New Revision: 155749

URL: http://llvm.org/viewvc/llvm-project?rev=155749&view=rev
Log:
Reapply 155668: Fix the SD scheduler to avoid gluing the same node twice.

This time, also fix the caller of AddGlue to properly handle
incomplete chains. AddGlue had failure modes, but shamefully hid them
from its caller. It's luck ran out.

Fixes rdar://11314175: BuildSchedUnits assert.

llvm-svn: 156376