gcc/ChangeLog:

	PR middle-end/81908
	* gimple-fold.c (size_must_be_zero_p): New function.
	(gimple_fold_builtin_memory_op): Call it.

gcc/testsuite/ChangeLog:

	PR middle-end/81908
	* gcc.dg/tree-ssa/builtins-folding-gimple-2.c: New test.
	* gcc.dg/tree-ssa/builtins-folding-gimple-3.c: New test.
	* gcc.dg/tree-ssa/pr81908.c: New test.

From-SVN: r251347