[LLVMbugs] [Bug 9976] New: Crash in LiveVariables::runOnMachineFunction in Release builds

[bugzilla-daemon at llvm.org]

http://llvm.org/bugs/show_bug.cgi?id=9976

           Summary: Crash in LiveVariables::runOnMachineFunction in
                    Release builds
           Product: new-bugs
           Version: trunk
          Platform: PC
        OS/Version: Windows 2000
            Status: NEW
          Severity: normal
          Priority: P
         Component: new bugs
        AssignedTo: unassignedbugs at nondot.org
        ReportedBy: sean at caustic.com
                CC: llvmbugs at cs.uiuc.edu


Created an attachment (id=6625)
 --> (http://llvm.org/bugs/attachment.cgi?id=6625)
Patch with test case and fix

I see a crash in LiveVariables::runOnMachineFunction where it transfers the
dead/kill information to machine instructions. The loop accesses memory past
the end of an array.

This crash occurs only on Windows and only with Release/RelWithDebInfo builds.
It does not occur in Debug builds, nor on Mac OS X or Linux.

I have attached a fix (w/ test case). I modified the loop to work like other
similar iterations in the LiveVariables class, and to use the "getVarInfo()"
method, which will grow the array in question as necessary, preventing the
out-of-bounds access.

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