flag-types.h (enum sanitize_code): Add SANITIZE_NONNULL_ATTRIBUTE and SANITIZE_RETURNS_NONNULL_ATTRIBUTE...

gcc/
	* flag-types.h (enum sanitize_code): Add SANITIZE_NONNULL_ATTRIBUTE
	and SANITIZE_RETURNS_NONNULL_ATTRIBUTE, or them into SANITIZE_UNDEFINED.
	* opts.c (common_handle_option): Handle SANITIZE_NONNULL_ATTRIBUTE and
	SANITIZE_RETURNS_NONNULL_ATTRIBUTE and disable
	flag_delete_null_pointer_checks for them.
	* sanitizer.def (BUILT_IN_UBSAN_HANDLE_NONNULL_ARG,
	BUILT_IN_UBSAN_HANDLE_NONNULL_ARG_ABORT,
	BUILT_IN_UBSAN_HANDLE_NONNULL_RETURN,
	BUILT_IN_UBSAN_HANDLE_NONNULL_RETURN_ABORT): New.
	* ubsan.c (instrument_bool_enum_load): Set *gsi back to
	stmt's iterator.
	(instrument_nonnull_arg, instrument_nonnull_return): New functions.
	(pass_ubsan::gate): Return true even for SANITIZE_NONNULL_ATTRIBUTE
	or SANITIZE_RETURNS_NONNULL_ATTRIBUTE.
	(pass_ubsan::execute): Call instrument_nonnull_{arg,return}.
	* doc/invoke.texi (-fsanitize=nonnull-attribute,
	-fsanitize=returns-nonnull-attribute): Document.
gcc/testsuite/
	* c-c++-common/ubsan/attrib-3.c: New test.
	* c-c++-common/ubsan/nonnull-1.c: New test.
	* c-c++-common/ubsan/nonnull-2.c: New test.
	* c-c++-common/ubsan/nonnull-3.c: New test.
	* c-c++-common/ubsan/nonnull-4.c: New test.
	* c-c++-common/ubsan/nonnull-5.c: New test.
libsanitizer/
	* ubsan/ubsan_handlers.cc, ubsan/ubsan_handlers.h: Cherry pick
	upstream r215485, r217389, r217391 and r217400.

From-SVN: r215118