* builtin-types.def (BT_FN_PTR_CONST_PTR_SIZE_VAR): New.
	* builtins.def (BUILT_IN_ASSUME_ALIGNED): New builtin.
	* tree-ssa-structalias.c (find_func_aliases_for_builtin_call,
	find_func_clobbers): Handle BUILT_IN_ASSUME_ALIGNED.
	* tree-ssa-ccp.c (bit_value_assume_aligned): New function.
	(evaluate_stmt, execute_fold_all_builtins): Handle
	BUILT_IN_ASSUME_ALIGNED.
	* tree-ssa-dce.c (propagate_necessity): Likewise.
	* tree-ssa-alias.c (ref_maybe_used_by_call_p_1,
	call_may_clobber_ref_p_1): Likewise.
	* builtins.c (is_simple_builtin, expand_builtin): Likewise.
	(expand_builtin_assume_aligned): New function.
	* doc/extend.texi (__builtin_assume_aligned): Document.

	* c-common.c (check_builtin_function_arguments): Handle
	BUILT_IN_ASSUME_ALIGNED.

	* gcc.dg/builtin-assume-aligned-1.c: New test.
	* gcc.dg/builtin-assume-aligned-2.c: New test.
	* gcc.target/i386/builtin-assume-aligned-1.c: New test.

From-SVN: r175541