[PATCH] D20768: [MC] Return early when .fill size is negative

[Petr Hosek via llvm-commits]

phosek added a comment.

This triggers an error on ubsan build because of an invalid shift in `MCStreamer::emitFill` because of the negative Size. This is not a bug; even though `Expr` has an incorrect value, it's never used because `NumValues` is set to `0`, but we want to avoid further ubsan failures.


Repository:
  rL LLVM

http://reviews.llvm.org/D20768