Use an -implicit-check-not to make sure an error which should not occur
in fact does not occur before the first CHECK line.
Suggested by Paul Robinson in post-commit feedback for r335897.
llvm-svn: 336123
The checking logic should not treat artificial locations as being
somehow problematic. Producing these locations can be the desired
behavior of some passes.
See llvm.org/PR37961.
llvm-svn: 335897