[lli] Fix crash on empty entry-function

[c-rhodes]

Summary

Empty entry-function triggers the following assertion:

llvm/lib/IR/Mangler.cpp:38: void getNameWithPrefixImpl(llvm::raw_ostream
&, const llvm::Twine &, (anonymous namespace)::ManglerPrefixTy, const
llvm::DataLayout &, char):

Assertion `!Name.empty() && "getNameWithPrefix requires non-empty name"' failed.

Throw an error if entry-function is empty.

[lhames]

Otherwise LGTM. Thanks @c-rhodes!

llvm/test/ExecutionEngine/Orc/empty-entry-function.ll

7–10

I think you can omit the IR entirely since you'll error out before attempting to parse it:

; RUN: not lli --entry-function= %s 2>&1 | FileCheck %s
;
; Test empty entry-function yield an error.
;
; CHECK: error: entry-function empty

llvm/tools/lli/lli.cpp

449–452

Could you change the error message to "--entry-function name cannot be empty"?

[c-rhodes]

In D156516#4543072, @lhames wrote:

Otherwise LGTM. Thanks @c-rhodes!

Addressed your comments before landing, thanks for reviewing!

llvm/test/ExecutionEngine/Orc/empty-entry-function.ll

+; RUN: not lli --entry-function= %s 2>&1 | FileCheck %s
+;
+; Test empty --entry-function yields an error.
+; CHECK: error: --entry-function name cannot be empty

llvm/tools/lli/lli.cpp

cl::ParseCommandLineOptions(argc, argv,
                               "llvm interpreter & dynamic compiler\n");
 
   // If the user doesn't want core files, disable them.
   if (DisableCoreFiles)
     sys::Process::PreventCoreFiles();
 
   ExitOnErr(loadDylibs());
 
+  if (EntryFunc.empty()) {
+    WithColor::error(errs(), argv[0])
+        << "--entry-function name cannot be empty\n";
+    exit(1);
+  }
+
   if (UseJITKind == JITKind::MCJIT)
     disallowOrcOptions();
   else
     return runOrcJIT(argv[0]);
 
   // Old lli implementation based on ExecutionEngine and MCJIT.
   LLVMContext Context;