Re: [PATCH v2 4/5] target/riscv: Add support for PC-relative translation

[Richard Henderson]

On 3/28/23 20:23, Weiwei Li wrote:
>   static bool trans_auipc(DisasContext *ctx, arg_auipc *a)
>   {
> -    gen_set_gpri(ctx, a->rd, a->imm + ctx->base.pc_next);
> +    assert(ctx->pc_save != -1);
> +    if (tb_cflags(ctx->base.tb) & CF_PCREL) {
> +        TCGv target_pc = tcg_temp_new();

dest_gpr(s, a->rd)

> @@ -51,26 +59,43 @@ static bool trans_jal(DisasContext *ctx, arg_jal *a)
>   static bool trans_jalr(DisasContext *ctx, arg_jalr *a)
>   {
>       TCGLabel *misaligned = NULL;
> +    TCGv succ_pc = tcg_temp_new();

succ_pc can by null for !CF_PCREL...

> +    TCGv target_pc = tcg_temp_new();
> +
> +    if (tb_cflags(ctx->base.tb) & CF_PCREL) {
> +        tcg_gen_addi_tl(succ_pc, cpu_pc, ctx->pc_succ_insn - ctx->pc_save);
> +    }

... or initialized like

       } else {
           succ_pc = tcg_constant_tl(ctx->pc_succ_insn);
       }

> -    gen_set_pc(ctx, cpu_pc);
>       if (!has_ext(ctx, RVC)) {
>           TCGv t0 = tcg_temp_new();
>   
>           misaligned = gen_new_label();
> -        tcg_gen_andi_tl(t0, cpu_pc, 0x2);
> +        tcg_gen_andi_tl(t0, target_pc, 0x2);
>           tcg_gen_brcondi_tl(TCG_COND_NE, t0, 0x0, misaligned);
>       }
...
>       if (misaligned) {
>           gen_set_label(misaligned);
> -        gen_exception_inst_addr_mis(ctx);
> +        gen_exception_inst_addr_mis(ctx, target_pc);
>       }

This is what I expected from patch 3: cpu_pc is unchanged, with the new (incorrect) 
address passed to inst_addr_mis for assigning to badaddr.  Bug being fixed here, thus 
should really be a separate patch.

> @@ -172,7 +197,7 @@ static bool gen_branch(DisasContext *ctx, arg_b *a, TCGCond 
> cond)
>       if (!has_ext(ctx, RVC) && ((ctx->base.pc_next + a->imm) & 0x3)) {
>           /* misaligned */
>           gen_set_pc_imm(ctx, ctx->base.pc_next + a->imm);
> -        gen_exception_inst_addr_mis(ctx);
> +        gen_exception_inst_addr_mis(ctx, cpu_pc);

But this one's different and (probably) incorrect.

> @@ -552,13 +567,21 @@ static void gen_jal(DisasContext *ctx, int rd, 
> target_ulong imm)
>       if (!has_ext(ctx, RVC)) {
>           if ((next_pc & 0x3) != 0) {
>               gen_set_pc_imm(ctx, next_pc);
> -            gen_exception_inst_addr_mis(ctx);
> +            gen_exception_inst_addr_mis(ctx, cpu_pc);

Likewise.

> +    assert(ctx->pc_save != -1);
> +    if (tb_cflags(ctx->base.tb) & CF_PCREL) {
> +        TCGv succ_pc = tcg_temp_new();
> +        tcg_gen_addi_tl(succ_pc, cpu_pc, ctx->pc_succ_insn - ctx->pc_save);
> +        gen_set_gpr(ctx, rd, succ_pc);

dest_gpr.



r~