[tom_mellior]

If you know about abstract interpretation, here are the relevant papers:

https://www.cs.utexas.edu/~tdillig/cs395/octagon.pdf

https://www-apr.lip6.fr/~mine/publi/article-mine-HOSC06.pdf

If you don't know about abstract interpretation, start at https://en.wikipedia.org/wiki/Data-flow_analysis and https://en.wikipedia.org/wiki/Abstract_interpretation

[tom_mellior]

Having said the above, I can't find any other information on JavaScriptCore using octagons. Searching https://trac.webkit.org/browser/trunk/Source/JavaScriptCore for "octagon" yields nothing.