McCarthy is generally credited with the first JIT for his early LISP work, but SmallTalk and SmallTalk-inspired languages were involved in a lot of the pioneeri

McCarthy is generally credited with the first JIT for his early LISP work, but SmallTalk and SmallTalk-inspired languages were involved in a lot of the pioneering work related to modern JITs. My understanding is that McCarthy's JIT generated machine code as source code was first loaded, not when it was first invoked. As far as I know, the earliest VMs to wait until a function's first invocation to JIT the function were SmallTalk VMs. The Self language by David Ungar and others was an expansion of some of the SmallTalk ideas. If I remember correctly, Self is where polymorphic inline caching originated. Sun acqui-hired Urs Holzle (who did his PhD under Ungar), David Griswald, Gilad Bracha, and Lars Bak for their StrongTalk (statically typed dialect of SmallTalk) hybrid bytecode interpreter/JIT, which was the basis for the HotSpot JVM. Lars Bak later created the original V8 JavaScript JIT for Chrome. When I was on the Google web search indexing team, I did a bit of work running a pre-release V8 in the indexing pipeline (to analyze text and formatting changes made to pages by JavaScript). If I remember correctly, at that time V8 wasn't a hybrid interpreter/JIT, but did quick-and-dirty generation of x86 machine code when a function was first invoked, and leaned heavily on polymorphic inline caching. My understanding is that early V8 was rather similar to the Self VM. I believe ideas like tracing JITs originated a bit further from the SmallTalk ecosystem, but a lot of modern JIT ideas and techniques came from early SmallTalk and related research.