PR tree-optimization/29877

	PR tree-optimization/29877
	gcc/
	* tree-ssa-ter.c (is_replaceable_p): Deem assignments with
	a register variable on the RHS to not be replaceable.

	gcc/testsuite/
	* gcc.dg/pr16194.c: Skip test entirely if we don't know the
	name of a hard register for the target concerned.  Adjust dg-error
	directives to cope with new behaviour of TER.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@120571 138bc75d-0d04-0410-961f-82ee72b054a4