[Qemu-devel] Re: [PATCH 2/3] target-sparc: Free instruction temporaries.

[Blue Swirl <blauwirbel@gmail.com>]

On 4/16/10, Richard Henderson <rth@twiddle.net> wrote:
> Rather than creating new temporaries for constants, use the
>  ones created in disas_sparc_insn.  Remember the temps created
>  there so that they can be freed at the end of the function.
>
>  Profile data collected by TCG while booting sparc-test kernel:
>
>  -avg temps/TB    70.61 max=421
>  +avg temps/TB    62.75 max=66
>
>  Signed-off-by: Richard Henderson <rth@twiddle.net>

Thanks, applied whole series.

About this patch: it's good that we now free the constants, but
constant handling is still not optimal and I think this series
actually may add extra 'movi' ops in the worst case. It would be nice
if we detected if constants are in play and call immediate versions
(addi, subi etc) automatically. This may need bigger refactoring,
though.

>  ---
>   target-sparc/translate.c |   52 +++++++++++++++++++++++----------------------
>   1 files changed, 27 insertions(+), 25 deletions(-)
>
>  diff --git a/target-sparc/translate.c b/target-sparc/translate.c
>  index 2c07385..2c833ab 100644
>  --- a/target-sparc/translate.c
>  +++ b/target-sparc/translate.c
>  @@ -49,7 +49,7 @@ static TCGv cpu_y;
>   #ifndef CONFIG_USER_ONLY
>   static TCGv cpu_tbr;
>   #endif
>  -static TCGv cpu_cond, cpu_src1, cpu_src2, cpu_dst, cpu_addr, cpu_val;
>  +static TCGv cpu_cond, cpu_dst, cpu_addr, cpu_val;
>   #ifdef TARGET_SPARC64
>   static TCGv_i32 cpu_xcc, cpu_asi, cpu_fprs;
>   static TCGv cpu_gsr;
>  @@ -1631,12 +1631,13 @@ static inline TCGv get_src1(unsigned int insn, TCGv def)
>      unsigned int rs1;
>
>      rs1 = GET_FIELD(insn, 13, 17);
>  -    if (rs1 == 0)
>  -        r_rs1 = tcg_const_tl(0); // XXX how to free?
>  -    else if (rs1 < 8)
>  +    if (rs1 == 0) {
>  +        tcg_gen_movi_tl(def, 0);
>  +    } else if (rs1 < 8) {
>          r_rs1 = cpu_gregs[rs1];
>  -    else
>  +    } else {
>          tcg_gen_ld_tl(def, cpu_regwptr, (rs1 - 8) * sizeof(target_ulong));
>  +    }
>      return r_rs1;
>   }
>
>  @@ -1645,20 +1646,17 @@ static inline TCGv get_src2(unsigned int insn, TCGv def)
>      TCGv r_rs2 = def;
>
>      if (IS_IMM) { /* immediate */
>  -        target_long simm;
>  -
>  -        simm = GET_FIELDs(insn, 19, 31);
>  -        r_rs2 = tcg_const_tl(simm); // XXX how to free?
>  +        target_long simm = GET_FIELDs(insn, 19, 31);
>  +        tcg_gen_movi_tl(def, simm);
>      } else { /* register */
>  -        unsigned int rs2;
>  -
>  -        rs2 = GET_FIELD(insn, 27, 31);
>  -        if (rs2 == 0)
>  -            r_rs2 = tcg_const_tl(0); // XXX how to free?
>  -        else if (rs2 < 8)
>  +        unsigned int rs2 = GET_FIELD(insn, 27, 31);
>  +        if (rs2 == 0) {
>  +            tcg_gen_movi_tl(def, 0);
>  +        } else if (rs2 < 8) {
>              r_rs2 = cpu_gregs[rs2];
>  -        else
>  +        } else {
>              tcg_gen_ld_tl(def, cpu_regwptr, (rs2 - 8) * sizeof(target_ulong));
>  +        }
>      }
>      return r_rs2;
>   }
>  @@ -1701,6 +1699,7 @@ static inline void gen_load_trap_state_at_tl(TCGv_ptr r_tsptr, TCGv_ptr cpu_env)
>   static void disas_sparc_insn(DisasContext * dc)
>   {
>      unsigned int insn, opc, rs1, rs2, rd;
>  +    TCGv cpu_src1, cpu_src2, cpu_tmp1, cpu_tmp2;
>      target_long simm;
>
>      if (unlikely(qemu_loglevel_mask(CPU_LOG_TB_OP)))
>  @@ -1710,8 +1709,8 @@ static void disas_sparc_insn(DisasContext * dc)
>
>      rd = GET_FIELD(insn, 2, 6);
>
>  -    cpu_src1 = tcg_temp_new(); // const
>  -    cpu_src2 = tcg_temp_new(); // const
>  +    cpu_tmp1 = cpu_src1 = tcg_temp_new();
>  +    cpu_tmp2 = cpu_src2 = tcg_temp_new();
>
>      switch (opc) {
>      case 0:                     /* branches/sethi */
>  @@ -4599,7 +4598,7 @@ static void disas_sparc_insn(DisasContext * dc)
>          dc->npc = dc->npc + 4;
>      }
>   jmp_insn:
>  -    return;
>  +    goto egress;
>   illegal_insn:
>      {
>          TCGv_i32 r_const;
>  @@ -4610,7 +4609,7 @@ static void disas_sparc_insn(DisasContext * dc)
>          tcg_temp_free_i32(r_const);
>          dc->is_br = 1;
>      }
>  -    return;
>  +    goto egress;
>   unimp_flush:
>      {
>          TCGv_i32 r_const;
>  @@ -4621,7 +4620,7 @@ static void disas_sparc_insn(DisasContext * dc)
>          tcg_temp_free_i32(r_const);
>          dc->is_br = 1;
>      }
>  -    return;
>  +    goto egress;
>   #if !defined(CONFIG_USER_ONLY)
>   priv_insn:
>      {
>  @@ -4633,19 +4632,19 @@ static void disas_sparc_insn(DisasContext * dc)
>          tcg_temp_free_i32(r_const);
>          dc->is_br = 1;
>      }
>  -    return;
>  +    goto egress;
>   #endif
>   nfpu_insn:
>      save_state(dc, cpu_cond);
>      gen_op_fpexception_im(FSR_FTT_UNIMPFPOP);
>      dc->is_br = 1;
>  -    return;
>  +    goto egress;
>   #if !defined(CONFIG_USER_ONLY) && !defined(TARGET_SPARC64)
>   nfq_insn:
>      save_state(dc, cpu_cond);
>      gen_op_fpexception_im(FSR_FTT_SEQ_ERROR);
>      dc->is_br = 1;
>  -    return;
>  +    goto egress;
>   #endif
>   #ifndef TARGET_SPARC64
>   ncp_insn:
>  @@ -4658,8 +4657,11 @@ static void disas_sparc_insn(DisasContext * dc)
>          tcg_temp_free(r_const);
>          dc->is_br = 1;
>      }
>  -    return;
>  +    goto egress;
>   #endif
>  + egress:
>  +    tcg_temp_free(cpu_tmp1);
>  +    tcg_temp_free(cpu_tmp2);
>   }
>
>   static inline void gen_intermediate_code_internal(TranslationBlock * tb,
>
> --
>  1.6.6.1
>
>