[llvm-dev] Strange verifier error with LLVM 3.9

[Tim Northover via llvm-dev]

On 12 July 2016 at 07:32, Sergey Anufrienko via llvm-dev
<llvm-dev at lists.llvm.org> wrote:
> Global is referenced by parentless instruction!

If you really do create all your GEPs with i64, it could be an
orphaned mutation of the original one (after you've called
ReplaceAllUsesWith on @.str). The one wrinkle there is that the
original was a Constant, not an Instruction; something you did might
have promoted it to an Instruction but not put it into any basic block
but I can't think of anything right now.

I'd start by using a much shorter string, stopping the debugger on
your pass, and setting a breakpoint on
GetElementPtrInst::GetElementPtrInst. Hopefully the context will
suggest what you need to do to remove the instruction entirely.

Tim.