Support stepping into CallFunction stubs

src/debug.cc

 // Copyright 2006-2008 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 57 matching lines @@
 
 static Handle<Code> ComputeCallDebugPrepareStepIn(int argc) {
   CALL_HEAP_FUNCTION(StubCache::ComputeCallDebugPrepareStepIn(argc), Code);
 }
 
 
 BreakLocationIterator::BreakLocationIterator(Handle<DebugInfo> debug_info,
                                              BreakLocatorType type) {
   debug_info_ = debug_info;
   type_ = type;
+  // Get the stub early to avoid possible GC during iterations. We may need
+  // this stub to detect debugger calls generated from debugger statements.
+  debug_break_stub_ = RuntimeStub(Runtime::kDebugBreak, 0).GetCode();
   reloc_iterator_ = NULL;
   reloc_iterator_original_ = NULL;
   Reset();  // Initialize the rest of the member variables.
 }
 
 
 BreakLocationIterator::~BreakLocationIterator() {
   ASSERT(reloc_iterator_ != NULL);
   ASSERT(reloc_iterator_original_ != NULL);
   delete reloc_iterator_;
@@ skipping 31 matching lines @@
     // break points can cause the code targets in the running (debugged) code to
     // be of a different kind than in the original code.
     if (RelocInfo::IsCodeTarget(rmode())) {
       Address target = original_rinfo()->target_address();
       Code* code = Code::GetCodeFromTargetAddress(target);
       if (code->is_inline_cache_stub() || RelocInfo::IsConstructCall(rmode())) {
         break_point_++;
         return;
       }
       if (code->kind() == Code::STUB) {
+        if (IsDebuggerStatement()) {
+          break_point_++;
+          return;
+        }
         if (type_ == ALL_BREAK_LOCATIONS) {
           if (Debug::IsBreakStub(code)) {
             break_point_++;
             return;
           }
         } else {
           ASSERT(type_ == SOURCE_BREAK_LOCATIONS);
           if (Debug::IsSourceBreakStub(code)) {
             break_point_++;
             return;
@@ skipping 92 matching lines @@
   return RinfoDone();
 }
 
 
 void BreakLocationIterator::SetBreakPoint(Handle<Object> break_point_object) {
   // If there is not already a real break point here patch code with debug
   // break.
   if (!HasBreakPoint()) {
     SetDebugBreak();
   }
-  ASSERT(IsDebugBreak());
+  ASSERT(IsDebugBreak() || IsDebuggerStatement());
   // Set the break point information.
   DebugInfo::SetBreakPoint(debug_info_, code_position(),
                            position(), statement_position(),
                            break_point_object);
 }
 
 
 void BreakLocationIterator::ClearBreakPoint(Handle<Object> break_point_object) {
   // Clear the break point information.
   DebugInfo::ClearBreakPoint(debug_info_, code_position(), break_point_object);
   // If there are no more break points here remove the debug break.
   if (!HasBreakPoint()) {
     ClearDebugBreak();
     ASSERT(!IsDebugBreak());
   }
 }
 
 
 void BreakLocationIterator::SetOneShot() {
+  // Debugger statement always calls debugger. No need to modify it.
+  if (IsDebuggerStatement()) {
+    return;
+  }
+
   // If there is a real break point here no more to do.
   if (HasBreakPoint()) {
     ASSERT(IsDebugBreak());
     return;
   }
 
   // Patch code with debug break.
   SetDebugBreak();
 }
 
 
 void BreakLocationIterator::ClearOneShot() {
+  // Debugger statement always calls debugger. No need to modify it.
+  if (IsDebuggerStatement()) {
+    return;
+  }
+
   // If there is a real break point here no more to do.
   if (HasBreakPoint()) {
     ASSERT(IsDebugBreak());
     return;
   }
 
   // Patch code removing debug break.
   ClearDebugBreak();
   ASSERT(!IsDebugBreak());
 }
 
 
 void BreakLocationIterator::SetDebugBreak() {
+  // Debugger statement always calls debugger. No need to modify it.
+  if (IsDebuggerStatement()) {
+    return;
+  }
+
   // If there is already a break point here just return. This might happen if
   // the same code is flooded with break points twice. Flooding the same
   // function twice might happen when stepping in a function with an exception
   // handler as the handler and the function is the same.
   if (IsDebugBreak()) {
     return;
   }
 
   if (RelocInfo::IsJSReturn(rmode())) {
     // Patch the frame exit code with a break point.
     SetDebugBreakAtReturn();
   } else {
     // Patch the IC call.
     SetDebugBreakAtIC();
   }
   ASSERT(IsDebugBreak());
 }
 
 
 void BreakLocationIterator::ClearDebugBreak() {
+  // Debugger statement always calls debugger. No need to modify it.
+  if (IsDebuggerStatement()) {
+    return;
+  }
+
   if (RelocInfo::IsJSReturn(rmode())) {
     // Restore the frame exit code.
     ClearDebugBreakAtReturn();
   } else {
     // Patch the IC call.
     ClearDebugBreakAtIC();
   }
   ASSERT(!IsDebugBreak());
 }
 
 
 void BreakLocationIterator::PrepareStepIn() {
   HandleScope scope;
 
-  // Step in can only be prepared if currently positioned on an IC call or
-  // construct call.
+  // Step in can only be prepared if currently positioned on an IC call,
+  // construct call or CallFunction stub call.
   Address target = rinfo()->target_address();
-  Code* code = Code::GetCodeFromTargetAddress(target);
+  Handle<Code> code(Code::GetCodeFromTargetAddress(target));
   if (code->is_call_stub()) {
     // Step in through IC call is handled by the runtime system. Therefore make
     // sure that the any current IC is cleared and the runtime system is
     // called. If the executing code has a debug break at the location change
     // the call in the original code as it is the code there that will be
     // executed in place of the debug break call.
     Handle<Code> stub = ComputeCallDebugPrepareStepIn(code->arguments_count());
     if (IsDebugBreak()) {
       original_rinfo()->set_target_address(stub->entry());
     } else {
       rinfo()->set_target_address(stub->entry());
     }
   } else {
+#ifdef DEBUG
+    // All the following stuff is needed only for assertion checks so the code
+    // is wrapped in ifdef.
+    Handle<Code> maybe_call_function_stub = code;
+    if (IsDebugBreak()) {
+      Address original_target = original_rinfo()->target_address();
+      maybe_call_function_stub =
+          Handle<Code>(Code::GetCodeFromTargetAddress(original_target));
+    }
+    bool is_call_function_stub =
+        (maybe_call_function_stub->kind() == Code::STUB &&
+         maybe_call_function_stub->major_key() == CodeStub::CallFunction);
+
     // Step in through construct call requires no changes to the running code.
     // Step in through getters/setters should already be prepared as well
     // because caller of this function (Debug::PrepareStep) is expected to
     // flood the top frame's function with one shot breakpoints.
-    ASSERT(RelocInfo::IsConstructCall(rmode()) || code->is_inline_cache_stub());
+    // Step in through CallFunction stub should also be prepared by caller of
+    // this function (Debug::PrepareStep) which should flood target function
+    // with breakpoints.
+    ASSERT(RelocInfo::IsConstructCall(rmode()) || code->is_inline_cache_stub()
+           || is_call_function_stub);
+#endif
   }
 }
 
 
 // Check whether the break point is at a position which will exit the function.
 bool BreakLocationIterator::IsExit() const {
   return (RelocInfo::IsJSReturn(rmode()));
 }
 
 
@@ skipping 50 matching lines @@
     // Restore the inlined version of keyed stores to get back to the
     // fast case.  We need to patch back the keyed store because no
     // patching happens when running normally.  For keyed loads, the
     // map check will get patched back when running normally after ICs
     // have been cleared at GC.
     if (code->is_keyed_store_stub()) KeyedStoreIC::RestoreInlinedVersion(pc());
   }
 }
 
 
+bool BreakLocationIterator::IsDebuggerStatement() {
+  if (RelocInfo::IsCodeTarget(rmode())) {
+    Address target = original_rinfo()->target_address();
+    Code* code = Code::GetCodeFromTargetAddress(target);
+    if (code->kind() == Code::STUB) {
+      CodeStub::Major major_key = code->major_key();
+      if (major_key == CodeStub::Runtime) {
+        return (*debug_break_stub_ == code);
+      }
+    }
+  }
+  return false;
+}
+
+
 Object* BreakLocationIterator::BreakPointObjects() {
   return debug_info_->GetBreakPointObjects(code_position());
 }
 
 
 // Clear out all the debug break code. This is ONLY supposed to be used when
 // shutting down the debugger as it will leave the break point information in
 // DebugInfo even though the code is patched back to the non break point state.
 void BreakLocationIterator::ClearAllDebugBreak() {
   while (!Done()) {
@@ skipping 663 matching lines @@
   Handle<DebugInfo> debug_info = GetDebugInfo(shared);
 
   // Find the break location where execution has stopped.
   BreakLocationIterator it(debug_info, ALL_BREAK_LOCATIONS);
   it.FindBreakLocationFromAddress(frame->pc());
 
   // Compute whether or not the target is a call target.
   bool is_call_target = false;
   bool is_load_or_store = false;
   bool is_inline_cache_stub = false;
+  Handle<Code> call_function_stub;
   if (RelocInfo::IsCodeTarget(it.rinfo()->rmode())) {
     Address target = it.rinfo()->target_address();
     Code* code = Code::GetCodeFromTargetAddress(target);
     if (code->is_call_stub()) {
       is_call_target = true;
     }
     if (code->is_inline_cache_stub()) {
       is_inline_cache_stub = true;
       is_load_or_store = !is_call_target;
     }
+
+    // Check if target code is CallFunction stub.
+    Code* maybe_call_function_stub = code;
+    // If there is a breakpoint at this line look at the original code to
+    // check if it is a CallFunction stub.
+    if (it.IsDebugBreak()) {
+      Address original_target = it.original_rinfo()->target_address();
+      maybe_call_function_stub =
+          Code::GetCodeFromTargetAddress(original_target);
+    }
+    if (maybe_call_function_stub->kind() == Code::STUB &&
+        maybe_call_function_stub->major_key() == CodeStub::CallFunction) {
+      // Save reference to the code as we may need it to find out arguments
+      // count for 'step in' later.
+      call_function_stub = Handle<Code>(maybe_call_function_stub);
+    }
   }
 
   // If this is the last break code target step out is the only possibility.
   if (it.IsExit() || step_action == StepOut) {
     // Step out: If there is a JavaScript caller frame, we need to
     // flood it with breakpoints.
     frames_it.Advance();
     if (!frames_it.done()) {
       // Fill the function to return to with one-shot break points.
       JSFunction* function = JSFunction::cast(frames_it.frame()->function());
       FloodWithOneShot(Handle<SharedFunctionInfo>(function->shared()));
     }
-  } else if (!(is_inline_cache_stub || RelocInfo::IsConstructCall(it.rmode()))
+  } else if (!(is_inline_cache_stub || RelocInfo::IsConstructCall(it.rmode()) ||
+               !call_function_stub.is_null())
              || step_action == StepNext || step_action == StepMin) {
     // Step next or step min.
 
     // Fill the current function with one-shot break points.
     FloodWithOneShot(shared);
 
     // Remember source position and frame to handle step next.
     thread_local_.last_statement_position_ =
         debug_info->code()->SourceStatementPosition(frame->pc());
     thread_local_.last_fp_ = frame->fp();
   } else {
+    // If it's CallFunction stub ensure target function is compiled and flood
+    // it with one shot breakpoints.
+    if (!call_function_stub.is_null()) {
+      // Find out number of arguments from the stub minor key.
+      // Reverse lookup required as the minor key cannot be retrieved
+      // from the code object.
+      Handle<Object> obj(
+          Heap::code_stubs()->SlowReverseLookup(*call_function_stub));
+      ASSERT(*obj != Heap::undefined_value());
+      ASSERT(obj->IsSmi());
+      // Get the STUB key and extract major and minor key.
+      uint32_t key = Smi::cast(*obj)->value();
+      // Argc in the stub is the number of arguments passed - not the
+      // expected arguments of the called function.
+      int call_function_arg_count = CodeStub::MinorKeyFromKey(key);
+      ASSERT(call_function_stub->major_key() ==
+             CodeStub::MajorKeyFromKey(key));
+
+      // Find target function on the expression stack.
+      // Expression stack lools like this (top to bottom):
+      // argN
+      // ...
+      // arg0
+      // Receiver
+      // Function to call
+      int expressions_count = frame->ComputeExpressionsCount();
+      ASSERT(expressions_count - 2 - call_function_arg_count >= 0);
+      Object* fun = frame->GetExpression(
+          expressions_count - 2 - call_function_arg_count);
+      if (fun->IsJSFunction()) {
+        Handle<JSFunction> js_function(JSFunction::cast(fun));
+        // Don't step into builtins.
+        if (!js_function->IsBuiltin()) {
+          // It will also compile target function if it's not compiled yet.
+          FloodWithOneShot(Handle<SharedFunctionInfo>(js_function->shared()));
+        }
+      }
+    }
+
     // Fill the current function with one-shot break points even for step in on
     // a call target as the function called might be a native function for
     // which step in will not stop. It also prepares for stepping in
     // getters/setters.
     FloodWithOneShot(shared);
 
     if (is_load_or_store) {
       // Remember source position and frame to handle step in getter/setter. If
       // there is a custom getter/setter it will be handled in
       // Object::Get/SetPropertyWithCallback, otherwise the step action will be
@@ skipping 1424 matching lines @@
 
 
 void LockingCommandMessageQueue::Clear() {
   ScopedLock sl(lock_);
   queue_.Clear();
 }
 
 #endif  // ENABLE_DEBUGGER_SUPPORT
 
 } }  // namespace v8::internal