Re: [PATCH v12 08/61] target/riscv: add fault-only-first unit stride load

[Richard Henderson]

On 12/17/22 10:21, Philippe Mathieu-Daudé wrote:
> (unburying an old patch)
>
> On 1/7/20 17:24, LIU Zhiwei wrote:
> > The unit-stride fault-only-fault load instructions are used to
> > vectorize loops with data-dependent exit conditions(while loops).
> > These instructions execute as a regular load except that they
> > will only take a trap on element 0.
> >
> > Signed-off-by: LIU Zhiwei <zhiwei_liu@c-sky.com>
> > Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
> > Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
> > ---
> >   target/riscv/helper.h                   |  22 +++++
> >   target/riscv/insn32.decode              |   7 ++
> >   target/riscv/insn_trans/trans_rvv.inc.c |  73 ++++++++++++++++
> >   target/riscv/vector_helper.c            | 110 ++++++++++++++++++++++++
> >   4 files changed, 212 insertions(+)
>
> > +/*
> > + *** unit-stride fault-only-fisrt load instructions
> > + */
> > +static inline void
> > +vext_ldff(void *vd, void *v0, target_ulong base,
> > +          CPURISCVState *env, uint32_t desc,
> > +          vext_ldst_elem_fn *ldst_elem,
> > +          clear_fn *clear_elem,
> > +          uint32_t esz, uint32_t msz, uintptr_t ra)
> > +{
> > +    void *host;
> > +    uint32_t i, k, vl = 0;
> > +    uint32_t mlen = vext_mlen(desc);
> > +    uint32_t nf = vext_nf(desc);
> > +    uint32_t vm = vext_vm(desc);
> > +    uint32_t vlmax = vext_maxsz(desc) / esz;
> > +    target_ulong addr, offset, remain;
> > +
> > +    /* probe every access*/
> > +    for (i = 0; i < env->vl; i++) {
> > +        if (!vm && !vext_elem_mask(v0, mlen, i)) {
> > +            continue;
> > +        }
> > +        addr = base + nf * i * msz;
> > +        if (i == 0) {
> > +            probe_pages(env, addr, nf * msz, ra, MMU_DATA_LOAD);
>
> Shouldn't we check page_check_range() in user-mode here?

No, stick to the common interface.


r~