[PATCH] target/arm: Fix SVE2 WHILEWR/WHILERW zero diff boundary case

From: YanjunYang <[email protected]>

The trans_WHILE_ptr function incorrectly handles the case where the
address difference divided by ESIZE results in zero. This happens when
the address difference is less than ESIZE but greater than zero.

In this boundary case, the address difference is less than ESIZE, which
means all elements are safe from conflicts. The previous code would set
the predicate to all zeros, but the correct behavior is to set all
elements to one.

Fix by checking if diff == 0 after the shift and setting diff to tmax
(all elements true) in this case.

Fixes the following test cases:
  whilewr p0.s, x9, x10  ; x9=8, x10=11 => p0=0xffffffff (all ones)
  whilerw p0.s, x9, x10  ; x9=8, x10=11 => p0=0xffffffff (all ones)

Signed-off-by: YanjunYang <[email protected]>
---
 target/arm/tcg/translate-sve.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/target/arm/tcg/translate-sve.c b/target/arm/tcg/translate-sve.c
index fc4cc8c479..33613ebf58 100644
--- a/target/arm/tcg/translate-sve.c
+++ b/target/arm/tcg/translate-sve.c
@@ -3736,6 +3736,10 @@ static bool trans_WHILE_ptr(DisasContext *s, arg_WHILE_ptr *a)
         tcg_gen_movcond_i64(TCG_COND_GEU, diff, op0, op1, tmax, diff);
     }

+    /* If diff == 0, the address difference is less than ESIZE,
+       so all elements are safe from conflicts. */
+    tcg_gen_movcond_i64(TCG_COND_EQ, diff, diff, tcg_constant_i64(0), tmax, diff);
+
     /* Bound to the maximum.  */
     tcg_gen_umin_i64(diff, diff, tmax);

-- 
2.43.0