Re: [PATCH 1/4] target/ppc/mem_helper.c: Remove a conditional from dcbz_common()

["Nicholas Piggin" <npiggin@gmail.com>]

On Wed Jul 3, 2024 at 9:46 AM AEST, Richard Henderson wrote:
> From: BALATON Zoltan <balaton@eik.bme.hu>
>
> Instead of passing a bool and select a value within dcbz_common() let
> the callers pass in the right value to avoid this conditional
> statement. On PPC dcbz is often used to zero memory and some code uses
> it a lot. This change improves the run time of a test case that copies
> memory with a dcbz call in every iteration from 6.23 to 5.83 seconds.
>

Reviewed-by: Nicholas Piggin <npiggin@gmail.com>

> Signed-off-by: BALATON Zoltan <balaton@eik.bme.hu>
> Message-Id: <20240622204833.5F7C74E6000@zero.eik.bme.hu>
> Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
> ---
>  target/ppc/mem_helper.c | 7 +++----
>  1 file changed, 3 insertions(+), 4 deletions(-)
>
> diff --git a/target/ppc/mem_helper.c b/target/ppc/mem_helper.c
> index f88155ad45..361fd72226 100644
> --- a/target/ppc/mem_helper.c
> +++ b/target/ppc/mem_helper.c
> @@ -271,12 +271,11 @@ void helper_stsw(CPUPPCState *env, target_ulong addr, uint32_t nb,
>  }
>  
>  static void dcbz_common(CPUPPCState *env, target_ulong addr,
> -                        uint32_t opcode, bool epid, uintptr_t retaddr)
> +                        uint32_t opcode, int mmu_idx, uintptr_t retaddr)
>  {
>      target_ulong mask, dcbz_size = env->dcache_line_size;
>      uint32_t i;
>      void *haddr;
> -    int mmu_idx = epid ? PPC_TLB_EPID_STORE : ppc_env_mmu_index(env, false);
>  
>  #if defined(TARGET_PPC64)
>      /* Check for dcbz vs dcbzl on 970 */
> @@ -309,12 +308,12 @@ static void dcbz_common(CPUPPCState *env, target_ulong addr,
>  
>  void helper_dcbz(CPUPPCState *env, target_ulong addr, uint32_t opcode)
>  {
> -    dcbz_common(env, addr, opcode, false, GETPC());
> +    dcbz_common(env, addr, opcode, ppc_env_mmu_index(env, false), GETPC());
>  }
>  
>  void helper_dcbzep(CPUPPCState *env, target_ulong addr, uint32_t opcode)
>  {
> -    dcbz_common(env, addr, opcode, true, GETPC());
> +    dcbz_common(env, addr, opcode, PPC_TLB_EPID_STORE, GETPC());
>  }
>  
>  void helper_icbi(CPUPPCState *env, target_ulong addr)