[PATCH], PR 71201, Fix xxperm on PowerPC ISA 3.0, add vpermr/xxpermr support

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

GCC 6.1 added support for the XXPERM instruction for the PowerPC ISA 3.0.  The
XXPERM instruction is essentially a 4 operand instruction, with only 3 operands
in the instruction (the target register overlaps with the first input
register).  The Power9 hardware has fusion support where if the instruction
that precedes the XXPERM is a XXLOR move instruction to set the first input
argument, it is fused with the XXPERM.  I added code to support this fusion.

Unfortunately, in running the testsuite on the power9 simulator, we discovered
that the test gcc.c-torture/execute/pr56866.c would fail because the fusion
alternatives confused the register allocator and/or the passes after the
register allocator.  This patch removes the explicit fusion support from
XXPERM.

In addition, ISA 3.0 added XXPERMR and VPERMR instructions for little endian
support where the permute vector reverses the bytes.  This patch adds support
for XXPERMR/VPERMR.

[gcc]
2016-05-19  Michael Meissner  <meissner@linux.vnet.ibm.com>
	    Kelvin Nilsen  <kelvin@gcc.gnu.org>

	PR target/71201
	* config/rs6000/rs6000.c (rs6000_expand_vector_set): Generate
	vpermr/xxpermr on ISA 3.0.
	(altivec_expand_vec_perm_le): Likewise.
	* config/rs6000/altivec.md (UNSPEC_VPERMR): New unspec.
	(altivec_vperm_<mode>_internal): Drop ISA 3.0 xxperm fusion
	alternative.
	(altivec_vperm_v8hiv16qi): Likewise.
	(altivec_vperm_<mode>_uns_internal): Likewise.
	(vperm_v8hiv4si): Likewise.
	(vperm_v16qiv8hi): Likewise.
	(altivec_vpermr_<mode>_internal): Add VPERMR/XXPERMR support for
	ISA 3.0.

[gcc/testsuite]
2016-05-19  Michael Meissner  <meissner@linux.vnet.ibm.com>
	    Kelvin Nilsen  <kelvin@gcc.gnu.org>

	* gcc.target/powerpc/p9-permute.c: Run test on big endian as well
	as little endian.
	* gcc.target/powerpc/p9-vpermr.c: New test for ISA 3.0 vpermr
	support.


-- 
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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