Do not look for existing shared function info when compiling a new script.

src/compiler.cc

 // Copyright 2012 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.
 
 #include "src/compiler.h"
 
 #include <algorithm>
 
 #include "src/ast-numbering.h"
 #include "src/bootstrapper.h"
@@ skipping 1057 matching lines @@
         // Eager parsing cannot benefit from cached data, and producing cached
         // data while parsing eagerly is not implemented.
         parse_info->set_cached_data(nullptr);
         parse_info->set_compile_options(ScriptCompiler::kNoCompileOptions);
       }
       if (!Parser::ParseStatic(parse_info)) {
         return Handle<SharedFunctionInfo>::null();
       }
     }
 
+    info->MarkAsNewScript();
+
     FunctionLiteral* lit = info->function();
     LiveEditFunctionTracker live_edit_tracker(isolate, lit);
 
     // Measure how long it takes to do the compilation; only take the
     // rest of the function into account to avoid overlap with the
     // parsing statistics.
     HistogramTimer* rate = info->is_eval()
           ? info->isolate()->counters()->compile_eval()
           : info->isolate()->counters()->compile();
     HistogramTimerScope timer(rate);
@@ skipping 240 matching lines @@
   // TODO(marja): FLAG_serialize_toplevel is not honoured and won't be; when the
   // real code caching lands, streaming needs to be adapted to use it.
   return CompileToplevel(&compile_info);
 }
 
 
 Handle<SharedFunctionInfo> Compiler::GetSharedFunctionInfo(
     FunctionLiteral* literal, Handle<Script> script,
     CompilationInfo* outer_info) {
   // Precondition: code has been parsed and scopes have been analyzed.
-  MaybeHandle<SharedFunctionInfo> maybe_existing =
-      script->FindSharedFunctionInfo(literal);
+  MaybeHandle<SharedFunctionInfo> maybe_existing;
+  if (outer_info->is_new_script()) {
+    // There is no existing shared function info when compiling a new script.
+    DCHECK(script->FindSharedFunctionInfo(literal).is_null());
+  } else {
+    maybe_existing = script->FindSharedFunctionInfo(literal);
+  }
   // We found an existing shared function info. If it's already compiled,
   // don't worry about compiling it, and simply return it. If it's not yet
   // compiled, continue to decide whether to eagerly compile.
   Handle<SharedFunctionInfo> existing;
   if (maybe_existing.ToHandle(&existing) && existing->is_compiled()) {
     return existing;
   }
 
   Zone zone;
   ParseInfo parse_info(&zone, script);
   CompilationInfo info(&parse_info);
   parse_info.set_literal(literal);
   parse_info.set_scope(literal->scope());
   parse_info.set_language_mode(literal->scope()->language_mode());
   if (outer_info->will_serialize()) info.PrepareForSerializing();
+  if (outer_info->is_new_script()) info.MarkAsNewScript();
 
   Isolate* isolate = info.isolate();
   Factory* factory = isolate->factory();
   LiveEditFunctionTracker live_edit_tracker(isolate, literal);
   // Determine if the function can be lazily compiled. This is necessary to
   // allow some of our builtin JS files to be lazily compiled. These
   // builtins cannot be handled lazily by the parser, since we have to know
   // if a function uses the special natives syntax, which is something the
   // parser records.
   // If the debugger requests compilation for break points, we cannot be
@@ skipping 221 matching lines @@
 
 
 #if DEBUG
 void CompilationInfo::PrintAstForTesting() {
   PrintF("--- Source from AST ---\n%s\n",
          PrettyPrinter(isolate(), zone()).PrintProgram(function()));
 }
 #endif
 }  // namespace internal
 }  // namespace v8