re PR debug/52048 (-fcompare-debug failure with -O2 -fcompare-debug -fnon-call-exceptions -fno-tree-dominator-opts)

	PR debug/52048
	* tree-ssa-tail-merge.c (local_def): Ignore debug uses.

	* g++.dg/other/pr52048.C: New test.

From-SVN: r183723