Re: [Qemu-devel] [PATCH v2 23/29] target/riscv: Move gen_arith_imm() decoding into trans_* functions

[Richard Henderson]

On 10/20/18 8:14 AM, Bastian Koppelmann wrote:
>  static bool trans_srli(DisasContext *ctx, arg_srli *a, uint32_t insn)
>  {
> -    gen_arith_imm(ctx, OPC_RISC_SHIFT_RIGHT_I, a->rd, a->rs1, a->shamt);
> +    if (a->rd != 0) {
> +        TCGv t = tcg_temp_new();
> +        gen_get_gpr(t, a->rs1);
> +        tcg_gen_extract_tl(t, t, a->shamt, 64 - a->shamt);

tcg_gen_shri_tl(t, t, a->shamt);

This is a mis-translation of the original code which handled srliw too.
You should be able to see this assert on riscv32.

>  static bool trans_srai(DisasContext *ctx, arg_srai *a, uint32_t insn)
>  {
> -    gen_arith_imm(ctx, OPC_RISC_SHIFT_RIGHT_I, a->rd, a->rs1, a->shamt | 
> 0x400);
> +    if (a->rd != 0) {
> +        TCGv t = tcg_temp_new();
> +        gen_get_gpr(t, a->rs1);
> +        tcg_gen_sextract_tl(t, t, a->shamt, 64 - a->shamt);

Similarly.


r~