Remove deprecated `preloadDialectInContext` flag for MlirOptMain that has been deprecated for 2 years

[mehdi_amini]

Summary

See https://discourse.llvm.org/t/psa-preloaddialectincontext-has-been-deprecated-for-1y-and-will-be-removed/68992

flang/tools/fir-opt/fir-opt.cpp

int main(int argc, char **argv) {
   fir::registerOptTransformPasses();
   hlfir::registerHLFIRPasses();
 #ifdef FLANG_INCLUDE_TESTS
   fir::test::registerTestFIRAliasAnalysisPass();
 #endif
   DialectRegistry registry;
   fir::support::registerDialects(registry);
   return failed(MlirOptMain(argc, argv, "FIR modular optimizer driver\n",
-      registry, /*preloadDialectsInContext=*/false));
+      registry));
 }

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

public:
 
   /// Populate the passmanager, if any callback was set.
   LogicalResult setupPassPipeline(PassManager &pm) const {
     if (passPipelineCallback)
       return passPipelineCallback(pm);
     return success();
   }
 
-  // Deprecated.
-  MlirOptMainConfig &preloadDialectsInContext(bool preload) {
-    preloadDialectsInContextFlag = preload;
-    return *this;
-  }
-  bool shouldPreloadDialectsInContext() const {
-    return preloadDialectsInContextFlag;
-  }
-
   /// Show the registered dialects before trying to load the input file.
   MlirOptMainConfig &showDialects(bool show) {
     showDialectsFlag = show;
     return *this;
   }
   bool shouldShowDialects() const { return showDialectsFlag; }
 
   /// Set whether to split the input file based on the `// -----` marker into
protected:
   std::string irdlFileFlag = "";
 
   /// Location Breakpoints to filter the action logging.
   std::vector<tracing::BreakpointManager *> logActionLocationFilter;
 
   /// The callback to populate the pass manager.
   std::function<LogicalResult(PassManager &)> passPipelineCallback;
 
-  /// Deprecated.
-  bool preloadDialectsInContextFlag = false;
-
   /// Show the registered dialects before trying to load the input file.
   bool showDialectsFlag = false;
 
   /// Split the input file based on the `// -----` marker into pieces and
   /// process each chunk independently.
   bool splitInputFileFlag = false;
 
   /// Use an explicit top-level module op during parsing.

 LogicalResult MlirOptMain(llvm::raw_ostream &outputStream,
                           std::unique_ptr<llvm::MemoryBuffer> buffer,
                           DialectRegistry &registry,
                           const MlirOptMainConfig &config);
 
 /// Implementation for tools like `mlir-opt`.
 /// - toolName is used for the header displayed by `--help`.
 /// - registry should contain all the dialects that can be parsed in the source.
-/// - preloadDialectsInContext will trigger the upfront loading of all
-///   dialects from the global registry in the MLIRContext. This option is
-///   deprecated and will be removed soon.
 LogicalResult MlirOptMain(int argc, char **argv, llvm::StringRef toolName,
-                          DialectRegistry &registry,
-                          bool preloadDialectsInContext = false);
+                          DialectRegistry &registry);
 
 /// Helper wrapper to return the result of MlirOptMain directly from main.
 ///
 /// Example:
 ///
 ///     int main(int argc, char **argv) {
 ///       // ...
 ///       return mlir::asMainReturnCode(mlir::MlirOptMain(

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

static LogicalResult processBuffer(raw_ostream &os,
   if (threadPool)
     context.setThreadPool(*threadPool);
 
   StringRef irdlFile = config.getIrdlFile();
   if (!irdlFile.empty() && failed(loadIRDLDialects(irdlFile, context)))
     return failure();
 
   // Parse the input file.
-  if (config.shouldPreloadDialectsInContext())
-    context.loadAllAvailableDialects();
   context.allowUnregisteredDialects(config.shouldAllowUnregisteredDialects());
   if (config.shouldVerifyDiagnostics())
     context.printOpOnDiagnostic(false);
 
   tracing::InstallDebugHandler installDebugHandler(context,
                                                    config.getDebugConfig());
 
   // If we are in verify diagnostics mode then we have a lot of work to do,
return processBuffer(os, std::move(chunkBuffer), config, registry,
                          threadPool);
   };
   return splitAndProcessBuffer(std::move(buffer), chunkFn, outputStream,
                                config.shouldSplitInputFile(),
                                /*insertMarkerInOutput=*/true);
 }
 
 LogicalResult mlir::MlirOptMain(int argc, char **argv, llvm::StringRef toolName,
-                                DialectRegistry &registry,
-                                bool preloadDialectsInContext) {
+                                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("-"));
 
   InitLLVM y(argc, argv);
LogicalResult mlir::MlirOptMain(int argc, char **argv, llvm::StringRef toolName,
   {
     llvm::raw_string_ostream os(helpHeader);
     interleaveComma(registry.getDialectNames(), os,
                     [&](auto name) { os << name; });
   }
   // Parse pass names in main to ensure static initialization completed.
   cl::ParseCommandLineOptions(argc, argv, helpHeader);
   MlirOptMainConfig config = MlirOptMainConfig::createFromCLOptions();
-  config.preloadDialectsInContext(preloadDialectsInContext);
 
   // When reading from stdin and the input is a tty, it is often a user mistake
   // and the process "appears to be stuck". Print a message to let the user know
   // about it!
   if (inputFilename == "-" &&
       sys::Process::FileDescriptorIsDisplayed(fileno(stdin)))
     llvm::errs() << "(processing input from stdin now, hit ctrl-c/ctrl-d to "
                     "interrupt)\n";

mlir/tools/mlir-opt/mlir-opt.cpp

#endif
   DialectRegistry registry;
   registerAllDialects(registry);
 #ifdef MLIR_INCLUDE_TESTS
   ::test::registerTestDialect(registry);
   ::test::registerTestTransformDialectExtension(registry);
   ::test::registerTestDynDialect(registry);
 #endif
   return mlir::asMainReturnCode(
-      mlir::MlirOptMain(argc, argv, "MLIR modular optimizer driver\n", registry,
-                        /*preloadDialectsInContext=*/false));
+      mlir::MlirOptMain(argc, argv, "MLIR modular optimizer driver\n", registry));
 }