2011-12-22  Bin Cheng  <bin.cheng@arm.com>
	Richard Guenther  <rguenther@suse.de>

	PR tree-optimization/43491
	* tree-ssa-pre.c (eliminate): Don't replace global register
	variable when it is the RHS of a single assign.

	testsuite:
	* gcc.dg/tree-ssa/pr43491.c: New test.


Co-Authored-By: Richard Guenther <rguenther@suse.de>

From-SVN: r182650