[PATCH] D65802: [DAGCombiner] Rebuild (setcc x, y, ==) from (xor (xor x, y), 1)

[Roger Ferrer Ibanez via Phabricator via llvm-commits]

rogfer01 marked an inline comment as done.
rogfer01 added inline comments.
Herald added a subscriber: pzheng.


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Comment at: llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp:13496-13499
+  // Transform (brcond (xor x, y)) -> (brcond (setcc, x, y, ne))
+  // Transform (brcond (xor (xor x, y), -1)) -> (brcond (setcc, x, y, eq))
+  if (N.getOpcode() == ISD::XOR && N->hasOneUse() &&
+      (*N->use_begin())->getOpcode() == ISD::BRCOND) {
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lebedev.ri wrote:
> Why is this one-use restriction being introduced here?
There are two callers of this function `visitSETCC`, which passes a node generated by `SimplifySetCC`, and `visitBRCOND` which does indeed check that the passed node has just one use.

I'm less sure about the the node coming out of `SimplifySetCC` so it might make sense to err on the safe side here?


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https://reviews.llvm.org/D65802