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Forgot to mention a funny fact I found. Minify everything [1] [1] https://top.fse.guru/nodejs-a-quick-optimization-advice-7353b820c92e#.nfvi89hjc https://top.f

Forgot to mention a funny fact I found. Minify everything [1] [1] https://top.fse.guru/nodejs-a-quick-optimization-advice-7353b820c92e#.nfvi89hjc https://top.fse.guru/nodejs-a-quick-optimization-advice-7353...

vanderZwan 10y ago
> v8 optimizer (crankshaft) inlines the functions whose body length, including the comments, is less than 600 characters. In what kind of world is that a sensible metric to decide if a function can be inlined?
- luckystarr 10y ago
  In the "I need to do this quickly to finish my sprint" world.
  - konschubert 10y ago
    Wasn't V8 written in a cottage in Denmark? http://www.ft.com/cms/s/0/03775904-177c-11de-8c9d-0000779fd2ac.html http://www.ft.com/cms/s/0/03775904-177c-11de-8c9d-0000779fd2... I cannot imagine that they would take unreasonable shortcuts.
    - luckystarr 10y ago
      Well, unreasonable now was probably perfectly reasonable at the time of implementation. Perhaps they even have or had a plan to improve upon it, but given other tasks (ES6, etc.) it hasn't been given much priority. I mean, why would they fix it with high priority if the engine already has reasonable performance and the benchmarks are happy as well?
  - egeozcan 10y ago
    Even then, why include comments? Is it to support stuff like multi-line strings as comments hack[1]? [1]: https://github.com/sindresorhus/multiline https://github.com/sindresorhus/multiline
- lorenzhs 10y ago
  In the world where you have to make these decisions quickly, and don't have time to parse the function.
  - vanderZwan 10y ago
    I don't buy it: that would only make sense if you could copy/paste the source or something, and even JS respects function scoping so you can't. You'd have to wait until later anyway, so why not count AST nodes or something instead?
    - lorenzhs 10y ago
      I can't make useful guesses about the V8 developers' reasoning, but I'd assume they considered several options and chose this one for a reason, concerning how much performance is at stake. I don't know about Crankshaft's inner workings, though, so I can't make qualified comments about it. Maybe something like http://jayconrod.com/posts/54/a-tour-of-v8-crankshaft-the-optimizing-compiler http://jayconrod.com/posts/54/a-tour-of-v8-crankshaft-the-op... can answer some of your questions?
      - vanderZwan 10y ago
        Thanks. Quick CTRL+F for "inlining" produces: > Graph generation: Crankshaft builds the Hydrogen control flow graph using the AST, scope info, and type feedback data extracted from the full-compiled code. Inlining also happens at this stage. Hydrogen is Crankshaft's high-level architecture-independent intermediate representation. > Inlining: Performed during the graph generation phase. The inlining heuristic is very simple: basically, if the function being called is known, and it is safe to inline, the function will be inlined. Large functions (>600 source characters including whitespace or 196 AST nodes) will not be inlined. Cumulatively, a total of 196 AST nodes can be inlined in a single function. So they do use AST nodes as a heuristic; I don't really understand why they would also use "source characters including whitespace" though. Guess I better keep my comments outside the function body from now on when possible.

vanderZwan 10y ago

> v8 optimizer (crankshaft) inlines the functions whose body length, including the comments, is less than 600 characters. In what kind of world is that a sensible metric to decide if a function can be inlined?

luckystarr 10y ago
In the "I need to do this quickly to finish my sprint" world.
- konschubert 10y ago
  Wasn't V8 written in a cottage in Denmark? http://www.ft.com/cms/s/0/03775904-177c-11de-8c9d-0000779fd2ac.html http://www.ft.com/cms/s/0/03775904-177c-11de-8c9d-0000779fd2... I cannot imagine that they would take unreasonable shortcuts.
  - luckystarr 10y ago
    Well, unreasonable now was probably perfectly reasonable at the time of implementation. Perhaps they even have or had a plan to improve upon it, but given other tasks (ES6, etc.) it hasn't been given much priority. I mean, why would they fix it with high priority if the engine already has reasonable performance and the benchmarks are happy as well?
- egeozcan 10y ago
  Even then, why include comments? Is it to support stuff like multi-line strings as comments hack[1]? [1]: https://github.com/sindresorhus/multiline https://github.com/sindresorhus/multiline
lorenzhs 10y ago
In the world where you have to make these decisions quickly, and don't have time to parse the function.
- vanderZwan 10y ago
  I don't buy it: that would only make sense if you could copy/paste the source or something, and even JS respects function scoping so you can't. You'd have to wait until later anyway, so why not count AST nodes or something instead?
  - lorenzhs 10y ago
    I can't make useful guesses about the V8 developers' reasoning, but I'd assume they considered several options and chose this one for a reason, concerning how much performance is at stake. I don't know about Crankshaft's inner workings, though, so I can't make qualified comments about it. Maybe something like http://jayconrod.com/posts/54/a-tour-of-v8-crankshaft-the-optimizing-compiler http://jayconrod.com/posts/54/a-tour-of-v8-crankshaft-the-op... can answer some of your questions?
    - vanderZwan 10y ago
      Thanks. Quick CTRL+F for "inlining" produces: > Graph generation: Crankshaft builds the Hydrogen control flow graph using the AST, scope info, and type feedback data extracted from the full-compiled code. Inlining also happens at this stage. Hydrogen is Crankshaft's high-level architecture-independent intermediate representation. > Inlining: Performed during the graph generation phase. The inlining heuristic is very simple: basically, if the function being called is known, and it is safe to inline, the function will be inlined. Large functions (>600 source characters including whitespace or 196 AST nodes) will not be inlined. Cumulatively, a total of 196 AST nodes can be inlined in a single function. So they do use AST nodes as a heuristic; I don't really understand why they would also use "source characters including whitespace" though. Guess I better keep my comments outside the function body from now on when possible.