[LLVMbugs] [Bug 420] NEW: [licm] Use of PromoteMemToReg causes invalidation of alias analysis info

[bugzilla-daemon at cs.uiuc.edu]

http://llvm.cs.uiuc.edu/bugs/show_bug.cgi?id=420

           Summary: [licm] Use of PromoteMemToReg causes invalidation of
                    alias analysis info
           Product: libraries
           Version: 1.3
          Platform: All
        OS/Version: All
            Status: NEW
          Severity: normal
          Priority: P2
         Component: Scalar Optimizations
        AssignedTo: unassignedbugs at nondot.org
        ReportedBy: sabre at nondot.org


gccld on 253.perlbmk crashes when run on persephone, because the LICM pass is
promoting a memory location out of a loop, and not updating the alias analysis.

The problem is that LICM uses a call to PromoteMemToReg to do all of the heavy
lifting and insertion of PHI nodes.  Unfortunately, this causes some reasonably
large churn to the code and the alias analysis impl (glocalsmodref-aa in this
case) is not informed.  Later, the stale information is used by LICM and a crash
results.

I will attach a reduced testcase for the problem.

-Chris



------- You are receiving this mail because: -------
You are on the CC list for the bug, or are watching someone who is.