2011-10-28  Chung-Lin Tang  <cltang@codesourcery.com>

	PR rtl-optimization/49720
	* simplify-rtx.c (simplify_relational_operation_1): Detect
	infinite recursion condition in "(eq/ne (plus x cst1) cst2)
	simplifies to (eq/ne x (cst2 - cst1))" case.

	testsuite/
	* g++.dg/torture/pr49720.C: New test.

From-SVN: r180604