[llvm-bugs] [Bug 35630] New: Illegal ARM THUMB udiv instruction generated from llc with -filetype=asm, but not -filetype=obj

via llvm-bugs llvm-bugs at lists.llvm.org
Mon Dec 11 12:30:13 PST 2017


            Bug ID: 35630
           Summary: Illegal ARM THUMB udiv instruction generated from llc
                    with -filetype=asm, but not -filetype=obj
           Product: new-bugs
           Version: unspecified
          Hardware: PC
                OS: All
            Status: NEW
          Severity: enhancement
          Priority: P
         Component: new bugs
          Assignee: unassignedbugs at nondot.org
          Reporter: jackcarter at arxan.com
                CC: llvm-bugs at lists.llvm.org

Created attachment 19537
  --> https://bugs.llvm.org/attachment.cgi?id=19537&action=edit
gzipped .ll bitcode file that demonstrates the problem

The test attached was produced by llvm-extract. The size actually is deceiving
because the actual code in the bitcode takes up less than 120 lines.
llvm-extract pulls in a lot if not all of the original declarations and types
it seems.
This produces the illegal instruction:
llc -filetype=asm -relocation-model=pic -no-stack-coloring
./hkey_expansion_core.bc -o hkey_expansion_core.s
grep udiv hkey_expansion_core.s

Direct object output does not:
llc -filetype=obj -relocation-model=pic -no-stack-coloring
./hkey_expansion_core.bc -o hkey_expansion_core.o
llvm-objdump -arch-name=arm hkey_expansion_core.o > hkey_expansion_core.dis
If I need to reduce the problem further using bugpoint I would be glad for any
suggestions on how to do that since it seems that I would need a .s file with
the desired output and for now I am not sure what that would be other than not
“udiv”. Possibly setting up registers and calling one of the udiv intrinsics.

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