Fix overflow bug for >2^32 elements in thrust::shuffle #1074
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RAMitchell
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gevtushenko
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| @@ -69,7 +69,7 @@ class feistel_bijection { | |||
| state[1] = lo & right_side_mask; | |||
| } | |||
| // Combine the left and right sides together to get result | |||
| return static_cast<std::uint64_t>(state[0] << right_side_bits) | static_cast<std::uint64_t>(state[1]); | |||
| return (static_cast<std::uint64_t>(state[0]) << right_side_bits) | static_cast<std::uint64_t>(state[1]); | |||
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remark: right_side_bits is equal to half of problem size. When problem size exceeds 2^31 elements, we used to shift state out of 32 bits, potentially returning 0 instead of state[0] in high 32 bits of 64 bit value. This change fixes the issue by casting the state to 64-bit value first.
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/ok to test |
|
/ok to test |
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Description
closes #1073
This fixes an integer overflow bug caused by an incorrect cast in the
thrust::shuffle()Philox implementation. It also optimises theTestFunctionIsBijection()test to not sort large arrays on the hostChecklist