[turbofan] Introduce TruncateTaggedToWord32 simplified operator.

test/unittests/compiler/simplified-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/compiler/access-builder.h"
 #include "src/compiler/js-graph.h"
 #include "src/compiler/node-properties.h"
 #include "src/compiler/simplified-operator.h"
 #include "src/compiler/simplified-operator-reducer.h"
 #include "src/conversions-inl.h"
@@ skipping 383 matching lines @@
 TEST_F(SimplifiedOperatorReducerTest, ChangeUint32ToTagged) {
   TRACED_FOREACH(uint32_t, n, kUint32Values) {
     Reduction reduction =
         Reduce(graph()->NewNode(simplified()->ChangeUint32ToTagged(),
                                 Int32Constant(bit_cast<int32_t>(n))));
     ASSERT_TRUE(reduction.Changed());
     EXPECT_THAT(reduction.replacement(), IsNumberConstant(BitEq(FastUI2D(n))));
   }
 }
 
+// -----------------------------------------------------------------------------
+// TruncateTaggedToWord32
+
+TEST_F(SimplifiedOperatorReducerTest,
+       TruncateTaggedToWord3WithChangeFloat64ToTagged) {
+  Node* param0 = Parameter(0);
+  Reduction reduction = Reduce(graph()->NewNode(
+      simplified()->TruncateTaggedToWord32(),
+      graph()->NewNode(simplified()->ChangeFloat64ToTagged(), param0)));
+  ASSERT_TRUE(reduction.Changed());
+  EXPECT_THAT(reduction.replacement(), IsTruncateFloat64ToWord32(param0));
+}
+
+TEST_F(SimplifiedOperatorReducerTest, TruncateTaggedToWord32WithConstant) {
+  TRACED_FOREACH(double, n, kFloat64Values) {
+    Reduction reduction = Reduce(graph()->NewNode(
+        simplified()->TruncateTaggedToWord32(), NumberConstant(n)));
+    ASSERT_TRUE(reduction.Changed());
+    EXPECT_THAT(reduction.replacement(), IsInt32Constant(DoubleToInt32(n)));
+  }
+}
+
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8