[PATCH] D88578: [InstCombine] recognizeBSwapOrBitReverseIdiom - support for 'partial' bswap patterns (PR47191)

[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



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Comment at: llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp:2052-2056
   // (A >> B) | (C << D)  and  (A << B) | (B >> C)  -> bswap if possible.
-  bool OrOfShifts = match(Op0, m_LogicalShift(m_Value(), m_Value())) &&
-                    match(Op1, m_LogicalShift(m_Value(), m_Value()));
+  bool OrWithShifts = match(Op0, m_LogicalShift(m_Value(), m_Value())) ||
+                      match(Op1, m_LogicalShift(m_Value(), m_Value()));
 
   // (A & B) | (C & D)                              -> bswap if possible.
----------------
The comments are now more specific than the logic now. Adjust to be more like the OrWithOrs?
  // (A >> B) | C or A | (B >> C)
  // (A & B) | C or A | (B & C)

Presumably, recognizeBSwapOrBitReverseIdiom() can deal with the more general patterns.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D88578/new/

https://reviews.llvm.org/D88578