re PR tree-optimization/38807 (ice: gimple check: expected gimple_assign(error_mark), have gimple_phi())

	PR tree-optimization/38807
	* tree-ssa-reassoc.c (remove_visited_stmt_chain): Don't look at
	gimple_visited_p unless stmt is GIMPLE_ASSIGN.

	* gcc.c-torture/compile/pr38807.c: New test.

From-SVN: r143289