Summary:
During remat, some subranges might end up having invalid segments which caused problems for later
coalescing.
Added in a check to remove segments that are invalidated as part of the remat.
See http://llvm.org/PR33524
Subscribers: MatzeB, qcolombet
Differential Revision: https://reviews.llvm.org/D34391
llvm-svn: 307247
David Stuttard