Fix mlir-reduce to explicitly register dialects and disable the global dialect registry by default

[mehdi_amini]

Summary

Clients who rely on the Context loading dialects from the global
registry can call mlir::enableGlobalDialectRegistry(true); before
creating an MLIRContext

mlir/lib/IR/Dialect.cpp

 // Dialect Registration (DEPRECATED)
 //===----------------------------------------------------------------------===//
 
 /// Registry for all dialect allocation functions.
 static llvm::ManagedStatic<DialectRegistry> dialectRegistry;
 DialectRegistry &mlir::getGlobalDialectRegistry() { return *dialectRegistry; }
 
 // Note: deprecated, will be removed soon.
-static bool isGlobalDialectRegistryEnabledFlag = true;
+static bool isGlobalDialectRegistryEnabledFlag = false;
 void mlir::enableGlobalDialectRegistry(bool enable) {
   isGlobalDialectRegistryEnabledFlag = enable;
 }
 bool mlir::isGlobalDialectRegistryEnabled() {
   return isGlobalDialectRegistryEnabledFlag;
 }
 
 void mlir::registerAllDialects(MLIRContext *context) {

mlir/tools/mlir-reduce/CMakeLists.txt

 get_property(dialect_libs GLOBAL PROPERTY MLIR_DIALECT_LIBS)
 get_property(conversion_libs GLOBAL PROPERTY MLIR_CONVERSION_LIBS)
 set(LLVM_LINK_COMPONENTS
   AllTargetsAsmParsers
   AllTargetsCodeGens
   AllTargetsDescs
   AllTargetsInfos
   AsmParser
   Core
   IRReader
   Support
   Target
   TransformUtils
   )
 
+if(MLIR_INCLUDE_TESTS)
+  set(test_libs
+    MLIRAffineTransformsTestPasses
+    MLIRSPIRVTestPasses
+    MLIRTestDialect
+    MLIRTestIR
+    MLIRTestPass
+    MLIRTestReducer
+    MLIRTestTransforms
+    )
+endif()
+
 set(LIBS
   ${dialect_libs}
   ${conversion_libs}
   ${test_libs}
   MLIRAnalysis
   MLIRDialect
   MLIREDSC
   MLIRIR

mlir/tools/mlir-reduce/mlir-reduce.cpp

 #include "mlir/Support/FileUtilities.h"
 #include "mlir/Support/LogicalResult.h"
 #include "mlir/Transforms/Passes.h"
 #include "llvm/Support/InitLLVM.h"
 #include "llvm/Support/ToolOutputFile.h"
 
 using namespace mlir;
 
+namespace mlir {
+void registerTestDialect(DialectRegistry &);
+}
+
 static llvm::cl::opt<std::string> inputFilename(llvm::cl::Positional,
                                                 llvm::cl::Required,
                                                 llvm::cl::desc("<input file>"));
 
 static llvm::cl::opt<std::string>
     testFilename("test", llvm::cl::Required, llvm::cl::desc("Testing script"));
 
 static llvm::cl::list<std::string>
int main(int argc, char **argv) {
   if (!testscript)
     llvm::report_fatal_error(errorMessage);
 
   auto output = openOutputFile(outputFilename, &errorMessage);
   if (!output)
     llvm::report_fatal_error(errorMessage);
 
   mlir::MLIRContext context;
-  mlir::OwningModuleRef moduleRef;
-  context.allowUnregisteredDialects(true);
+  registerAllDialects(context.getDialectRegistry());
+#ifdef MLIR_INCLUDE_TESTS
+  mlir::registerTestDialect(context.getDialectRegistry());
+#endif
 
+  mlir::OwningModuleRef moduleRef;
   if (failed(loadModule(context, moduleRef, inputFilename)))
     llvm::report_fatal_error("Input test case can't be parsed");
 
   // Initialize test environment.
   const Tester test(testFilename, testArguments);
 
   if (!test.isInteresting(inputFilename))
     llvm::report_fatal_error(