PA problem

[Richard Earnshaw]

> 
> 
>   In message < orr90ihodn.fsf@guarana.lsd.ic.unicamp.br >you write:
>   > On Feb 28, 2001, Richard Earnshaw <rearnsha@arm.com> wrote:
>   > 
>   > > Shouldn't there also be a non-overlap of op[4] with op[3]?
>   > 
>   > Wouldn't the earlyclobber prevent it from being shared with any input
>   > operand, op[3] inclusive?
> Yes, but the earlyclobber is only examined by the register allocators.
> 
> In the case where we split the instruction before register allocation we
> need the ! reg_overlap_mentioned_p stuff. [OK, we *could* arrange to generate
> the right code if we have an overlap, it's not worth the headache. ]  
> 
> In the case where we do not split the instruction (say a -O1 compilation)
> then we need to tell the register allocator about the operands can not
> overlap, which we do via the earlyclobber.
> 
> As to Richard's question, yes, I believe you're right.

Of course, the other alternative is to disable the splitter until after 
reload has completed.  I'm not sure which will lead to the best code.

R.