[LLVMbugs] [Bug 12425] New: Assertion when using scc_iterator when NDEBUG is defined

[bugzilla-daemon at llvm.org]

http://llvm.org/bugs/show_bug.cgi?id=12425

             Bug #: 12425
           Summary: Assertion when using scc_iterator when NDEBUG is
                    defined
           Product: libraries
           Version: trunk
          Platform: PC
        OS/Version: Linux
            Status: NEW
          Severity: normal
          Priority: P
         Component: Core LLVM classes
        AssignedTo: unassignedbugs at nondot.org
        ReportedBy: jobnoorman at gmail.com
                CC: llvmbugs at cs.uiuc.edu
    Classification: Unclassified


Created attachment 8298
  --> http://llvm.org/bugs/attachment.cgi?id=8298
Test case

I'm hitting an assertion when using scc_iterator but *only* if NDEBUG is
defined while compiling my module. The assertion happens when calling
operator++ on the iterator:

opt: /.../llvm/lib/VMCore/Value.cpp:539: void
llvm::ValueHandleBase::RemoveFromUseList(): Assertion `VP && VP->HasValueHandle
&& "Pointer doesn't have a use list!"' failed.

I have attached a simple loadable module to demonstrate the issue. I also
included a Makefile that generates two modules, one with -DNDEBUG and one
without. You can trigger the crash by running

$ opt -load ./Test-crash.so -test test.ll

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