On 07/18/2011 12:15 PM, Georg-Johann Lay wrote: >> However, what you've done is try very hard to work around reload >> doing the Right Thing with constant spilling, namely re-generate >> the constant rather than spill and restore it. I cannot believe >> that's the right way to proceed. > > You mean that with a clobber reload will rematerialize the constant > if there are not enough registers instead of spilling it? > And with an ordinary move like > (set (reg) (const_int)) > reload will not see that it can reaterialize it and spill it to > the stack?
Well, it certainly didn't use to. Vlad, do you know what the current state of the register allocator is wrt this sort of rematerialization? > Moreover, I wonder why target-independent code does not already > catch the situation because the pattern to be generated is just > an ordinary umulqihi3 widening multiplication. Yes, it is sad that the backends have to work around the fact that sign/zero_extension of constants is invalid rtl. r~
