[$] Improved code generation in the CPython JIT

Ken Jin from the
Faster CPython
project has been working on
taking Python's
recently-added just-in-time (JIT) compiler
further by adding
support for a peephole optimizer
that rewrites the JIT's intermediate representation to introduce
constant folding, type specialization, and other optimizations.
Those techniques should provide significant benefits for the
performance of many different types of code running on CPython.