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author | Jonathan Wakely <jwakely@redhat.com> | 2018-11-21 18:40:37 +0000 |
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committer | Jonathan Wakely <redi@gcc.gnu.org> | 2018-11-21 18:40:37 +0000 |
commit | afd02e4c676dec5b06088a27c2152d772902e0be (patch) | |
tree | db39b72dbf03665f8a60d374f1be08578b689aa0 /libstdc++-v3/src/c++17 | |
parent | 4cd5da011d6174e7cb152913acac760fb4a84c11 (diff) | |
download | gcc-afd02e4c676dec5b06088a27c2152d772902e0be.zip gcc-afd02e4c676dec5b06088a27c2152d772902e0be.tar.gz gcc-afd02e4c676dec5b06088a27c2152d772902e0be.tar.bz2 |
PR libstdc++/88113 use size_type consistently instead of size_t
On 16-bit msp430-elf size_t is either 16 bits or 20 bits, and so can't
represent all values of the uint32_t type used for bitset::size_type.
Using the smaller of size_t and uint32_t for size_type ensures it fits
in size_t.
PR libstdc++/88113
* src/c++17/memory_resource.cc (bitset::size_type): Use the smaller
of uint32_t and size_t.
(bitset::size(), bitset::free(), bitset::update_next_word())
(bitset::max_blocks_per_chunk(), bitset::max_word_index()): Use
size_type consistently instead of size_t.
(chunk): Adjust static_assert checking sizeof(chunk).
From-SVN: r266352
Diffstat (limited to 'libstdc++-v3/src/c++17')
-rw-r--r-- | libstdc++-v3/src/c++17/memory_resource.cc | 29 |
1 files changed, 17 insertions, 12 deletions
diff --git a/libstdc++-v3/src/c++17/memory_resource.cc b/libstdc++-v3/src/c++17/memory_resource.cc index a376631..6198e6b 100644 --- a/libstdc++-v3/src/c++17/memory_resource.cc +++ b/libstdc++-v3/src/c++17/memory_resource.cc @@ -252,11 +252,13 @@ namespace pmr namespace { - // Simple bitset with runtime size. Tracks used blocks in a pooled chunk. + // Simple bitset with runtime size. + // Tracks which blocks in a pool chunk are used/unused. struct bitset { using word = uint64_t; - using size_type = uint32_t; + using size_type // unsigned integer type with no more than 32 bits + = conditional_t<numeric_limits<size_t>::digits <= 32, size_t, uint32_t>; static constexpr unsigned bits_per_word = numeric_limits<word>::digits; @@ -269,7 +271,7 @@ namespace pmr __builtin_memset(_M_words, 0, last_word * sizeof(*_M_words)); // Set bits beyond _M_size, so they are not treated as free blocks: if (const size_type extra_bits = num_blocks % bits_per_word) - _M_words[last_word] = (word)-1 << extra_bits; + _M_words[last_word] = word(-1) << extra_bits; __glibcxx_assert( empty() ); __glibcxx_assert( free() == num_blocks ); } @@ -278,12 +280,12 @@ namespace pmr ~bitset() = default; // Number of blocks - size_t size() const noexcept { return _M_size; } + size_type size() const noexcept { return _M_size; } // Number of free blocks (unset bits) - size_t free() const noexcept + size_type free() const noexcept { - size_t n = 0; + size_type n = 0; for (size_type i = _M_next_word; i < nwords(); ++i) n += (bits_per_word - std::__popcount(_M_words[i])); return n; @@ -376,7 +378,7 @@ namespace pmr // this function saturates _M_next_word at max_word_index(). void update_next_word() noexcept { - size_t next = _M_next_word; + size_type next = _M_next_word; while (_M_words[next] == word(-1) && ++next < nwords()) { } _M_next_word = std::min(next, max_word_index()); @@ -397,11 +399,11 @@ namespace pmr { return (_M_size + bits_per_word - 1) / bits_per_word; } // Maximum value that can be stored in bitset::_M_size member (approx 500k) - static constexpr size_t max_blocks_per_chunk() noexcept - { return (1ull << _S_size_digits) - 1; } + static constexpr size_type max_blocks_per_chunk() noexcept + { return (size_type(1) << _S_size_digits) - 1; } // Maximum value that can be stored in bitset::_M_next_word member (8191). - static constexpr size_t max_word_index() noexcept + static constexpr size_type max_word_index() noexcept { return (max_blocks_per_chunk() + bits_per_word - 1) / bits_per_word; } word* data() const noexcept { return _M_words; } @@ -519,9 +521,12 @@ namespace pmr { return std::less<const void*>{}(p, c._M_p); } }; - // For 64-bit this is 3*sizeof(void*) and for 32-bit it's 4*sizeof(void*). + // For 64-bit pointers this is the size of three pointers i.e. 24 bytes. + // For 32-bit and 20-bit pointers it's four pointers (16 bytes). + // For 16-bit pointers it's five pointers (10 bytes). // TODO pad 64-bit to 4*sizeof(void*) to avoid splitting across cache lines? - static_assert(sizeof(chunk) == 2 * sizeof(uint32_t) + 2 * sizeof(void*)); + static_assert(sizeof(chunk) + == sizeof(bitset::size_type) + sizeof(uint32_t) + 2 * sizeof(void*)); // An oversized allocation that doesn't fit in a pool. struct big_block |