[performance-test] node static map vs is_a() check of node type

[TomasVotruba]

I was wonder whether this is the fastest way to mach a $node object against getNodeTypes() string node-class types.
As we do now in RectorNodeTraverser:

/**
     * @return NodeVisitor[]
     */
    public function getVisitorsForNode(Node $node): array
    {
        $nodeClass = $node::class;

        if (! isset($this->visitorsPerNodeClass[$nodeClass])) {
            $this->visitorsPerNodeClass[$nodeClass] = [];
            /** @var RectorInterface $visitor */
            foreach ($this->visitors as $visitor) {
                foreach ($visitor->getNodeTypes() as $nodeType) {
                    if (is_a($nodeClass, $nodeType, true)) {
                        $this->visitorsPerNodeClass[$nodeClass][] = $visitor;
                        continue 2;
                    }
                }
            }
        }

        return $this->visitorsPerNodeClass[$nodeClass];
    }

Alternative approach - constant map

• has a node class map that checks instance mapping e.g. FunctionLike::class => [ClassMethod::class, Function_::class]... and in_array()

I'm dumping the script here, so we know how it performs, and have comparison for the future. + For anyone who might be interasted in real numbers :)

Run

php scripts/bench/node-lookup-vs-instanceof.php

Results

Traversals per run: 10000
Runs: 10

Average time per traversed file (nanoseconds):
Static table:           9821.06816 ns
is_a() check:           8219.7443 ns

Ratio (table / is_a): 1.1948143155743

Ignore sink: 0

The is_a() is still fastest way to check node type, by ~20 % ✔️

[TomasVotruba]

cc @staabm Hi Markus, I'm ccing you here in case you'd be working on php-parser related optimizations :)
I'm testing various experiment to see what is the bottleneck when it comes to node instances and traversing.