Summary:
When an i1-value is defined inside of a loop and used outside of it, we
cannot simply use the SGPR bitmask from the loop's last iteration.
There are also useful and correct cases of an i1-value being copied between
basic blocks, e.g. when a condition is computed outside of a loop and used
inside it. The concept of dominators is not sufficient to capture what is
going on, so I propose the notion of "lane-dominators".
Fixes a bug encountered in Nier: Automata.
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=103743
Change-Id: If37b969ddc71d823ab3004aeafb9ea050e45bd9a
Reviewers: arsenm, rampitec
Subscribers: kzhuravl, wdng, mgorny, yaxunl, dstuttard, tpr, llvm-commits, t-tye
Differential Revision: https://reviews.llvm.org/D40547
llvm-svn: 329164
Nicolai Haehnle