[PATCH] D127831: BasicBlockUtils: Add a new way for CreateControlFlowHub()

[Brendon Cahoon via Phabricator via llvm-commits]

bcahoon added a comment.

In D127831#3887582 <https://reviews.llvm.org/D127831#3887582>, @foad wrote:

> Why do we still need the "old way"? Does the "new way" generate worse code in some cases?

Good question. The new way does require an additional compare instruction to test where control continues after the loop. One for each output edge. But, yes, there is a tradeoff here. I think it's worth assessing if the "new way" can replace the "old way" at some point. My thinking here is to be conservative and keep the "old way" for now as I'm a little hesitant to replace it without more performance data.


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  https://reviews.llvm.org/D127831/new/

https://reviews.llvm.org/D127831