Support for precise stepping in functions compiled before debugging was started (step 1)

src/debug.cc

 // Copyright 2011 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 22 matching lines @@
 #include "code-stubs.h"
 #include "codegen.h"
 #include "compilation-cache.h"
 #include "compiler.h"
 #include "debug.h"
 #include "deoptimizer.h"
 #include "execution.h"
 #include "global-handles.h"
 #include "ic.h"
 #include "ic-inl.h"
+#include "list.h"
 #include "messages.h"
 #include "natives.h"
 #include "stub-cache.h"
 #include "log.h"
 
 #include "../include/v8-debug.h"
 
 namespace v8 {
 namespace internal {
 
@@ skipping 1045 matching lines @@
   ASSERT(HasDebugInfo(shared));
   return Handle<DebugInfo>(DebugInfo::cast(shared->debug_info()));
 }
 
 
 void Debug::SetBreakPoint(Handle<SharedFunctionInfo> shared,
                           Handle<Object> break_point_object,
                           int* source_position) {
   HandleScope scope(isolate_);
 
+  PrepareForBreakPoints();
+
   if (!EnsureDebugInfo(shared)) {
     // Return if retrieving debug info failed.
     return;
   }
 
   Handle<DebugInfo> debug_info = GetDebugInfo(shared);
   // Source positions starts with zero.
   ASSERT(source_position >= 0);
 
   // Find the break point and change it.
@@ skipping 53 matching lines @@
   }
 
   // Remove all debug info.
   while (debug_info_list_ != NULL) {
     RemoveDebugInfo(debug_info_list_->debug_info());
   }
 }
 
 
 void Debug::FloodWithOneShot(Handle<SharedFunctionInfo> shared) {
+  PrepareForBreakPoints();
   // Make sure the function has setup the debug info.
   if (!EnsureDebugInfo(shared)) {
     // Return if we failed to retrieve the debug info.
     return;
   }
 
   // Flood the function with break points.
   BreakLocationIterator it(GetDebugInfo(shared), ALL_BREAK_LOCATIONS);
   while (!it.Done()) {
     it.SetOneShot();
@@ skipping 36 matching lines @@
   if (type == BreakUncaughtException) {
     return break_on_uncaught_exception_;
   } else {
     return break_on_exception_;
   }
 }
 
 
 void Debug::PrepareStep(StepAction step_action, int step_count) {
   HandleScope scope(isolate_);
+
+  PrepareForBreakPoints();
+
   ASSERT(Debug::InDebugger());
 
   // Remember this step action and count.
   thread_local_.last_step_action_ = step_action;
   if (step_action == StepOut) {
     // For step out target frame will be found on the stack so there is no need
     // to set step counter for it. It's expected to always be 0 for StepOut.
     thread_local_.step_count_ = 0;
   } else {
     thread_local_.step_count_ = step_count;
@@ skipping 422 matching lines @@
 }
 
 
 void Debug::ClearStepNext() {
   thread_local_.last_step_action_ = StepNone;
   thread_local_.last_statement_position_ = RelocInfo::kNoPosition;
   thread_local_.last_fp_ = 0;
 }
 
 
+bool SortedListContains(List<JSFunction*>* functions, JSFunction* function) {

[Sven Panne, 2011/09/08 08:07:59]

Perhaps this should be moved to the List template class, probably with a
different signature (something like C's bsearch)

[Søren Thygesen Gjesse, 2011/09/13 07:31:19]

Added the following template functions to list.h. I decided against adding
bsearch directly to list as I did not want to add a flag for bookkeeping whether
the list is currently sorted.

// Perform binary search for an element in an already sorted
// list. Returns the index of the element of -1 if it was not found.
template <typename T>
int SortedListBSearch(List<T>& list, T elem, int (*cmp)(const T* x, const T*
y));
template <typename T>
int SortedListBSearch(List<T>& list, T elem);

+  int low = 0;
+  int high = functions->length() - 1;
+  while (low <= high) {
+    int mid = (low + high) / 2;
+    JSFunction* mid_function = (*functions)[mid];
+
+    if (mid_function > function) {
+      high = mid - 1;
+      continue;
+    }
+    if (mid_function < function) {
+      low = mid + 1;
+      continue;
+    }
+    // Found the function.
+    return true;
+  }
+  return false;
+}
+
+
+void Debug::PrepareForBreakPoints() {
+  // If preparing for the first break point make sure to deoptimize all
+  // functions as debugging does not work with optimized code.
+  if (!has_break_points_) {
+    Deoptimizer::DeoptimizeAll();
+
+    AssertNoAllocation no_allocation;
+    Builtins* builtins = isolate_->builtins();
+    Code* lazy_compile = builtins->builtin(Builtins::kLazyCompile);
+
+    // Find all non-optimized code functions with activation frames on
+    // the stack.
+    List<JSFunction*> functions(100);

[Sven Panne, 2011/09/08 08:07:59]

functions => active_functions

[Søren Thygesen Gjesse, 2011/09/13 07:31:19]

Done.

+    for (JavaScriptFrameIterator it(isolate_); !it.done(); it.Advance()) {
+      JavaScriptFrame* frame = it.frame();
+      if (frame->function()->IsJSFunction()) {
+        JSFunction* function = JSFunction::cast(frame->function());
+        if (function->code()->kind() == Code::FUNCTION)
+          functions.Add(function);
+      }
+    }
+    functions.Sort();
+
+    // Scan the heap for all non-optimized functions which has no
+    // debug break slots.
+    HeapIterator iterator;
+    HeapObject* obj = NULL;
+    while (((obj = iterator.next()) != NULL)) {
+      if (obj->IsJSFunction()) {
+        JSFunction* function = JSFunction::cast(obj);
+        if (function->shared()->allows_lazy_compilation() &&
+            function->shared()->script()->IsScript() &&
+            function->code()->kind() == Code::FUNCTION &&
+            !function->code()->has_debug_break_slots()) {
+          bool has_activation = SortedListContains(&functions, function);
+          if (!has_activation) {
+            function->set_code(lazy_compile);
+            function->shared()->set_code(lazy_compile);
+          }
+        }
+      }
+    }
+  }
+}
+
+
 // Ensures the debug information is present for shared.
 bool Debug::EnsureDebugInfo(Handle<SharedFunctionInfo> shared) {
   // Return if we already have the debug info for shared.
-  if (HasDebugInfo(shared)) return true;
+  if (HasDebugInfo(shared)) {
+    ASSERT(shared->is_compiled());
+    return true;
+  }
 
   // Ensure shared in compiled. Return false if this failed.
   if (!EnsureCompiled(shared, CLEAR_EXCEPTION)) return false;
 
-  // If preparing for the first break point make sure to deoptimize all
-  // functions as debugging does not work with optimized code.
-  if (!has_break_points_) {
-    Deoptimizer::DeoptimizeAll();
-  }
-
   // Create the debug info object.
   Handle<DebugInfo> debug_info = FACTORY->NewDebugInfo(shared);
 
   // Add debug info to the list.
   DebugInfoListNode* node = new DebugInfoListNode(*debug_info);
   node->set_next(debug_info_list_);
   debug_info_list_ = node;
 
   // Now there is at least one break point.
   has_break_points_ = true;
@@ skipping 29 matching lines @@
     prev = current;
     current = current->next();
   }
   UNREACHABLE();
 }
 
 
 void Debug::SetAfterBreakTarget(JavaScriptFrame* frame) {
   HandleScope scope(isolate_);
 
+  PrepareForBreakPoints();
+
   // Get the executing function in which the debug break occurred.
   Handle<SharedFunctionInfo> shared =
       Handle<SharedFunctionInfo>(JSFunction::cast(frame->function())->shared());
   if (!EnsureDebugInfo(shared)) {
     // Return if we failed to retrieve the debug info.
     return;
   }
   Handle<DebugInfo> debug_info = GetDebugInfo(shared);
   Handle<Code> code(debug_info->code());
   Handle<Code> original_code(debug_info->original_code());
@@ skipping 70 matching lines @@
 bool Debug::IsBreakAtReturn(JavaScriptFrame* frame) {
   HandleScope scope(isolate_);
 
   // If there are no break points this cannot be break at return, as
   // the debugger statement and stack guard bebug break cannot be at
   // return.
   if (!has_break_points_) {
     return false;
   }
 
+  PrepareForBreakPoints();
+
   // Get the executing function in which the debug break occurred.
   Handle<SharedFunctionInfo> shared =
       Handle<SharedFunctionInfo>(JSFunction::cast(frame->function())->shared());
   if (!EnsureDebugInfo(shared)) {
     // Return if we failed to retrieve the debug info.
     return false;
   }
   Handle<DebugInfo> debug_info = GetDebugInfo(shared);
   Handle<Code> code(debug_info->code());
 #ifdef DEBUG
@@ skipping 1284 matching lines @@
     {
       Locker locker;
       Isolate::Current()->debugger()->CallMessageDispatchHandler();
     }
   }
 }
 
 #endif  // ENABLE_DEBUGGER_SUPPORT
 
 } }  // namespace v8::internal