Adrian Prantl e07824ace6 Document the shortcomings of DwarfExpression::addMachineReg().
Also make a drive-by-fix of a bug in the subregister scan code that
only triggers with an incomplete or otherwise very irregular machine
description.

rdar://problem/37404493

This re-applies r324972 with an early exit in the case of a complete
failure to make this commit NFC again as intended.

llvm-svn: 325041
2018-02-13 19:54:00 +00:00
..
2018-02-09 10:06:56 +00:00
2018-02-06 23:45:59 +00:00