arm: MVE: Add C++ polymorphism and fix some more issues

This patch adds C++ polymorphism for the MVE intrinsics, by using the native C++
polymorphic functions when C++ is used.

It also moves the PRESERVE name macro definitions to the right place so that the
variants without the '__arm_' prefix are not available if we define the PRESERVE
NAMESPACE macro.

This patch further fixes two testisms that were brought to light by C++ testing
added in this patch.

gcc/ChangeLog:
2020-04-07  Andre Vieira  <andre.simoesdiasvieira@arm.com>

	* config/arm/arm_mve.h: Add C++ polymorphism and fix preserve MACROs.

gcc/testsuite/ChangeLog:
2020-04-07  Andre Vieira  <andre.simoesdiasvieira@arm.com>

	* g++.target/arm/mve.exp: New.
	* gcc.target/arm/mve/intrinsics/vcmpneq_n_f16: Fix testism.
	* gcc.target/arm/mve/intrinsics/vcmpneq_n_f32: Likewise.

gcc/ChangeLog

 2020-04-07  Andre Vieira  <andre.simoesdiasvieira@arm.com>
 
+	* config/arm/arm_mve.h: Add C++ polymorphism and fix preserve MACROs.
+
+2020-04-07  Andre Vieira  <andre.simoesdiasvieira@arm.com>
+
 	* config/arm/arm_mve.h: Cast some pointers to expected types.
 
 2020-04-07  Andre Vieira  <andre.simoesdiasvieira@arm.com>

gcc/testsuite/ChangeLog

 2020-04-07  Andre Vieira  <andre.simoesdiasvieira@arm.com>
 
+	* g++.target/arm/mve.exp: New.
+	* gcc.target/arm/mve/intrinsics/vcmpneq_n_f16: Fix testism.
+	* gcc.target/arm/mve/intrinsics/vcmpneq_n_f32: Likewise.
+
+2020-04-07  Andre Vieira  <andre.simoesdiasvieira@arm.com>
+
 	* gcc.target/arm/mve/intrinsics/vuninitializedq_float.c: Fix testism.
 	* gcc.target/arm/mve/intrinsics/vuninitializedq_float1.c: Likewise.
 	* gcc.target/arm/mve/intrinsics/vuninitializedq_int.c: Likewise.

gcc/testsuite/g++.target/arm/mve.exp

+# Copyright (C) 2019-2020 Free Software Foundation, Inc.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with GCC; see the file COPYING3.  If not see
+# <http://www.gnu.org/licenses/>.
+
+# GCC testsuite that uses the `dg.exp' driver.
+
+# Exit immediately if this isn't an ARM target.
+if ![istarget arm*-*-*] then {
+  return
+}
+
+# Load support procs.
+load_lib g++-dg.exp
+
+# If a testcase doesn't have special options, use these.
+global DEFAULT_CXXFLAGS
+if ![info exists DEFAULT_CXXFLAGS] then {
+    set DEFAULT_CXXFLAGS " -pedantic-errors"
+}
+
+# This variable should only apply to tests called in this exp file.
+global dg_runtest_extra_prunes
+set dg_runtest_extra_prunes ""
+lappend dg_runtest_extra_prunes "warning: switch -m(cpu|arch)=.* conflicts with -m(cpu|arch)=.* switch"
+
+set dg-do-what-default "assemble"
+
+# Initialize `dg'.
+dg-init
+
+# Main loop.
+dg-runtest [lsort [glob -nocomplain $srcdir/$subdir/../../gcc.target/arm/mve/intrinsics/*.\[cCS\]]] \
+	"" $DEFAULT_CXXFLAGS
+
+# All done.
+set dg_runtest_extra_prunes ""
+dg-finish

gcc/testsuite/gcc.target/arm/mve/intrinsics/vcmpgeq_n_f16.c

@@ -15,7 +15,7 @@ foo (float16x8_t a, float16_t b)
 mve_pred16_t
 foo1 (float16x8_t a, float16_t b)
 {
-  return vcmpgeq_n (a, b);
+  return vcmpgeq (a, b);
 }
 
 /* { dg-final { scan-assembler "vcmp.f16"  }  } */

gcc/testsuite/gcc.target/arm/mve/intrinsics/vcmpgeq_n_f32.c

@@ -15,7 +15,7 @@ foo (float32x4_t a, float32_t b)
 mve_pred16_t
 foo1 (float32x4_t a, float32_t b)
 {
-  return vcmpgeq_n (a, b);
+  return vcmpgeq (a, b);
 }
 
 /* { dg-final { scan-assembler "vcmp.f32"  }  } */