S390: [interpreter] Heal closures when bytecode array is gone.

Port 5c8609de

Original commit message:

    This ensures the InterpreterEntryTrampoline heals code entry fields
    inside closures when being called without a valid bytecode array. This
    is preparatory work to allow removal of bytecode when switching some
    functions to other types of code.

R=mstarzinger@chromium.org, joransiu@ca.ibm.com, bjaideep@ca.ibm.com, michael_dawson@ca.ibm.com, mbrandy@us.ibm.com

BUG=v8:4280
LOG=N

Review URL: https://codereview.chromium.org/1921673004

Cr-Commit-Position: refs/heads/master@{#35776}

src/s390/builtins-s390.cc

@@ -987,8 +987,8 @@ void Builtins::Generate_InterpreterEntryTrampoline(MacroAssembler* masm) {
   FrameScope frame_scope(masm, StackFrame::MANUAL);
   __ PushStandardFrame(r3);
 
-  // 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.
   __ LoadP(r2, FieldMemOperand(r3, JSFunction::kSharedFunctionInfoOffset));
   Label array_done;
   Register debug_info = r4;
@@ -1004,8 +1004,13 @@ void Builtins::Generate_InterpreterEntryTrampoline(MacroAssembler* masm) {
            FieldMemOperand(debug_info, DebugInfo::kAbstractCodeIndex));
   __ bind(&array_done);
 
+  // Check function data field is actually a BytecodeArray object.
+  Label bytecode_array_not_present;
+  __ CompareRoot(kInterpreterBytecodeArrayRegister,
+                 Heap::kUndefinedValueRootIndex);
+  __ beq(&bytecode_array_not_present);
+
   if (FLAG_debug_code) {
-    // Check function data field is actually a BytecodeArray object.
     __ TestIfSmi(kInterpreterBytecodeArrayRegister);
     __ Assert(ne, kFunctionDataShouldBeBytecodeArrayOnInterpreterEntry);
     __ CompareObjectType(kInterpreterBytecodeArrayRegister, r2, no_reg,
@@ -1066,6 +1071,18 @@ void Builtins::Generate_InterpreterEntryTrampoline(MacroAssembler* masm) {
 
   // 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);
+  __ LoadP(r6, FieldMemOperand(r3, JSFunction::kSharedFunctionInfoOffset));
+  __ LoadP(r6, FieldMemOperand(r6, SharedFunctionInfo::kCodeOffset));
+  __ AddP(r6, r6, Operand(Code::kHeaderSize - kHeapObjectTag));
+  __ StoreP(r6, FieldMemOperand(r3, JSFunction::kCodeEntryOffset), r0);
+  __ RecordWriteCodeEntryField(r3, r6, r7);
+  __ JumpToJSEntry(r6);
 }
 
 void Builtins::Generate_InterpreterExitTrampoline(MacroAssembler* masm) {