Assembly output of JavaScript program

[espruino-discuss]

Posted at 2015-05-08 by petergombos

I'm interested in the assembly output of different JavaScript interpreters, and I was wondering if there's any way of running espruino on Linux and get a dump of the instructions that the interpreter outputs? Something like this for node/io.js.

[gfwilliams]

Posted at 2015-05-08 by @gfwilliams

Espruino is kind of unique in that it doesn't actually compile to bytecode. If you've got a small embedded device then there isn't enough room for the sourcecode and bytecode - and one of the main points of Espruino is to have the sourcecode on-chip so you can edit it without any special tools on the host PC.

There's some info at:

• http://www.espruino.com/Performance
• http://www.espruino.com/Internals

However you can easily compile for Linux: https://github.com/espruino/Espruino

And there's an experimental compiler that compiles a subset of JavaScript into C++ code, that can then be compiled to native code.

[espruino-discuss]

Posted at 2015-05-08 by petergombos

So there's no easy way of comparing what Espruino runs against other interpreters?

[gfwilliams]

Posted at 2015-05-08 by @gfwilliams

So there's no easy way of comparing what Espruino runs against other interpreters?

No, in fact it's running the code in a totally different way - interpreting directly from the characters you wrote, rather than via bytecode.

It means it's super-fast for stuff like eval, but the more iteration gets done, the more it loses out to interpreters that compile to bytecode or JIT.