[interpreter, debugger] support debug breaks via bytecode array copy

src/arm/builtins-arm.cc

Index: src/arm/builtins-arm.cc
diff --git a/src/arm/builtins-arm.cc b/src/arm/builtins-arm.cc
index 4d6c30ee679b6a230dc06a6fde803fa73296ce98..398478eecfece51e52ee011a5462f7675cc5885b 100644
--- a/src/arm/builtins-arm.cc
+++ b/src/arm/builtins-arm.cc
@@ -861,8 +861,15 @@ void Builtins::Generate_InterpreterEntryTrampoline(MacroAssembler* masm) {
   // Get the bytecode array from the function object and load the pointer to the
   // first entry into kInterpreterBytecodeRegister.
   __ 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));
+         FieldMemOperand(r0, SharedFunctionInfo::kFunctionDataOffset), eq);
+  __ ldr(kInterpreterBytecodeArrayRegister,
+         FieldMemOperand(debug_info, DebugInfo::kAbstractCodeIndex), ne);
 
   if (FLAG_debug_code) {
     // Check function data field is actually a BytecodeArray object.