[LLVMbugs] [Bug 1082] NEW: llvm-upgrade can't upgrade this

[bugzilla-daemon at cs.uiuc.edu]

http://llvm.org/bugs/show_bug.cgi?id=1082

           Summary: llvm-upgrade can't upgrade this
           Product: tools
           Version: trunk
          Platform: All
        OS/Version: All
            Status: NEW
          Severity: normal
          Priority: P2
         Component: llvm-upgrade
        AssignedTo: unassignedbugs at nondot.org
        ReportedBy: rspencer at x10sys.com


Unfortunately, the current algorithm in llvm-upgrade depends on each value being
preceded by its type. However, with signedness elimination, the following is
quite possible:

    %tmp7360 = bitcast ubyte %tmp7354 to sbyte
    %tmp7361 = sub ubyte 0, %tmp7360

llvm-upgrade current translates this to:

    %tmp7360.s = bitcast i8 %x.u to i8
    %tmp7361.u = sub i8 0, %tmp7360.u

%tmp7360.u in the sub instruction should be %tmp7360.s, the intended value.
However, since the first argument to sub is ubyte, it gets the .u suffix.

llvm-as rightly declares that %tmp7360.u is undefined in the i8 type plane.



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