Slow compilation speed

[jakobnissen]

Automa is a compiler that compiles regular expressions into Julia code. While it produces fast code, the compiler itself (i.e. Automa) is slow. Having worked on the code, I can tell you that it's absolutely not optimised for compilation speed. I'm not sure how big of a deal this is. Presumably all the heavy lifting is done in the precompilation stage. Nonetheless, it would be nice to profile codegen from a complex regex to see just where the bottlenecks are.

[jakobnissen]

A quick profile of compiling a moderately complex regex to a machine:

• 65 % is reduce_nodes(::DFA)
• 18 % is nfa2dfa
• 6% is remove_dead_nodes(::NFA)
• 5 % is re2nfa
• 3 % is remove_dead_nodes(::DFA)

Codegen is more than 10x faster for the same machine, even when using the goto-generator.

That's 97% of total run time. So, optimisation should focus on reduce_nodes and nfa2dfa.

[jakobnissen]

It turns out the large majority was latency. Precompiling made Automa more than 10x faster I'll close this with v1 and reopen if we need more runtime perf in the future