jhorstmann commented on code in PR #9848:
URL: https://github.com/apache/arrow-rs/pull/9848#discussion_r3293010151
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parquet/src/util/bit_util.rs:
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@@ -786,6 +786,30 @@ impl From<Vec<u8>> for BitReader {
}
}
+/// Portable parallel bit extract: for each set bit in `mask`, extract
+/// the corresponding bit from `value` and pack them contiguously into
+/// the low bits of the return value.
+///
+/// Equivalent to the x86 BMI2 `PEXT` instruction.
+///
+/// Replace with `value.compress(mask)` when `uint_gather_scatter_bits`
+/// is stabilised: <https://github.com/rust-lang/rust/issues/149069>
+#[inline]
+#[cfg(feature = "arrow")]
+pub(crate) fn compress(value: u64, mut mask: u64) -> u64 {
Review Comment:
We don't have much platform or architecture specific code in arrow-rs, but I
think here it would be worthwhile to use the `std::arch::x86_64::_pext_u64`
intrinsic if the `bmi2` target feature is enabled at compile time. `x86-64-v3`
might be a common enough compilation target.
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