) never destroys anything
> besides the hardreg behind that one subreg (if its a SImode hardreg), but
> e.g. a (set (subreg:QI (reg:SI 123) 0)) destroys a
> (subreg:QI (reg:SI 123) 1)?  (I'm asking all this in context of register
> allocation only, that's why that 'hardreg "behind" the subreg')

Yes, for a processor like the x86 where a word is four addressable units.