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NFC: external_pointer s/size/chunkmap_slab_kind/

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While here, SNMALLOC_ASSERT() that large allocs end up with sensible slab kind
values.
This commit is contained in:
Nathaniel Filardo
2021-03-05 16:52:40 +00:00
committed by Matthew Parkinson
parent 4f6cf8cb40
commit 08344cfa94
1 changed files with 13 additions and 9 deletions
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22
src/mem/alloc.h
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@@ -363,10 +363,10 @@ namespace snmalloc
error("Unsupported");
UNUSED(p);
#else
uint8_t size = ChunkMap::get(address_cast(p));
uint8_t chunkmap_slab_kind = ChunkMap::get(address_cast(p));
Superslab* super = Superslab::get(p);
if (size == CMSuperslab)
if (chunkmap_slab_kind == CMSuperslab)
{
Slab* slab = Metaslab::get_slab(p);
Metaslab& meta = super->get_meta(slab);
@@ -376,7 +376,7 @@ namespace snmalloc
return external_pointer<location>(p, sc, slab_end);
}
if (size == CMMediumslab)
if (chunkmap_slab_kind == CMMediumslab)
{
Mediumslab* slab = Mediumslab::get(p);
@@ -388,17 +388,17 @@ namespace snmalloc
auto ss = super;
while (size >= CMLargeRangeMin)
while (chunkmap_slab_kind >= CMLargeRangeMin)
{
// This is a large alloc redirect.
ss = pointer_offset_signed(
ss,
-(static_cast<ptrdiff_t>(1)
<< (size - CMLargeRangeMin + SUPERSLAB_BITS)));
size = ChunkMap::get(ss);
<< (chunkmap_slab_kind - CMLargeRangeMin + SUPERSLAB_BITS)));
chunkmap_slab_kind = ChunkMap::get(ss);
}
if (size == 0)
if (chunkmap_slab_kind == CMNotOurs)
{
if constexpr ((location == End) || (location == OnePastEnd))
// We don't know the End, so return MAX_PTR
@@ -408,13 +408,17 @@ namespace snmalloc
return nullptr;
}
SNMALLOC_ASSERT(
(chunkmap_slab_kind >= CMLargeMin) &&
(chunkmap_slab_kind <= CMLargeMax));
// This is a large alloc, mask off to the slab size.
if constexpr (location == Start)
return ss;
else if constexpr (location == End)
return pointer_offset(ss, (bits::one_at_bit(size)) - 1);
return pointer_offset(ss, (bits::one_at_bit(chunkmap_slab_kind)) - 1);
else
return pointer_offset(ss, bits::one_at_bit(size));
return pointer_offset(ss, bits::one_at_bit(chunkmap_slab_kind));
#endif
}