Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
 tcg/optimize.c | 20 +++++++-------------
 1 file changed, 7 insertions(+), 13 deletions(-)

diff --git a/tcg/optimize.c b/tcg/optimize.c
index 49ef039932..d9ccbb36e2 100644
--- a/tcg/optimize.c
+++ b/tcg/optimize.c
@@ -1422,7 +1422,7 @@ static bool fold_addco(OptContext *ctx, TCGOp *op)
 
 static bool fold_and(OptContext *ctx, TCGOp *op)
 {
-    uint64_t z1, z2, z_mask, s_mask;
+    uint64_t z_mask, o_mask, s_mask, a_mask;
     TempOptInfo *t1, *t2;
 
     if (fold_const2_commutative(ctx, op) ||
@@ -1434,18 +1434,9 @@ static bool fold_and(OptContext *ctx, TCGOp *op)
 
     t1 = arg_info(op->args[1]);
     t2 = arg_info(op->args[2]);
-    z1 = t1->z_mask;
-    z2 = t2->z_mask;
 
-    /*
-     * Known-zeros does not imply known-ones.  Therefore unless
-     * arg2 is constant, we can't infer affected bits from it.
-     */
-    if (ti_is_const(t2) && fold_affected_mask(ctx, op, z1 & ~z2)) {
-        return true;
-    }
-
-    z_mask = z1 & z2;
+    z_mask = t1->z_mask & t2->z_mask;
+    o_mask = t1->o_mask & t2->o_mask;
 
     /*
      * Sign repetitions are perforce all identical, whether they are 1 or 0.
@@ -1453,7 +1444,10 @@ static bool fold_and(OptContext *ctx, TCGOp *op)
      */
     s_mask = t1->s_mask & t2->s_mask;
 
-    return fold_masks_zs(ctx, op, z_mask, s_mask);
+    /* Affected bits are those not known zero, masked by those known one. */
+    a_mask = t1->z_mask & ~t2->o_mask;
+
+    return fold_masks_zosa(ctx, op, z_mask, o_mask, s_mask, a_mask);
 }
 
 static bool fold_andc(OptContext *ctx, TCGOp *op)
-- 
2.43.0

On 6/3/25 1:08 AM, Richard Henderson wrote:
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
> ---
>   tcg/optimize.c | 20 +++++++-------------
>   1 file changed, 7 insertions(+), 13 deletions(-)

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