[interpreter] Fix self-healing with preserved bytecode.

src/builtins/mips/builtins-mips.cc

 // Copyright 2012 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_MIPS
 
 #include "src/codegen.h"
 #include "src/debug/debug.h"
 #include "src/deoptimizer.h"
 #include "src/full-codegen/full-codegen.h"
@@ skipping 1027 matching lines @@
   Label load_debug_bytecode_array, bytecode_array_loaded;
   Register debug_info = kInterpreterBytecodeArrayRegister;
   DCHECK(!debug_info.is(a0));
   __ lw(debug_info, FieldMemOperand(a0, SharedFunctionInfo::kDebugInfoOffset));
   __ Branch(&load_debug_bytecode_array, ne, debug_info,
             Operand(DebugInfo::uninitialized()));
   __ lw(kInterpreterBytecodeArrayRegister,
         FieldMemOperand(a0, SharedFunctionInfo::kFunctionDataOffset));
   __ bind(&bytecode_array_loaded);
 
+  // Check whether we should continue to use the interpreter.
+  Label switch_to_different_code_kind;
+  __ lw(a0, FieldMemOperand(a0, SharedFunctionInfo::kCodeOffset));
+  __ Branch(&switch_to_different_code_kind, ne, a0,
+            Operand(masm->CodeObject()));  // Self-reference to this code.
+
   // Check function data field is actually a BytecodeArray object.
-  Label bytecode_array_not_present;
-  __ JumpIfRoot(kInterpreterBytecodeArrayRegister,
-                Heap::kUndefinedValueRootIndex, &bytecode_array_not_present);
   if (FLAG_debug_code) {
     __ SmiTst(kInterpreterBytecodeArrayRegister, t0);
     __ Assert(ne, kFunctionDataShouldBeBytecodeArrayOnInterpreterEntry, t0,
               Operand(zero_reg));
     __ GetObjectType(kInterpreterBytecodeArrayRegister, t0, t0);
     __ Assert(eq, kFunctionDataShouldBeBytecodeArrayOnInterpreterEntry, t0,
               Operand(BYTECODE_ARRAY_TYPE));
   }
 
   // Load initial bytecode offset.
@@ skipping 50 matching lines @@
   // The return value is in v0.
   LeaveInterpreterFrame(masm, t0);
   __ Jump(ra);
 
   // Load debug copy of the bytecode array.
   __ bind(&load_debug_bytecode_array);
   __ lw(kInterpreterBytecodeArrayRegister,
         FieldMemOperand(debug_info, DebugInfo::kDebugBytecodeArrayIndex));
   __ Branch(&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);
   __ lw(t0, FieldMemOperand(a1, JSFunction::kSharedFunctionInfoOffset));
   __ lw(t0, FieldMemOperand(t0, SharedFunctionInfo::kCodeOffset));
   __ Addu(t0, t0, Operand(Code::kHeaderSize - kHeapObjectTag));
   __ sw(t0, FieldMemOperand(a1, JSFunction::kCodeEntryOffset));
   __ RecordWriteCodeEntryField(a1, t0, t1);
   __ Jump(t0);
 }
 
 void Builtins::Generate_InterpreterMarkBaselineOnReturn(MacroAssembler* masm) {
@@ skipping 1866 matching lines @@
     __ break_(0xCC);
   }
 }
 
 #undef __
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_MIPS