From d28b6a024826aaa48a8b3e69c096d01c91aff2c9 Mon Sep 17 00:00:00 2001
From: Kai Koehne <kai.koehne@nokia.com>
Date: Thu, 10 Nov 2011 16:00:37 +0100
Subject: [PATCH 12/12] Add flag to avoid breakpoint relocation

Add a flag that prevents v8 from relocating breakpoints across
line boundaries.
---
 src/debug.cc              |   29 +++++++++++++++++++---
 src/flag-definitions.h    |    1 +
 test/cctest/test-debug.cc |   59 +++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 85 insertions(+), 4 deletions(-)

diff --git a/src/debug.cc b/src/debug.cc
index dc9f297..d32574b 100644
--- a/src/debug.cc
+++ b/src/debug.cc
@@ -1131,6 +1131,17 @@ Handle<DebugInfo> Debug::GetDebugInfo(Handle<SharedFunctionInfo> shared) {
   return Handle<DebugInfo>(DebugInfo::cast(shared->debug_info()));
 }
 
+static bool ContainsLineBreak(String *string, int from, int to)
+{
+  ASSERT(from >= 0);
+  ASSERT(from <= to);
+  const int end = (string->length() < to) ? string->length() : to;
+  for (int pos = from; pos < end; ++pos) {
+    if (string->Get(pos) == '\n')
+      return true;
+  }
+  return false;
+}
 
 void Debug::SetBreakPoint(Handle<SharedFunctionInfo> shared,
                           Handle<Object> break_point_object,
@@ -1151,12 +1162,22 @@ void Debug::SetBreakPoint(Handle<SharedFunctionInfo> shared,
   // Find the break point and change it.
   BreakLocationIterator it(debug_info, SOURCE_BREAK_LOCATIONS);
   it.FindBreakLocationFromPosition(*source_position);
-  it.SetBreakPoint(break_point_object);
 
-  *source_position = it.position();
+  bool acceptBreak = true;
+  if (!FLAG_breakpoint_relocation) {
+    if (String *sourceStr = String::cast(shared->GetSourceCode())) {
+      acceptBreak = !ContainsLineBreak(sourceStr, *source_position, it.position());
+    }
+  }
+
+  if (acceptBreak) {
+    it.SetBreakPoint(break_point_object);
 
-  // At least one active break point now.
-  ASSERT(debug_info->GetBreakPointCount() > 0);
+    *source_position = it.position();
+
+    // At least one active break point now.
+    ASSERT(debug_info->GetBreakPointCount() > 0);
+  }
 }
 
 
diff --git a/src/flag-definitions.h b/src/flag-definitions.h
index ee6ef01..fe64a96 100644
--- a/src/flag-definitions.h
+++ b/src/flag-definitions.h
@@ -233,6 +233,7 @@ DEFINE_bool(trace_debug_json, false, "trace debugging JSON request/response")
 DEFINE_bool(debugger_auto_break, true,
             "automatically set the debug break flag when debugger commands are "
             "in the queue")
+DEFINE_bool(breakpoint_relocation, true, "relocate breakpoints to the next executable line")
 DEFINE_bool(enable_liveedit, true, "enable liveedit experimental feature")
 
 // execution.cc
diff --git a/test/cctest/test-debug.cc b/test/cctest/test-debug.cc
index cf723ba..7e51c34 100644
--- a/test/cctest/test-debug.cc
+++ b/test/cctest/test-debug.cc
@@ -2305,6 +2305,65 @@ TEST(ScriptBreakPointTopLevelCrash) {
   CheckDebuggerUnloaded();
 }
 
+// Test that breakpoint_relocation flag is honored
+TEST(ScriptBreakPointNoRelocation) {
+    i::FLAG_breakpoint_relocation = false;
+
+    v8::HandleScope scope;
+    DebugLocalContext env;
+    env.ExposeDebug();
+
+    // Create a function for checking the function when hitting a break point.
+    frame_function_name = CompileFunction(&env,
+                                          frame_function_name_source,
+                                          "frame_function_name");
+
+    v8::Debug::SetDebugEventListener(DebugEventBreakPointHitCount,
+                                     v8::Undefined());
+
+    v8::Local<v8::String> script1 = v8::String::New(
+      "a = 0                      // line 0\n"
+      "                           // line 1\n"
+      "                           // line 2\n"
+      "                           // line 3\n"
+      "function f() {             // line 4\n"
+      "  return 0;                // line 5\n"
+      "}                          // line 6");
+
+    // Set the script break point on the empty line
+    SetScriptBreakPointByNameFromJS("test.html", 2, -1);
+
+    // Compile the script and call the function.
+    v8::ScriptOrigin origin(v8::String::New("test.html"), v8::Integer::New(0));
+    v8::Script::Compile(script1, &origin)->Run();
+    v8::Local<v8::Function> f
+            = v8::Local<v8::Function>::Cast(env->Global()->Get(v8::String::New("f")));
+    f->Call(env->Global(), 0, NULL);
+
+    // Check that a break point was not hit
+    CHECK_EQ(0, break_point_hit_count);
+
+    v8::Local<v8::String> script2 = v8::String::New(
+      "a = 0                      // line 0\n"
+      "function g() {             // line 1\n"
+      "  return 0;                // line 2\n"
+      "}                          // line 3\n"
+      "function f() {             // line 4\n"
+      "  return 0;                // line 5\n"
+      "}                          // line 6");
+
+    // Compile the script and call the new function
+    v8::Script::Compile(script2, &origin)->Run();
+    v8::Local<v8::Function> g
+            = v8::Local<v8::Function>::Cast(env->Global()->Get(v8::String::New("g")));
+    g->Call(env->Global(), 0, NULL);
+
+    // Check that a break point was not hit
+    CHECK_EQ(1, break_point_hit_count);
+
+    v8::Debug::SetDebugEventListener(NULL);
+    CheckDebuggerUnloaded();
+}
 
 // Test that it is possible to remove the last break point for a function
 // inside the break handling of that break point.
-- 
1.7.7.3