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Re: [PATCH 4/4] target/s390x: Improve SUB LOGICAL WITH BORROW
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From: |
David Hildenbrand |
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Subject: |
Re: [PATCH 4/4] target/s390x: Improve SUB LOGICAL WITH BORROW |
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Date: |
Tue, 20 Oct 2020 17:12:14 +0200 |
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User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.3.1 |
On 20.10.20 17:11, Richard Henderson wrote:
> 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}
Ok, so it's really that simple :)
Thanks!
--
Thanks,
David / dhildenb