[turbofan] Do constant folding for Float64Pow.

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/compiler/machine-operator-reducer.h"
 #include "src/base/bits.h"
 #include "src/base/division-by-constant.h"
 #include "src/base/ieee754.h"
 #include "src/compiler/js-graph.h"
 #include "src/compiler/typer.h"
@@ skipping 1754 matching lines @@
     Reduction const r =
         Reduce(graph()->NewNode(machine()->Float64Log1p(), Float64Constant(x)));
     ASSERT_TRUE(r.Changed());
     EXPECT_THAT(
         r.replacement(),
         IsFloat64Constant(NanSensitiveDoubleEq(base::ieee754::log1p(x))));
   }
 }
 
 // -----------------------------------------------------------------------------
+// Float64Pow
+
+TEST_F(MachineOperatorReducerTest, Float64PowWithConstant) {
+  TRACED_FOREACH(double, x, kFloat64Values) {
+    TRACED_FOREACH(double, y, kFloat64Values) {
+      Reduction const r = Reduce(graph()->NewNode(
+          machine()->Float64Pow(), Float64Constant(x), Float64Constant(y)));
+      ASSERT_TRUE(r.Changed());
+      EXPECT_THAT(r.replacement(),
+                  IsFloat64Constant(NanSensitiveDoubleEq(Pow(x, y))));
+    }
+  }
+}
+
+TEST_F(MachineOperatorReducerTest, Float64PowWithZeroExponent) {
+  Node* const p0 = Parameter(0);
+  {
+    Reduction const r = Reduce(
+        graph()->NewNode(machine()->Float64Pow(), p0, Float64Constant(-0.0)));
+    ASSERT_TRUE(r.Changed());
+    EXPECT_THAT(r.replacement(), IsFloat64Constant(1.0));
+  }
+  {
+    Reduction const r = Reduce(
+        graph()->NewNode(machine()->Float64Pow(), p0, Float64Constant(0.0)));
+    ASSERT_TRUE(r.Changed());
+    EXPECT_THAT(r.replacement(), IsFloat64Constant(1.0));
+  }
+}
+
+// -----------------------------------------------------------------------------
 // Float64Sin
 
 TEST_F(MachineOperatorReducerTest, Float64SinWithConstant) {
   TRACED_FOREACH(double, x, kFloat64Values) {
     Reduction const r =
         Reduce(graph()->NewNode(machine()->Float64Sin(), Float64Constant(x)));
     ASSERT_TRUE(r.Changed());
     EXPECT_THAT(r.replacement(),
                 IsFloat64Constant(NanSensitiveDoubleEq(base::ieee754::sin(x))));
   }
@@ skipping 284 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