[PATCH] D30437: [DAGCombiner] Do various combine on usubo.

[Zvi Rackover via Phabricator via llvm-commits]

zvi added inline comments.


================
Comment at: lib/CodeGen/SelectionDAG/DAGCombiner.cpp:2130
+
+  // Canonicalize (usubo -1, x) -> ~x, i.e. (xor x, -1) + no borrow
+  if (isAllOnesConstant(N0))
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If i am not mistaken, we don't have a similar LLVM IR transform in InstCombine or InstSimplify.


https://reviews.llvm.org/D30437