[PATCH] D13685: [SCEV] Commute sign extends through nsw additions

[Nick Lewycky via llvm-commits]

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

LGTM, but please do the obvious thing with zext too. I don't feel like the zext tests will need my review, but you can ask me to look at them if you feel otherwise. Thanks for the patch!


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Comment at: lib/Analysis/ScalarEvolution.cpp:1635-1637
@@ +1634,5 @@
+
+    // sext((A + B + ...)<nsw>) --> (sext(A) + sext(B) + ...)<nsw>
+    if (SA->getNoWrapFlags(SCEV::FlagNSW)) {
+      // If the addition does not sign overflow then we can, by definition,
+      // commute the sign extension with the addition operation.
----------------
Please do. You'll find the functions exceptionally symmetric already. :)



http://reviews.llvm.org/D13685