[PATCH] D107692: [DAGCombine] Prevent the transform of combine for multi-use operand

Sanjay Patel via Phabricator via llvm-commits llvm-commits at lists.llvm.org
Mon Aug 16 05:54:43 PDT 2021


spatel added a comment.

In D107692#2946669 <https://reviews.llvm.org/D107692#2946669>, @lebedev.ri wrote:

> Please,
>
> 1. either add a comment explaining why the one-use check needed
> 2. or rewrite the transform the right way, so that the lack of one-use check shows up as extra instruction bloat and not a miscompilation

Since there's a visible miscompile, I'm ok with the quick/small fix since that will be an easy backport for the 13.0 release. But I agree that there should be a FIXME comment on this transform; it is clearly not ideal.


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