Hi,
This patch set factors out runtime alias check code from tree-vect-data-refs.c
and tree-vect-loop-manip.c as general interfaces in tree-data-ref.c.  With this
change other optimizers like tree loop distribution could version loop wrto the
runtime alias checks.  During this work, I also found current code has issues
with negative DR_STEP.  This patch set fixes the issue as tracked in PR80815.

This is the first patch simply moves compare_tree to tree.c and exposes it.
Bootstrap and test on x86_64 and AArch64, is it OK?

Thanks,
bin

2017-05-22  Bin Cheng  <bin.cheng@arm.com>

	* tree-vect-data-refs.c (compare_tree): Move ...
	* tree.c (compare_tree): ... to here.
	* tree.h (compare_tree): New decalaration.