[PATCH] D75982: [DAGCombine] Respect the uses when combine FMA for a*b+/-c*d and add target hook if there uses are the same

[Roman Lebedev via Phabricator via llvm-commits]

lebedev.ri added reviewers: cameron.mcinally, uweigand.
lebedev.ri added a comment.

> If their uses are the same, add a target hook to allow some platform such as PowerPC to make the choice, as it has different precisions between these two folding which is caused by round a*b or c*d.
>  In PowerPC, we have some floating precision quite sensitive libraries that depend on the slightly difference between rounding a*b or c*d. So, we need some way to control the behavior of this combine.

To me that sounds like strict floating point semantics should be used there?


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  https://reviews.llvm.org/D75982/new/

https://reviews.llvm.org/D75982