[PATCH] D51664: [IR] Lazily number instructions for local dominance queries

Chandler Carruth via Phabricator via llvm-commits llvm-commits at lists.llvm.org
Wed Jan 16 02:22:07 PST 2019


chandlerc added a comment.

In D51664#1358377 <https://reviews.llvm.org/D51664#1358377>, @rnk wrote:

> In D51664#1357417 <https://reviews.llvm.org/D51664#1357417>, @lattner wrote:
>
> > After giving you a hard time about this a few months ago, I've come around to believing that this is the right thing to do.  Certain classes of algorithms really do benefit from having a lexicographic ordering comparison that is fast, and I think that this general approach is the best way to go.
>
>
> Thanks! I'll bring it up on the dev list. I do know that @chandlerc wants to see a version of this that uses out of line numbers in a hash table, similar to the way we maintain value names out of line in a symbol table, but still done as part of the IR. I wanted to prototype that and compare.


To be super clear, I definitely want *some* solution here. I'm completely on board with this being a real problem and we should solve it.

And if even getting reasonable data proves to be tons of work, I think its fine to say that and move on. In our conversation I was worried we weren't even checking to see if a side table was an effective strategy. I don't have any reason to believe this is going to be so important that it is worth *tons* of effort to validate both alternatives, it just seems useful to try a quick prototype.


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https://reviews.llvm.org/D51664





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