| I think the WASM world is a clear example that bridges the gap you're describing. You usually compile from SSA to WASM bytecode, and then immediately JIT (Cranelift) by reconstructing an SSA-like graph IR. If you look at the flow, it's basically: Graph IR -> WASM (stack-based bytecode) -> Graph IR So the stack-based IR is used as a kind of IR serialization layer. Then I realized that this works well because a stack-based IR is just a linearized encoding of a dataflow graph. The data dependencies are implicit in the stack discipline, but they can be recovered mechanically.
Once you see that, the blindness mostly disappears, since the difference between SSA/graph IRs and expression/stack-based IRs is about how the dataflow (mostly around def-use chains) is represented rather than about what optimizations are possible. Fom there it becomes fairly obvious that graph IR techniques can be applied to expression-based structures as well, since the underlying information is the same, just represented differently. Didn't look close enough to JSIR, but from looking around (and from building a restricted Source <-> Graph IR on JS for some code transforms), it basically shows you have at least a homomorphic mapping between expression-oriented JS and graph IR, if not even a proper isomorphism (at least in a structured and side-effect-constrained subsets). |