re PR target/81959 (PowerPC __float128 optimization fails with integer PRE_INC addresses)

re PR target/81959 (PowerPC __float128 optimization fails with integer PRE_INC addresses)

[gcc]
2017-12-01  Michael Meissner  <meissner@linux.vnet.ibm.com>

	PR target/81959
	* config/rs6000/rs6000.c (rs6000_address_for_fpconvert): Check for
	whether we can allocate pseudos before trying to fix an address.
	* config/rs6000/rs6000.md (float_<mode>si2_hw): Make sure the
	memory address is indexed or indirect.
	(floatuns_<mode>si2_hw2): Likewise.

[gcct/testsuite]
2017-12-01  Michael Meissner  <meissner@linux.vnet.ibm.com>

	PR target/81959
	* gcc.target/powerpc/pr81959.c: New test.

From-SVN: r255341