[Debugify] Handle failure to get fragment size when checking dbg.values

It's not possible to get the fragment size of some dbg.values. Teach the
mis-sized dbg.value diagnostic to detect this scenario and bail out.

Tested with:
$ find test/Transforms -print -exec opt -debugify-each -instcombine {} \;

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@335695 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed