[v2,42/51] tcg/optimize: Simplify sign bit test in fold_shift

Commit Message

Richard Henderson Dec. 20, 2024, 4:10 a.m. UTC

Merge the two conditions, sign != 0 && !(z_mask & sign),
by testing ~z_mask & sign.   If sign == 0, the logical and
will produce false.

Signed-off-by: Richard Henderson <[e-mail]>
---
 tcg/optimize.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Pierrick Bouvier Dec. 20, 2024, 8:19 p.m. UTC | #1

On 12/19/24 20:10, Richard Henderson wrote:
> Merge the two conditions, sign != 0 && !(z_mask & sign),
> by testing ~z_mask & sign.   If sign == 0, the logical and
> will produce false.
> 
> Signed-off-by: Richard Henderson <[e-mail]>
> ---
>   tcg/optimize.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/tcg/optimize.c b/tcg/optimize.c
> index da48aadd12..7219415fe2 100644
> --- a/tcg/optimize.c
> +++ b/tcg/optimize.c
> @@ -2590,7 +2590,7 @@ static bool fold_shift(OptContext *ctx, TCGOp *op)
>            * will not reduce the number of input sign repetitions.
>            */
>           sign = (s_mask & -s_mask) >> 1;
> -        if (sign && !(z_mask & sign)) {
> +        if (~z_mask & sign) {
>               return fold_masks_s(ctx, op, s_mask);
>           }
>           break;

Reviewed-by: Pierrick Bouvier <[e-mail]>

Patch

diff --git a/tcg/optimize.c b/tcg/optimize.c
index da48aadd12..7219415fe2 100644
--- a/tcg/optimize.c
+++ b/tcg/optimize.c
@@ -2590,7 +2590,7 @@  static bool fold_shift(OptContext *ctx, TCGOp *op)
          * will not reduce the number of input sign repetitions.
          */
         sign = (s_mask & -s_mask) >> 1;
-        if (sign && !(z_mask & sign)) {
+        if (~z_mask & sign) {
             return fold_masks_s(ctx, op, s_mask);
         }
         break;