S/390: PR69709 Fix risbg splitter

S/390: PR69709 Fix risbg splitter

This fixes a wrong code generation problem with the splitters introduced
with that patch: https://gcc.gnu.org/ml/gcc-patches/2015-07/msg01840.html

The target operand is used as temporary.  This fails if it matches the
source of the left shift which is read after writing the temporary.

Thanks to Dominik for debugging it and thanks to Richard for the fix!

Bootstrapped and regtested on s390x with-arch=z13.

Bye,

-Andreas-

gcc/ChangeLog:

2016-02-26  Richard Henderson  <rth@redhat.com>

	PR target/69709
	* config/s390/s390.md (risbg and risbgn splitters): Allocate new
	pseudo in case the target rtx matches the source of the left
	shift.

gcc/testsuite/ChangeLog:

2016-02-26  Andreas Krebbel  <krebbel@linux.vnet.ibm.com>

	PR target/69709
	* gcc.target/s390/pr69709.c: New test.

From-SVN: r233752