Merge branch 'optimize-bounds-refinement-by-reordering-deductions'

Paul Chaignon says:

====================
Optimize bounds refinement by reordering deductions

This patchset optimizes the bounds refinement (reg_bounds_sync) by
reordering deductions in __reg_deduce_bounds. This reordering allows us
to improve precision slightly while losing one call to
__reg_deduce_bounds.

The first patch from Eduard refactors the __reg_deduce_bounds
subfunctions, the second patch implements the reordering, and the last
one adds a selftest.

Changes in v3:
  - Added first commit from Eduard that significantly helps with
    readability of second commit.
  - Reshuffled a bit more the functions in the second commit to improve
    precision (Eduard).
  - Rebased.
Changes in v2:
  - Updated description to mention potential precision improvement and
    to clarify the sequence of refinements (Shung-Hsi).
  - Added the second patch.
  - Rebased.
====================

Link: https://patch.msgid.link/cover.1773401138.git.paul.chaignon@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>