Improved performance of comparison with SIMD feature flag (2x-3.5x)

[jorgecarleitao]

This PR adds explicit SIMD implementations to comparison compute.

By operating over groups of 8 and applying the relevant conversions with native packed_simd2 apis, we gain 2-3.5x in performance. There is no difference in performance over the non-simd implementation; it was just written in a more abstract fashion to allow the simd version to be plugged in.

cargo bench --no-default-features --features benchmarks,compute --bench comparison_kernels
cargo bench --no-default-features --features benchmarks,compute,simd --bench comparison_kernels

eq Float32              time:   [20.319 us 20.394 us 20.492 us]                        
                        change: [-70.496% -70.317% -70.165%] (p = 0.00 < 0.05)

eq scalar Float32       time:   [16.452 us 16.512 us 16.585 us]                               
                        change: [-54.292% -53.941% -53.602%] (p = 0.00 < 0.05)

lt Float32              time:   [19.904 us 19.972 us 20.063 us]                        
                        change: [-67.563% -67.329% -67.084%] (p = 0.00 < 0.05)

lt scalar Float32       time:   [16.410 us 16.467 us 16.541 us]                               
                        change: [-54.324% -54.088% -53.814%] (p = 0.00 < 0.05)

[jorgecarleitao]

There is an extra optimization in using the more natural md representation of the native types, but it requires a bit more work on the MutableBitmap to be safely constructed from u8-u64 chunks

[codecov]

Codecov Report

Merging #305 (afaff93) into main (bbe607c) will increase coverage by 0.01%.
The diff coverage is 94.64%.

@@            Coverage Diff             @@
##             main     #305      +/-   ##
==========================================
+ Coverage   80.52%   80.53%   +0.01%     
==========================================
  Files         323      324       +1     
  Lines       21135    21151      +16     
==========================================
+ Hits        17019    17034      +15     
- Misses       4116     4117       +1     

Impacted Files	Coverage Δ
src/compute/comparison/mod.rs	93.61% <ø> (ø)
src/compute/nullif.rs	0.00% <0.00%> (ø)
src/compute/comparison/simd/mod.rs	95.83% <95.83%> (ø)
src/compute/comparison/primitive.rs	95.09% <100.00%> (-0.23%)	⬇️

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