[PATCH] D146810: [CodeGen] Compile-time improvement for Machine Late Instructions Cleanup Pass.

[Valery Pykhtin via Phabricator via llvm-commits]

vpykhtin added a comment.

> If the map lookup time really matters, maybe it could be worth trying a vector of DefMI/KillMI pairs, so lookup time would be O(n) into the vector..?

I don't think it's that critical

> BTW, I really hope we don't have to use first/second accesses, something like RegInstrs[Reg].DefMI seems more readable...

RegInstrs[Reg] is a lookup in the map, I don't know if compilers are good enough to optimize several identical map lookups.

> If it's not possible to speed it up further, I think the simple version I tried is acceptable: it avoids the slowdowns in huge functions and is just barely slower on SPEC, which is then probably preferrable...

I agree, I'll abandon this review then. Maybe it worth to use SmallDenseMap in your version instead of std::map.


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https://reviews.llvm.org/D146810