The empty husk of a JSFunction is useful to us.

test/cctest/compiler/test-changes-lowering.cc

 // Copyright 2014 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 <limits>
 
 #include "src/compiler/change-lowering.h"
 #include "src/compiler/control-builders.h"
 #include "src/compiler/generic-node-inl.h"
 #include "src/compiler/js-graph.h"
 #include "src/compiler/node-properties-inl.h"
 #include "src/compiler/pipeline.h"
 #include "src/compiler/typer.h"
 #include "src/compiler/verifier.h"
 #include "src/execution.h"
 #include "src/globals.h"
 #include "src/parser.h"
 #include "src/rewriter.h"
 #include "src/scopes.h"
 #include "test/cctest/cctest.h"
 #include "test/cctest/compiler/codegen-tester.h"
+#include "test/cctest/compiler/function-tester.h"
 #include "test/cctest/compiler/graph-builder-tester.h"
 #include "test/cctest/compiler/value-helper.h"
 
 using namespace v8::internal;
 using namespace v8::internal::compiler;
 
 template <typename ReturnType>
 class ChangesLoweringTester : public GraphBuilderTester<ReturnType> {
  public:
   explicit ChangesLoweringTester(MachineType p0 = kMachNone)
       : GraphBuilderTester<ReturnType>(p0),
         typer(this->zone()),
         javascript(this->zone()),
         jsgraph(this->graph(), this->common(), &javascript, &typer,
                 this->machine()),
         function(Handle<JSFunction>::null()) {}
 
   Typer typer;
   JSOperatorBuilder javascript;
   JSGraph jsgraph;
   Handle<JSFunction> function;
 
   Node* start() { return this->graph()->start(); }
 
   template <typename T>
   T* CallWithPotentialGC() {
-    // TODO(titzer): we need to wrap the code in a JSFunction and call it via
-    // Execution::Call() so that the GC knows about the frame, can walk it,
-    // relocate the code object if necessary, etc.
-    // This is pretty ugly and at the least should be moved up to helpers.
+    // TODO(titzer): we wrap the code in a JSFunction here to reuse the
+    // JSEntryStub; that could be done with a special prologue or other stub.
     if (function.is_null()) {
-      function =
-          v8::Utils::OpenHandle(*v8::Handle<v8::Function>::Cast(CompileRun(
-              "(function() { 'use strict'; return 2.7123; })")));
-      CompilationInfoWithZone info(function);
-      CHECK(Parser::Parse(&info));
-      info.SetOptimizing(BailoutId::None(), Handle<Code>(function->code()));
-      CHECK(Rewriter::Rewrite(&info));
-      CHECK(Scope::Analyze(&info));
-      CHECK_NE(NULL, info.scope());
-      Handle<ScopeInfo> scope_info =
-          ScopeInfo::Create(info.scope(), info.zone());
-      info.shared_info()->set_scope_info(*scope_info);
-      Pipeline pipeline(&info);
-      Linkage linkage(&info);
-      Handle<Code> code =
-          pipeline.GenerateCodeForMachineGraph(&linkage, this->graph());
-      CHECK(!code.is_null());
-      function->ReplaceCode(*code);
+      function = FunctionTester::ForMachineGraph(this->graph());
     }
     Handle<Object>* args = NULL;
     MaybeHandle<Object> result =
         Execution::Call(this->isolate(), function, factory()->undefined_value(),
                         0, args, false);
     return T::cast(*result.ToHandleChecked());
   }
 
   void StoreFloat64(Node* node, double* ptr) {
     Node* ptr_node = this->PointerConstant(ptr);
@@ skipping 323 matching lines @@
 
         input = *i;
         Object* result = t.CallWithPotentialGC<Object>();
         t.CheckNumber(input, result);
       }
     }
   }
 }
 
 #endif  // V8_TURBOFAN_BACKEND