[PATCH] D22858: Fix DbgValue handling in SelectionDAG.

[Hans Wennborg via llvm-commits]

hans added a comment.

In https://reviews.llvm.org/D22858#499283, @niravd wrote:

> i strongly believe (but have not checked because I had not been able to reproduce the bug locally and have been relying on Ismall running the test) that the sole part of the fix necessary is the change of  location TransferDbgValues in ReplaceAllUsesWith to be consistent with the other N instances of ReplaceAllUses and do the transfer before changing the SDUses and doing CSE. This was clearly wrong the dest SDNode may be merged in CSE and the old pointer may point to free space.
>
> Now that I (hopefully) can reproduce this bug with pr28749, I can verify that the second half of the patch is not necessary for correctness and we can potentially split that off.


sgtm. Hopefully splitting it off (if that works) means this will be easy to review and can be merged to 3.9 soon (I'd like to have this before cutting rc1).


https://reviews.llvm.org/D22858