[PATCH] D48970: [DAGCombiner] extend(ifpositive(X)) -> shift-right (not X)

[Roman Lebedev via Phabricator via llvm-commits]

lebedev.ri accepted this revision.
lebedev.ri added a comment.
This revision is now accepted and ready to land.

Code looks good, but i can't comment on the test changes.



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Comment at: lib/CodeGen/SelectionDAG/DAGCombiner.cpp:8006
+    // Invert and smear the sign bit:
+    // sext i1 (setgt iN X, -1) --> sra (not X), (N - 1)
+    // zext i1 (setgt iN X, -1) --> srl (not X), (N - 1)
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We are assuming that we won't get `setge <>, 0`, because some dagcombine already canonicalizes that?


https://reviews.llvm.org/D48970