[LLVMbugs] [Bug 17876] New: TailDuplicate makes bad assumption about SSA form

[bugzilla-daemon at llvm.org]

http://llvm.org/bugs/show_bug.cgi?id=17876

            Bug ID: 17876
           Summary: TailDuplicate makes bad assumption about SSA form
           Product: libraries
           Version: trunk
          Hardware: PC
                OS: All
            Status: NEW
          Severity: normal
          Priority: P
         Component: Common Code Generator Code
          Assignee: unassignedbugs at nondot.org
          Reporter: justin.holewinski at gmail.com
                CC: llvmbugs at cs.uiuc.edu
    Classification: Unclassified

Created attachment 11508
  --> http://llvm.org/bugs/attachment.cgi?id=11508&action=edit
Repro for TailDuplicate assert failure

During late machine code optimization with NVPTX, the following code in
TailDuplicate.cpp may be hit:

236├>      MachineInstr *DefMI = MRI->getVRegDef(VReg);

MachineRegisterInfo::getVRegDef() assumes SSA form, but when running
TailDuplicate MRI->isSSA() is false.

For repro, the attached .ll file can be used with the nvptx target with the
following change to NVPTXTargetMachine.cpp:

1. Remove "disablePass(&TailDuplicateID);"

The TailDuplicate pass is currently disabled in NVPTX for a few reasons,
including this one.

-- 
You are receiving this mail because:
You are on the CC list for the bug.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/llvm-bugs/attachments/20131111/b05d9955/attachment.html>