[turbofan] Gracefully bail out if OSR encounters a loop too deeply nested.

src/compiler/osr.h

 // 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.
 
 #ifndef V8_COMPILER_OSR_H_
 #define V8_COMPILER_OSR_H_
 
 #include "src/zone.h"
 
 // TurboFan structures OSR graphs in a way that separates almost all phases of
@@ skipping 81 matching lines @@
 class OsrHelper {
  public:
   explicit OsrHelper(CompilationInfo* info);
   // Only for testing.
   OsrHelper(size_t parameter_count, size_t stack_slot_count)
       : parameter_count_(parameter_count),
         stack_slot_count_(stack_slot_count) {}
 
   // Deconstructs the artificial {OsrNormalEntry} and rewrites the graph so
   // that only the path corresponding to {OsrLoopEntry} remains.
-  void Deconstruct(JSGraph* jsgraph, CommonOperatorBuilder* common,
+  // Return {false} if the OSR deconstruction failed somehow.
+  bool Deconstruct(JSGraph* jsgraph, CommonOperatorBuilder* common,
                    Zone* tmp_zone);
 
   // Prepares the frame w.r.t. OSR.
   void SetupFrame(Frame* frame);
 
   // Returns the number of unoptimized frame slots for this OSR.
   size_t UnoptimizedFrameSlots() { return stack_slot_count_; }
 
   // Returns the environment index of the first stack slot.
   static int FirstStackSlotIndex(int parameter_count) {
     // n.b. unlike Crankshaft, TurboFan environments do not contain the context.
     return 1 + parameter_count;  // receiver + params
   }
 
  private:
   size_t parameter_count_;
   size_t stack_slot_count_;
 };
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_OSR_H_