[torque] Always run all ImplementationVisitor steps

The language server and unit tests pass in an empty output directory
to signal that no C++ files should be generated. As these
generation steps include some validations, they should also be
included in language server and unit test compilation runs.

This CL introduces a "dry run" flag on the ImplementationVisitor.
Additionaly, the implementation visitor wraps the file writing
functionality. In case of a dry-run, file writing becomes a no-op.

R=sigurds@chromium.org

Bug: v8:7793
Change-Id: Id699fdf0b35311ddd3c1f5419baa0237b40ddce4
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1617244Reviewed-by: Sigurd Schneider <sigurds@chromium.org>
Commit-Queue: Simon Zünd <szuend@chromium.org>
Cr-Commit-Position: refs/heads/master@{#61599}

src/torque/implementation-visitor.cc

@@ -1541,10 +1541,10 @@ void ImplementationVisitor::GenerateImplementation(const std::string& dir,
       "builtins-" + DashifyString(nspace->name()) + "-gen-tq";
 
   std::string source_file_name = dir + "/" + base_file_name + ".cc";
-  ReplaceFileContentsIfDifferent(source_file_name, new_source);
+  WriteFile(source_file_name, new_source);
   std::string new_header(nspace->header());
   std::string header_file_name = dir + "/" + base_file_name + ".h";
-  ReplaceFileContentsIfDifferent(header_file_name, new_header);
+  WriteFile(header_file_name, new_header);
 }
 
 void ImplementationVisitor::GenerateMacroFunctionDeclaration(
@@ -2795,8 +2795,7 @@ void ImplementationVisitor::GenerateBuiltinDefinitions(
     new_contents_stream << "\n";
   }
   std::string new_contents(new_contents_stream.str());
-  ReplaceFileContentsIfDifferent(output_directory + "/" + file_name,
-                                 new_contents);
+  WriteFile(output_directory + "/" + file_name, new_contents);
 }
 
 namespace {
@@ -3057,9 +3056,9 @@ void ImplementationVisitor::GenerateClassDefinitions(
       g.GenerateClass();
     }
   }
-  ReplaceFileContentsIfDifferent(file_basename + ".h", header.str());
-  ReplaceFileContentsIfDifferent(file_basename + "-inl.h", inline_header.str());
-  ReplaceFileContentsIfDifferent(file_basename + ".cc", implementation.str());
+  WriteFile(file_basename + ".h", header.str());
+  WriteFile(file_basename + "-inl.h", inline_header.str());
+  WriteFile(file_basename + ".cc", implementation.str());
 }
 
 void ImplementationVisitor::GenerateClassFieldOffsets(
@@ -3129,7 +3128,7 @@ void ImplementationVisitor::GenerateClassFieldOffsets(
   }
   const std::string output_header_path = output_directory + "/" + file_name;
   std::string new_contents(new_contents_stream.str());
-  ReplaceFileContentsIfDifferent(output_header_path, new_contents);
+  WriteFile(output_header_path, new_contents);
 }
 
 namespace {
@@ -3188,8 +3187,7 @@ void ImplementationVisitor::GeneratePrintDefinitions(
   }
 
   std::string new_contents(impl.str());
-  ReplaceFileContentsIfDifferent(output_directory + "/" + file_name,
-                                 new_contents);
+  WriteFile(output_directory + "/" + file_name, new_contents);
 }
 
 namespace {
@@ -3350,10 +3348,8 @@ void ImplementationVisitor::GenerateClassVerifiers(
 
     h_contents << "};\n";
   }
-  ReplaceFileContentsIfDifferent(output_directory + "/" + file_name + ".h",
-                                 h_contents.str());
-  ReplaceFileContentsIfDifferent(output_directory + "/" + file_name + ".cc",
-                                 cc_contents.str());
+  WriteFile(output_directory + "/" + file_name + ".h", h_contents.str());
+  WriteFile(output_directory + "/" + file_name + ".cc", cc_contents.str());
 }
 
 }  // namespace torque

src/torque/implementation-visitor.h

@@ -388,6 +388,8 @@ class ImplementationVisitor {
     LabelBindingsManager::Scope label_bindings_manager;
   };
 
+  void SetDryRun(bool is_dry_run) { is_dry_run_ = is_dry_run; }
+
  private:
   base::Optional<Block*> GetCatchBlock();
   void GenerateCatchBlock(base::Optional<Block*> catch_block);
@@ -593,8 +595,14 @@ class ImplementationVisitor {
     return return_value;
   }
 
+  void WriteFile(const std::string& file, const std::string& content) {
+    if (is_dry_run_) return;
+    ReplaceFileContentsIfDifferent(file, content);
+  }
+
   base::Optional<CfgAssembler> assembler_;
   NullOStream null_stream_;
+  bool is_dry_run_;
 };
 
 }  // namespace torque

src/torque/torque-compiler.cc

@@ -67,25 +67,26 @@ void CompileCurrentAst(TorqueCompilerOptions options) {
   // mutually refer to each others.
   TypeOracle::FinalizeClassTypes();
 
+  std::string output_directory = options.output_directory;
+
   ImplementationVisitor implementation_visitor;
+  implementation_visitor.SetDryRun(output_directory.length() == 0);
+
   for (Namespace* n : GlobalContext::Get().GetNamespaces()) {
     implementation_visitor.BeginNamespaceFile(n);
   }
 
   implementation_visitor.VisitAllDeclarables();
 
-  std::string output_directory = options.output_directory;
-  if (output_directory.length() != 0) {
-    implementation_visitor.GenerateBuiltinDefinitions(output_directory);
-    implementation_visitor.GenerateClassFieldOffsets(output_directory);
-    implementation_visitor.GeneratePrintDefinitions(output_directory);
-    implementation_visitor.GenerateClassDefinitions(output_directory);
-    implementation_visitor.GenerateClassVerifiers(output_directory);
-
-    for (Namespace* n : GlobalContext::Get().GetNamespaces()) {
-      implementation_visitor.EndNamespaceFile(n);
-      implementation_visitor.GenerateImplementation(output_directory, n);
-    }
+  implementation_visitor.GenerateBuiltinDefinitions(output_directory);
+  implementation_visitor.GenerateClassFieldOffsets(output_directory);
+  implementation_visitor.GeneratePrintDefinitions(output_directory);
+  implementation_visitor.GenerateClassDefinitions(output_directory);
+  implementation_visitor.GenerateClassVerifiers(output_directory);
+
+  for (Namespace* n : GlobalContext::Get().GetNamespaces()) {
+    implementation_visitor.EndNamespaceFile(n);
+    implementation_visitor.GenerateImplementation(output_directory, n);
   }
 
   if (GlobalContext::collect_language_server_data()) {