This issue was originally filed by @davidB

What steps will reproduce the problem?

I make game (physics + rendering) that do lot of vectors manipulation each frame (via vector_math lib). But too many useless (IMHO as I test, and run the code in dartvm) defensive code is generated and run every frame.

See bug http://code.google.com/p/dart/issues/detail?id=9139 (Can someone re-open it)

I result is that the code run at 1 fps on firefox and I can up to 10 fps if I manually replace the generated js by the raw code (same as dart) in simple add, sub, setFrom function of Vector3.

What is the expected output?

a raw js without without range check, without $index, without bailout.

It seems to be a hard task for the code analyzer and ... So why not provide an option (command line, code annotation) to disable this defensive code and simply trust the developper (at its own risk).

I use dart as a better tool to create js (for chrome and firefox). If the generated js is useless (as is), then I don't need dart.