[mlir][NFC] Split registerAndParseCLIOptions() in mlir-opt

mlir/include/mlir/Tools/mlir-opt/MlirOptMain.h

@@ -359,6 +359,20 @@ class MlirOptMainConfig {
 /// the loaded IR.
 using PassPipelineFn = llvm::function_ref<LogicalResult(PassManager &pm)>;
 
+/// Register basic command line options.
+/// - toolName is used for the header displayed by `--help`.
+/// - registry should contain all the dialects that can be parsed in the source.
+/// - return std::string for help header.
+std::string registerCLIOptions(llvm::StringRef toolName,
+                               DialectRegistry &registry);
+
+/// Parse command line options.
+/// - helpHeader is used for the header displayed by `--help`.
+/// - return std::pair<std::string, std::string> for
+///   inputFilename and outputFilename command line option values.
+std::pair<std::string, std::string> parseCLIOptions(int argc, char **argv,
+                                                    llvm::StringRef helpHeader);
+
 /// Register and parse command line options.
 /// - toolName is used for the header displayed by `--help`.
 /// - registry should contain all the dialects that can be parsed in the source.

mlir/lib/Tools/mlir-opt/MlirOptMain.cpp

@@ -681,17 +681,8 @@ processBuffer(raw_ostream &os, std::unique_ptr<MemoryBuffer> ownedBuffer,
   return success();
 }
 
-std::pair<std::string, std::string>
-mlir::registerAndParseCLIOptions(int argc, char **argv,
-                                 llvm::StringRef toolName,
-                                 DialectRegistry &registry) {
-  static cl::opt<std::string> inputFilename(
-      cl::Positional, cl::desc("<input file>"), cl::init("-"));
-
-  static cl::opt<std::string> outputFilename("o", cl::desc("Output filename"),
-                                             cl::value_desc("filename"),
-                                             cl::init("-"));
-  // Register any command line options.
+std::string mlir::registerCLIOptions(llvm::StringRef toolName,
+                                     DialectRegistry &registry) {
   MlirOptMainConfig::registerCLOptions(registry);
   registerAsmPrinterCLOptions();
   registerMLIRContextCLOptions();
@@ -706,11 +697,29 @@ mlir::registerAndParseCLIOptions(int argc, char **argv,
     interleaveComma(registry.getDialectNames(), os,
                     [&](auto name) { os << name; });
   }
-  // Parse pass names in main to ensure static initialization completed.
+  return helpHeader;
+}
+
+std::pair<std::string, std::string>
+mlir::parseCLIOptions(int argc, char **argv, llvm::StringRef helpHeader) {
+  static cl::opt<std::string> inputFilename(
+      cl::Positional, cl::desc("<input file>"), cl::init("-"));
+
+  static cl::opt<std::string> outputFilename("o", cl::desc("Output filename"),
+                                             cl::value_desc("filename"),
+                                             cl::init("-"));
   cl::ParseCommandLineOptions(argc, argv, helpHeader);
   return std::make_pair(inputFilename.getValue(), outputFilename.getValue());
 }
 
+std::pair<std::string, std::string>
+mlir::registerAndParseCLIOptions(int argc, char **argv,
+                                 llvm::StringRef toolName,
+                                 DialectRegistry &registry) {
+  auto helpHeader = registerCLIOptions(toolName, registry);
+  return parseCLIOptions(argc, argv, helpHeader);
+}
+
 static LogicalResult printRegisteredDialects(DialectRegistry &registry) {
   llvm::outs() << "Available Dialects: ";
   interleave(registry.getDialectNames(), llvm::outs(), ",");