Re: [PATCH v1 5/6] s390x/tcg: Fix VECTOR SUBTRACT WITH BORROW INDICATION

[David Hildenbrand]

On 18.10.19 21:11, Richard Henderson wrote:
> On 10/18/19 9:10 AM, David Hildenbrand wrote:
>> Testing this, there seems to be something messed up. We are dealing with
>> unsigned numbers. "Each operand is treated as an unsigned binary integer."
>> Let's just implement as written in the PoP:
>>
>> "A subtraction is performed by adding the contents of
>>   the second operand with the bitwise complement of
>>   the third operand along with a borrow indication from
>>   the rightmost bit position of the fourth operand and
>>   the result is placed in the first operand."
>>
>> Fixes: 48390a7c2716 ("s390x/tcg: Implement VECTOR SUBTRACT WITH BORROW 
>> INDICATION")
>> Signed-off-by: David Hildenbrand <address@hidden>
>> ---
>>   target/s390x/translate_vx.inc.c | 12 +++++++++---
>>   1 file changed, 9 insertions(+), 3 deletions(-)
> 
> Reviewed-by: Richard Henderson <address@hidden>
> 

I'll convert this patch to

diff --git a/target/s390x/translate_vx.inc.c b/target/s390x/translate_vx.inc.c
index 40bcc1604e..d9403a8163 100644
--- a/target/s390x/translate_vx.inc.c
+++ b/target/s390x/translate_vx.inc.c
@@ -2207,13 +2207,13 @@ static void gen_sbi2_i64(TCGv_i64 dl, TCGv_i64 dh, 
TCGv_i64 al, TCGv_i64 ah,
                          TCGv_i64 bl, TCGv_i64 bh, TCGv_i64 cl, TCGv_i64 ch)
 {
     TCGv_i64 tl = tcg_temp_new_i64();
-    TCGv_i64 zero = tcg_const_i64(0);
+    TCGv_i64 th = tcg_temp_new_i64();
 
-    tcg_gen_andi_i64(tl, cl, 1);
-    tcg_gen_sub2_i64(dl, dh, al, ah, bl, bh);
-    tcg_gen_sub2_i64(dl, dh, dl, dh, tl, zero);
+    tcg_gen_not_i64(tl, bl);
+    tcg_gen_not_i64(th, bh);
+    gen_ac2_i64(dl, dh, al, ah, tl, th, cl, ch);
     tcg_temp_free_i64(tl);
-    tcg_temp_free_i64(zero);
+    tcg_temp_free_i64(th);
 }



-- 

Thanks,

David / dhildenb