[PATCH] D84309: [InstCombine] Preserve FMA opportunities when combining PHI nodes

[Sanjay Patel via Phabricator via llvm-commits]

spatel added a reviewer: lebedev.ri.
spatel added a comment.

Avoiding the canonicalization seems unlikely to be a universal win and won't solve the problem if the source was already in the form that we want to avoid.
I think we need to reverse the transform in CodeGenPrepare. There we can use TTI/TLI to decide if it is profitable (at the least, the target should have custom/legal FMA lowering for the value type in question?).


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https://reviews.llvm.org/D84309