[PATCH], Fix PR 81959 (power9 IEEE 128-bit float convert from 32-bit memory)

[Michael Meissner <meissner at linux dot vnet dot ibm dot com>]

When I added the optimization for loading 32-bit values directly into the
vector registers from memory to convert to IEEE 128-bit floating point, I
forgot to make sure the address did not have PRE_INCREMENT, etc. addressing.

I checked the compiler on a little endian power8 system.  Is it ok to check
this patch into the trunk and back port it GCC 7?  GCC 6 did not have the
optimization.

[gcc]
2017-08-28  Michael Meissner  <meissner@linux.vnet.ibm.com>

	PR target/81959
	* config/rs6000/rs6000.md (float_<mode>si2_hw): If register
	allocation hasn't been done, make sure the memory address is
	X-FORM (register+register).
	(floatuns_<mode>si2_hw2): Likewise.

[gcct/testsuite]
2017-08-28  Michael Meissner  <meissner@linux.vnet.ibm.com>

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

-- 
Michael Meissner, IBM
IBM, M/S 2506R, 550 King Street, Littleton, MA 01460-6245, USA
email: meissner@linux.vnet.ibm.com, phone: +1 (978) 899-4797

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