Reload with jump_insn that have a 'set' side effect.

Richard Sandiford rdsandiford@googlemail.com
Wed Sep 18 07:26:00 GMT 2013


Hendrik Greving <hendrik.greving.intel@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



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