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Description of problem:

Our current Python3 packages are built without "Expensive" (e.g. LTO, PGO) optimizations enabled. There's a section in specfile that looks like this:

$ grep -A7 Expensive python3.spec
# Expensive optimizations (mainly, profile-guided optimizations)
%ifarch %{ix86} x86_64
%bcond_without optimizations
%else
# On some architectures, the optimized build takes tens of hours, possibly
# longer than Koji's 24-hour timeout. Disable optimizations here.
%bcond_with optimizations
%endif

Where apparently we don't turn on these performance optimizations for aarch64, but only for x86, however allegedly the perf benefit would be 30%! We should thus consider urgently enabling these performance features if the builds aren't negatively impacted in terms of build time, etc.

# On some architectures, the optimized build takes tens of hours, possibly
# longer than Koji's 24-hour timeout. Disable optimizations here.
%bcond_with optimizations

A solution for that is to backport the following change from Python 3.8 (upstream) to Python 3.6 (downstream):

* https://bugs.python.org/issue36044
* https://github.com/python/cpython/commit/4e16a4a3112161a5c6981c0588142d4a4673a934
* https://github.com/python/cpython/commit/e1b900247227dad49d8231f1d028872412230ab4

In short: the PGO build runs only a few tests rather than the full Python test suite to train the compiler, so the build is way faster.

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://access.redhat.com/errata/RHSA-2020:1764