[llvm-reduce] Exit when input module is malformed

[langston-barrett]

Summary

The parseInputFile function returns an empty unique_ptr to signal an
error, like when the input file doesn't exist, or is malformed. In this
case, the tool should exit immediately rather than segfault by
dereferencing the unique_ptr later.

[aeubanks]

could you add a simple test case?

[langston-barrett]

Add a test case

[aeubanks]

lgtm with the test CHECK change

llvm/test/tools/llvm-reduce/fail-file-open.test

5 ↗

(On Diff #347075)

is this error message cross platform? for example, I see

# Don't check the OS-dependent message "No such file or directory".

in llvm/test/tools/llvm-objdump/invalid-input.test

I think everything up to the error: is good enough. The main thing is that it doesn't crash.

[langston-barrett]

Update test to not depend on platform-specific error message

[aeubanks]

do you need help landing this?

[langston-barrett]

do you need help landing this?

I don't have commit access if that's what you mean. Thanks very much for the review, much appreciated!

llvm/tools/llvm-reduce/llvm-reduce.cpp

if (PrintDeltaPasses) {
     printDeltaPasses(errs());
     return 0;
   }
 
   LLVMContext Context;
   std::unique_ptr<Module> OriginalProgram =
       parseInputFile(InputFilename, Context);
 
+  if (!OriginalProgram) {
+    return 1;
+  }
+
   // Initialize test environment
   TestRunner Tester(TestFilename, TestArguments);
   Tester.setProgram(std::move(OriginalProgram));
 
   // Try to reduce code
   runDeltaPasses(Tester);
 
   if (!Tester.getProgram()) {