[interpreter] Heal closures when bytecode array is gone.

src/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 978 matching lines @@
 void Builtins::Generate_InterpreterEntryTrampoline(MacroAssembler* masm) {
   ProfileEntryHookStub::MaybeCallEntryHook(masm);
 
   // Open a frame scope to indicate that there is a frame on the stack.  The
   // MANUAL indicates that the scope shouldn't actually generate code to set up
   // the frame (that is done below).
   FrameScope frame_scope(masm, StackFrame::MANUAL);
   __ Push(lr, fp, cp, x1);
   __ Add(fp, jssp, StandardFrameConstants::kFixedFrameSizeFromFp);
 
-  // Get the bytecode array from the function object and load the pointer to the
-  // first entry into kInterpreterBytecodeRegister.
+  // Get the bytecode array from the function object (or from the DebugInfo if
+  // it is present) and load it into kInterpreterBytecodeArrayRegister.
   __ Ldr(x0, FieldMemOperand(x1, JSFunction::kSharedFunctionInfoOffset));
   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 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) {
-    // Check function data field is actually a BytecodeArray object.
     __ AssertNotSmi(kInterpreterBytecodeArrayRegister,
                     kFunctionDataShouldBeBytecodeArrayOnInterpreterEntry);
     __ CompareObjectType(kInterpreterBytecodeArrayRegister, x0, x0,
                          BYTECODE_ARRAY_TYPE);
     __ Assert(eq, kFunctionDataShouldBeBytecodeArrayOnInterpreterEntry);
   }
 
   // Push new.target, bytecode array and zero for bytecode array offset.
   __ Mov(x0, Operand(0));
   __ Push(x3, kInterpreterBytecodeArrayRegister, x0);
@@ skipping 43 matching lines @@
   __ Call(ip0);
 
   // Even though the first bytecode handler was called, we will never return.
   __ Abort(kUnexpectedReturnFromBytecodeHandler);
 
   // Load debug copy of the bytecode array.
   __ Bind(&load_debug_bytecode_array);
   __ Ldr(kInterpreterBytecodeArrayRegister,
          FieldMemOperand(debug_info, DebugInfo::kAbstractCodeIndex));
   __ 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);
+  __ 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_InterpreterExitTrampoline(MacroAssembler* masm) {
   // The return value is in accumulator, which is already in x0.
 
   // Leave the frame (also dropping the register file).
   __ LeaveFrame(StackFrame::JAVA_SCRIPT);
 
   // Drop receiver + arguments and return.
@@ skipping 1799 matching lines @@
   }
 }
 
 
 #undef __
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_ARM