Re: [Qemu-devel] [PATCH v2 11/27] target/mips: Tidy control flow in mips_cpu_handle_mmu_fault

[Philippe Mathieu-Daudé]

On 5/9/19 8:02 AM, Richard Henderson wrote:
> Since the only non-negative TLBRET_* value is TLBRET_MATCH,
> the subsequent test for ret < 0 is useless.  Use early return
> to allow subsequent blocks to be unindented.
> 
> Signed-off-by: Richard Henderson <address@hidden>
> ---
>  target/mips/helper.c | 54 ++++++++++++++++++++------------------------
>  1 file changed, 24 insertions(+), 30 deletions(-)
> 
> diff --git a/target/mips/helper.c b/target/mips/helper.c
> index cc7be7703a..86e622efb8 100644
> --- a/target/mips/helper.c
> +++ b/target/mips/helper.c
> @@ -915,41 +915,35 @@ int mips_cpu_handle_mmu_fault(CPUState *cs, vaddr 
> address, int size, int rw,
>          tlb_set_page(cs, address & TARGET_PAGE_MASK,
>                       physical & TARGET_PAGE_MASK, prot | PAGE_EXEC,
>                       mmu_idx, TARGET_PAGE_SIZE);
> -        ret = 0;
> -    } else if (ret < 0)
> -#endif
> -    {
> -#if !defined(CONFIG_USER_ONLY)
> +        return 0;
> +    }
>  #if !defined(TARGET_MIPS64)
> -        if ((ret == TLBRET_NOMATCH) && (env->tlb->nb_tlb > 1)) {
> -            /*
> -             * Memory reads during hardware page table walking are performed
> -             * as if they were kernel-mode load instructions.
> -             */
> -            int mode = (env->hflags & MIPS_HFLAG_KSU);
> -            bool ret_walker;
> -            env->hflags &= ~MIPS_HFLAG_KSU;
> -            ret_walker = page_table_walk_refill(env, address, rw, mmu_idx);
> -            env->hflags |= mode;
> -            if (ret_walker) {
> -                ret = get_physical_address(env, &physical, &prot,
> -                                           address, rw, access_type, 
> mmu_idx);
> -                if (ret == TLBRET_MATCH) {
> -                    tlb_set_page(cs, address & TARGET_PAGE_MASK,
> -                            physical & TARGET_PAGE_MASK, prot | PAGE_EXEC,
> -                            mmu_idx, TARGET_PAGE_SIZE);
> -                    ret = 0;
> -                    return ret;
> -                }
> +    if ((ret == TLBRET_NOMATCH) && (env->tlb->nb_tlb > 1)) {
> +        /*
> +         * Memory reads during hardware page table walking are performed
> +         * as if they were kernel-mode load instructions.
> +         */
> +        int mode = (env->hflags & MIPS_HFLAG_KSU);
> +        bool ret_walker;
> +        env->hflags &= ~MIPS_HFLAG_KSU;
> +        ret_walker = page_table_walk_refill(env, address, rw, mmu_idx);
> +        env->hflags |= mode;
> +        if (ret_walker) {
> +            ret = get_physical_address(env, &physical, &prot,
> +                                       address, rw, access_type, mmu_idx);
> +            if (ret == TLBRET_MATCH) {
> +                tlb_set_page(cs, address & TARGET_PAGE_MASK,
> +                             physical & TARGET_PAGE_MASK, prot | PAGE_EXEC,
> +                             mmu_idx, TARGET_PAGE_SIZE);
> +                return 0;
>              }
>          }
> -#endif
> -#endif
> -        raise_mmu_exception(env, address, rw, ret);
> -        ret = 1;
>      }
> +#endif
> +#endif
>  
> -    return ret;
> +    raise_mmu_exception(env, address, rw, ret);
> +    return 1;
>  }
>  
>  #if !defined(CONFIG_USER_ONLY)
> 

Reviewed-by: Philippe Mathieu-Daudé <address@hidden>