Skip to content

GH-55247: [C++][Parquet] Optimize ALP Decompress in clang + x86 #55248

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
mapleFU wants to merge 1 commit into
base: main
Choose a base branch
from
+4 −1
Open

GH-55247: [C++][Parquet] Optimize ALP Decompress in clang + x86 #55248

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
5 changes: 4 additions & 1 deletion cpp/src/arrow/util/alp/alp_compression.cc
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -561,10 +561,13 @@ void AlpCompression<T>::Decompress(const AlpEncodedVectorView<T>& encoded_view,
// Fused unFOR + decode loop: undo FOR in unsigned arithmetic, reinterpret the
// result as signed encoded integers, then apply the normative decimal decode.
const EncodedUnsigned frame_of_ref = for_info.frame_of_reference();
// Read the exponent/factor once. AlpInfo stores them as uint8_t, which may
// alias the output stores, so reading them inside the loop blocks vectorization.
const AlpExponentAndFactor exponent_and_factor = alp_info.GetExponentAndFactor();
for (size_t i = 0; i < output.size(); ++i) {
const EncodedUnsigned unfored_value = scratch[i] + frame_of_ref;
const EncodedSigned signed_value = util::SafeCopy<EncodedSigned>(unfored_value);
output[i] = AlpInlines<T>::DecodeValue(signed_value, alp_info.GetExponentAndFactor());
output[i] = AlpInlines<T>::DecodeValue(signed_value, exponent_and_factor);
}

PatchExceptions<TargetType>(
Expand Down
Loading