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axic
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Aug 23, 2020
axic
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Aug 23, 2020
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| return result; | ||
| const auto t = std::trunc(value); | ||
| if (const auto diff = std::abs(value - t); diff > 0.5f || (diff == 0.5f && !is_even(t))) |
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Wouldn't it be less branching to have two if cases than using abs? Or is abs constexpr and the compiler can optimise all this out?
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The abs (or fabs in C) is recognized and replaced with __builtin_abs or something. This just masks out the sign bit: x & 0x7fffffff.
Codecov Report
@@ Coverage Diff @@
## master #504 +/- ##
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- Coverage 99.69% 99.69% -0.01%
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Files 54 54
Lines 17198 17180 -18
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- Hits 17146 17128 -18
Misses 52 52 |
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I also have another implementation based on bit manipulation which looks to be faster but I did not perform proper benchmarks yet. We may wait with that for the next release until having more FP test cases. |
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I'm checking some additional options because there are some performance regressions. |
This implementation does not need to modify rounding direction to work correctly under any rounding direction.
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GCC: GCC+LTO: So not really significant difference (none of the benchmarks uses this instruction). The change is not driven by performance anyway. When marking the function with |
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This implementation does not need to modify rounding direction to work
correctly under any rounding direction.