[mlir-translate] Teach these tools about --allow-unregistered-dialect

[lattner]

Summary

Some translations do work with unregistered dialects, this allows one
to write testcases against them. It works the same way as it does for
mlir-opt.

[lattner]

Thank you for the review!

mlir/lib/Translation/Translation.cpp

LogicalResult mlir::mlirTranslateMain(int argc, char **argv,
   static llvm::cl::opt<std::string> inputFilename(
       llvm::cl::Positional, llvm::cl::desc("<input file>"),
       llvm::cl::init("-"));
 
   static llvm::cl::opt<std::string> outputFilename(
       "o", llvm::cl::desc("Output filename"), llvm::cl::value_desc("filename"),
       llvm::cl::init("-"));
 
+  static llvm::cl::opt<bool> allowUnregisteredDialects(
+      "allow-unregistered-dialect",
+      llvm::cl::desc("Allow operation with no registered dialects"),
+      llvm::cl::init(false));
+
   static llvm::cl::opt<bool> splitInputFile(
       "split-input-file",
       llvm::cl::desc("Split the input file into pieces and "
                      "process each chunk independently"),
       llvm::cl::init(false));
 
   static llvm::cl::opt<bool> verifyDiagnostics(
       "verify-diagnostics",
if (!output) {
     llvm::errs() << errorMessage << "\n";
     return failure();
   }
 
   // Processes the memory buffer with a new MLIRContext.
   auto processBuffer = [&](std::unique_ptr<llvm::MemoryBuffer> ownedBuffer,
                            raw_ostream &os) {
     MLIRContext context;
+    context.allowUnregisteredDialects(allowUnregisteredDialects);
     context.printOpOnDiagnostic(!verifyDiagnostics);
     llvm::SourceMgr sourceMgr;
     sourceMgr.AddNewSourceBuffer(std::move(ownedBuffer), SMLoc());
 
     if (!verifyDiagnostics) {
       SourceMgrDiagnosticHandler sourceMgrHandler(sourceMgr, &context);
       return (*translationRequested)(sourceMgr, os, &context);
     }

mlir/test/mlir-translate/unregistered-dialects.mlir

+// RUN: not mlir-translate %s --allow-unregistered-dialect --mlir-to-llvmir -verify-diagnostics 2>&1 | FileCheck --check-prefix=UNREGOK %s
+// RUN: not mlir-translate %s --mlir-to-llvmir -verify-diagnostics 2>&1 | FileCheck --check-prefix=REGONLY %s
+
+
+// If the parser allows unregistered operations, then the translation fails,
+// otherwise the parse fails.
+
+// UNREGOK: cannot be converted to LLVM IR
+// REGONLY: operation being parsed with an unregistered dialect
+
+func @trivial() {
+  "simple.terminator"() : () -> ()
+}