The FTL JIT is JavaScriptCore's top-tier optimizing compiler. It's a combination of our DFG compiler for doing high-level optimizations and type inference, and a lowering phase that turns that code into C-like SSA. The FTL JIT started out as a marriage of the DFG and LLVM, but later LLVM backend was replaced with B3. See https://bugs.webkit.org/show_bug.cgi?id=112840 for the bug that tracked the
