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

[ankur29.garg]

Summary

Hi everyone,

This patch implements the transformation (A|B)^((A^C)|B) --> (~B)C

Please help in reviewing it.

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

Thanks,
Ankur Garg

[suyog]

Please run clang format before submitting any patch.

More info on the same can be found here - http://clang.llvm.org/docs/ClangFormat.html

[ankur29.garg]

Ran the clang-format on the code.

[ankur29.garg]

Gentle Ping !

[ankur29.garg]

Gentle Ping! Please help in reviewing the patch.

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) -> ((~B) & C)
+    if (match(Op0I, m_Or(m_Value(A), m_Value(B))) &&
+        match(Op1I, m_Or(m_Xor(m_Specific(A), m_Value(C)), m_Specific(B))))
+      return BinaryOperator::CreateAnd(Builder->CreateNot(B), 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 %x, i32 %y, i32 %z) {
+; CHECK-LABEL: @test15(
+; CHECK-NEXT: %1 = xor i32 %y, -1
+; CHECK-NEXT: %xor1 = and i32 %1, %z
+; CHECK-NEXT: ret i32 %xor1
+ %and = or i32 %x, %y
+ %xor = xor i32 %x, %z
+ %or = or i32 %xor, %y
+ %xor1 = xor i32 %and, %or
+ ret i32 %xor1
+}