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Re: [PATCH 4/4] target/s390x: Improve SUB LOGICAL WITH BORROW
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From: |
Richard Henderson |
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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 08:11:07 -0700 |
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User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 |
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~