= The State of JSC =

- Moved from LLVM to B3/Air
	- Transition is complete
	- FTL Jit in 64-bit platforms
	- Big Jetstream improvements 
	- Big Kraken improvements

- Moved from Tracing to Sampling profiler
	- Performance is an order of magnitude better in Web Inspector
	- 10-20x faster with the sampling profiler

- ES6 Feature Complete
	- Block Scoping
	- Generator Functions

- Current work
	- ES6 Sample Bench
		- Fast Generators
		- Fast Map/Set
		- gotten 20% faster
		- Runs 2 different tests
		- Takes geometric mean of tests
		- Steady state
	- Concurrent Garbage Collection
		- Gonna mean pauses in JSC
		- Pauses won’t be nearly as long
		- Execute JS during GC
		- There will be points where you pause the world but it won’t be in high milliseconds
	- Working on WebAssembly
		- It’s being implemented
	- DOM JIT
		- Creating an abstraction for the JSC for operations on the DOM
		- Be aware of getter accessors of being compiled
	- Integrating ES6 Modules in HTML
		- <script type=“module”>
	- Almost done ES2017
		- Support everything buy async/await
		- Patches on async/await

	- Demo of command line:
		- `./Tools/Scripts/run-jsc —release —sample ~/test.js`
		- Shows sampling rate
		- and the hottest byte code samples
		- The hash identifies the code blocks and just
		- These tools would be nice for WebContent process
			- Too difficult to use with the sample profiles
		- Would be cool to add byte code information in inspector
		- At a high level a Heat Map would be nice (being worked on)
		- If it is in inspector, it can impact performance and throw off the profile
		- `JSC_dumpDFGDisassembly=1 ./Tools/Scripts/run-jsc —release —sample ~/test.js`

	- How to async/await
		- async func with await is a shorthand for promises
		- await automatically wraps the given function in a Promise and returns the promise

	- WebAssembly
		- Work is underway
		- There is a trapping semantic in WebAssembly
		- Cant export a function that takes 64-bit integer
		- Internally in WebAssembly you can handle 64-bit integers
		- You have to check that the memory is in bounds, if not then you have to unwind the webassembly
		- Does the exception flatten the webassembly?
			- The plan is to have each WebAssembly frame visible
		- You can have import and export in WebAssembly to call from WebAssembly to JS
		- Developers would likely have WebAssembly that calls to a JS helper to modify DOM since you can’t modify the DOM from WebAssembly
		- There is a lot of debate still happening
		- You can use the JS GC for whatever language your using
		- How fast is WebAssembly?
			- Significantly faster for common cases of compiling C code
			- WASM is quite slow compared to native codes
			- WebAssembly has more info about how things work that allow for more optimizations
			- Close to native performance
		- How do I compile to WebAssembly?
			- Compile through clang, that pass it to LLVM IR then pass it back to WebAssembly
			- It will likely get easier as tools are created