[LLVMbugs] [Bug 6427] New: LLVM doesn't gracefully handle bitcode generated by newer version

[bugzilla-daemon at llvm.org]

http://llvm.org/bugs/show_bug.cgi?id=6427

           Summary: LLVM doesn't gracefully handle bitcode generated by
                    newer version
           Product: libraries
           Version: 2.6
          Platform: All
        OS/Version: All
            Status: NEW
          Severity: enhancement
          Priority: P5
         Component: Bitcode Writer
        AssignedTo: unassignedbugs at nondot.org
        ReportedBy: justin.lebar at gmail.com
                CC: llvmbugs at cs.uiuc.edu


Forgive me if this is already well-understood.

I have two versions of Klee installed on my machine; one uses LLVM 2.3, and the
other uses LLVM 2.6.  I accidentally tried to run some bitcode compiled with
the 2.6 compiler through my copy of Klee which uses LLVM 2.3.  Rather than fail
gracefully, LLVM treated me to a strange assertion:

ParameterAttributes.cpp:121: static llvm::PAListPtr
llvm::PAListPtr::get(const llvm::ParamAttrsWithIndex*, unsigned int):
Assertion `Attrs[i].Attrs != ParamAttr::None && "Pointless parameter
attribute!"' failed.

It appears that Klee built off LLVM 2.6 can read LLVM 2.3 bitcode files without
a problem, so perhaps this is a non-issue in terms of forward-compatibility. 
But certainly going forward, it would be nice if future versions could fail
more gracefully on bitcode they can't understand.

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