Lit's builtin diff command had some Python 2.7 code paths lying around
that we can probably get rid of at this point. LLVM at this point
requires Python 3.8 at minimum. Keeping lit working at a lower version
is a reasonable goal, but I think we can probably drop python 2 support
at this point given how long it has been deprecated and how long LLVM
has supported Python 3.

Reviewers: jdenny-ornl, ilovepi, petrhosek

Reviewed By: ilovepi

Pull Request: https://github.com/llvm/llvm-project/pull/157558

Previously, llvm-readelf dumped hex format values in different ways.
Some of them were printed in upper-case, while the others were in
lower-case format. This change switches the format to lower-case in all
cases.

Why is this useful? As an example, FileCheck comparisons are
case-sensitive by default. This change means it's easier to compare
those values, because they have the same format.

This patch adds MC support for Zvfbfa
https://github.com/aswaterman/riscv-misc/blob/main/isa/zvfbfa.adoc

Since Zvfbfa implies Zve32f, vector floating-point instructions can be
used directly with Zvfbfa extension.

These extensions were ratified in November 2024.

The script copies `ReleaseNotesTemplate.txt` to corresponding
`ReleaseNotes.rst`/`.md` to clear release notes.

The suffix of `ReleaseNotesTemplate.txt` must be `.txt`. If it is
`.rst`/`.md`, it will be treated as a documentation source file when
building documentation.

It's probably useful for users to know how to get the old scalar
epilogue back if they need it.

Added initial check for potential fmad conversion in reductions and
operands vectorization.

Added the check for instruction to fix #152683

Skipped the code for reduction to avoid regressions.

This reverts commit 0fffb9f9ed81f4c2084b8fe040c88b60bb6c372a due to major
performance regressions.

Added initial check for potential fmad conversion in reductions and
operands vectorization.

Added the check for instruction to fix #152683