[interpreter] Heal closures when bytecode array is gone.

src/arm/builtins-arm.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_ARM
 
 #include "src/codegen.h"
 #include "src/debug/debug.h"
 #include "src/deoptimizer.h"
 #include "src/full-codegen/full-codegen.h"
@@ skipping 974 matching lines @@
 // frames.h for its layout.
 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);
   __ PushStandardFrame(r1);
 
-  // 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(r0, FieldMemOperand(r1, JSFunction::kSharedFunctionInfoOffset));
   Register debug_info = kInterpreterBytecodeArrayRegister;
   DCHECK(!debug_info.is(r0));
   __ ldr(debug_info, FieldMemOperand(r0, SharedFunctionInfo::kDebugInfoOffset));
   __ cmp(debug_info, Operand(DebugInfo::uninitialized()));
   // Load original bytecode array or the debug copy.
   __ ldr(kInterpreterBytecodeArrayRegister,
          FieldMemOperand(r0, SharedFunctionInfo::kFunctionDataOffset), eq);
   __ ldr(kInterpreterBytecodeArrayRegister,
          FieldMemOperand(debug_info, DebugInfo::kAbstractCodeIndex), ne);
 
+  // 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.
     __ SmiTst(kInterpreterBytecodeArrayRegister);
     __ Assert(ne, kFunctionDataShouldBeBytecodeArrayOnInterpreterEntry);
     __ CompareObjectType(kInterpreterBytecodeArrayRegister, r0, no_reg,
                          BYTECODE_ARRAY_TYPE);
     __ Assert(eq, kFunctionDataShouldBeBytecodeArrayOnInterpreterEntry);
   }
 
   // Push new.target, bytecode array and zero for bytecode array offset.
   __ mov(r0, Operand(0));
   __ Push(r3, kInterpreterBytecodeArrayRegister, r0);
@@ skipping 39 matching lines @@
 
   // Dispatch to the first bytecode handler for the function.
   __ ldrb(r1, MemOperand(kInterpreterBytecodeArrayRegister,
                          kInterpreterBytecodeOffsetRegister));
   __ ldr(ip, MemOperand(kInterpreterDispatchTableRegister, r1, LSL,
                         kPointerSizeLog2));
   __ Call(ip);
 
   // Even though the first bytecode handler was called, we will never return.
   __ Abort(kUnexpectedReturnFromBytecodeHandler);
+
+  // 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(r4, FieldMemOperand(r1, JSFunction::kSharedFunctionInfoOffset));
+  __ ldr(r4, FieldMemOperand(r4, SharedFunctionInfo::kCodeOffset));
+  __ add(r4, r4, Operand(Code::kHeaderSize - kHeapObjectTag));
+  __ str(r4, FieldMemOperand(r1, JSFunction::kCodeEntryOffset));
+  __ RecordWriteCodeEntryField(r1, r4, r5);
+  __ Jump(r4);
 }
 
 
 void Builtins::Generate_InterpreterExitTrampoline(MacroAssembler* masm) {
   // The return value is in accumulator, which is already in r0.
 
   // Leave the frame (also dropping the register file).
   __ LeaveFrame(StackFrame::JAVA_SCRIPT);
 
   // Drop receiver + arguments and return.
@@ skipping 1695 matching lines @@
   }
 }
 
 
 #undef __
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_ARM