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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 3.0 on 10.30.177.17 On 9/17/26 18:09, Hao Peng wrote: >> ... I love it, but it's unreadable. The "mask << -delta >> -delta" >> basically means no overflow on shift left. So just write >> >> if (!check_shl_overflow(mask, -delta, shifted_mask)) { >> cur_offset = next_offset; >> mask = shifted_mask | 1; >> } >> > Yes, check_shl_overflow() expresses the intent much more clearly than > the leading-zero calculation. > > I will use it together with an unsigned shift calculated directly from > cur_offset and next_offset. That also avoids evaluating -delta when > delta is S64_MIN. That would require a 2^(64+12) bit address space, so it cannot happen I think? > Something along these lines: > > unsigned long shifted_mask; > u64 shift = abs_diff(next_offset, cur_offset); > > if (next_offset < cur_offset && > !check_shl_overflow(mask, shift, &shifted_mask)) { > cur_offset = next_offset; > mask = shifted_mask | BIT(0); > continue; > } shift can be just cur_offset - next_offset here, and it can be placed in the call to check_shl_overflow(). Paolo