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Eliminated SmallIntSet #7934

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Eliminated SmallIntSet #7934

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sfackler
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SmallIntSet is equivalent to BitvSet but with 64 times the memory
overhead. There's no reason for it to exist.

SmallIntSet's overhead should really only be 8 times, but for some
reason, sys::size_of::<Option<()>>() == 8, not 1.

@huonw
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huonw commented Jul 20, 2013

The reason that Option<()> is 8 bytes is because the discriminant is always word size, rather than shrinking to be the minimum possible (#1647).

@thestinger
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I don't think these are really equivalent. If you add 1, 2 and 3 to SmallIntSet, it will contain them as 3 distinct elements. If you only insert 1 and 2, it will not contain 3. I might be misunderstanding what BitvSet is, but I thought it was a set of bits.

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huonw commented Jul 21, 2013

@thestinger nth bit set == n in the BitvSet. (At least, that's the current semantics.)

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Ah.

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huonw commented Jul 21, 2013

@sfackler needs a rebase.

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@huonw Done.

@sfackler
Eliminated SmallIntSet
8eb6d2d 
SmallIntSet is equivalent to BitvSet but with 8 times the memory
overhead. There's no reason for it to exist.
bors added a commit that referenced this pull request Jul 23, 2013
@bors
auto merge of #7934 : sfackler/rust/smallintset, r=alexcrichton
dfdb72d 
SmallIntSet is equivalent to BitvSet but with 64 times the memory
overhead. There's no reason for it to exist.

SmallIntSet's overhead should really only be 8 times, but for some
reason, `sys::size_of::<Option<()>>() == 8`, not 1.
@bors bors closed this Jul 23, 2013
flip1995 pushed a commit to flip1995/rust that referenced this pull request Nov 23, 2021
@bors
Auto merge of rust-lang#7945 - Serial-ATA:issue-7934, r=flip1995
6fcdf81 
Fix ICE in undocumented_unsafe_blocks

changelog: Fix ICE in [`undocumented_unsafe_blocks`]

closes: rust-lang#7934
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@sfackler @huonw @thestinger @alexcrichton @bors