Re: [PATCH 1/1] target-ppc: fix rlwimi, rlwinm, rlwnm for Clang-9

[David Gibson <david@gibson.dropbear.id.au>]

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On Fri, May 01, 2020 at 03:09:13PM -0400, Daniele Buono wrote:
> Starting with Clang v9, -Wtype-limits is implemented and triggers a
> few "result of comparison is always true" errors when compiling PPC32
> targets.
> 
> The comparisons seem to be necessary only on PPC64, since the
> else branch in PPC32 only has a "g_assert_not_reached();" in all cases.
> 
> This patch restructures the code so that PPC32 does not execute the
> check, while PPC64 works like before
> 
> Signed-off-by: Daniele Buono <dbuono@linux.vnet.ibm.com>

Urgh.  #ifdefs intertangled with if statements gets pretty ugly.  But,
then, it's already pretty ugly, so, applied.

> ---
>  target/ppc/translate.c | 34 +++++++++++++++++++---------------
>  1 file changed, 19 insertions(+), 15 deletions(-)
> 
> diff --git a/target/ppc/translate.c b/target/ppc/translate.c
> index 807d14faaa..9400fa2c7c 100644
> --- a/target/ppc/translate.c
> +++ b/target/ppc/translate.c
> @@ -1882,6 +1882,7 @@ static void gen_rlwimi(DisasContext *ctx)
>          tcg_gen_deposit_tl(t_ra, t_ra, t_rs, sh, me - mb + 1);
>      } else {
>          target_ulong mask;
> +        TCGv_i32 t0;
>          TCGv t1;
>  
>  #if defined(TARGET_PPC64)
> @@ -1891,20 +1892,20 @@ static void gen_rlwimi(DisasContext *ctx)
>          mask = MASK(mb, me);
>  
>          t1 = tcg_temp_new();
> +#if defined(TARGET_PPC64)
>          if (mask <= 0xffffffffu) {
> -            TCGv_i32 t0 = tcg_temp_new_i32();
> +#endif
> +            t0 = tcg_temp_new_i32();
>              tcg_gen_trunc_tl_i32(t0, t_rs);
>              tcg_gen_rotli_i32(t0, t0, sh);
>              tcg_gen_extu_i32_tl(t1, t0);
>              tcg_temp_free_i32(t0);
> -        } else {
>  #if defined(TARGET_PPC64)
> +        } else {
>              tcg_gen_deposit_i64(t1, t_rs, t_rs, 32, 32);
>              tcg_gen_rotli_i64(t1, t1, sh);
> -#else
> -            g_assert_not_reached();
> -#endif
>          }
> +#endif
>  
>          tcg_gen_andi_tl(t1, t1, mask);
>          tcg_gen_andi_tl(t_ra, t_ra, ~mask);
> @@ -1938,7 +1939,9 @@ static void gen_rlwinm(DisasContext *ctx)
>          me += 32;
>  #endif
>          mask = MASK(mb, me);
> +#if defined(TARGET_PPC64)
>          if (mask <= 0xffffffffu) {
> +#endif
>              if (sh == 0) {
>                  tcg_gen_andi_tl(t_ra, t_rs, mask);
>              } else {
> @@ -1949,15 +1952,13 @@ static void gen_rlwinm(DisasContext *ctx)
>                  tcg_gen_extu_i32_tl(t_ra, t0);
>                  tcg_temp_free_i32(t0);
>              }
> -        } else {
>  #if defined(TARGET_PPC64)
> +        } else {
>              tcg_gen_deposit_i64(t_ra, t_rs, t_rs, 32, 32);
>              tcg_gen_rotli_i64(t_ra, t_ra, sh);
>              tcg_gen_andi_i64(t_ra, t_ra, mask);
> -#else
> -            g_assert_not_reached();
> -#endif
>          }
> +#endif
>      }
>      if (unlikely(Rc(ctx->opcode) != 0)) {
>          gen_set_Rc0(ctx, t_ra);
> @@ -1972,6 +1973,9 @@ static void gen_rlwnm(DisasContext *ctx)
>      TCGv t_rb = cpu_gpr[rB(ctx->opcode)];
>      uint32_t mb = MB(ctx->opcode);
>      uint32_t me = ME(ctx->opcode);
> +    TCGv_i32 t0;
> +    TCGv_i32 t1;
> +
>      target_ulong mask;
>  
>  #if defined(TARGET_PPC64)
> @@ -1980,9 +1984,11 @@ static void gen_rlwnm(DisasContext *ctx)
>  #endif
>      mask = MASK(mb, me);
>  
> +#if defined(TARGET_PPC64)
>      if (mask <= 0xffffffffu) {
> -        TCGv_i32 t0 = tcg_temp_new_i32();
> -        TCGv_i32 t1 = tcg_temp_new_i32();
> +#endif
> +        t0 = tcg_temp_new_i32();
> +        t1 = tcg_temp_new_i32();
>          tcg_gen_trunc_tl_i32(t0, t_rb);
>          tcg_gen_trunc_tl_i32(t1, t_rs);
>          tcg_gen_andi_i32(t0, t0, 0x1f);
> @@ -1990,17 +1996,15 @@ static void gen_rlwnm(DisasContext *ctx)
>          tcg_gen_extu_i32_tl(t_ra, t1);
>          tcg_temp_free_i32(t0);
>          tcg_temp_free_i32(t1);
> -    } else {
>  #if defined(TARGET_PPC64)
> +    } else {
>          TCGv_i64 t0 = tcg_temp_new_i64();
>          tcg_gen_andi_i64(t0, t_rb, 0x1f);
>          tcg_gen_deposit_i64(t_ra, t_rs, t_rs, 32, 32);
>          tcg_gen_rotl_i64(t_ra, t_ra, t0);
>          tcg_temp_free_i64(t0);
> -#else
> -        g_assert_not_reached();
> -#endif
>      }
> +#endif
>  
>      tcg_gen_andi_tl(t_ra, t_ra, mask);
>  

-- 
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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