RFR(S): 8154943: AArch64: redundant address computation instructions with vectorization

[Roland Westrelin]

> Are there any platforms where this won't help?

Yes. x86 needs it:

operand indPosIndexScale(any_RegP reg, rRegI idx, immI2 scale)
%{
  constraint(ALLOC_IN_RC(ptr_reg));
  predicate(n->in(3)->in(1)->as_Type()->type()->is_long()->_lo >= 0);
  match(AddP reg (LShiftL (ConvI2L idx) scale));

>From a quick look through ppc.ad, it seems it needs it to.

> How about adding a Matcher function instead of a cpu-specific ifdef.

Sounds like a good suggestion.

Roland.