[glibc/fw/glibc-hwcaps] s390x: Add Add glibc-hwcaps support

[Florian Weimer <fw@sourceware.org>]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=ce8a9e1ad5fd496e5038425fa3f72d859ce9c425

commit ce8a9e1ad5fd496e5038425fa3f72d859ce9c425
Author: Florian Weimer <fweimer@redhat.com>
Date:   Fri Jun 19 16:02:04 2020 +0200

    s390x: Add Add glibc-hwcaps support
    
    Subdirectories z13, z14, z15 can be selected, mostly based on the
    level of support for vector instructions.

Diff:
---
 sysdeps/s390/s390-64/dl-hwcaps-subdirs.c | 54 ++++++++++++++++++++++++++++++++
 1 file changed, 54 insertions(+)

diff --git a/sysdeps/s390/s390-64/dl-hwcaps-subdirs.c b/sysdeps/s390/s390-64/dl-hwcaps-subdirs.c
new file mode 100644
index 0000000000..255af22f02
--- /dev/null
+++ b/sysdeps/s390/s390-64/dl-hwcaps-subdirs.c
@@ -0,0 +1,54 @@
+/* Architecture-specific glibc-hwcaps subdirectories.  s390x version.
+   Copyright (C) 2020 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library 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
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include <dl-hwcaps.h>
+#include <ldsodefs.h>
+
+const char _dl_hwcaps_subdirs[] = "z15:z14:z13";
+
+int32_t
+_dl_hwcaps_subdirs_active (void)
+{
+  int32_t result = 0;
+  int32_t bit = 1 << 2;
+
+  /* Test in reverse preference order.  */
+
+  /* z13.  */
+  if (!(GLRO (dl_hwcap) & HWCAP_S390_VX))
+    return result;
+  result |= bit;
+  bit >>= 1;
+
+  /* z14.  */
+  if (!((GLRO (dl_hwcap) & HWCAP_S390_VXD)
+        && (GLRO (dl_hwcap) & HWCAP_S390_VXE)
+        && (GLRO (dl_hwcap) & HWCAP_S390_GS)))
+    return result;
+  result |= bit;
+  bit >>= 1;
+
+  /* z15.  */
+  if (!((GLRO (dl_hwcap) & HWCAP_S390_VXRS_EXT2)
+        && (GLRO (dl_hwcap) & HWCAP_S390_VXRS_PDE)))
+    return result;
+  result |= bit;
+  bit >>= 1;
+
+  return result;
+}