[llvm-bugs] [Bug 33565] New: SystemZISelLowering.cpp: Assertion `Mask != 0 && "ANDs with zero should have been removed by now"' failed.

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https://bugs.llvm.org/show_bug.cgi?id=33565

            Bug ID: 33565
           Summary: SystemZISelLowering.cpp: Assertion `Mask != 0 && "ANDs
                    with zero should have been removed by now"' failed.
           Product: libraries
           Version: trunk
          Hardware: PC
                OS: Linux
            Status: NEW
          Severity: normal
          Priority: P
         Component: Backend: SystemZ
          Assignee: unassignedbugs at nondot.org
          Reporter: paulsson at linux.vnet.ibm.com
                CC: llvm-bugs at lists.llvm.org

Created attachment 18695
  --> https://bugs.llvm.org/attachment.cgi?id=18695&action=edit
reduced testcase

(Csmith)

bin/llc -mtriple=s390x-linux-gnu -mcpu=z13 tc_ANDZero.ll

getTestUnderMaskCond() is called with a Mask==0. Mask is 0 because CmpVal==9294
and ShiftVal==63.

Not sure what's going wrong here, but it seems that this is a case that perhaps
should never have been passed to getTestUnderMaskCond(). The comment there says

// Check whether an AND with Mask is suitable for a TEST UNDER MASK...

, but the setcc looks like:

SelectionDAG has 17 nodes:
...
  t34: i64,ch = load<Volatile LD8...
          t52: i64 = srl t34, Constant:i32<63>
        t48: i32 = setcc t52, Constant:i64<9293>, setgt:ch

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