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[libcxx] Call __count_bool_true for bitset count

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This patch aims to help clang with better information so it can inline
__bit_reference count function usage for both std::biset. Current clang
inliner can not infer that the passed typed will be used only to select
the optimized variant, it evaluates the type argument and type check as
a load plus compare (although later optimization phases correctly
optimized this out).

It is mainly to help llvm inliner to generate better code for std::bitset
count for aarch64. It helps on both runtime and code size, since if inline
decides that _VSTD::count should not be inlined the vectorization will
create both aligned and unaligned variants (which add both code size and
runtime costs)

llvm-svn: 350936
This commit is contained in:
Adhemerval Zanella 2019-01-11 17:31:17 +00:00
parent 1d36253fd8
commit 63ea958521
1 changed files with 1 additions and 1 deletions
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2
libcxx/include/bitset
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@ -991,7 +991,7 @@ inline
size_t
bitset<_Size>::count() const _NOEXCEPT
{
return static_cast<size_t>(_VSTD::count(base::__make_iter(0), base::__make_iter(_Size), true));
return static_cast<size_t>(__count_bool_true(base::__make_iter(0), _Size));
}
template <size_t _Size>