backport r257541, r259936, r260294, r260623, r261098, r261333, r268585 from trunk

backport r257541, r259936, r260294, r260623, r261098, r261333, r268585 from trunk

These patches are followed changes for r255555 on testcases
vsx-vector-6*.c.  Backport them to update file names and fix regressions
for GCC7 on power9.
See e.g. https://gcc.gnu.org/ml/gcc-testresults/2019-04/msg00159.html
for the failures this patch fixes; the patch is for GCC 7.

gcc/ChangeLog:

2019-04-19  Xiong Hu Luo  <luoxhu@linux.ibm.com>

	Backport from trunk
	2018-05-23  Segher Boessenkool  <segher@kernel.crashing.org>

	* doc/sourcebuild.texi (Endianness): New subsubsection.

gcc/testsuite/ChangeLog:

2019-04-19  Xiong Hu Luo  <luoxhu@linux.ibm.com>

	Backport from trunk
	2018-02-07  Will Schmidt  <will_schmidt@vnet.ibm.com>

	* gcc.target/powerpc/vsx-vector-6-le.c: Update CPU target.
	* gcc.target/powerpc/vsx-vector-6-le.p9.c: New.

	Backport from trunk
	2018-05-04  Carl Love  <cel@us.ibm.com>
	* gcc.target/powerpc/vsx-vector-6.h (foo): Add test for vec_max,
	vec_trunc.
	* gcc.target/powerpc/vsx-vector-6-le.c (dg-final): Update xvcmpeqdp,
	xvcmpgtdp, xvcmpgedp counts. Add xxsel counts.
	* gcc.target/powerpc/vsx-vector-6-be.c (dg-final): Update xvcmpgtdp,
	xvcmpgedp counts. Add xxsel counts.

	Backport from trunk
	2018-05-16  Carl Love  <cel@us.ibm.com>
	* gcc.target/powerpc/vsx-vector-6-be.c: Remove file.
	* gcc.target/powerpc/vsx-vector-6-be.p7.c: New test file.
	* gcc.target/powerpc/vsx-vector-6-be.p8.c: New test file.
	* gcc.target/powerpc/vsx-vector-6-le.c (dg-final): Update counts for
	xvcmpeqdp., xvcmpgtdp., xvcmpgedp., xxlxor, xvrdpi.

	Backport from trunk
	2018-05-23  Segher Boessenkool  <segher@kernel.crashing.org>

	* lib/target-supports.exp (check_effective_target_be): New.
	(check_effective_target_le): New.

	Backport from trunk
	2018-06-01  Carl Love  <cel@us.ibm.com>

	* gcc.target/powerpc/altivec-7-be.c: Delete file.
	* gcc.target/powerpc/altivec-7-le.c: Delete file.
	* gcc.target/powerpc/vsx-7-be.c: Remove file.

	Backport from trunk
	2018-06-01  Carl Love  <cel@us.ibm.com>

	Commit 260294 on 2018-05-16 by Carl Love was supposed to add the
	following files.

	* gcc.target/powerpc/vsx-vector-6-be.p7.c: New test file.
	* gcc.target/powerpc/vsx-vector-6-be.p8.c: New test file.

	Backport from trunk
	2018-06-08  Carl Love  <cel@us.ibm.com>

	* gcc.target/powerpc/vsx-vector-6-be.p7.c: Rename this file to
	vsx-vector-6.p7.c.
	* gcc.target/powerpc/vsx-vector-6-le.p9.c: Rename this file to
	vsx-vector-6.p9.c.
	* gcc.target/powerpc/vsx-vector-6-be.p8.c: Move instruction counts
	for BE system that are different then for an LE system from this file
	into vsx-vector-6-le.c using be target qualifier.  Remove this file.
	* gcc.target/powerpc/vsx-vector-6-le.c: Add le qualifiers as needed for
	the various instruction counts.  Rename file to vsx-vector-6.p8.c.

	Backport from trunk
	2019-02-06  Bill Seurer  <seurer@linux.vnet.ibm.com>

	* gcc.target/powerpc/vsx-vector-6.p7.c: Update instruction
	counts and target.
	* gcc.target/powerpc/vsx-vector-6.p8.c: Update instruction
	counts and target.
	* gcc.target/powerpc/vsx-vector-6.p9.c: Update instruction
	counts and target.

From-SVN: r270452