[turbofan] Reduce ~~x to x.

test/unittests/compiler/machine-operator-reducer-unittest.cc

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/base/bits.h"
 #include "src/base/division-by-constant.h"
 #include "src/compiler/js-graph.h"
 #include "src/compiler/machine-operator-reducer.h"
 #include "src/compiler/typer.h"
 #include "test/unittests/compiler/graph-unittest.h"
@@ skipping 464 matching lines @@
         graph()->NewNode(machine()->TruncateInt64ToInt32(), Int64Constant(x)));
     ASSERT_TRUE(reduction.Changed());
     EXPECT_THAT(reduction.replacement(),
                 IsInt32Constant(bit_cast<int32_t>(
                     static_cast<uint32_t>(bit_cast<uint64_t>(x)))));
   }
 }
 
 
 // -----------------------------------------------------------------------------
+// Word32Xor
+
+
+TEST_F(MachineOperatorReducerTest, Word32XorWithWord32XorAndMinusOne) {
+  Node* const p0 = Parameter(0);
+
+  // (x ^ -1) ^ -1 => x
+  Reduction r1 = Reduce(graph()->NewNode(
+      machine()->Word32Xor(),
+      graph()->NewNode(machine()->Word32Xor(), p0, Int32Constant(-1)),
+      Int32Constant(-1)));
+  ASSERT_TRUE(r1.Changed());
+  EXPECT_EQ(r1.replacement(), p0);
+
+  // -1 ^ (x ^ -1) => x
+  Reduction r2 = Reduce(graph()->NewNode(
+      machine()->Word32Xor(), Int32Constant(-1),
+      graph()->NewNode(machine()->Word32Xor(), p0, Int32Constant(-1))));
+  ASSERT_TRUE(r2.Changed());
+  EXPECT_EQ(r2.replacement(), p0);
+
+  // (-1 ^ x) ^ -1 => x
+  Reduction r3 = Reduce(graph()->NewNode(
+      machine()->Word32Xor(),
+      graph()->NewNode(machine()->Word32Xor(), Int32Constant(-1), p0),
+      Int32Constant(-1)));
+  ASSERT_TRUE(r3.Changed());
+  EXPECT_EQ(r3.replacement(), p0);
+
+  // -1 ^ (-1 ^ x) => x
+  Reduction r4 = Reduce(graph()->NewNode(
+      machine()->Word32Xor(), Int32Constant(-1),
+      graph()->NewNode(machine()->Word32Xor(), Int32Constant(-1), p0)));
+  ASSERT_TRUE(r4.Changed());
+  EXPECT_EQ(r4.replacement(), p0);
+}
+
+
+// -----------------------------------------------------------------------------
 // Word32Ror
 
 
 TEST_F(MachineOperatorReducerTest, ReduceToWord32RorWithParameters) {
   Node* value = Parameter(0);
   Node* shift = Parameter(1);
   Node* shl = graph()->NewNode(machine()->Word32Shl(), value, shift);
   Node* shr = graph()->NewNode(
       machine()->Word32Shr(), value,
       graph()->NewNode(machine()->Int32Sub(), Int32Constant(32), shift));
@@ skipping 421 matching lines @@
     Reduction r = Reduce(node);
     ASSERT_TRUE(r.Changed());
     EXPECT_THAT(r.replacement(),
                 IsStore(rep, base, index, value, effect, control));
   }
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8