Re: [PATCH v5 03/23] target/ppc: Replace POWERPC_EXCP_BRANCH with DISAS_NORETURN

[David Gibson]

On Mon, May 17, 2021 at 05:50:05PM -0300, matheus.ferst@eldorado.org.br wrote:
> From: Richard Henderson <richard.henderson@linaro.org>
> 
> The translation of branch instructions always results in exit from
> the TB. Remove the synthetic "exception" after no more uses.
> 
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
> Signed-off-by: Matheus Ferst <matheus.ferst@eldorado.org.br>

Applied to ppc-for-6.1, thanks.

> ---
>  linux-user/ppc/cpu_loop.c | 3 ---
>  target/ppc/cpu.h          | 2 --
>  target/ppc/translate.c    | 8 ++------
>  3 files changed, 2 insertions(+), 11 deletions(-)
> 
> diff --git a/linux-user/ppc/cpu_loop.c b/linux-user/ppc/cpu_loop.c
> index fe526693d2..fa91ea0eed 100644
> --- a/linux-user/ppc/cpu_loop.c
> +++ b/linux-user/ppc/cpu_loop.c
> @@ -423,9 +423,6 @@ void cpu_loop(CPUPPCState *env)
>              cpu_abort(cs, "Maintenance exception while in user mode. "
>                        "Aborting\n");
>              break;
> -        case POWERPC_EXCP_BRANCH:   /* branch instruction:                   
> */
> -            /* We just stopped because of a branch. Go on */
> -            break;
>          case POWERPC_EXCP_SYSCALL_USER:
>              /* system call in user-mode emulation */
>              /* WARNING:
> diff --git a/target/ppc/cpu.h b/target/ppc/cpu.h
> index 9e38df685d..cab33a3680 100644
> --- a/target/ppc/cpu.h
> +++ b/target/ppc/cpu.h
> @@ -131,8 +131,6 @@ enum {
>      POWERPC_EXCP_SYSCALL_VECTORED = 102, /* scv exception                    
>  */
>      /* EOL                                                                   
> */
>      POWERPC_EXCP_NB       = 103,
> -    /* QEMU exceptions: used internally during code translation              
> */
> -    POWERPC_EXCP_BRANCH       = 0x201, /* branch instruction                 
> */
>      /* QEMU exceptions: special cases we want to stop translation            
> */
>      POWERPC_EXCP_SYSCALL_USER = 0x203, /* System call in user mode only      
> */
>  };
> diff --git a/target/ppc/translate.c b/target/ppc/translate.c
> index f57b67be5f..d019454550 100644
> --- a/target/ppc/translate.c
> +++ b/target/ppc/translate.c
> @@ -4692,7 +4692,6 @@ static void gen_b(DisasContext *ctx)
>  {
>      target_ulong li, target;
>  
> -    ctx->exception = POWERPC_EXCP_BRANCH;
>      /* sign extend LI */
>      li = LI(ctx->opcode);
>      li = (li ^ 0x02000000) - 0x02000000;
> @@ -4706,6 +4705,7 @@ static void gen_b(DisasContext *ctx)
>      }
>      gen_update_cfar(ctx, ctx->cia);
>      gen_goto_tb(ctx, 0, target);
> +    ctx->base.is_jmp = DISAS_NORETURN;
>  }
>  
>  #define BCOND_IM  0
> @@ -4718,7 +4718,6 @@ static void gen_bcond(DisasContext *ctx, int type)
>      uint32_t bo = BO(ctx->opcode);
>      TCGLabel *l1;
>      TCGv target;
> -    ctx->exception = POWERPC_EXCP_BRANCH;
>  
>      if (type == BCOND_LR || type == BCOND_CTR || type == BCOND_TAR) {
>          target = tcg_temp_local_new();
> @@ -4825,6 +4824,7 @@ static void gen_bcond(DisasContext *ctx, int type)
>          gen_set_label(l1);
>          gen_goto_tb(ctx, 1, ctx->base.pc_next);
>      }
> +    ctx->base.is_jmp = DISAS_NORETURN;
>  }
>  
>  static void gen_bc(DisasContext *ctx)
> @@ -9102,7 +9102,6 @@ static void ppc_tr_translate_insn(DisasContextBase 
> *dcbase, CPUState *cs)
>      /* Check trace mode exceptions */
>      if (unlikely(ctx->singlestep_enabled & CPU_SINGLE_STEP &&
>                   (ctx->base.pc_next <= 0x100 || ctx->base.pc_next > 0xF00) &&
> -                 ctx->exception != POWERPC_EXCP_BRANCH &&
>                   ctx->base.is_jmp != DISAS_NORETURN)) {
>          uint32_t excp = gen_prep_dbgex(ctx);
>          gen_exception_nip(ctx, excp, ctx->base.pc_next);
> @@ -9118,9 +9117,6 @@ static void ppc_tr_translate_insn(DisasContextBase 
> *dcbase, CPUState *cs)
>          switch (ctx->exception) {
>          case POWERPC_EXCP_NONE:
>              break;
> -        case POWERPC_EXCP_BRANCH:
> -            ctx->base.is_jmp = DISAS_NORETURN;
> -            break;
>          default:
>              /* Every other ctx->exception should have set NORETURN. */
>              g_assert_not_reached();

-- 
David Gibson                    | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au  | minimalist, thank you.  NOT _the_ _other_
                                | _way_ _around_!
http://www.ozlabs.org/~dgibson

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