[turbofan] Ensure that NTLs are always properly connected to the end.

test/unittests/compiler/control-reducer-unittest.cc

+// Copyright 2015 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/control-reducer.h"
+#include "src/compiler/js-graph.h"
+#include "src/compiler/js-operator.h"
+#include "src/compiler/machine-operator.h"
+#include "src/compiler/node.h"
+#include "test/unittests/compiler/graph-unittest.h"
+#include "test/unittests/compiler/node-test-utils.h"
+#include "testing/gmock-support.h"
+
+using testing::_;
+using testing::AllOf;
+using testing::Capture;
+using testing::CaptureEq;
+
+namespace v8 {
+namespace internal {
+namespace compiler {
+
+class ControlReducerTest : public GraphTest {
+ protected:
+  void ReduceGraph() {
+    JSOperatorBuilder javascript(zone());
+    MachineOperatorBuilder machine(zone());
+    JSGraph jsgraph(isolate(), graph(), common(), &javascript, &machine);
+    ControlReducer::ReduceGraph(zone(), &jsgraph, common());
+  }
+};
+
+
+TEST_F(ControlReducerTest, NonTerminatingLoop) {
+  Node* loop = graph()->NewNode(common()->Loop(2), graph()->start());
+  loop->AppendInput(graph()->zone(), loop);
+  ReduceGraph();
+  Capture<Node*> branch;
+  EXPECT_THAT(
+      graph()->end(),
+      IsEnd(IsMerge(
+          graph()->start(),
+          IsReturn(IsUndefinedConstant(), graph()->start(),
+                   IsIfFalse(
+                       AllOf(CaptureEq(&branch),
+                             IsBranch(IsAlways(),
+                                      AllOf(loop, IsLoop(graph()->start(),
+                                                         IsIfTrue(CaptureEq(
+                                                             &branch)))))))))));
+}
+
+
+TEST_F(ControlReducerTest, NonTerminatingLoopWithEffectPhi) {
+  Node* loop = graph()->NewNode(common()->Loop(2), graph()->start());
+  loop->AppendInput(graph()->zone(), loop);
+  Node* ephi = graph()->NewNode(common()->EffectPhi(2), graph()->start());
+  ephi->AppendInput(graph()->zone(), ephi);
+  ephi->AppendInput(graph()->zone(), loop);
+  ReduceGraph();
+  Capture<Node*> branch;
+  EXPECT_THAT(
+      graph()->end(),
+      IsEnd(IsMerge(
+          graph()->start(),
+          IsReturn(IsUndefinedConstant(),
+                   AllOf(ephi, IsEffectPhi(graph()->start(), ephi, loop)),
+                   IsIfFalse(
+                       AllOf(CaptureEq(&branch),
+                             IsBranch(IsAlways(),
+                                      AllOf(loop, IsLoop(graph()->start(),
+                                                         IsIfTrue(CaptureEq(
+                                                             &branch)))))))))));
+}
+
+
+TEST_F(ControlReducerTest, NonTerminatingLoopWithTwoEffectPhis) {
+  Node* loop = graph()->NewNode(common()->Loop(2), graph()->start());
+  loop->AppendInput(graph()->zone(), loop);
+  Node* ephi1 = graph()->NewNode(common()->EffectPhi(2), graph()->start());
+  ephi1->AppendInput(graph()->zone(), ephi1);
+  ephi1->AppendInput(graph()->zone(), loop);
+  Node* ephi2 = graph()->NewNode(common()->EffectPhi(2), graph()->start());
+  ephi2->AppendInput(graph()->zone(), ephi2);
+  ephi2->AppendInput(graph()->zone(), loop);
+  ReduceGraph();
+  Capture<Node*> branch;
+  EXPECT_THAT(
+      graph()->end(),
+      IsEnd(IsMerge(
+          graph()->start(),
+          IsReturn(
+              IsUndefinedConstant(),
+              IsEffectSet(
+                  AllOf(ephi1, IsEffectPhi(graph()->start(), ephi1, loop)),
+                  AllOf(ephi2, IsEffectPhi(graph()->start(), ephi2, loop))),
+              IsIfFalse(AllOf(
+                  CaptureEq(&branch),
+                  IsBranch(
+                      IsAlways(),
+                      AllOf(loop, IsLoop(graph()->start(),
+                                         IsIfTrue(CaptureEq(&branch)))))))))));
+}
+
+
+TEST_F(ControlReducerTest, NonTerminatingLoopWithDeadEnd) {
+  Node* loop = graph()->NewNode(common()->Loop(2), graph()->start());
+  loop->AppendInput(graph()->zone(), loop);
+  graph()->end()->ReplaceInput(0, graph()->NewNode(common()->Dead()));
+  ReduceGraph();
+  Capture<Node*> branch;
+  EXPECT_THAT(
+      graph()->end(),
+      IsEnd(IsReturn(
+          IsUndefinedConstant(), graph()->start(),
+          IsIfFalse(AllOf(
+              CaptureEq(&branch),
+              IsBranch(IsAlways(),
+                       AllOf(loop, IsLoop(graph()->start(),
+                                          IsIfTrue(CaptureEq(&branch))))))))));
+}
+
+}  // namespace compiler
+}  // namespace internal
+}  // namespace v8