Re: [PATCH v2 05/51] tcg/optimize: Augment s_mask from z_mask in fold_masks_zs

[Pierrick Bouvier]

On 12/19/24 20:10, Richard Henderson wrote:
> Consider the passed s_mask to be a minimum deduced from
> either existing s_mask or from a sign-extension operation.
> We may be able to deduce more from the set of known zeros.
> Remove identical logic from several opcode folders.
>
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
> ---
>   tcg/optimize.c | 12 +++---------
>   1 file changed, 3 insertions(+), 9 deletions(-)
>
> diff --git a/tcg/optimize.c b/tcg/optimize.c
> index d70127b88d..17b72fe759 100644
> --- a/tcg/optimize.c
> +++ b/tcg/optimize.c
> @@ -1048,6 +1048,7 @@ static bool fold_const2_commutative(OptContext *ctx, 
> TCGOp *op)
>    * Record "zero" and "sign" masks for the single output of @op.
>    * See TempOptInfo definition of z_mask and s_mask.
>    * If z_mask allows, fold the output to constant zero.
> + * The passed s_mask may be augmented by z_mask.
>    */
>   static bool fold_masks_zs(OptContext *ctx, TCGOp *op,
>                             uint64_t z_mask, uint64_t s_mask)
> @@ -1080,7 +1081,7 @@ static bool fold_masks_zs(OptContext *ctx, TCGOp *op,
>   
>       ti = ts_info(ts);
>       ti->z_mask = z_mask;
> -    ti->s_mask = s_mask;
> +    ti->s_mask = s_mask | smask_from_zmask(z_mask);
>       return true;
>   }
>   
> @@ -1519,8 +1520,8 @@ static bool fold_bswap(OptContext *ctx, TCGOp *op)
>       default:
>           g_assert_not_reached();
>       }
> -    s_mask = smask_from_zmask(z_mask);
>   
> +    s_mask = 0;
>       switch (op->args[2] & (TCG_BSWAP_OZ | TCG_BSWAP_OS)) {
>       case TCG_BSWAP_OZ:
>           break;
> @@ -1534,7 +1535,6 @@ static bool fold_bswap(OptContext *ctx, TCGOp *op)
>       default:
>           /* The high bits are undefined: force all bits above the sign to 1. */
>           z_mask |= sign << 1;
> -        s_mask = 0;
>           break;
>       }
>       ctx->z_mask = z_mask;
> @@ -1605,7 +1605,6 @@ static bool fold_count_zeros(OptContext *ctx, TCGOp *op)
>           g_assert_not_reached();
>       }
>       ctx->z_mask = arg_info(op->args[2])->z_mask | z_mask;
> -    ctx->s_mask = smask_from_zmask(ctx->z_mask);
>       return false;
>   }
>   
> @@ -1625,7 +1624,6 @@ static bool fold_ctpop(OptContext *ctx, TCGOp *op)
>       default:
>           g_assert_not_reached();
>       }
> -    ctx->s_mask = smask_from_zmask(ctx->z_mask);
>       return false;
>   }
>   
> @@ -1746,7 +1744,6 @@ static bool fold_extract(OptContext *ctx, TCGOp *op)
>           return true;
>       }
>       ctx->z_mask = z_mask;
> -    ctx->s_mask = smask_from_zmask(z_mask);
>   
>       return fold_masks(ctx, op);
>   }
> @@ -1851,7 +1848,6 @@ static bool fold_extu(OptContext *ctx, TCGOp *op)
>       }
>   
>       ctx->z_mask = z_mask;
> -    ctx->s_mask = smask_from_zmask(z_mask);
>       if (!type_change && fold_affected_mask(ctx, op, z_mask_old ^ z_mask)) {
>           return true;
>       }
> @@ -2354,7 +2350,6 @@ static bool fold_setcond(OptContext *ctx, TCGOp *op)
>       fold_setcond_tst_pow2(ctx, op, false);
>   
>       ctx->z_mask = 1;
> -    ctx->s_mask = smask_from_zmask(1);
>       return false;
>   }
>   
> @@ -2455,7 +2450,6 @@ static bool fold_setcond2(OptContext *ctx, TCGOp *op)
>       }
>   
>       ctx->z_mask = 1;
> -    ctx->s_mask = smask_from_zmask(1);
>       return false;
>   
>    do_setcond_const:

Reviewed-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>