[turbofan] Add --csa-verify flag that enables machine graph verification of code stubs.

test/cctest/test-code-stub-assembler.cc

Index: test/cctest/test-code-stub-assembler.cc
diff --git a/test/cctest/test-code-stub-assembler.cc b/test/cctest/test-code-stub-assembler.cc
index 8657819c60eea82bc158313875fe75f21f014efc..4115021727aae61112c2fe8f1047f2e056686909 100644
--- a/test/cctest/test-code-stub-assembler.cc
+++ b/test/cctest/test-code-stub-assembler.cc
@@ -1927,5 +1927,40 @@ TEST(BuildAppendJSArrayFastDoubleElementsObject) {
       isolate->heap()->undefined_value(), Smi::FromInt(6), 6, 4);
 }
 
+namespace {
+
+template <typename Stub, typename... Args>
+void Recompile(Args... args) {
+  Stub stub(args...);
+  stub.DeleteStubFromCacheForTesting();
+  stub.GetCode();
+}
+
+}  // namespace
+
+TEST(CodeStubAssemblerGraphsCorrectness) {
+  // The test does not work with interpreter because bytecode handlers taken
+  // from the snapshot already refer to precompiled stubs from the snapshot
+  // and there is no way to trigger bytecode handlers recompilation.
+  if (FLAG_ignition || FLAG_turbo) return;
+
+  v8::Isolate::CreateParams create_params;
+  create_params.array_buffer_allocator = CcTest::array_buffer_allocator();
+  v8::Isolate* v8_isolate = v8::Isolate::New(create_params);
+  Isolate* isolate = reinterpret_cast<Isolate*>(v8_isolate);
+
+  {
+    v8::Isolate::Scope isolate_scope(v8_isolate);
+    LocalContext env(v8_isolate);
+    v8::HandleScope scope(v8_isolate);
+
+    FLAG_csa_verify = true;
+
+    // Recompile some stubs here.
+    Recompile<LoadGlobalICStub>(isolate, LoadGlobalICState(NOT_INSIDE_TYPEOF));
+  }
+  v8_isolate->Dispose();
+}
+
 }  // namespace internal
 }  // namespace v8