https://outerproduct.net/boring/2023-03-22_cpu-compiler-gc-ohmy.html

A CPU is a compiler

2023-03-22

Strictly speaking, a CPU is an interpreter; it is certainly not a
compiler and, unless you can come up with a second implementation of
physics, the standard tricks to turn it into one won't work either.
And yet, when comparing with software implementations of programming
languages, a CPU seems closest to the back end of an optimising
compiler; all sorts of duals seem to show up:

   Compiler         CPU                        Notes
Instruction    Instruction
scheduling     scheduling
JIT            Microcoding,
               uop cache
Branch         Branch
probability    prediction     I find the contrast here particularly
analysis                      interesting.
Inline cache   Branch target
               buffer
Instruction    Fusion
selection
Register       Register
allocation     renaming
Coalescing     Move
               elimination
Alias analysis Memory
               disambiguation
Scalar         Memory
replacement of renaming
aggregates
                              For instance, a compiler might
                              recognise a sequence for performing a
Peephole                      rotate, byte-swap, or population count,
optimisations, Idioms         when such functionality is supported
idioms                        natively by the target, but not by the
                              source. A CPU might recognise an xor or
                              subtraction of a register from itself
                              as producing a zero.
Parallelising  Superscalar
compiler,      CPU
scheduler
               Pipelining,
Pipelining     memory-level   Very different types of pipelining!
               parallelism
Block, trace   Trace

I find it somewhat irksome that we don't refer to static register
allocation and dynamic register allocation--etc.--as this would make
the relationship between CPUs and compilers much clearer. Some of the
ties here are admittedly too tenuous for this to really work out, but
many are not.

Here's some garbage collection, as a bonus:

    Garbage collector             CPU                  Notes
Generational garbage       QLRU cache
collection                 replacement
Write barrier              Snooping
Read barrier               TLB lookup         Particularly a use
                                              barrier.
Self-healing               TLB miss/update
Forwarding pointer         Page table entry
Snapshot or recolour roots TLB shootdown