[LLVMbugs] [Bug 748] NEW: LLC Failure if linked without optimization on Pentium4 Linux

[bugzilla-daemon at cs.uiuc.edu]

http://llvm.org/bugs/show_bug.cgi?id=748

           Summary: LLC Failure if linked without optimization on Pentium4
                    Linux
           Product: libraries
           Version: 1.7
          Platform: PC
        OS/Version: Linux
            Status: NEW
          Severity: critical
          Priority: P2
         Component: Backend: X86
        AssignedTo: unassignedbugs at nondot.org
        ReportedBy: jingyuuiuc at gmail.com


I find that if "-disable-opt" is passed to gccld (meaning that I disable all
linking optimization), some SPEC2000 int benchmarks will fail the LLC backend.
Specificly, llc produces an assertion failure for 255.vortex; miscompilation is
observed for 256.bzip2 and 252.eon (output file mismatch).

I have tried on out-of-box spec benchmarks and lastest LLVM on CVS. The problem
can be easily reproduced when you add "EXTRA_LINKTIME_OPT_FLAGS = -disable-opt"
on projects/llvm-test/Makefile.programs.

I am not sure if this is llc X86 bug or a linking bug. If linking optimizations
are allowed, there will be no problem. And seems that C-backend is fine, with/or
without linking optimizations.



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