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base repository: postgresql-cfbot/postgresql
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  • 2 commits
  • 10 files changed
  • 3 contributors

Commits on May 31, 2025

  1. Added crc32c extension for ibm s390x based on VX intrinsics 

    The original crc32c-vx code is provided by Hendrik Brueckner
<rueckner@linux.ibm.com>. He kindly gave permission to relicense it under
postgresql-license. I adapted it for the use in postgres.

The IBM S390X platform has no dedicated CRC infrastructure. The algorithm
works by using `reduction constants to fold and process particular chunks
of the input data stream in parallel.` This makes grate use of the S390X
vector units. Depending on the size of the input stream a speedup in the
order of magnitude can be achieved(compared to sb8).

The runtime detection strategy follows the same approach as the ARM code.
If the code is compiled with all needed flags enabled the runtime
detection will not be compiled in. If the build system can enable all
needed flags itself it will also enable runtime detection.

The standard sb8 code is still always compiled and will be used for this
cases:
- the vector units need to operate on double word boundaries. If the input
  stream is not aligned we use sb8 up to the next boundary
- using the vector units for data smaller then 64 byte will neglect the
  speed improvement of the algorithm, as register setup and post
  processing will eat up all benefits.
- the reduction and folding constants are precalculated for 64 byte
  chunks. Adding code for smaller chunks would drastically increase the
  complexity.

Co-authored-by: Hendrik Brueckner <rueckner@linux.ibm.com>
    @fneddy
    2 people authored and Commitfest Bot committed May 31, 2025
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  2. [CF 5779] v1 - Review/Pull Request: Adding new CRC32C implementation … 

    …for IBM S390X

This branch was automatically generated by a robot using patches from an
email thread registered at:

https://commitfest.postgresql.org/patch/5779

The branch will be overwritten each time a new patch version is posted to
the thread, and also periodically to check for bitrot caused by changes
on the master branch.

Patch(es): https://www.postgresql.org/message-id/918d9941377f6e83fbfebe96ba496ccaefa3803f.camel@ibm.com
Author(s): Eduard Stefes
    Commitfest Bot committed May 31, 2025
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