re PR tree-optimization/81740 (wrong code at -O3 in both 32-bit and 64-bit modes on x86_64-linux-gnu)

2019-03-26  Bin Cheng  <bin.cheng@linux.alibaba.com>

	PR tree-optimization/81740
	* tree-vect-data-refs.c (vect_analyze_data_ref_dependence):
	In case of outer loop vectorization, check for backward dependence
	at the inner loop if outer loop dependence is reversed.

	* gcc.dg/vect/pr81740-1.c: New testcase.
	* gcc.dg/vect/pr81740-2.c: Likewise.

From-SVN: r269938