S/390: Add splitter for "and" with complement.

S/390: Add splitter for "and" with complement.

Split ~b & a to (b & a) ^ a.  This is benefitial on z Systems since we
otherwise need a big -1 constant to be loaded for the ~b.

gcc/ChangeLog:

2016-08-23  Dominik Vogt  <vogt@linux.vnet.ibm.com>

	* config/s390/s390.md ("*andc_split"): New splitter for and with
	complement.

gcc/testsuite/ChangeLog:

2016-08-23  Dominik Vogt  <vogt@linux.vnet.ibm.com>

	* gcc.target/s390/md/andc-splitter-1.c: New test case.
	* gcc.target/s390/md/andc-splitter-2.c: Likewise.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@239685 138bc75d-0d04-0410-961f-82ee72b054a4