[InstCombine] Improve the expansion in SimplifyUsingDistributiveLaws to handle cases where one side doesn't simplify, but the other side resolves to an identity value

Summary:
If one side simplifies to the identity value for inner opcode, we can replace the value with just the operation that can't be simplified.

I've removed a couple now unneeded special cases in visitAnd and visitOr. There are probably other cases I missed.

Reviewers: spatel, majnemer, hfinkel, dberlin

Reviewed By: spatel

Subscribers: grandinj, llvm-commits, spatel

Differential Revision: https://reviews.llvm.org/D35451

llvm-svn: 308111

1 files changed, 0 insertions, 18 deletions

diff --git a/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp b/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
index 6f0703178f3..f2f174e5c24 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
@@ -1414,12 +1414,6 @@ Instruction *InstCombiner::visitAnd(BinaryOperator &I) {
       }
     }
 
-    // (A&((~A)|B)) -> A&B
-    if (match(Op0, m_c_Or(m_Not(m_Specific(Op1)), m_Value(A))))
-      return BinaryOperator::CreateAnd(A, Op1);
-    if (match(Op1, m_c_Or(m_Not(m_Specific(Op0)), m_Value(A))))
-      return BinaryOperator::CreateAnd(A, Op0);
-
     // (A ^ B) & ((B ^ C) ^ A) -> (A ^ B) & ~C
     if (match(Op0, m_Xor(m_Value(A), m_Value(B))))
       if (match(Op1, m_Xor(m_Xor(m_Specific(B), m_Value(C)), m_Specific(A))))
@@ -2017,18 +2011,6 @@ Instruction *InstCombiner::visitOr(BinaryOperator &I) {
 
   Value *A, *B;
 
-  // ((~A & B) | A) -> (A | B)
-  if (match(Op0, m_c_And(m_Not(m_Specific(Op1)), m_Value(A))))
-    return BinaryOperator::CreateOr(A, Op1);
-  if (match(Op1, m_c_And(m_Not(m_Specific(Op0)), m_Value(A))))
-    return BinaryOperator::CreateOr(Op0, A);
-
-  // ((A & B) | ~A) -> (~A | B)
-  // The NOT is guaranteed to be in the RHS by complexity ordering.
-  if (match(Op1, m_Not(m_Value(A))) &&
-      match(Op0, m_c_And(m_Specific(A), m_Value(B))))
-    return BinaryOperator::CreateOr(Op1, B);
-
   // (A & C)|(B & D)
   Value *C = nullptr, *D = nullptr;
   if (match(Op0, m_And(m_Value(A), m_Value(C))) &&