1 files changed, 28 insertions, 14 deletions

diff --git a/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp b/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
index 22832aadf4a..e70171ce989 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
@@ -1620,6 +1620,30 @@ Instruction *InstCombiner::visitAnd(BinaryOperator &I) {
 /// Given an OR instruction, check to see if this is a bswap idiom. If so,
 /// insert the new intrinsic and return it.
 Instruction *InstCombiner::MatchBSwap(BinaryOperator &I) {
+  Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
+
+  // Look through zero extends.
+  if (Instruction *Ext = dyn_cast<ZExtInst>(Op0))
+    Op0 = Ext->getOperand(0);
+
+  if (Instruction *Ext = dyn_cast<ZExtInst>(Op1))
+    Op1 = Ext->getOperand(0);
+
+  // (A | B) | C  and  A | (B | C)                  -> bswap if possible.
+  bool OrOfOrs = match(Op0, m_Or(m_Value(), m_Value())) ||
+                 match(Op1, m_Or(m_Value(), m_Value()));
+
+  // (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()));
+
+  // (A & B) | (C & D)                              -> bswap if possible.
+  bool OrOfAnds = match(Op0, m_And(m_Value(), m_Value())) &&
+                  match(Op1, m_And(m_Value(), m_Value()));
+
+  if (!OrOfOrs && !OrOfShifts && !OrOfAnds)
+    return nullptr;
+
   SmallVector<Instruction*, 4> Insts;
   if (!recognizeBSwapOrBitReverseIdiom(&I, true, false, Insts))
     return nullptr;
@@ -2162,23 +2186,13 @@ Instruction *InstCombiner::visitOr(BinaryOperator &I) {
         return NV;
   }
 
+  // Given an OR instruction, check to see if this is a bswap.
+  if (Instruction *BSwap = MatchBSwap(I))
+    return BSwap;
+
   Value *A = nullptr, *B = nullptr;
   ConstantInt *C1 = nullptr, *C2 = nullptr;
 
-  // (A | B) | C  and  A | (B | C)                  -> bswap if possible.
-  bool OrOfOrs = match(Op0, m_Or(m_Value(), m_Value())) ||
-                 match(Op1, m_Or(m_Value(), m_Value()));
-  // (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()));
-  // (A & B) | (C & D)                              -> bswap if possible.
-  bool OrOfAnds = match(Op0, m_And(m_Value(), m_Value())) &&
-                  match(Op1, m_And(m_Value(), m_Value()));
-
-  if (OrOfOrs || OrOfShifts || OrOfAnds)
-    if (Instruction *BSwap = MatchBSwap(I))
-      return BSwap;
-
   // (X^C)|Y -> (X|Y)^C iff Y&C == 0
   if (Op0->hasOneUse() &&
       match(Op0, m_Xor(m_Value(A), m_ConstantInt(C1))) &&