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[97.113.7.119]) by smtp.gmail.com with ESMTPSA id x19sm23076348pgc.59.2019.10.21.08.23.51 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 21 Oct 2019 08:23:51 -0700 (PDT) Subject: Re: [PATCH v2 4/6] s390x/tcg: Fix VECTOR SUBTRACT COMPUTE BORROW INDICATION To: David Hildenbrand , qemu-devel@nongnu.org References: <20191021085715.3797-1-david@redhat.com> <20191021085715.3797-5-david@redhat.com> From: Richard Henderson Openpgp: preference=signencrypt Message-ID: Date: Mon, 21 Oct 2019 08:23:49 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.9.0 MIME-Version: 1.0 In-Reply-To: <20191021085715.3797-5-david@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-Received-From: 2607:f8b0:4864:20::543 X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Ivan Warren , qemu-s390x@nongnu.org, Cornelia Huck , Thomas Huth Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 10/21/19 1:57 AM, David Hildenbrand wrote: > Looks like my idea of what a "borrow" is was wrong. The PoP says: > > "If the resulting subtraction results in a carry out of bit zero, a value > of one is placed in the corresponding element of the first operand; > otherwise, a value of zero is placed in the corresponding element" > > As clarified by Richard, all we have to do is invert the result. > > Fixes: 1ee2d7ba72f6 ("s390x/tcg: Implement VECTOR SUBTRACT COMPUTE BORROW INDICATION") > Signed-off-by: David Hildenbrand > --- > target/s390x/translate_vx.inc.c | 7 ++++--- > target/s390x/vec_int_helper.c | 2 +- > 2 files changed, 5 insertions(+), 4 deletions(-) Reviewed-by: Richard Henderson r~