[PATCH] D71657: [SDAG] Handle BUILD_PAIR in ComputeNumSignBits

[Danila Malyutin via Phabricator via llvm-commits]

danilaml added a comment.

@craig.topper this pass runs on IR. In the real code that prompted me to come up with this patch the BB block was split during ISel building phase, because (IUC) it was too big. And just so happens that the split was right between sext to i64 and mul. I've tried to simulate it with the code above.
@bjope Thanks. That might be a valid option for testing (although it's not really target specific at this point). However, it might be moot if it turns out there is no way to either 1) check whether two CopyFromRegs came from the same IR value or 2) find out in other ways that one node is just replicated sign bit of the other node.


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  https://reviews.llvm.org/D71657/new/

https://reviews.llvm.org/D71657