mem: Short-circuit identical slices

abd19748a096878108a455f9c0b6d8afa244b2f533849ab65289ae64e1471e13 
`eq` compared every byte even when equal-length slices shared the
same backing address.

Recognize pointer identity after checking the lengths. Canonical
strings and repeated slice comparisons can now return without
traversing their contents.

Assisted-by: Codex:gpt-5.6-sol
Alexis Sellier committed ago 1 parent f2ff6b8e
lib/std/mem.rad +3 -0
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/// Check whether two byte slices have the same length and contents.
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export fn eq(a: *[u8], b: *[u8]) -> bool {
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    if a.len <> b.len {
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        return false;
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    }
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    if a.ptr == b.ptr {
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        return true;
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    }
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    for i in 0..a.len {
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        if a[i] <> b[i] {
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            return false;
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        }
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    }