[interpreter] Fix self-healing with preserved bytecode.

src/builtins/arm64/builtins-arm64.cc

 // Copyright 2013 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.
 
 #if V8_TARGET_ARCH_ARM64
 
 #include "src/arm64/frames-arm64.h"
 #include "src/codegen.h"
 #include "src/debug/debug.h"
 #include "src/deoptimizer.h"
@@ skipping 1041 matching lines @@
   Register debug_info = kInterpreterBytecodeArrayRegister;
   Label load_debug_bytecode_array, bytecode_array_loaded;
   DCHECK(!debug_info.is(x0));
   __ Ldr(debug_info, FieldMemOperand(x0, SharedFunctionInfo::kDebugInfoOffset));
   __ Cmp(debug_info, Operand(DebugInfo::uninitialized()));
   __ B(ne, &load_debug_bytecode_array);
   __ Ldr(kInterpreterBytecodeArrayRegister,
          FieldMemOperand(x0, SharedFunctionInfo::kFunctionDataOffset));
   __ Bind(&bytecode_array_loaded);
 
+  // Check whether we should continue to use the interpreter.
+  Label switch_to_different_code_kind;
+  __ Ldr(x0, FieldMemOperand(x0, SharedFunctionInfo::kCodeOffset));
+  __ Cmp(x0, Operand(masm->CodeObject()));  // Self-reference to this code.
+  __ B(ne, &switch_to_different_code_kind);
+
   // Check function data field is actually a BytecodeArray object.
-  Label bytecode_array_not_present;
-  __ CompareRoot(kInterpreterBytecodeArrayRegister,
-                 Heap::kUndefinedValueRootIndex);
-  __ B(eq, &bytecode_array_not_present);
   if (FLAG_debug_code) {
     __ AssertNotSmi(kInterpreterBytecodeArrayRegister,
                     kFunctionDataShouldBeBytecodeArrayOnInterpreterEntry);
     __ CompareObjectType(kInterpreterBytecodeArrayRegister, x0, x0,
                          BYTECODE_ARRAY_TYPE);
     __ Assert(eq, kFunctionDataShouldBeBytecodeArrayOnInterpreterEntry);
   }
 
   // Load the initial bytecode offset.
   __ Mov(kInterpreterBytecodeOffsetRegister,
@@ skipping 47 matching lines @@
   // The return value is in x0.
   LeaveInterpreterFrame(masm, x2);
   __ Ret();
 
   // Load debug copy of the bytecode array.
   __ Bind(&load_debug_bytecode_array);
   __ Ldr(kInterpreterBytecodeArrayRegister,
          FieldMemOperand(debug_info, DebugInfo::kDebugBytecodeArrayIndex));
   __ B(&bytecode_array_loaded);
 
-  // If the bytecode array is no longer present, then the underlying function
-  // has been switched to a different kind of code and we heal the closure by
-  // switching the code entry field over to the new code object as well.
-  __ Bind(&bytecode_array_not_present);
+  // If the shared code is no longer this entry trampoline, then the underlying
+  // function has been switched to a different kind of code and we heal the
+  // closure by switching the code entry field over to the new code as well.
+  __ bind(&switch_to_different_code_kind);
   __ LeaveFrame(StackFrame::JAVA_SCRIPT);
   __ Ldr(x7, FieldMemOperand(x1, JSFunction::kSharedFunctionInfoOffset));
   __ Ldr(x7, FieldMemOperand(x7, SharedFunctionInfo::kCodeOffset));
   __ Add(x7, x7, Operand(Code::kHeaderSize - kHeapObjectTag));
   __ Str(x7, FieldMemOperand(x1, JSFunction::kCodeEntryOffset));
   __ RecordWriteCodeEntryField(x1, x7, x5);
   __ Jump(x7);
 }
 
 void Builtins::Generate_InterpreterMarkBaselineOnReturn(MacroAssembler* masm) {
@@ skipping 1887 matching lines @@
     __ Unreachable();
   }
 }
 
 #undef __
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_ARM