re PR rtl-optimization/54871 (gfortran.dg/vector_subscript_1.f90 FAILs)

re PR rtl-optimization/54871 (gfortran.dg/vector_subscript_1.f90 FAILs)

	PR rtl-optimization/54871
	* loop-iv.c (simplify_using_initial_values): When scanning previous
	basic blocks, prune the recorded conditions if the current insn was
	not used to make a replacement.

	* loop-unroll.c (decide_unroll_constant_iterations): Clean up message.
	(unroll_loop_constant_iterations): Clarify head comment.
	(decide_unroll_runtime_iterations): Clean up message.
	(unroll_loop_runtime_iterations): Clarify head comment.
	(decide_peel_simple): Clean up message.
	(peel_loop_simple): Clarify head comment.
	(decide_unroll_stupid): Clean up message.
	(unroll_loop_stupid): Clarify head comment.

From-SVN: r192426