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by lorenzhs
3653 days ago
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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-op... can answer some of your questions? |
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> 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.