[turbofan] Do constant folding for Float64Pow.

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

Index: test/unittests/compiler/machine-operator-reducer-unittest.cc
diff --git a/test/unittests/compiler/machine-operator-reducer-unittest.cc b/test/unittests/compiler/machine-operator-reducer-unittest.cc
index b81ec2f3c568d41af52fa2a45f811ed851716408..127ddf355718cf677ce26f9a9630fc65fa39e63c 100644
--- a/test/unittests/compiler/machine-operator-reducer-unittest.cc
+++ b/test/unittests/compiler/machine-operator-reducer-unittest.cc
@@ -1772,6 +1772,37 @@ TEST_F(MachineOperatorReducerTest, Float64Log1pWithConstant) {
 }
 
 // -----------------------------------------------------------------------------
+// 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) {