PR63633: May middle-end come up width hard regs for insn expanders?

[Jeff Law]

On 10/28/14 06:40, Jakub Jelinek wrote:
>
> I'd say if on the target reg26 or reg27 is used or clobbered by
> multiplication, then it is a user error to use it this way, the register
> then isn't suitable for the local hard register usage.
Right.

And this situation is a great example of why clobbering hard registers 
in patterns is a bad idea.

This has a much greater chance of working if the patterns instead 
clobbered a pseudo/scratch where the constraint specifies a class that 
has r26/r27 as a member (possibly its only member).

Jeff