rtl-optimization/96812 - remap dependence info on RTL loop unrolling

rtl-optimization/96812 - remap dependence info on RTL loop unrolling

This carries over the PR87609 fix also to RTL loop unrolling.  The
gcc.dg/torture/pr90328.c testcase otherwise is miscompiled with
the tree-ssa-address.c hunk (or alternatively with -fno-ivopts
on master).  I've tried to find the correct abstraction and
adjusted two other duplicate_insn_chain users for which I do not
have testcases.  There may be other insn-chain copying routines
that could be affected but hopefully most appropriately go through
CFG hooks.

2020-08-27  Richard Biener  <rguenther@suse.de>

	PR rtl-optimization/96812
	* tree-ssa-address.c (copy_ref_info): Also copy dependence info.
	* cfgrtl.h (duplicate_insn_chain): Adjust prototype.
	* cfgrtl.c (duplicate_insn_chain): Remap dependence info
	if requested.
	(cfg_layout_duplicate_bb): Make sure we remap dependence info.
	* modulo-sched.c (duplicate_insns_of_cycles): Remap dependence
	info.
	(generate_prolog_epilog): Adjust.
	* config/c6x/c6x.c (hwloop_optimize): Remap dependence info.