[01/20] Initial empty CPU run-time library for C: libcpu-rt-c

diff --git a/Makeconfig b/Makeconfig
index 1afe86475c..ed894b7c8f 100644
--- a/Makeconfig
+++ b/Makeconfig
@@ -566,7 +566,7 @@  link-libc-printers-tests = $(link-libc-rpath) \
 			   $(link-libc-tests-after-rpath-link)
 
 # This is how to find at build-time things that will be installed there.
-rpath-dirs = math elf dlfcn nss nis rt resolv crypt mathvec support
+rpath-dirs = math elf dlfcn nss nis rt resolv crypt mathvec cpu-rt-c support
 rpath-link = \
 $(common-objdir):$(subst $(empty) ,:,$(patsubst ../$(subdir),.,$(rpath-dirs:%=$(common-objpfx)%)))
 else  # build-static
@@ -1206,7 +1206,7 @@  all-subdirs = csu assert ctype locale intl catgets math setjmp signal	    \
 	      grp pwd posix io termios resource misc socket sysvipc gmon    \
 	      gnulib iconv iconvdata wctype manual shadow gshadow po argp   \
 	      crypt localedata timezone rt conform debug mathvec support    \
-	      dlfcn elf
+	      dlfcn elf cpu-rt-c
 
 ifndef avoid-generated
 # sysd-sorted itself will contain rules making the sysd-sorted target
diff --git a/configure b/configure
index 7a8bd3f817..580bebb75d 100755
--- a/configure
+++ b/configure
@@ -788,6 +788,7 @@  enable_nscd
 enable_pt_chown
 enable_tunables
 enable_mathvec
+enable_cpu_rt
 with_cpu
 '
       ac_precious_vars='build_alias
@@ -1461,6 +1462,8 @@  Optional Features:
                           'no' and 'valstring'
   --enable-mathvec        Enable building and installing mathvec [default
                           depends on architecture]
+  --enable-cpu-rt         Enable building and installing CPU run-time library
+                          [default depends on architecture]
 
 Optional Packages:
   --with-PACKAGE[=ARG]    use PACKAGE [ARG=yes]
@@ -3741,6 +3744,14 @@  else
 fi
 
 
+# Check whether --enable-cpu-rt was given.
+if test "${enable_cpu_rt+set}" = set; then :
+  enableval=$enable_cpu_rt; build_cpu_rt=$enableval
+else
+  build_cpu_rt=notset
+fi
+
+
 # We keep the original values in `$config_*' and never modify them, so we
 # can write them unchanged into config.make.  Everything else uses
 # $machine, $vendor, and $os, and changes them whenever convenient.
@@ -6678,6 +6689,12 @@  fi
 config_vars="$config_vars
 build-mathvec = $build_mathvec"
 
+if test x"$build_cpu_rt" = xnotset; then
+  build_cpu_rt=no
+fi
+config_vars="$config_vars
+build-cpu-rt = $build_cpu_rt"
+
 
 
 
diff --git a/configure.ac b/configure.ac
index ca1282a6b3..a851d958f1 100644
--- a/configure.ac
+++ b/configure.ac
@@ -453,6 +453,12 @@  AC_ARG_ENABLE([mathvec],
 	      [build_mathvec=$enableval],
 	      [build_mathvec=notset])
 
+AC_ARG_ENABLE([cpu-rt],
+	      [AS_HELP_STRING([--enable-cpu-rt],
+	      [Enable building and installing CPU run-time library @<:@default depends on architecture@:>@])],
+	      [build_cpu_rt=$enableval],
+	      [build_cpu_rt=notset])
+
 # We keep the original values in `$config_*' and never modify them, so we
 # can write them unchanged into config.make.  Everything else uses
 # $machine, $vendor, and $os, and changes them whenever convenient.
@@ -1737,6 +1743,11 @@  if test x"$build_mathvec" = xnotset; then
 fi
 LIBC_CONFIG_VAR([build-mathvec], [$build_mathvec])
 
+if test x"$build_cpu_rt" = xnotset; then
+  build_cpu_rt=no
+fi
+LIBC_CONFIG_VAR([build-cpu-rt], [$build_cpu_rt])
+
 AC_SUBST(libc_extra_cflags)
 AC_SUBST(libc_extra_cppflags)
 
diff --git a/cpu-rt-c/Makefile b/cpu-rt-c/Makefile
new file mode 100644
index 0000000000..f138911347
--- /dev/null
+++ b/cpu-rt-c/Makefile
@@ -0,0 +1,42 @@ 
+# Copyright (C) 2018 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
+# <http://www.gnu.org/licenses/>.
+
+# Makefile for the CPU run-time library for C.
+
+subdir		:= cpu-rt-c
+
+include ../Makeconfig
+
+ifeq ($(build-cpu-rt),yes)
+extra-libs	:= libcpu-rt-c
+extra-libs-others = $(extra-libs)
+
+libcpu-rt-c-sysdep_routines += $(cpu-rt-c-routines)
+libcpu-rt-c-tests += $(addprefix test-,$(cpu-rt-c-routines))
+tests += $(libcpu-rt-c-tests)
+endif
+
+include ../Rules
+
+ifeq ($(build-cpu-rt),yes)
+ifeq ($(build-shared),yes)
+libcpu-rt-c = $(objpfx)libcpu-rt-c.so
+else
+libcpu-rt-c = $(objpfx)libcpu-rt-c.a
+endif
+$(addprefix $(objpfx),$(libcpu-rt-c-tests)): $(libcpu-rt-c)
+endif
diff --git a/shlib-versions b/shlib-versions
index b9cb99d2fb..43e4c63f54 100644
--- a/shlib-versions
+++ b/shlib-versions
@@ -75,3 +75,6 @@  libgcc_s=1
 
 # The vector math library
 libmvec=1
+
+# The CPU run-time library for C
+libcpu_rt_c=1