[Webkit-unassigned] [Bug 73187] Don't try to optimize huge code blocks

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=73187





--- Comment #6 from Filip Pizlo <fpizlo at apple.com>  2011-11-28 12:45:24 PST ---
(In reply to comment #5)
> To reduce the risk of missing an optimization opportunity in a huge code block, perhaps the huge code block heuristic could be a multiplier instead of an absolute number. E.g.:
> 
> size_t iterationsUntilOptimizingCompile = N;
> size_t iterationsUntilOptimizingCompileInHugeCodeBlock = N * M;

I was thinking about this as well.  But:

1) We still want to have a size at which we will simply not compile at all.  Even before my CFA and propagation stuff, the DFG already had O(n^2) memory usage, since it needs to track all variables at all basic blocks.  Pretty easy to write a program that will cause the DFG to run out of memory.

2) Delaying optimization means that we still eat profiling overhead.

Taking these two things together, I think that at least for now, until we have more sophisticated heuristics, we want to just have a threshold at which we disable any optimization for the code block, including removing profiling.

-- 
Configure bugmail: https://bugs.webkit.org/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
You are the assignee for the bug.