> Yeah, rtx_costs (or preferably insn_cost, if that works) seem like the
> best way of addressing this. If the target says that register moves are
> cheaper than constant moves then it's a feature that CSE & co remove
> duplicate constants. The REG_EQUIV note is still useful in those cases
> beca
Robin Dapp via Gcc-patches writes:
> Hi,
>
> I have been working on making better use of s390's vzero instruction.
> Currently we rather zero a vector register once and load it into other
> registers via vlr instead of emitting multiple vzeros.
>
> At IRA/reload point we e.g. have
>
> (insn 8 5 19
Small addition to clarify: (insn 8) from the example is of course
matched to a vzero. The "problem" begins when (reg 64) is later moved
into another register and the (const_vector) has been optimized to a
single definition e.g. by CSE, i.e. we have several
(insn yy (set (reg:V2DI xx) (reg:V2DI 6
