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

src/ia32/builtins-ia32.cc

Index: src/ia32/builtins-ia32.cc
diff --git a/src/ia32/builtins-ia32.cc b/src/ia32/builtins-ia32.cc
index 1715ac156291f14d4e3d03c57872e2b169d29faf..4f2a33d4a6c0913481ce764ceeec49efd92a0f9c 100644
--- a/src/ia32/builtins-ia32.cc
+++ b/src/ia32/builtins-ia32.cc
@@ -556,8 +556,14 @@ void Builtins::Generate_InterpreterEntryTrampoline(MacroAssembler* masm) {
   // Get the bytecode array from the function object and load the pointer to the
   // first entry into edi (InterpreterBytecodeRegister).
   __ mov(eax, FieldOperand(edi, JSFunction::kSharedFunctionInfoOffset));
+
+  Label load_debug_bytecode_array, bytecode_array_loaded;
+  __ cmp(FieldOperand(eax, SharedFunctionInfo::kDebugInfoOffset),
+         Immediate(DebugInfo::uninitialized()));
+  __ j(not_equal, &load_debug_bytecode_array);
   __ mov(kInterpreterBytecodeArrayRegister,
          FieldOperand(eax, SharedFunctionInfo::kFunctionDataOffset));
+  __ bind(&bytecode_array_loaded);
 
   if (FLAG_debug_code) {
     // Check function data field is actually a BytecodeArray object.
@@ -633,6 +639,14 @@ void Builtins::Generate_InterpreterEntryTrampoline(MacroAssembler* masm) {
 
   // 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);
+  Register debug_info = kInterpreterBytecodeArrayRegister;
+  __ mov(debug_info, FieldOperand(eax, SharedFunctionInfo::kDebugInfoOffset));
+  __ mov(kInterpreterBytecodeArrayRegister,
+         FieldOperand(debug_info, DebugInfo::kAbstractCodeIndex));
+  __ jmp(&bytecode_array_loaded);
 }
 
 
@@ -755,8 +769,14 @@ static void Generate_EnterBytecodeDispatch(MacroAssembler* masm) {
   __ mov(ebx, Operand(kInterpreterRegisterFileRegister,
                       InterpreterFrameConstants::kFunctionFromRegisterPointer));
   __ mov(ebx, FieldOperand(ebx, JSFunction::kSharedFunctionInfoOffset));
+
+  Label load_debug_bytecode_array, bytecode_array_loaded;
+  __ cmp(FieldOperand(ebx, SharedFunctionInfo::kDebugInfoOffset),
+         Immediate(DebugInfo::uninitialized()));
+  __ j(not_equal, &load_debug_bytecode_array);
   __ mov(kInterpreterBytecodeArrayRegister,
          FieldOperand(ebx, SharedFunctionInfo::kFunctionDataOffset));
+  __ bind(&bytecode_array_loaded);
 
   if (FLAG_debug_code) {
     // Check function data field is actually a BytecodeArray object.
@@ -795,6 +815,14 @@ static void Generate_EnterBytecodeDispatch(MacroAssembler* masm) {
   // and header removal.
   __ add(ebx, Immediate(Code::kHeaderSize - kHeapObjectTag));
   __ jmp(ebx);
+
+  // Load debug copy of the bytecode array.
+  __ bind(&load_debug_bytecode_array);
+  Register debug_info = kInterpreterBytecodeArrayRegister;
+  __ mov(debug_info, FieldOperand(ebx, SharedFunctionInfo::kDebugInfoOffset));
+  __ mov(kInterpreterBytecodeArrayRegister,
+         FieldOperand(debug_info, DebugInfo::kAbstractCodeIndex));
+  __ jmp(&bytecode_array_loaded);
 }