DmitrySoshnikov

Generated code optimizations and tricks

I've been playing with generated (native) code in order to test how compilers (specific or in general) translate a = a + 1 and a++, and found some other interesting optimizations. I used gcc compiler for this simple program:

int main() {
  int a = 0;
  a = a + 1;

  int b = 0;

DmitrySoshnikov

/**
 * Callable objects in ES2015.
 * by Dmitry Soshnikov <[email protected]>
 * MIT Style License
 */

class Callable extends Function {
  constructor() {
    super('(' + Callable.prototype.__call__ + ')();');
    return this.bind(this);

DmitrySoshnikov

/**
 * = AST printer =
 *
 * by Dmitry Soshnikov <[email protected]>
 * MIT Style License
 *
 * Once we have finished operating on our AST, we need to generate the
 * code back from that (possibly transformed) AST.
 *
 * We choose a very simple AST format here, which we used in the

DmitrySoshnikov

/**
 * = Recursive descent parser =
 *
 * MIT Style License
 * By Dmitry Soshnikov <[email protected]>
 *
 * In this short lecture we'll cover the basic (non-predictive, backtracking)
 * recursive descent parsing algorithm.
 *
 * Recursive descent is an LL parser: scan from left to right, doing

DmitrySoshnikov

/**
 * = LL parser =
 *
 * by Dmitry Soshnikov <[email protected]>
 * MIT Style license
 *
 * Often one can see manually written LL parsers implemented as
 * recursive descent. Approach in this diff is a classical parse table
 * state machine.
 *

DmitrySoshnikov

ES7 String trim functions

String.prototype.trim ( )

Return result of StringTrim abstract operation passing this value as thisArg, and TrimBoth as the type.

String.prototype.trimRight ( )

Return result of StringTrim abstract operation passing this value as thisArg, and TrimRight as the type.

DmitrySoshnikov

1. A system without hoisting

An example of Scheme program without hoisting:

(define x 10)     ; global `x`
(print x)         ; 10

((lambda ()
    (print x)     ; still 10, not shadowed yet

DmitrySoshnikov

/**
 * Educational Stack-based VM.
 *
 * See also:
 *  - A simplified example without recursion: https://gist.github.com/DmitrySoshnikov/76e1cfb930df8d36145c
 *  - Register-based VM example: https://gist.github.com/DmitrySoshnikov/6407781
 *
 * by Dmitry Soshnikov <[email protected]>
 * http://dmitrysoshnikov.com
 * MIT Stye License (C) 2015

DmitrySoshnikov

/**
 * Educational Stack-based VM.
 *
 * See also:
 *  - More complex example with recursion: https://gist.github.com/DmitrySoshnikov/afda459222e96e6002ac
 *  - Register-based VM example: https://gist.github.com/DmitrySoshnikov/6407781
 *
 * by Dmitry Soshnikov <[email protected]>
 * http://dmitrysoshnikov.com
 * MIT Stye License (C) 2015

DmitrySoshnikov

/**
 * ES6 delegating generators.
 * 
 * ES6 dramatically simplified calling of nested generators
 * using "yield *" construct, which is called delegating
 * generator.
 * 
 * From history:
 * Previously (in the original SpiderMonkey/Python) implementation
 * we had to maintain a manual stack for it. The technique was