Re: [PATCH v6 9/9] target/riscv/vector_helper.c: optimize loops in ldst helpers

[Alistair Francis <alistair23@gmail.com>]

On Thu, Feb 22, 2024 at 7:33 AM Daniel Henrique Barboza
<dbarboza@ventanamicro.com> wrote:
>
> Change the for loops in ldst helpers to do a single increment in the
> counter, and assign it env->vstart, to avoid re-reading from vstart
> every time.
>
> Suggested-by: Richard Henderson <richard.henderson@linaro.org>
> Signed-off-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>

Reviewed-by: Alistair Francis <alistair.francis@wdc.com>

Alistair

> ---
>  target/riscv/vector_helper.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/target/riscv/vector_helper.c b/target/riscv/vector_helper.c
> index cc7290a1bb..1ab386830a 100644
> --- a/target/riscv/vector_helper.c
> +++ b/target/riscv/vector_helper.c
> @@ -208,7 +208,7 @@ vext_ldst_stride(void *vd, void *v0, target_ulong base,
>      uint32_t esz = 1 << log2_esz;
>      uint32_t vma = vext_vma(desc);
>
> -    for (i = env->vstart; i < env->vl; i++, env->vstart++) {
> +    for (i = env->vstart; i < env->vl; env->vstart = ++i) {
>          k = 0;
>          while (k < nf) {
>              if (!vm && !vext_elem_mask(v0, i)) {
> @@ -274,7 +274,7 @@ vext_ldst_us(void *vd, target_ulong base, CPURISCVState *env, uint32_t desc,
>      uint32_t esz = 1 << log2_esz;
>
>      /* load bytes from guest memory */
> -    for (i = env->vstart; i < evl; i++, env->vstart++) {
> +    for (i = env->vstart; i < evl; env->vstart = ++i) {
>          k = 0;
>          while (k < nf) {
>              target_ulong addr = base + ((i * nf + k) << log2_esz);
> @@ -388,7 +388,7 @@ vext_ldst_index(void *vd, void *v0, target_ulong base,
>      uint32_t vma = vext_vma(desc);
>
>      /* load bytes from guest memory */
> -    for (i = env->vstart; i < env->vl; i++, env->vstart++) {
> +    for (i = env->vstart; i < env->vl; env->vstart = ++i) {
>          k = 0;
>          while (k < nf) {
>              if (!vm && !vext_elem_mask(v0, i)) {
> --
> 2.43.2
>
>