9prady9 commented on a change in pull request #11674:
URL: https://github.com/apache/arrow/pull/11674#discussion_r748047932
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File path: cpp/src/arrow/util/bitmap_ops.cc
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@@ -249,59 +249,92 @@ void AlignedBitmapOp(const uint8_t* left, int64_t
left_offset, const uint8_t* ri
left += left_offset / 8;
right += right_offset / 8;
out += out_offset / 8;
+ uint64_t outPopCount = 0;
for (int64_t i = 0; i < nbytes; ++i) {
out[i] = op(left[i], right[i]);
+ if (ComputeNewValidityCount) {
+ outPopCount += BitUtil::kBytePopcount[out[i]];
Review comment:
I have checked it with clang shouldn't be different with gcc/msvc. Here
is the godbolt snippet with vectorization flags showing same type of
vectorization happening with pop-count and without.
https://godbolt.org/z/bGhdGEjr6
Yeah, M/s is my mistake. Those are numbers from debug build I did, I forgot
to switch to release. With release, the numbers are much higher. I shall
update the description with new numbers soon and with benchmark labels.
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