llvm-mc & llc tools hang if no input arguments are present

[jyoti.allur]

Summary

Hello,

llvm-mc & llc tools hang if no input arguments are present, until ctrlC is used to get the command prompt back.
New developers many not know about these tool's usage. Hence the fix.
Could you please help review it.

Thanks.

[• rafael]

This will break

./bin/llc < ~/llvm/test.ll

no?

[jyoti.allur]

Yes, it breaks, i hadn't considered file redirection.

[asl]

Please run LLVM tests before submitting any patches.

[jyoti.allur]

sorry, my fault. Abandoning this patch as parsing the argv[] strings to check if there is a redirection operator is not worthy of the end result.

llvm/tools/llc/llc.cpp

   cl::AddExtraVersionPrinter(TargetRegistry::printRegisteredTargetsForVersion);
 
   cl::ParseCommandLineOptions(argc, argv, "llvm system compiler\n");
-
+  if (argc == 1) {
+    llvm::errs() << "Try: '" << argv[0] << " -help'\n";
+    return 1;
+  }
   // Compile the module TimeCompilations times to give better compile time
   // metrics.
   for (unsigned I = TimeCompilations; I; --I)

llvm/tools/llvm-mc/llvm-mc.cpp

   cl::AddExtraVersionPrinter(TargetRegistry::printRegisteredTargetsForVersion);
 
   cl::ParseCommandLineOptions(argc, argv, "llvm machine code playground\n");
+  if (argc == 1) {
+    llvm::errs() << "Try: '" << argv[0] << " -help'\n";
+    return 1;
+  }
   MCTargetOptions MCOptions = InitMCTargetOptionsFromFlags();
   TripleName = Triple::normalize(TripleName);
   setDwarfDebugFlags(argc, argv);