On Mon, 13 Sept 2021 at 14:56, Richard Henderson
<[email protected]> wrote:
>
> On 9/13/21 2:54 AM, Peter Maydell wrote:
> > +static void do_gvec_shri_s(unsigned vece, uint32_t dofs, uint32_t aofs,
> > + int64_t shift, uint32_t oprsz, uint32_t maxsz)
> > +{
> > + /*
> > + * We get here with a negated shift count, and we must handle
> > + * shifts by the element size, which tcg_gen_gvec_sari() does not do.
> > + */
> > + shift = -shift;
>
> You've already performed the negation in do_2shift_vec.
Here we are undoing the negation we did there, so as to get a
"positive means shift right" shift count back again, which is what
the instruction encoding has and what tcg_gen_gvic_shri() wants.
> > + if (shift == (8 << vece)) {
> > + shift--;
> > + }
> > + tcg_gen_gvec_sari(vece, dofs, aofs, shift, oprsz, maxsz);
> ...
> > + if (shift == (8 << vece)) {
> > + tcg_gen_gvec_dup_imm(vece, dofs, oprsz, maxsz, 0);
> > + } else {
> > + tcg_gen_gvec_shri(vece, dofs, aofs, shift, oprsz, maxsz);
> > + }
>
>
> Perhaps worth placing these functions somewhere we can share code with NEON?
> Tactical
> error, perhaps, open-coding these tests in trans_VSHR_S_2sh and
> trans_VSHR_U_2sh.
I'm not convinced the resemblance is close enough to be worth the
effort...
-- PMM
