Revert of Revert of Debugger: deduplicate shared function info when s…

…etting script break points. (patchset nwjs#1 id:1 of https://codereview.chromium.org/999273003/)

Reason for revert:
Reland since the failure has been fixed in https://codereview.chromium.org/1035523005/

Original issue's description:
> Revert of Debugger: deduplicate shared function info when setting script break points. (patchset nwjs#4 id:60001 of https://codereview.chromium.org/998253005/)
>
> Reason for revert:
> Code caching failures.
>
> Original issue's description:
> > Debugger: deduplicate shared function info when setting script break points.
> >
> > Also fix Debug.showBreakPoints for multiple break points at the same location.
> >
> > BUG=v8:3960
> > LOG=N
> >
> > Committed: https://crrev.com/73b17a71a22564c0b66d9aa7c00948c748f5b290
> > Cr-Commit-Position: refs/heads/master@{#27444}
>
> TBR=mstarzinger@chromium.org
> NOPRESUBMIT=true
> NOTREECHECKS=true
> NOTRY=true
> BUG=v8:3960
>
> Committed: https://crrev.com/9b29d008dfcc00bf56be8040add1d2c5e404673b
> Cr-Commit-Position: refs/heads/master@{#27448}

TBR=mstarzinger@chromium.org
BUG=v8:3960
LOG=N

Review URL: https://codereview.chromium.org/1037013002

Cr-Commit-Position: refs/heads/master@{#27472}

src/compiler.cc

@@ -1428,7 +1428,7 @@ Handle<SharedFunctionInfo> Compiler::BuildFunctionInfo(
   result->set_is_toplevel(false);
 
   RecordFunctionCompilation(Logger::FUNCTION_TAG, &info, result);
-  result->set_allows_lazy_compilation(allow_lazy);
+  result->set_allows_lazy_compilation(literal->AllowsLazyCompilation());
   result->set_allows_lazy_compilation_without_context(allow_lazy_without_ctx);
 
   // Set the expected number of properties for instances and return

src/debug.cc

@@ -1506,23 +1506,22 @@ Handle<Object> Debug::GetSourceBreakLocations(
   Handle<FixedArray> locations =
       isolate->factory()->NewFixedArray(debug_info->GetBreakPointCount());
   int count = 0;
-  for (int i = 0; i < debug_info->break_points()->length(); i++) {
+  for (int i = 0; i < debug_info->break_points()->length(); ++i) {
     if (!debug_info->break_points()->get(i)->IsUndefined()) {
       BreakPointInfo* break_point_info =
           BreakPointInfo::cast(debug_info->break_points()->get(i));
-      if (break_point_info->GetBreakPointCount() > 0) {
-        Smi* position = NULL;
-        switch (position_alignment) {
-          case STATEMENT_ALIGNED:
-            position = break_point_info->statement_position();
-            break;
-          case BREAK_POSITION_ALIGNED:
-            position = break_point_info->source_position();
-            break;
-        }
-
-        locations->set(count++, position);
+      int break_points = break_point_info->GetBreakPointCount();
+      if (break_points == 0) continue;
+      Smi* position = NULL;
+      switch (position_alignment) {
+        case STATEMENT_ALIGNED:
+          position = break_point_info->statement_position();
+          break;
+        case BREAK_POSITION_ALIGNED:
+          position = break_point_info->source_position();
+          break;
       }
+      for (int j = 0; j < break_points; ++j) locations->set(count++, position);
     }
   }
   return locations;
@@ -1822,7 +1821,6 @@ static void RecompileAndRelocateSuspendedGenerators(
 static bool SkipSharedFunctionInfo(SharedFunctionInfo* shared,
                                    Object* active_code_marker) {
   if (!shared->allows_lazy_compilation()) return true;
-  if (!shared->script()->IsScript()) return true;
   Object* script = shared->script();
   if (!script->IsScript()) return true;
   if (Script::cast(script)->type()->value() == Script::TYPE_NATIVE) return true;
@@ -2103,6 +2101,21 @@ Handle<Object> Debug::FindSharedFunctionInfoInScript(Handle<Script> script,
     }
   }  // End while loop.
 
+  // JSFunctions from the same literal may not have the same shared function
+  // info. Find those JSFunctions and deduplicate the shared function info.
+  HeapIterator iterator(heap, FLAG_lazy ? HeapIterator::kNoFiltering
+                                        : HeapIterator::kFilterUnreachable);
+  for (HeapObject* obj = iterator.next(); obj != NULL; obj = iterator.next()) {
+    if (!obj->IsJSFunction()) continue;
+    JSFunction* function = JSFunction::cast(obj);
+    SharedFunctionInfo* shared = function->shared();
+    if (shared != *target && shared->script() == target->script() &&
+        shared->start_position_and_type() ==
+            target->start_position_and_type()) {
+      function->set_shared(*target);
+    }
+  }
+
   return target;
 }
 

src/liveedit.cc

@@ -1222,6 +1222,7 @@ void LiveEdit::SetFunctionScript(Handle<JSValue> function_wrapper,
       UnwrapSharedFunctionInfoFromJSValue(function_wrapper);
   CHECK(script_handle->IsScript() || script_handle->IsUndefined());
   shared_info->set_script(*script_handle);
+  shared_info->DisableOptimization(kLiveEdit);
 
   function_wrapper->GetIsolate()->compilation_cache()->Remove(shared_info);
 }

src/runtime/runtime-debug.cc

@@ -2646,6 +2646,15 @@ RUNTIME_FUNCTION(Runtime_ExecuteInDebugContext) {
 }
 
 
+RUNTIME_FUNCTION(Runtime_GetDebugContext) {
+  HandleScope scope(isolate);
+  DCHECK(args.length() == 0);
+  Handle<Context> context = isolate->debug()->GetDebugContext();
+  context->set_security_token(isolate->native_context()->security_token());
+  return context->global_proxy();
+}
+
+
 // Performs a GC.
 // Presently, it only does a full GC.
 RUNTIME_FUNCTION(Runtime_CollectGarbage) {

src/runtime/runtime.h

@@ -577,7 +577,7 @@ namespace internal {
   F(LiveEditRestartFrame, 2, 1)                     \
   F(GetFunctionCodePositionFromSource, 2, 1)        \
   F(ExecuteInDebugContext, 1, 1)                    \
-                                                    \
+  F(GetDebugContext, 0, 1)                          \
   F(SetFlags, 1, 1)                                 \
   F(CollectGarbage, 1, 1)                           \
   F(GetHeapUsage, 0, 1)

test/mjsunit/debug-liveedit-2.js

@@ -25,7 +25,7 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-// Flags: --expose-debug-as debug
+// Flags: --expose-debug-as debug --noalways-opt
 // Get the Debug object exposed from the debug context global object.
 
 

test/mjsunit/debug-liveedit-4.js

@@ -25,7 +25,7 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-// Flags: --expose-debug-as debug
+// Flags: --expose-debug-as debug --noalways-opt
 // Get the Debug object exposed from the debug context global object.
 
 // In this test case we edit a script so that techincally function text

test/mjsunit/regress/regress-3960.js

@@ -0,0 +1,36 @@
+// Copyright 2015 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// Flags: --allow-natives-syntax
+
+// Test that setting break point is works correctly when the debugger is
+// activated late, which leads to duplicate shared function infos.
+
+(function() {
+  var Debug = %GetDebugContext().Debug;
+
+  function listener(event, exec_state, event_data, data) {
+    if (event != Debug.DebugEvent.Break) return;
+    try {
+      assertTrue(/foo/.test(exec_state.frame(0).sourceLineText()));
+      break_count++;
+    } catch (e) {
+      exception = e;
+    }
+  }
+
+  for (var i = 0; i < 3; i++) {
+    var foo = function() { a = 1; }
+    var exception = null;
+    var break_count = 0;
+    Debug.setListener(listener);
+    if (i < 2) Debug.setBreakPoint(foo, 0, 0);
+    assertTrue(/\[B\d\]a = 1/.test(Debug.showBreakPoints(foo)));
+    foo();
+    assertEquals(1, break_count);
+    assertNull(exception);
+  }
+
+  Debug.setListener(null);
+})();