[wasm] [cleanup] Remove unneeded field in WasmCompilationJob

The FixedArray holding the export wrappers is never being used before
creating the WasmCompiledModule, so there is no need to store it in a
field on the WasmCompilationJob. Just create it when creating the
WasmCompiledModule.

R=ahaas@chromium.org
CC=​mtrofin@chromium.org

Change-Id: Ibdca3d5c58faf4b52df10560bdf2734fdd7a4656
Reviewed-on: https://chromium-review.googlesource.com/758242Reviewed-by: Andreas Haas <ahaas@chromium.org>
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#49214}

src/wasm/module-compiler.cc

@@ -3089,10 +3089,7 @@ class AsyncCompileJob::PrepareAndStartCompile : public CompileStep {
     // Initialize {code_table_} with the illegal builtin. All call sites
     // will be patched at instantiation.
     int code_table_size = static_cast<int>(module_->functions.size());
-    int export_wrapper_size = static_cast<int>(module_->num_exported_functions);
     job_->code_table_ = factory->NewFixedArray(code_table_size, TENURED);
-    job_->export_wrappers_ =
-        factory->NewFixedArray(export_wrapper_size, TENURED);
 
     for (int i = 0, e = module_->num_imported_functions; i < e; ++i) {
       job_->code_table_->set(i, *illegal_builtin);
@@ -3107,8 +3104,6 @@ class AsyncCompileJob::PrepareAndStartCompile : public CompileStep {
 
       centry_stub = Handle<Code>(*centry_stub, isolate);
       job_->code_table_ = Handle<FixedArray>(*job_->code_table_, isolate);
-      job_->export_wrappers_ =
-          Handle<FixedArray>(*job_->export_wrappers_, isolate);
       compiler::ModuleEnv* env = job_->module_env_.get();
       ReopenHandles(isolate, env->function_code);
       Handle<Code>* mut =
@@ -3297,9 +3292,13 @@ class AsyncCompileJob::FinishCompile : public CompileStep {
     // and information needed at instantiation time. This object needs to be
     // serializable. Instantiation may occur off a deserialized version of
     // this object.
+    int export_wrapper_size =
+        static_cast<int>(module_wrapper->get()->num_exported_functions);
+    Handle<FixedArray> export_wrappers =
+        job_->isolate_->factory()->NewFixedArray(export_wrapper_size, TENURED);
     job_->compiled_module_ =
         NewCompiledModule(job_->isolate_, shared, job_->code_table_,
-                          job_->export_wrappers_, job_->module_env_.get());
+                          export_wrappers, job_->module_env_.get());
     // Finish the wasm script now and make it public to the debugger.
     script->set_wasm_compiled_module(*job_->compiled_module_);
     job_->isolate_->debug()->OnAfterCompile(script);

src/wasm/module-compiler.h

@@ -165,7 +165,6 @@ class AsyncCompileJob {
   Handle<WasmModuleObject> module_object_;
   Handle<WasmCompiledModule> compiled_module_;
   Handle<FixedArray> code_table_;
-  Handle<FixedArray> export_wrappers_;
   size_t outstanding_units_ = 0;
   std::unique_ptr<CompileStep> step_;
   CancelableTaskManager background_task_manager_;