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Re: [rs6000] Enable scalar shifts of vectors


From: Richard Henderson <rth@redhat.com>
Date: Wed, 12 Oct 2011 15:32:46 -0700

> I suppose technically the middle-end could be improved to implement
> ashl<mode> as vashl<mode> by broadcasting the scalar, but Altivec
> is the only extant SIMD ISA that would make use of this.  All of
> the others can arrange for constant shifts to be encoded into the
> insn, and so implement the ashl<mode> named pattern.

I'm pretty sure Sparc's VIS3 can do this too, see the
'<vis3_shift_insn><vbits>_vis' patterns in sparc.md


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