[PATCH] D69120: [TargetLowering][DAGCombine][MSP430] Shift Amount Threshold in DAGCombine (2/2)

[Anton Korobeynikov via Phabricator via llvm-commits]

asl added a comment.

@joanlluch Yes, having the version with amount does make sense as target may know how to efficiently lower some of the shifts with crazy tricks. And in the view of this patch it's easier to preserve the sequences rather than match and undo later. I guess for MSP430 we'd need to allow 9 as possible "special" shift value, as select is lowered to 3 instructions (test + branch + mov of some kind) and removing branch overall has some additional value like allowing more code folding / reducing register pressure.


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  https://reviews.llvm.org/D69120/new/

https://reviews.llvm.org/D69120