Re: [PATCH 09/31] target/arm: Implement SVE2 integer pairwise arithmetic

[Laurent Desnogues]

On Fri, Mar 27, 2020 at 12:16 AM Richard Henderson
<address@hidden> wrote:
[...]
> diff --git a/target/arm/sve_helper.c b/target/arm/sve_helper.c
> index 5d75aed7b7..d7c181ddb8 100644
> --- a/target/arm/sve_helper.c
> +++ b/target/arm/sve_helper.c
> @@ -681,6 +681,73 @@ DO_ZPZZ_D(sve2_uhsub_zpzz_d, uint64_t, DO_HSUB_D)
>  #undef DO_ZPZZ
>  #undef DO_ZPZZ_D
>
> +/*
> + * Three operand expander, operating on element pairs.
> + * If the slot I is even, the elements from from VN {I, I+1}.
> + * If the slot I is odd, the elements from from VM {I-1, I}.
> + */
> +#define DO_ZPZZ_PAIR(NAME, TYPE, H, OP)                                 \
> +void HELPER(NAME)(void *vd, void *vn, void *vm, void *vg, uint32_t desc) \
> +{                                                                       \
> +    intptr_t i, opr_sz = simd_oprsz(desc);                              \
> +    for (i = 0; i < opr_sz; ) {                                         \
> +        uint16_t pg = *(uint16_t *)(vg + H1_2(i >> 3));                 \
> +        do {                                                            \
> +            if (pg & 1) {                                               \
> +                void *p = (i & 1 ? vm : vn);                            \
> +                TYPE nn = *(TYPE *)(p + H(i & ~1));                     \
> +                TYPE mm = *(TYPE *)(p + H(i | 1));                      \
> +                *(TYPE *)(vd + H(i)) = OP(nn, mm);                      \
> +            }                                                           \
> +            i += sizeof(TYPE), pg >>= sizeof(TYPE);                     \
> +        } while (i & 15);                                               \
> +    }                                                                   \
> +}

You should not use 1 as mask but sizeof(TYPE).
A temporary should be used because vd also is a source.

> +/* Similarly, specialized for 64-bit operands.  */
> +#define DO_ZPZZ_PAIR_D(NAME, TYPE, OP)                                  \
> +void HELPER(NAME)(void *vd, void *vn, void *vm, void *vg, uint32_t desc) \
> +{                                                               \
> +    intptr_t i, opr_sz = simd_oprsz(desc) / 8;                  \
> +    TYPE *d = vd, *n = vn, *m = vm;                             \
> +    uint8_t *pg = vg;                                           \
> +    for (i = 0; i < opr_sz; i += 1) {                           \
> +        if (pg[H1(i)] & 1) {                                    \
> +            TYPE *p = (i & 1 ? m : n) + (i & ~1);               \
> +            TYPE nn = p[0], mm = p[1];                          \
> +            d[i] = OP(nn, mm);                                  \
> +        }                                                       \
> +    }                                                           \
> +}

A temporary should be used because vd also is a source.

Laurent