[turbofan] Fold "boolean not"-like Selects into branches.

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

Index: test/unittests/compiler/common-operator-reducer-unittest.cc
diff --git a/test/unittests/compiler/common-operator-reducer-unittest.cc b/test/unittests/compiler/common-operator-reducer-unittest.cc
index f51a54d074c96cc141fc9378a213a708a080f1ec..d28477239535b9ebce60ec6c28206969bbd0c719 100644
--- a/test/unittests/compiler/common-operator-reducer-unittest.cc
+++ b/test/unittests/compiler/common-operator-reducer-unittest.cc
@@ -158,6 +158,26 @@ TEST_F(CommonOperatorReducerTest, BranchWithBooleanNot) {
   }
 }
 
+TEST_F(CommonOperatorReducerTest, BranchWithSelect) {
+  Node* const value = Parameter(0);
+  TRACED_FOREACH(BranchHint, hint, kBranchHints) {
+    Node* const control = graph()->start();
+    Node* const branch = graph()->NewNode(
+        common()->Branch(hint),
+        graph()->NewNode(common()->Select(MachineRepresentation::kTagged),
+                         value, FalseConstant(), TrueConstant()),
+        control);
+    Node* const if_true = graph()->NewNode(common()->IfTrue(), branch);
+    Node* const if_false = graph()->NewNode(common()->IfFalse(), branch);
+    Reduction const r = Reduce(branch);
+    ASSERT_TRUE(r.Changed());
+    EXPECT_EQ(branch, r.replacement());
+    EXPECT_THAT(branch, IsBranch(value, control));
+    EXPECT_THAT(if_false, IsIfTrue(branch));
+    EXPECT_THAT(if_true, IsIfFalse(branch));
+    EXPECT_EQ(NegateBranchHint(hint), BranchHintOf(branch->op()));
+  }
+}
 
 // -----------------------------------------------------------------------------
 // Merge