[PATCH] D33588: Fix two sources of UB in __next_hash_pow2 (from __hash_table)

[Vedant Kumar via Phabricator via cfe-commits]

vsk added inline comments.


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Comment at: include/__hash_table:139
 {
-    return size_t(1) << (std::numeric_limits<size_t>::digits - __clz(__n-1));
+    return (__n > 1) ? (size_t(1) << (std::numeric_limits<size_t>::digits - __clz(__n-1))) : __n;
 }
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EricWF wrote:
> Shouldn't this return  `__n + 1` when `__n <= 1`, or even 2 in both cases?
I thought "next_hash_pow2(n)" meant "a hash based on n or the first power-of-two GTE n", but I suppose it's actually "first power-of-two GTE than n, for hash tables". In this case, returning `1` when `__n <= 1` makes the most sense to me, since it's the first power of two GTE 0 and 1. What do you think?


https://reviews.llvm.org/D33588