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This project forked from brownplt/lambdas5

Semantics for ES5

License: BSD 3-Clause "New" or "Revised" License

JavaScript 27.55% OCaml 70.26% Racket 0.77% Makefile 0.13% Shell 0.61% Standard ML 0.17% Python 0.44% CSS 0.04% Batchfile 0.04%

lambdas5's Introduction

Semantics for ECMAScript 5.0
============================

Install and Usage
-----------------
See `INSTALL` for installation instruction.

s5 options are implemented as stack manipulation so the order of
options matters. Here are a few examples (in `src/` directory, and a
js file `test.js` exists):

Desugar a Javascript program and print the S5 source.

    $ ./s5.d.byte -desugar test.js -print-src

Desugar a Javascript program, wrap with an Environment and do evaluation.

    $ ./s5.d.byte -desugar test.js -env ../envs/es5.env -apply -eval

Desugar a Javascript program, wrap with an Environment, apply
optimizations and finally print out the optimized code (excluding the
environment).

    $ ./s5.d.byte -desugar test.js -env ../envs/es5-optimization.env -apply -opt-restore-id -opt-restore-function -opt-propagate-const -opt-clean-deadcode -print-user-s5

Slimming Language Options
-------------------------

All optimization options start with "-opt-". There are a few options
not compatible with the optimization flags:

1. `-internal-env env-vars`. This option introduces identifiers of
es5.env in the nested environment for `eval`. It has a huge negative
impact on the constant propagation.
2. `-env es5.env`. There are several `env` files in env/
directory. Optimization flags only work on `es5-optimization.env`,
which is similar to `es5.env`. The only difference is that it excludes
built-in `eval` support (-opt-restore-id would not work if `es5.env`
is used). See previous usage examples for how to pass a correct
environment.

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lambdas5's Issues

multiple assignment removing

try to clean

function iden(x){return x}
function iden(x){return x}
function iden(x){return x}
function iden(x){return x}

replace multiple-usage with is-single-use

convert assignment return undefined

for a whole program function iden(x) {return x;}, convert assignment transforms the program like this:

let (%fobj3 = ...)
   iden := %fobj3

let (iden = ...)
  undefined

This changed the return value.

function arity optimization

var o = { get foo() { return this; } } 
return o.foo===o;

Because o.foo will supply another object to the function foo: o["foo", {[]}]. Getter should not be changed(getter does not take arguments anyway)

improve has_side_effect

for a given expression, if the SetBang is on an id that is bound in the expression, the predicate should return NoSideEffect. Example expression:

let (y=1) {
  y:=2;
  let (z = 2) {
    z := 3
  }
}
=> NoSideEffect

propagate copy bugs

let (b=1)
     let (f=func(){b:=2})
          let (a=b) {
            f();
            a
          }

f has changed the meaning of b, no substitution should occur.

preprocess->less-mutation failed test

it fails ch10-nonstrict, ch11-nonstrict, ch15-nonstrict

ch10-nonstrict:

[nonstrict mode] 10.4.3-1-3-s.js use ‘this’ keyword in function as global variable.

ch11-nonstrict

[bug] S11.8.6_A2.4_T1.js
[bug] S11.8.6_A2.4_T1.js

bug of less-mutation

lijunsong / lambdas5 Goto Github PK

lambdas5's Introduction

lambdas5's People

Contributors

Stargazers

Watchers

lambdas5's Issues

multiple assignment removing

replace multiple-usage with is-single-use

convert assignment return undefined

function arity optimization

improve has_side_effect

propagate copy bugs

preprocess->less-mutation failed test

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