[Compiler] Use CompilationCache for StreamedScript compilation.

Previously GetSharedFunctionInfoForStreamedScript didn't either check the
compilation cache or put the result of compilation into the compilation
cache. This would mean future compiles would need to re-parse / compile
the same script even if the isolate had already seen it. This CL
fixes this.

BUG=v8:5203

Change-Id: I421627b80848feb9884e2440c4ee66556e05b3c9
Reviewed-on: https://chromium-review.googlesource.com/924285
Commit-Queue: Ross McIlroy <rmcilroy@chromium.org>
Reviewed-by: Mythri Alle <mythria@chromium.org>
Cr-Commit-Position: refs/heads/master@{#51469}

src/compiler.cc

@@ -1754,6 +1754,21 @@ Compiler::GetSharedFunctionInfoForStreamedScript(
   ParseInfo* parse_info = streaming_data->info.get();
   parse_info->UpdateBackgroundParseStatisticsOnMainThread(isolate);
 
+  // Check if compile cache already holds the SFI, if so no need to finalize
+  // the code compiled on the background thread.
+  CompilationCache* compilation_cache = isolate->compilation_cache();
+  MaybeHandle<SharedFunctionInfo> maybe_result =
+      compilation_cache->LookupScript(
+          source, script_details.name_obj, script_details.line_offset,
+          script_details.column_offset, origin_options,
+          isolate->native_context(), parse_info->language_mode());
+  if (!maybe_result.is_null()) {
+    compile_timer.set_hit_isolate_cache();
+  }
+
+  if (maybe_result.is_null()) {
+    // No cache entry found, finalize compilation of the script and add it to
+    // the isolate cache.
     Handle<Script> script = NewScript(isolate, source, script_details,
                                       origin_options, NOT_NATIVES_CODE);
     parse_info->set_script(script);
@@ -1769,12 +1784,11 @@ Compiler::GetSharedFunctionInfoForStreamedScript(
     }
 
     // Parsing has succeeded - finalize compilation.
-  MaybeHandle<SharedFunctionInfo> result;
     if (i::FLAG_background_compile) {
       // Finalize background compilation.
       if (streaming_data->outer_function_job) {
-      result = FinalizeTopLevel(parse_info, isolate,
-                                streaming_data->outer_function_job.get(),
+        maybe_result = FinalizeTopLevel(
+            parse_info, isolate, streaming_data->outer_function_job.get(),
             &streaming_data->inner_function_jobs);
       } else {
         // Compilation failed on background thread - throw an exception.
@@ -1782,14 +1796,20 @@ Compiler::GetSharedFunctionInfoForStreamedScript(
       }
     } else {
       // Compilation on main thread.
-    result = CompileToplevel(parse_info, isolate);
+      maybe_result = CompileToplevel(parse_info, isolate);
     }
 
-  if (!result.is_null()) {
+    // Add compiled code to the isolate cache.
+    Handle<SharedFunctionInfo> result;
+    if (!maybe_result.ToHandle(&result)) {
       isolate->debug()->OnAfterCompile(script);
+      compilation_cache->PutScript(source, isolate->native_context(),
+                                   parse_info->language_mode(), result);
+    }
   }
+
   streaming_data->Release();
-  return result;
+  return maybe_result;
 }
 
 Handle<SharedFunctionInfo> Compiler::GetSharedFunctionInfo(