From: Richard Henderson <richard.henderson@linaro.org>
To: David Hildenbrand <david@redhat.com>, qemu-devel@nongnu.org
Subject: Re: [PATCH 4/4] target/s390x: Improve SUB LOGICAL WITH BORROW
Date: Tue, 20 Oct 2020 08:11:07 -0700 [thread overview]
Message-ID: <3d014021-bf0c-c2d8-fcc1-a6a66a843353@linaro.org> (raw)
In-Reply-To: <e2bd9942-6fe3-1570-cdc1-2cfd1519e4be@redhat.com>
On 10/20/20 7:17 AM, David Hildenbrand wrote:
>> + case CC_OP_ADDU:
>
> Can you give me a hint how we're converting the carry into a borrow?
>
> Can we apply something similar to compute_carry()?
>
>> + tcg_gen_subi_i64(cc_src, cc_src, 1);
Right here: subtract one.
carry = {1,0} -> borrow = {0,-1}
I'll add some more comments for v2.
r~
next prev parent reply other threads:[~2020-10-20 15:14 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-17 2:28 [PATCH 0/4] target/s390x: Improve carry computation Richard Henderson
2020-10-17 2:28 ` [PATCH 1/4] target/s390x: Improve cc computation for ADD LOGICAL Richard Henderson
2020-10-20 14:08 ` David Hildenbrand
2020-10-17 2:28 ` [PATCH 2/4] target/s390x: Improve ADD LOGICAL WITH CARRY Richard Henderson
2020-10-20 14:12 ` David Hildenbrand
2020-10-17 2:29 ` [PATCH 3/4] target/s390x: Improve cc computation for SUBTRACT LOGICAL Richard Henderson
2020-10-20 14:14 ` David Hildenbrand
2020-10-17 2:29 ` [PATCH 4/4] target/s390x: Improve SUB LOGICAL WITH BORROW Richard Henderson
2020-10-20 14:17 ` David Hildenbrand
2020-10-20 15:11 ` Richard Henderson [this message]
2020-10-20 15:12 ` David Hildenbrand
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