[turbofan] Connect loops to end via Terminate during graph building.

src/compiler/ast-graph-builder.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/ast-graph-builder.h"
 
 #include "src/compiler.h"
 #include "src/compiler/ast-loop-assignment-analyzer.h"
 #include "src/compiler/control-builders.h"
 #include "src/compiler/js-type-feedback.h"
@@ skipping 3642 matching lines @@
     // Only build phis for those locals assigned in this loop.
     for (int i = 0; i < size; ++i) {
       if (i < assigned->length() && !assigned->Contains(i)) continue;
       Node* phi = builder_->NewPhi(1, values()->at(i), control);
       values()->at(i) = phi;
     }
   }
   Node* effect = builder_->NewEffectPhi(1, GetEffectDependency(), control);
   UpdateEffectDependency(effect);
 
+  // Connect the loop to end via Terminate if it's not marked as unreachable.
+  if (!IsMarkedAsUnreachable()) {
+    // Connect the Loop node to end via a Terminate node.
+    Node* terminate = builder_->graph()->NewNode(
+        builder_->common()->Terminate(), effect, control);
+    builder_->exit_controls_.push_back(terminate);
+  }
+
   if (builder_->info()->is_osr()) {
     // Introduce phis for all context values in the case of an OSR graph.
     for (int i = 0; i < static_cast<int>(contexts()->size()); ++i) {
       Node* val = contexts()->at(i);
       if (!IrOpcode::IsConstantOpcode(val->opcode())) {
         contexts()->at(i) = builder_->NewPhi(1, val, control);
       }
     }
   }
 
@@ skipping 105 matching lines @@
     // Phi does not exist yet, introduce one.
     value = NewPhi(inputs, value, control);
     value->ReplaceInput(inputs - 1, other);
   }
   return value;
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8