Years ago, I thought a single-tier design of an (offline) compiler was best (OVM). And then I thought a heavy offline compiler and two tiers of of the same JIT

Years ago, I thought a single-tier design of an (offline) compiler was best (OVM). And then I thought a heavy offline compiler and two tiers of of the same JIT was best (Jikes). Then I thought an interpreter with an an optimizing JIT was best (HotSpot server). Then I thought a slightly less optimizing JIT was best (HotSpot client). Then I thought that two JITs were best (V8 w/ Crankshaft). Then two JITs with a super heavy optimizing JIT was best (V8 w/ TurboFan). Then I thought a single tier for Wasm was best (V8 w/ TurboFan). Then I thought an interpreter and a heavy optimizing JIT was best (V8 w/ Ignition and TurboFan). Then I thought two JITs for Wasm was best (V8 w/ Liftoff and TurboFan). I've seen a single baseline compiler go through a metamorphosis from essentially streaming (HotSpot client V1) to full SSA-based with register allocation (HotSpot client today). In other words, prepare for change. A single tier is probably not going to be your final design.