BRbri3d·Dec 13, 2017
Many languages use "inline method caching" - that is, a "call_dynamic x_named_method" bytecode is replaced with a "guard_and_call_static 0xfffffff" once the callsite is evaluated. In some languages invalidating this cache by calling a method with polymorphic arguments or altering the receiving class can be extremely expensive, so there are usually second-order optimizations applied.
Objective-C: Takes one method pointer indirection / jmp trampoline forever, but caches "selectors" on the class so that they become a simple lookup rather than a full evaluation. See sibling comments for better write-ups than I could find.
Most JS runtimes: Trace JITs mean many method invocations are compiled into traces and become either inline instructions or native function calls. Also uses "hidden classes" to implement inline method caching, where the call
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site is replaced with the specific address of the call once the dispatch is resolved. https://github.com/sq/JSIL/wiki/Optimizing-dynamic-JavaScrip... , https://blog.ghaiklor.com/optimizations-tricks-in-v8-d284b6c...
Ruby: Also uses inline method caching - when a method is resolved that callsite is replaced with a jump straight to the resolved method in the bytecode. Invalidation used to occur any time a class was modified in any way but has been made more specific over time: https://github.com/charliesome/charlie.bz/blob/master/posts/...