[PATCH] D112338: [InstCombine] Fold `(~(a | b) & c) | ~(a | c)` into `~((b & c) | a)`

[Sanjay Patel via Phabricator via llvm-commits]

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

LGTM.
The commute tests are not complete, but they should be enough to ensure the pattern-matching won't silently break.



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Comment at: llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp:2822
+  // (~(A | B) & C) | ~(A | C) --> ~((B & C) | A)
+  if (match(Op0, m_OneUse(m_c_And(m_OneUse(m_Not(m_Or(m_Value(A), m_Value(B)))),
+                                  m_Value(C))))) {
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The use checks aren't what I suggested, but either way, it is overly conservative (and we would see improvements on some of the tests that are currently left unchanged), so please put a TODO comment on this block to suggest we can loosen the use checks.


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D112338/new/

https://reviews.llvm.org/D112338