Hendrik Greving <hendrik.greving.in...@gmail.com> writes: > One follow-up question here. Is it of any disadvantage to always > generate a clobber (scratch) during expansion? Meaning that in the > case we don't need one (we won't split, which I am checking with > memory_operand(myoutput_operand), that register won't get allocated > and adds to register pressure, does it?
Yeah, the idea is that if the match_scratch isn't needed for a particular alternative, the constraint for that alternative should be "X" rather than a register class. That way the (scratch) stays a (scratch) even after register allocation. Thanks, Richard
