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Don't call bit_width if value is nullptr in _Fmt_write #2097

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Merged
StephanTLavavej merged 11 commits into from
Aug 27, 2021
Merged

Don't call bit_width if value is nullptr in _Fmt_write #2097

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5058a74
Don't call bit_width if value is nullptr
AZero13 Aug 5, 2021
ea1b875
initialize variable at start
AZero13 Aug 7, 2021
ae6e1e6
Fix issue
AZero13 Aug 7, 2021
6b5f2e2
Remove newline
AZero13 Aug 9, 2021
00043fa
divide and then convert to int
AZero13 Aug 15, 2021
24bacea
make it even faster with builtin_expect
AZero13 Aug 15, 2021
dde4621
Fix
AZero13 Aug 15, 2021
fc51cbb
Format fix
AZero13 Aug 15, 2021
9034550
Remove __builtin_expect
AZero13 Aug 15, 2021
3894e54
Add comment
AZero13 Aug 15, 2021
737ce4a
Fix comment
AZero13 Aug 17, 2021
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17 changes: 8 additions & 9 deletions stl/inc/format
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Original file line number Diff line number Diff line change
Expand Up @@ -2493,15 +2493,14 @@ _NODISCARD _OutputIt _Fmt_write(
_THROW(format_error("const void* cannot be localized"));
}

// Compute the bit width of the pointer (i.e. how many bits it takes to be represented).
// Add 3 to the bit width so we always round up on the division.
// Divide that by the amount of bits a hexit represents (log2(16) = log2(2^4) = 4).
// Add 2 for the 0x prefix.
auto _Width = 2 + static_cast<int>(_STD bit_width(reinterpret_cast<uintptr_t>(_Value)) + 3) / 4;

// Since the bit width of 0 is 0, special case it instead of complicating the math even more.
if (_Value == nullptr) {
_Width = 3;
// Since the bit width of 0 is 0x0, special-case it instead of complicating the math even more.
int _Width = 3;
if (_Value != nullptr) {
// Compute the bit width of the pointer (i.e. how many bits it takes to be represented).
// Add 3 to the bit width so we always round up on the division.
// Divide that by the amount of bits a hexit represents (log2(16) = log2(2^4) = 4).
// Add 2 for the 0x prefix.
_Width = static_cast<int>(2 + (_STD bit_width(reinterpret_cast<uintptr_t>(_Value)) + 3) / 4);
}

return _Write_aligned(_STD move(_Out), _Width, _Specs, _Fmt_align::_Left,
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