2017-04-25  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/80492
	* alias.c (compare_base_decls): Handle registers with asm
	specification conservatively.
	* tree-ssa-alias.c (decl_refs_may_alias_p): Handle
	compare_base_decls returning dont-know properly.

	* gcc.dg/pr80492.c: New testcase.

From-SVN: r247208