Re: [PATCH 05/23] target/riscv: Add evl argument to vext_ldst_elem_fn_host

On 8/15/26 12:45, Richard Henderson wrote:
> This merges vext_continuous_ldst_host into the ldst_host function.
> We can then handle the byte little-endian optimization at compile-time.
> 
> Signed-off-by: Richard Henderson <[email protected]>
> ---
>   target/riscv/tcg/vector_helper.c | 83 +++++++++++++++-----------------
>   1 file changed, 40 insertions(+), 43 deletions(-)

In retrospect, this probably isn't a great idea.  The load side is fine, but the store 
side suffers from atomicity issues.  I'll think of something else.


r~


> 
> diff --git a/target/riscv/tcg/vector_helper.c b/target/riscv/tcg/vector_helper.c
> index 661f1ab2f6..3786a17231 100644
> --- a/target/riscv/tcg/vector_helper.c
> +++ b/target/riscv/tcg/vector_helper.c
> @@ -214,7 +214,8 @@ static inline MemOpIdx vext_make_memop_idx(CPURISCVState *env, size_t size)
>   /* elements operations for load and store */
>   typedef void vext_ldst_elem_fn_tlb(CPURISCVState *env, abi_ptr addr,
>                                      uint32_t idx, void *vd, uintptr_t retaddr);
> -typedef void vext_ldst_elem_fn_host(void *vd, uint32_t idx, void *host);
> +typedef void vext_ldst_elem_fn_host(void *vd, void *host,
> +                                    uint32_t idx, uint32_t evl);
>   
>   #define GEN_VEXT_TLB_LD_ELEM(NAME, ETYPE, H, LDSUF)         \
>   static inline QEMU_ALWAYS_INLINE                            \
> @@ -226,12 +227,15 @@ void NAME##_tlb(CPURISCVState *env, abi_ptr addr,           \
>       *cur = cpu_##LDSUF##_mmu(env, addr, oi, retaddr);       \
>   }                                                           \
>   
> -#define GEN_VEXT_HOST_LD_ELEM(NAME, ETYPE, H, LDSUF)        \
> -static inline QEMU_ALWAYS_INLINE                            \
> -void NAME##_host(void *vd, uint32_t idx, void *host)        \
> -{                                                           \
> -    ETYPE *cur = ((ETYPE *)vd + H(idx));                    \
> -    *cur = (ETYPE)LDSUF##_p(host);                          \
> +#define GEN_VEXT_HOST_LD_ELEM(NAME, ETYPE, H, LDSUF)                    \
> +static inline QEMU_ALWAYS_INLINE                                        \
> +void NAME##_host(void *vd, void *host, uint32_t idx, uint32_t evl)      \
> +{                                                                       \
> +    do {                                                                \
> +        ETYPE *cur = (ETYPE *)vd + H(idx);                              \
> +        *cur = LDSUF##_p(host);                                         \
> +        host += sizeof(ETYPE);                                          \
> +    } while (++idx < evl);                                              \
>   }
>   
>   GEN_VEXT_TLB_LD_ELEM(lde_b, uint8_t,  H1, ldb)
> @@ -239,7 +243,16 @@ GEN_VEXT_TLB_LD_ELEM(lde_h, uint16_t, H2, ldw)
>   GEN_VEXT_TLB_LD_ELEM(lde_w, uint32_t, H4, ldl)
>   GEN_VEXT_TLB_LD_ELEM(lde_d, uint64_t, H8, ldq)
>   
> +#if HOST_BIG_ENDIAN
>   GEN_VEXT_HOST_LD_ELEM(lde_b, uint8_t,  H1, ldub)
> +#else
> +static inline QEMU_ALWAYS_INLINE
> +void lde_b_host(void *vd, void *host, uint32_t idx, uint32_t evl)
> +{
> +    memcpy(vd + idx, host, evl - idx);
> +}
> +#endif
> +
>   GEN_VEXT_HOST_LD_ELEM(lde_h, uint16_t, H2, lduw_le)
>   GEN_VEXT_HOST_LD_ELEM(lde_w, uint32_t, H4, ldl_le)
>   GEN_VEXT_HOST_LD_ELEM(lde_d, uint64_t, H8, ldq_le)
> @@ -254,12 +267,15 @@ void NAME##_tlb(CPURISCVState *env, abi_ptr addr,           \
>       cpu_##STSUF##_mmu(env, addr, data, oi, retaddr);        \
>   }                                                           \
>   
> -#define GEN_VEXT_HOST_ST_ELEM(NAME, ETYPE, H, STSUF)        \
> -static inline QEMU_ALWAYS_INLINE                            \
> -void NAME##_host(void *vd, uint32_t idx, void *host)        \
> -{                                                           \
> -    ETYPE data = *((ETYPE *)vd + H(idx));                   \
> -    STSUF##_p(host, data);                                  \
> +#define GEN_VEXT_HOST_ST_ELEM(NAME, ETYPE, H, STSUF)                    \
> +static inline QEMU_ALWAYS_INLINE                                        \
> +void NAME##_host(void *vd, void *host, uint32_t idx, uint32_t evl)      \
> +{                                                                       \
> +    do {                                                                \
> +        ETYPE data = *((ETYPE *)vd + H(idx));                           \
> +        STSUF##_p(host, data);                                          \
> +        host += sizeof(ETYPE);                                          \
> +    } while (++idx < evl);                                              \
>   }
>   
>   GEN_VEXT_TLB_ST_ELEM(ste_b, uint8_t,  H1, stb)
> @@ -267,7 +283,16 @@ GEN_VEXT_TLB_ST_ELEM(ste_h, uint16_t, H2, stw)
>   GEN_VEXT_TLB_ST_ELEM(ste_w, uint32_t, H4, stl)
>   GEN_VEXT_TLB_ST_ELEM(ste_d, uint64_t, H8, stq)
>   
> +#if HOST_BIG_ENDIAN
>   GEN_VEXT_HOST_ST_ELEM(ste_b, uint8_t,  H1, stb)
> +#else
> +static inline QEMU_ALWAYS_INLINE
> +void ste_b_host(void *vd, void *host, uint32_t idx, uint32_t evl)
> +{
> +    memcpy(host, vd + idx, evl - idx);
> +}
> +#endif
> +
>   GEN_VEXT_HOST_ST_ELEM(ste_h, uint16_t, H2, stw_le)
>   GEN_VEXT_HOST_ST_ELEM(ste_w, uint32_t, H4, stl_le)
>   GEN_VEXT_HOST_ST_ELEM(ste_d, uint64_t, H8, stq_le)
> @@ -284,33 +309,6 @@ vext_continuous_ldst_tlb(CPURISCVState *env, vext_ldst_elem_fn_tlb *ldst_tlb,
>       }
>   }
>   
> -static inline QEMU_ALWAYS_INLINE void
> -vext_continuous_ldst_host(CPURISCVState *env, vext_ldst_elem_fn_host *ldst_host,
> -                        void *vd, uint32_t evl, uint32_t reg_start, void *host,
> -                        uint32_t esz, bool is_load)
> -{
> -    if (HOST_BIG_ENDIAN) {
> -        for (; reg_start < evl; reg_start++, host += esz) {
> -            ldst_host(vd, reg_start, host);
> -        }
> -    } else {
> -        if (esz == 1) {
> -            uint32_t byte_offset = reg_start * esz;
> -            uint32_t size = (evl - reg_start) * esz;
> -
> -            if (is_load) {
> -                memcpy(vd + byte_offset, host, size);
> -            } else {
> -                memcpy(host, vd + byte_offset, size);
> -            }
> -        } else {
> -            for (; reg_start < evl; reg_start++, host += esz) {
> -                ldst_host(vd, reg_start, host);
> -            }
> -        }
> -    }
> -}
> -
>   static void vext_set_tail_elems_1s(uint32_t vl, void *vd, uint32_t nf,
>                                      uint32_t esz, uint32_t max_elems)
>   {
> @@ -334,7 +332,7 @@ static void vext_ldst_nf_host(void *vd, void *host, uint32_t i, uint32_t nf,
>                                 vext_ldst_elem_fn_host *ldst_host)
>   {
>       for (uint32_t k = 0; k < nf; k++, host += esz) {
> -        ldst_host(vd, i + k * max_elems, host);
> +        ldst_host(vd + k * max_elems, host, i, i + 1);
>       }
>   }
>   
> @@ -450,8 +448,7 @@ vext_page_ldst_us(CPURISCVState *env, void *vd, target_ulong addr,
>        */
>       if (flags == 0 && (riscv_cpu_cfg(env)->ext_zicclsm || !misaligned)) {
>           if (nf == 1) {
> -            vext_continuous_ldst_host(env, ldst_host, vd, evl, env->vstart,
> -                                      host, esz, is_load);
> +            ldst_host(vd, host, env->vstart, evl);
>           } else {
>               for (uint32_t i = env->vstart; i < evl; ++i) {
>                   vext_ldst_nf_host(vd, host, i, nf, esz, max_elems, ldst_host);