Re: [PATCH v2 5/6] target/riscv: Update address modify functions to take into account pointer masking

[Richard Henderson]

On 12/24/23 15:48, Alexey Baturo wrote:
> From: Alexey Baturo <baturo.alexey@gmail.com>
>
> Signed-off-by: Alexey Baturo <baturo.alexey@gmail.com>
> ---
>   target/riscv/translate.c     | 23 +++++++++++++++++++++--
>   target/riscv/vector_helper.c | 10 ++++++++++
>   2 files changed, 31 insertions(+), 2 deletions(-)
>
> diff --git a/target/riscv/translate.c b/target/riscv/translate.c
> index 1eb501e0d3..c0c5030e05 100644
> --- a/target/riscv/translate.c
> +++ b/target/riscv/translate.c
> @@ -575,11 +575,20 @@ static void gen_jal(DisasContext *ctx, int rd, 
> target_ulong imm)
>   /* Compute a canonical address from a register plus offset. */
>   static TCGv get_address(DisasContext *ctx, int rs1, int imm)
>   {
> +    int pmlen = riscv_pm_get_pmlen(ctx->pm_pmm);
>       TCGv addr = tcg_temp_new();
>       TCGv src1 = get_gpr(ctx, rs1, EXT_NONE);
>   
>       tcg_gen_addi_tl(addr, src1, imm);
> -    if (get_address_xl(ctx) == MXL_RV32) {
> +    if (ctx->pm_pmm) {
> +        tcg_gen_shli_tl(addr, addr, pmlen);
> +        /* sign extend address by first non-masked bit otherwise zero extend */
> +        if (ctx->pm_signext) {
> +            tcg_gen_sari_tl(addr, addr, pmlen);
> +        } else {
> +            tcg_gen_shri_tl(addr, addr, pmlen);
> +        }
> +    } else if (get_address_xl(ctx) == MXL_RV32) {
>           tcg_gen_ext32u_tl(addr, addr);
>       }
>   
> @@ -589,11 +598,21 @@ static TCGv get_address(DisasContext *ctx, int rs1, int imm)
>   /* Compute a canonical address from a register plus reg offset. */
>   static TCGv get_address_indexed(DisasContext *ctx, int rs1, TCGv offs)
>   {
> +    int pmlen = riscv_pm_get_pmlen(ctx->pm_pmm);
>       TCGv addr = tcg_temp_new();
>       TCGv src1 = get_gpr(ctx, rs1, EXT_NONE);
>   
>       tcg_gen_add_tl(addr, src1, offs);
> -    if (get_xl(ctx) == MXL_RV32) {
> +    /* sign extend address by first non-masked bit */
> +    if (ctx->pm_pmm) {
> +        tcg_gen_shli_tl(addr, addr, pmlen);
> +        /* sign extend address by first non-masked bit otherwise zero extend */
> +        if (ctx->pm_signext) {
> +            tcg_gen_sari_tl(addr, addr, pmlen);
> +        } else {
> +            tcg_gen_shri_tl(addr, addr, pmlen);
> +        }
> +    } else if (get_xl(ctx) == MXL_RV32) {
>           tcg_gen_ext32u_tl(addr, addr);

Use tcg_gen_{s}extract_tl instead of two shifts.

Also, it looks like it would be worth doing all of this once in 
riscv_tr_init_disas_context:

    if (get_xl(ctx) == MXL_RV32) {
        ctx->addr_width = 32;
        ctx->addr_signed = false;
    } else {
        pm_pmm = FIELD_EX32(tb_flags, TB_FLAGS, PM_PMM);
        ctx->addr_width = 64 - riscv_pm_get_pmlen(pm_pmm);
        ctx->addr_signed = FIELD_EX32(tb_flags, TB_FLAGS, PM_SIGNEXTEND);
    }

then here in get_address_indexed

    if (ctx->addr_signed) {
        tcg_gen_sextract_tl(addr, addr, ctx->addr_width);
    } else {
        tcg_gen_extract_tl(addr, addr, ctx->addr_width);
    }

> diff --git a/target/riscv/vector_helper.c b/target/riscv/vector_helper.c
> index 8e7a8e80a0..faa8f5820d 100644
> --- a/target/riscv/vector_helper.c
> +++ b/target/riscv/vector_helper.c
> @@ -94,6 +94,16 @@ static inline uint32_t vext_max_elems(uint32_t desc, 
> uint32_t log2_esz)
>   
>   static inline target_ulong adjust_addr(CPURISCVState *env, target_ulong addr)
>   {
> +    RISCVPmPmm pmm = riscv_pm_get_pmm(env);
> +    int pmlen = riscv_pm_get_pmlen(pmm);
> +    bool signext = !riscv_cpu_bare_mode(env);
> +    addr = addr << pmlen;
> +    /* sign/zero extend masked address by N-1 bit */
> +    if (signext) {
> +        addr = (target_long)addr >> pmlen;
> +    } else {
> +        addr = addr >> pmlen;
> +    }
>       return addr;
>   }

I think you could usefully exit early when likely(pmm == PMM_FIELD_DISABLED), avoiding the 
other computation.


r~