[PATCH], Add PowerPC ISA 3.0 vector extract support

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

This patch adds support to generate the ISA 3.0 VEXTRACTUB, VEXTRACTUH, and
XXEXTRACTUW instructions to extract a constant element from the small vector
integer types.  I also added support to generate STXSIWX if a DImode is in an
Altivec register (which is needed for this patch when extracting char or short
elements).

I built this on a little endian power8 system, and there were no regressions in
make check.  Is it ok to install in the trunk?

Ideally, I would like to also install it on the GCC 6.2 branch.  Note, it
depends on the June 15th changes to allow DImode into Altivec registers, and
the fix for PR 71677 that was submitted on June 27th being installed before
these patches can be applied.

Assuming the above patches are supplied can I back port it to the GCC 6.2 after
a burn-in period?

[gcc]
2016-06-29  Michael Meissner  <meissner@linux.vnet.ibm.com>

	* config/rs6000/predicates.md (const_0_to_7_operand): New
	predicate, recognize 0..7.
	* config/rs6000/rs6000.c (rs6000_expand_vector_extract): Add
	support for doing extracts from V16QImode, V8HImode, V4SImode
	under ISA 3.0.
	* config/rs6000/vsx.md (VSX_EXTRACT_I): Mode iterator for ISA 3.0
	vector extract support.
	(VSX_EXTRACT_PREDICATE): Mode attribute to validate element number
	for ISA 3.0 vector extract.
	(VSX_EXTRACT_INSN): Mode attribute to give the instruction to use
	for ISA 3.0 vector extract.
	(VSX_EX): Constraints to use for ISA 3.0 vector extract.
	(vsx_extract_<mode>, VSX_EXTRACT_I): Add support for doing
	extracts of a constant element number from small integer vectors
	on 64-bit ISA 3.0 systems.
	(vsx_extract_<mode>_di): Likewise.
	* config/rs6000/rs6000.h (TARGET_VEXTRACTUB): New target macro to
	say when we can do ISA 3.0 vector extracts.
	* config/rs6000/rs6000.md (stfiwx): Allow DImode in Altivec
	registers, using the stxsiwx instruction.

[gcc/testsuite]
2016-06-29  Michael Meissner  <meissner@linux.vnet.ibm.com>

	* gcc.target/powerpc/p9-extract-1.c: New file to test ISA 3.0
	vector extract instructions.
	* gcc.target/powerpc/p9-extract-2.c: Likewise.

-- 
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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