[InstSimplify] Add patterns for folding (A & B) | (~A ^ B) -> (~A ^ B) and its commuted variants.

We already had (A & ~B) | (A ^ B), but we missed the cases where the not was part of the xor.

llvm-svn: 303004

1 files changed, 18 insertions, 0 deletions

diff --git a/llvm/lib/Analysis/InstructionSimplify.cpp b/llvm/lib/Analysis/InstructionSimplify.cpp
index 1457422b255..6a1ec0f84e5 100644
--- a/llvm/lib/Analysis/InstructionSimplify.cpp
+++ b/llvm/lib/Analysis/InstructionSimplify.cpp
@@ -1870,6 +1870,24 @@ static Value *SimplifyOrInst(Value *Op0, Value *Op1, const SimplifyQuery &Q,
        match(Op1, m_c_And(m_Not(m_Specific(A)), m_Specific(B)))))
     return Op0;
 
+  // (A & B) | (~A ^ B) -> (~A ^ B)
+  // (B & A) | (~A ^ B) -> (~A ^ B)
+  // (A & B) | (B ^ ~A) -> (B ^ ~A)
+  // (B & A) | (B ^ ~A) -> (B ^ ~A)
+  if (match(Op0, m_And(m_Value(A), m_Value(B))) &&
+      (match(Op1, m_c_Xor(m_Specific(A), m_Not(m_Specific(B)))) ||
+       match(Op1, m_c_Xor(m_Not(m_Specific(A)), m_Specific(B)))))
+    return Op1;
+
+  // (~A ^ B) | (A & B) -> (~A ^ B)
+  // (~A ^ B) | (B & A) -> (~A ^ B)
+  // (B ^ ~A) | (A & B) -> (B ^ ~A)
+  // (B ^ ~A) | (B & A) -> (B ^ ~A)
+  if (match(Op1, m_And(m_Value(A), m_Value(B))) &&
+      (match(Op0, m_c_Xor(m_Specific(A), m_Not(m_Specific(B)))) ||
+       match(Op0, m_c_Xor(m_Not(m_Specific(A)), m_Specific(B)))))
+    return Op0;
+
   if (Value *V = simplifyAndOrOfICmps(Op0, Op1, false))
     return V;