Re: [Qemu-devel] [PATCH 06/12] target-arm: optimize arm load/store multiple ops

[Laurent Desnogues]

On Wed, Oct 21, 2009 at 12:17 PM,  <address@hidden> wrote:
> ARM load/store multiple instructions can be slightly optimized by
> loading the register offset constant into a variable outside the
> register loop and using the preloaded variable inside the loop instead
> of reloading the offset value to a temporary variable on each loop
> iteration. This causes less TCG ops to be generated for a ARM load/
> store multiple instruction.
>
> Signed-off-by: Juha Riihimäki <address@hidden>

Acked-by: Laurent Desnogues <address@hidden>

> ---
> diff --git a/target-arm/translate.c b/target-arm/translate.c
> index e5a2881..bae1122 100644
> --- a/target-arm/translate.c
> +++ b/target-arm/translate.c
> @@ -6852,6 +6852,7 @@ static void disas_arm_insn(CPUState * env,
> DisasContext *s)
>                  }
>                  rn = (insn >> 16) & 0xf;
>                  addr = load_reg(s, rn);
> +                tmp2 = tcg_const_i32(4);
>
>                  /* compute total size */
>                  loaded_base = 0;
> @@ -6865,7 +6866,7 @@ static void disas_arm_insn(CPUState * env,
> DisasContext *s)
>                  if (insn & (1 << 23)) {
>                      if (insn & (1 << 24)) {
>                          /* pre increment */
> -                        tcg_gen_addi_i32(addr, addr, 4);
> +                        tcg_gen_add_i32(addr, addr, tmp2);
>                      } else {
>                          /* post increment */
>                      }
> @@ -6918,7 +6919,7 @@ static void disas_arm_insn(CPUState * env,
> DisasContext *s)
>                          j++;
>                          /* no need to add after the last transfer */
>                          if (j != n)
> -                            tcg_gen_addi_i32(addr, addr, 4);
> +                            tcg_gen_add_i32(addr, addr, tmp2);
>                      }
>                  }
>                  if (insn & (1 << 21)) {
> @@ -6928,7 +6929,7 @@ static void disas_arm_insn(CPUState * env,
> DisasContext *s)
>                              /* pre increment */
>                          } else {
>                              /* post increment */
> -                            tcg_gen_addi_i32(addr, addr, 4);
> +                            tcg_gen_add_i32(addr, addr, tmp2);
>                          }
>                      } else {
>                          if (insn & (1 << 24)) {
> @@ -6944,6 +6945,7 @@ static void disas_arm_insn(CPUState * env,
> DisasContext *s)
>                  } else {
>                      dead_tmp(addr);
>                  }
> +                tcg_temp_free_i32(tmp2);
>                  if (loaded_base) {
>                      store_reg(s, rn, loaded_var);
>                  }
>


Laurent