Simple diet tricks for asm.js

The ELIMINATE_DUPLICATE_FUNCTIONS support was contributed by Tableau Software, by the team I'm on. It's quite expensive processing wise, but is worth a shot seeing if your code base benefits from it. Our usecase leverages a lot of shared pointer based templated classes, which tends to create a lot of delete functions that boil down to free(this);

2 other points I'd add to this overall:

1) Can't emphasize enough how bad exception support is for size, expect in the neighborhood of 30% size increase. This is due to needing to handle all of the possible ways functions can return. Even with exception support disabled, you can still throw them, you just can't catch them in C++ land.

2) goto's. There's a few good reasons to use these, especially in code that needs to make sure cleanup code always runs. Emscripten supports that with a couple different code constructs, pretty much all of which cause a significant amount of bloat. We've saved ~100k in some cases by specifically targeting some 3rd party code that made use of them and rewritting them to not have gotos.

"The emscripten version is even smaller than the native version after compression, impossabru! I actually didn’t expect this myself (last time I did such comparisons the emscripten versions came out about 10..20% bigger)"

This is because JavaScript is alpha-numeric and is easier to compress than binary. There are a relatively 'small' number of characters in the alpha-numeric range, so they can be mapped together easier than the wider range of binary data.

Can someone ELI5 what asm.js is? I've tried Googling it multiple times now and every time I basically give up because I can't relate to anything it's talking about when all they use is buzzwords.

Those recommendations together almost sound like "write C in C++".

asm.js really seem to be a good solution, I hope some day it will be used to do more than web games. But at the same time, the vision of the future of compiling everything in javascript is pretty scary.

nit: the C style example, should use /* These kind of comments */ not // these kind of comments.