Added InstCombine Tranformation for (A | B) ^ ((A ^ C) & B) -> (A ^ (B & (~C)))

[ankur29.garg]

Summary

Hi everyone,
This patch implements the transformation (A | B) ^ ((A ^ C) & B) -> (A ^ (B & (~C))).
Please help in reviewing it.

Z3 Link: http://rise4fun.com/Z3/FoZS

Thanks,
Ankur Garg

[ankur29.garg]

Gentle Ping! David Can you please review this patch. It wont take much time :)

Thanks

[asl]

Please provide the information asked in other thread for similar pattern:

1. How often this transformation triggers in LLVM testsuite. Where, in which tests.
2. How often this transformation triggers in SPEC. Where, in which tests.

lib/Transforms/InstCombine/InstCombineAndOrXor.cpp

if (Op0I && Op1I) {
     // (A & B) ^ (A ^ B) -> (A | B)
     if (match(Op0I, m_And(m_Value(A), m_Value(B))) &&
         match(Op1I, m_Xor(m_Specific(A), m_Specific(B))))
       return BinaryOperator::CreateOr(A, B);
     // (A ^ B) ^ (A & B) -> (A | B)
     if (match(Op0I, m_Xor(m_Value(A), m_Value(B))) &&
         match(Op1I, m_And(m_Specific(A), m_Specific(B))))
       return BinaryOperator::CreateOr(A, B);
+    // (A | B) ^ ((A ^ C) & B) -> (A ^ (B & (~C)))
+    if (match(Op0I, m_Or(m_Value(A), m_Value(B))) &&
+        match(Op1I, m_And(m_Xor(m_Specific(A), m_Value(C)), m_Specific(B))))
+      return BinaryOperator::CreateXor(
+          A, Builder->CreateAnd(B, Builder->CreateNot(C)));
   }
 
   // (A | B)^(~A) -> (A | ~B)
   Value *A = nullptr, *B = nullptr;
   if (match(Op0, m_Or(m_Value(A), m_Value(B))) &&
       match(Op1, m_Not(m_Specific(A))))
     return BinaryOperator::CreateOr(A, Builder->CreateNot(B));
 

test/Transforms/InstCombine/xor2.ll

  %negb = xor i32 %b, -1
  %and = and i32 %a, %negb
  %xor = xor i32 %nega, %and
  ret i32 %xor
 ; CHECK-LABEL: @test14(
 ; CHECK-NEXT: %1 = and i32 %a, %b
 ; CHECK-NEXT: %xor = xor i32 %1, -1
 }
+
+define i32 @test15(i32 %a, i32 %b, i32 %c) {
+ %or = or i32 %a, %b
+ %not = xor i32 %a, %c
+ %and = and i32 %not, %b
+ %xor = xor i32 %or, %and
+ ret i32 %xor
+; CHECK-LABEL: @test15(
+; CHECK-NEXT: %1 = xor i32 %c, -1
+; CHECK-NEXT: %2 = and i32 %b, %1
+; CHECK-NEXT: %xor = xor i32 %2, %a
+}