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Re: [PATCH][C++] Improve PR15855 (compile-time/memory hog)



I sincerely doubt we actually have 5 million SFT's.  I'd be *incredibly*
surprised.
We have 5 million _mappings_ for SFT variables during an incremental
SSA update.  There's something like 20k SFT variables IIRC.


If you don't believe me, then take a looksie :-) Maybe I'm counting wrong :-)


No, you aren't, but actually, it shouldn't matter.


The first big incremental update for
static_initialization_and_destruction:


Number of virtual NEW -> OLD mappings: 43504 Number of real NEW -> OLD mappings: 0 Number of total NEW -> OLD mappings: 43504

Number of virtual symbols: 21950

Which seems fine.




The second big incremental update has:

Number of virtual NEW -> OLD mappings: 5443467
Number of real NEW -> OLD mappings:          0
Number of total NEW -> OLD mappings:   5443467

Number of virtual symbols: 21950


Uh, why did we need 5 million mappings here?


We are going to have to be able to handle 20000 symbols at once. It's really not *that* many.

You've created 262 mappings per variable.
That's quite a lot.

--Dan


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