Re: [PATCH v3 10/33] target/ppc/mmu_common.c: Move else branch to avoid large if block

[Nicholas Piggin]

On Wed May 8, 2024 at 10:15 AM AEST, BALATON Zoltan wrote:
> In mmu6xx_get_physical_address() we have a large if block with a two
> line else branch that effectively returns. Invert the condition and
> move the else there to allow deindenting the large if block to make
> the flow easier to follow.
>
> Signed-off-by: BALATON Zoltan <balaton@eik.bme.hu>
> ---
>  target/ppc/mmu_common.c | 71 ++++++++++++++++++++---------------------
>  1 file changed, 34 insertions(+), 37 deletions(-)
>
> diff --git a/target/ppc/mmu_common.c b/target/ppc/mmu_common.c
> index 181273579b..9d337a73ba 100644
> --- a/target/ppc/mmu_common.c
> +++ b/target/ppc/mmu_common.c
> @@ -405,47 +405,44 @@ static int mmu6xx_get_physical_address(CPUPPCState 
> *env, mmu_ctx_t *ctx,
>      ret = -1;
>      if (!ds) {
>          /* Check if instruction fetch is allowed, if needed */
> -        if (type != ACCESS_CODE || ctx->nx == 0) {
> -            /* Page address translation */
> -            qemu_log_mask(CPU_LOG_MMU, "htab_base " HWADDR_FMT_plx
> -                    " htab_mask " HWADDR_FMT_plx
> -                    " hash " HWADDR_FMT_plx "\n",
> -                    ppc_hash32_hpt_base(cpu), ppc_hash32_hpt_mask(cpu), 
> hash);
> -            ctx->hash[0] = hash;
> -            ctx->hash[1] = ~hash;
> -
> -            /* Initialize real address with an invalid value */
> -            ctx->raddr = (hwaddr)-1ULL;
> -            /* Software TLB search */
> -            ret = ppc6xx_tlb_check(env, ctx, eaddr, access_type);
> +        if (type == ACCESS_CODE && ctx->nx) {
> +            qemu_log_mask(CPU_LOG_MMU, "No access allowed\n");
> +            return -3;
> +        }

Function is already inconsistent with assigning ret and falling
through to the return ret at the end vs returning immediately, so
okay since you're tidying it up.

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

> +        /* Page address translation */
> +        qemu_log_mask(CPU_LOG_MMU, "htab_base " HWADDR_FMT_plx " htab_mask "
> +                      HWADDR_FMT_plx " hash " HWADDR_FMT_plx "\n",
> +                      ppc_hash32_hpt_base(cpu), ppc_hash32_hpt_mask(cpu), 
> hash);
> +        ctx->hash[0] = hash;
> +        ctx->hash[1] = ~hash;
> +
> +        /* Initialize real address with an invalid value */
> +        ctx->raddr = (hwaddr)-1ULL;
> +        /* Software TLB search */
> +        ret = ppc6xx_tlb_check(env, ctx, eaddr, access_type);
>  #if defined(DUMP_PAGE_TABLES)
> -            if (qemu_loglevel_mask(CPU_LOG_MMU)) {
> -                CPUState *cs = env_cpu(env);
> -                hwaddr curaddr;
> -                uint32_t a0, a1, a2, a3;
> -
> -                qemu_log("Page table: " HWADDR_FMT_plx " len " HWADDR_FMT_plx
> -                         "\n", ppc_hash32_hpt_base(cpu),
> -                         ppc_hash32_hpt_mask(cpu) + 0x80);
> -                for (curaddr = ppc_hash32_hpt_base(cpu);
> -                     curaddr < (ppc_hash32_hpt_base(cpu)
> -                                + ppc_hash32_hpt_mask(cpu) + 0x80);
> -                     curaddr += 16) {
> -                    a0 = ldl_phys(cs->as, curaddr);
> -                    a1 = ldl_phys(cs->as, curaddr + 4);
> -                    a2 = ldl_phys(cs->as, curaddr + 8);
> -                    a3 = ldl_phys(cs->as, curaddr + 12);
> -                    if (a0 != 0 || a1 != 0 || a2 != 0 || a3 != 0) {
> -                        qemu_log(HWADDR_FMT_plx ": %08x %08x %08x %08x\n",
> -                                 curaddr, a0, a1, a2, a3);
> -                    }
> +        if (qemu_loglevel_mask(CPU_LOG_MMU)) {
> +            CPUState *cs = env_cpu(env);
> +            hwaddr curaddr;
> +            uint32_t a0, a1, a2, a3;
> +
> +            qemu_log("Page table: " HWADDR_FMT_plx " len " HWADDR_FMT_plx 
> "\n",
> +                     ppc_hash32_hpt_base(cpu), ppc_hash32_hpt_mask(cpu) + 
> 0x80);
> +            for (curaddr = ppc_hash32_hpt_base(cpu);
> +                 curaddr < (ppc_hash32_hpt_base(cpu)
> +                            + ppc_hash32_hpt_mask(cpu) + 0x80);
> +                 curaddr += 16) {
> +                a0 = ldl_phys(cs->as, curaddr);
> +                a1 = ldl_phys(cs->as, curaddr + 4);
> +                a2 = ldl_phys(cs->as, curaddr + 8);
> +                a3 = ldl_phys(cs->as, curaddr + 12);
> +                if (a0 != 0 || a1 != 0 || a2 != 0 || a3 != 0) {
> +                    qemu_log(HWADDR_FMT_plx ": %08x %08x %08x %08x\n",
> +                             curaddr, a0, a1, a2, a3);
>                  }
>              }
> -#endif
> -        } else {
> -            qemu_log_mask(CPU_LOG_MMU, "No access allowed\n");
> -            ret = -3;
>          }
> +#endif
>      } else {
>          qemu_log_mask(CPU_LOG_MMU, "direct store...\n");
>          /* Direct-store segment : absolutely *BUGGY* for now */