[turbofan] Reduce shl with sar/shr and same shift amount to bit-and.

src/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/compiler/graph-unittest.h"
 #include "src/compiler/js-graph.h"
 #include "src/compiler/machine-operator-reducer.h"
 #include "src/compiler/typer.h"
 
@@ skipping 503 matching lines @@
       Reduction reduction = Reduce(node);
       EXPECT_TRUE(reduction.Changed());
       EXPECT_THAT(reduction.replacement(),
                   IsInt32Constant(base::bits::RotateRight32(x, y)));
     }
   }
 }
 
 
 // -----------------------------------------------------------------------------
+// Word32Shl
+
+
+TEST_F(MachineOperatorReducerTest, Word32ShlWithZeroShift) {
+  Node* p0 = Parameter(0);
+  Node* node = graph()->NewNode(machine()->Word32Shl(), p0, Int32Constant(0));
+  Reduction r = Reduce(node);
+  ASSERT_TRUE(r.Changed());
+  EXPECT_EQ(p0, r.replacement());
+}
+
+
+TEST_F(MachineOperatorReducerTest, Word32ShlWithWord32Sar) {
+  Node* p0 = Parameter(0);
+  TRACED_FORRANGE(int32_t, x, 1, 31) {
+    Node* node = graph()->NewNode(
+        machine()->Word32Shl(),
+        graph()->NewNode(machine()->Word32Sar(), p0, Int32Constant(x)),
+        Int32Constant(x));
+    Reduction r = Reduce(node);
+    ASSERT_TRUE(r.Changed());
+    int32_t m = bit_cast<int32_t>(~((1U << x) - 1U));
+    EXPECT_THAT(r.replacement(), IsWord32And(p0, IsInt32Constant(m)));
+  }
+}
+
+
+TEST_F(MachineOperatorReducerTest, Word32ShlWithWord32Shr) {
+  Node* p0 = Parameter(0);
+  TRACED_FORRANGE(int32_t, x, 1, 31) {
+    Node* node = graph()->NewNode(
+        machine()->Word32Shl(),
+        graph()->NewNode(machine()->Word32Shr(), p0, Int32Constant(x)),
+        Int32Constant(x));
+    Reduction r = Reduce(node);
+    ASSERT_TRUE(r.Changed());
+    int32_t m = bit_cast<int32_t>(~((1U << x) - 1U));
+    EXPECT_THAT(r.replacement(), IsWord32And(p0, IsInt32Constant(m)));
+  }
+}
+
+
+// -----------------------------------------------------------------------------
 // Int32AddWithOverflow
 
 
 TEST_F(MachineOperatorReducerTest, Int32AddWithOverflowWithZero) {
   Node* p0 = Parameter(0);
   {
     Node* add = graph()->NewNode(machine()->Int32AddWithOverflow(),
                                  Int32Constant(0), p0);
 
     Reduction r = Reduce(graph()->NewNode(common()->Projection(1), add));
@@ skipping 73 matching lines @@
       r = Reduce(graph()->NewNode(common()->Projection(0), add));
       ASSERT_TRUE(r.Changed());
       EXPECT_THAT(r.replacement(), IsInt32Constant(z));
     }
   }
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8