For people who enjoy these blogs, you would definitely like the Julia REPL as well. I used to play with this a lot to discover compiler things.
For example:
$ julia
julia> function f(n)
total = 0
for x in 1:n
total += x
end
return total
end
julia> @code_native f(10)
...
sub x9, x0, #2
mul x10, x8, x9
umulh x8, x8, x9
extr x8, x8, x10, #1
add x8, x8, x0, lsl #1
sub x0, x8, #1
ret
...
it shows this with nice colors right in the REPL.
In the example above, you see that LLVM figured out the arithmetic series and replaced the loop with a simple multiplication.
This and add_v3 in the OP fall into the general class of Scalar Evolution optimizations (SCEV). LLVM for example is able to handle almost all Brainfuck loops in practice---add_v3 indeed corresponds to a Brainfuck loop `[->+<]`---, and its SCEV implementation is truly massive: https://github.com/llvm/llvm-project/blob/main/llvm/lib/Anal...
For example:
it shows this with nice colors right in the REPL.In the example above, you see that LLVM figured out the arithmetic series and replaced the loop with a simple multiplication.