Debugger: correctly recompile toplevel eval functions for debugging.

src/compiler.cc

Index: src/compiler.cc
diff --git a/src/compiler.cc b/src/compiler.cc
index 861a34a2ce4522360310a6023daf65b4ad5797b3..58e345ffb17b5997bb1fe9f9adb5ea9b05360abd 100644
--- a/src/compiler.cc
+++ b/src/compiler.cc
@@ -112,7 +112,6 @@ CompilationInfo::CompilationInfo(ParseInfo* parse_info)
   // with deoptimization support.
   if (isolate_->serializer_enabled()) EnableDeoptimizationSupport();
 
-  if (isolate_->debug()->is_active()) MarkAsDebug();
   if (FLAG_context_specialization) MarkAsContextSpecializing();
   if (FLAG_turbo_inlining) MarkAsInliningEnabled();
   if (FLAG_turbo_source_positions) MarkAsSourcePositionsEnabled();
@@ -966,26 +965,68 @@ bool Compiler::EnsureDeoptimizationSupport(CompilationInfo* info) {
 }
 
 
-MaybeHandle<Code> CompileForDebugging(CompilationInfo* info) {
+bool CompileEvalForDebugging(Handle<JSFunction> function,
+                             Handle<SharedFunctionInfo> shared) {
+  Handle<Script> script(Script::cast(shared->script()));
+  Handle<Context> context(function->context());
+
+  Zone zone;
+  ParseInfo parse_info(&zone, script);
+  CompilationInfo info(&parse_info);
+  Isolate* isolate = info.isolate();
+
+  parse_info.set_eval();
+  parse_info.set_context(context);
+  if (context->IsNativeContext()) parse_info.set_global();
+  parse_info.set_toplevel();
+  parse_info.set_allow_lazy_parsing(false);
+  parse_info.set_language_mode(shared->language_mode());
+  parse_info.set_parse_restriction(NO_PARSE_RESTRICTION);
+  info.MarkAsDebug();
+
+  VMState<COMPILER> state(info.isolate());
+
+  if (!Parser::ParseStatic(&parse_info)) {
+    isolate->clear_pending_exception();
+    return false;
+  }
+
+  FunctionLiteral* lit = info.function();
+  LiveEditFunctionTracker live_edit_tracker(isolate, lit);
+
+  if (!CompileUnoptimizedCode(&info)) {
+    isolate->clear_pending_exception();
+    return false;
+  }
+  shared->ReplaceCode(*info.code());
+  return true;
+}
+
+
+bool CompileForDebugging(CompilationInfo* info) {
   info->MarkAsDebug();
-  VMState<COMPILER> state(info->isolate());
-  MaybeHandle<Code> maybe_new_code = GetUnoptimizedCodeCommon(info);
-  Handle<Code> new_code;
-  if (!maybe_new_code.ToHandle(&new_code)) {
+  if (GetUnoptimizedCodeCommon(info).is_null()) {
     info->isolate()->clear_pending_exception();
+    return false;
   }
-  return maybe_new_code;
+  return true;
 }
 
 
-MaybeHandle<Code> Compiler::GetDebugCode(Handle<JSFunction> function) {
-  CompilationInfoWithZone info(function);
-  VMState<COMPILER> state(info.isolate());
-  return CompileForDebugging(&info);
+bool Compiler::CompileDebugCode(Handle<JSFunction> function) {
+  Handle<SharedFunctionInfo> shared(function->shared());
+  if (shared->is_toplevel() && shared->script()->IsScript() &&
+      Script::cast(shared->script())->compilation_type() ==
+          Script::COMPILATION_TYPE_EVAL) {
+    return CompileEvalForDebugging(function, shared);
+  } else {
+    CompilationInfoWithZone info(function);
+    return CompileForDebugging(&info);
+  }
 }
 
 
-MaybeHandle<Code> Compiler::GetDebugCode(Handle<SharedFunctionInfo> shared) {
+bool Compiler::CompileDebugCode(Handle<SharedFunctionInfo> shared) {
   DCHECK(shared->allows_lazy_compilation_without_context());
   Zone zone;
   ParseInfo parse_info(&zone, shared);
@@ -1120,8 +1161,6 @@ static Handle<SharedFunctionInfo> CompileToplevel(CompilationInfo* info) {
     live_edit_tracker.RecordFunctionInfo(result, lit, info->zone());
   }
 
-  isolate->debug()->OnAfterCompile(script);
-
   return result;
 }
 
@@ -1142,8 +1181,9 @@ MaybeHandle<JSFunction> Compiler::GetFunctionFromEval(
                                     line_offset);
   Handle<SharedFunctionInfo> shared_info;
 
+  Handle<Script> script;
   if (!maybe_shared_info.ToHandle(&shared_info)) {
-    Handle<Script> script = isolate->factory()->NewScript(source);
+    script = isolate->factory()->NewScript(source);
     if (!script_name.is_null()) {
       script->set_name(*script_name);
       script->set_line_offset(Smi::FromInt(line_offset));
@@ -1159,8 +1199,6 @@ MaybeHandle<JSFunction> Compiler::GetFunctionFromEval(
     parse_info.set_parse_restriction(restriction);
     parse_info.set_context(context);
 
-    // If we eval from debug code, compile for debugging as well.
-    if (outer_info->HasDebugCode()) info.MarkAsDebug();
     Debug::RecordEvalCaller(script);
 
     shared_info = CompileToplevel(&info);
@@ -1184,8 +1222,13 @@ MaybeHandle<JSFunction> Compiler::GetFunctionFromEval(
     shared_info->ResetForNewContext(isolate->heap()->global_ic_age());
   }
 
-  return isolate->factory()->NewFunctionFromSharedFunctionInfo(
-      shared_info, context, NOT_TENURED);
+  Handle<JSFunction> result =
+      isolate->factory()->NewFunctionFromSharedFunctionInfo(
+          shared_info, context, NOT_TENURED);
+
+  isolate->debug()->OnAfterCompile(script);

[Yang, 2015/07/27 10:16:49]

Moving OnAfterCompile is necessary so that we have a function on the heap. We
can only compile eval again if we have a function, from which we can obtain the
context.

This is the scenario: we set a break point by name, but the function with that
name has not been introduced yet. So we hold onto that break point until we
compile a script that introduces the function. When we compile an eval that does
this, we call OnAfterCompile which looks through those break points. We then
realize that this eval needs to be recompiled for debug code. We comb the heap
to look for a function that can be used to compile that eval.

So we need to call OnAfterCompile after NewFunctionFromSharedFunctionInfo.

[mvstanton, 2015/07/27 12:42:56]

nit: this is good information, can a compressed form of it live somewhere in the
CL?

+
+  return result;
 }
 
 
@@ -1307,7 +1350,11 @@ Handle<SharedFunctionInfo> Compiler::CompileScript(
       }
     }
 
-    if (result.is_null()) isolate->ReportPendingMessages();
+    if (result.is_null()) {
+      isolate->ReportPendingMessages();
+    } else {
+      isolate->debug()->OnAfterCompile(script);
+    }
   } else if (result->ic_age() != isolate->heap()->global_ic_age()) {
     result->ResetForNewContext(isolate->heap()->global_ic_age());
   }
@@ -1332,7 +1379,9 @@ Handle<SharedFunctionInfo> Compiler::CompileStreamedScript(
   // If compiling for debugging, parse eagerly from scratch.
   if (compile_info.is_debug()) parse_info->set_literal(NULL);
 
-  return CompileToplevel(&compile_info);
+  Handle<SharedFunctionInfo> result = CompileToplevel(&compile_info);
+  if (!result.is_null()) isolate->debug()->OnAfterCompile(script);
+  return result;
 }