x86: Default CET run-time support to auto

CET has been added since GCC 8.  This patch defaults CET run-time support
to auto.  It enables CET run-time support if asssembler supports CET
instructions and multi-byte NOPs are enabled via SSE2.

config/

	* cet.m4 (GCC_CET_FLAGS): Change default to auto.

gcc/

	* configure: Regenerated.

libatomic/

	* configure: Regenerated.

libbacktrace/

	* configure: Regenerated.

libcc1/

	* configure: Regenerated.

libcpp/

	* configure: Regenerated.

libdecnumber/

	* configure: Regenerated.

libgcc/

	* configure: Regenerated.

libgfortran/

	* configure: Regenerated.

libgomp/

	* configure: Regenerated.

libitm/

	* configure: Regenerated.

libobjc/

	* configure: Regenerated.

libquadmath/

	* configure: Regenerated.

libsanitizer/

	* configure: Regenerated.

libssp/

	* configure: Regenerated.

libstdc++-v3/

	* configure: Regenerated.

libvtv/

	* configure: Regenerated.

zlib/

	* configure: Regenerated.

2 files changed, 87 insertions, 6 deletions

diff --git a/libdecnumber/ChangeLog b/libdecnumber/ChangeLog
index 6bdc7574c20..75627e4825d 100644
--- a/libdecnumber/ChangeLog
+++ b/libdecnumber/ChangeLog
@@ -1,3 +1,7 @@
+2020-05-14  H.J. Lu  <hongjiu.lu@intel.com>
+
+	* configure: Regenerated.
+
 2020-05-12  H.J. Lu  <hongjiu.lu@intel.com>
 
 	* Makefile.in (CET_HOST_FLAGS): New.
diff --git a/libdecnumber/configure b/libdecnumber/configure
index b4542781457..c2c8040f5f3 100755
--- a/libdecnumber/configure
+++ b/libdecnumber/configure
@@ -1904,6 +1904,52 @@ rm -f conftest.val
   as_fn_set_status $ac_retval
 
 } # ac_fn_c_compute_int
+
+# ac_fn_c_try_link LINENO
+# -----------------------
+# Try to link conftest.$ac_ext, and return whether this succeeded.
+ac_fn_c_try_link ()
+{
+  as_lineno=${as_lineno-"$1"} as_lineno_stack=as_lineno_stack=$as_lineno_stack
+  rm -f conftest.$ac_objext conftest$ac_exeext
+  if { { ac_try="$ac_link"
+case "(($ac_try" in
+  *\"* | *\`* | *\\*) ac_try_echo=\$ac_try;;
+  *) ac_try_echo=$ac_try;;
+esac
+eval ac_try_echo="\"\$as_me:${as_lineno-$LINENO}: $ac_try_echo\""
+$as_echo "$ac_try_echo"; } >&5
+  (eval "$ac_link") 2>conftest.err
+  ac_status=$?
+  if test -s conftest.err; then
+    grep -v '^ *+' conftest.err >conftest.er1
+    cat conftest.er1 >&5
+    mv -f conftest.er1 conftest.err
+  fi
+  $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
+  test $ac_status = 0; } && {
+	 test -z "$ac_c_werror_flag" ||
+	 test ! -s conftest.err
+       } && test -s conftest$ac_exeext && {
+	 test "$cross_compiling" = yes ||
+	 test -x conftest$ac_exeext
+       }; then :
+  ac_retval=0
+else
+  $as_echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+
+	ac_retval=1
+fi
+  # Delete the IPA/IPO (Inter Procedural Analysis/Optimization) information
+  # created by the PGI compiler (conftest_ipa8_conftest.oo), as it would
+  # interfere with the next link command; also delete a directory that is
+  # left behind by Apple's compiler.  We do this before executing the actions.
+  rm -rf conftest.dSYM conftest_ipa8_conftest.oo
+  eval $as_lineno_stack; ${as_lineno_stack:+:} unset as_lineno
+  as_fn_set_status $ac_retval
+
+} # ac_fn_c_try_link
 cat >config.log <<_ACEOF
 This file contains any messages produced by compilers while
 running configure, to aid debugging if configure makes a mistake.
@@ -5132,10 +5178,35 @@ rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
     ;;
 esac
 
+save_CFLAGS="$CFLAGS"
+CFLAGS="$CFLAGS -fcf-protection=none"
+save_LDFLAGS="$LDFLAGS"
+LDFLAGS="$LDFLAGS -Wl,-z,ibt,-z,shstk"
 if test x$may_have_cet = xyes; then
-  save_LDFLAGS="$LDFLAGS"
-  LDFLAGS="$LDFLAGS -Wl,-z,ibt,-z,shstk"
-  if test "$cross_compiling" = yes; then :
+  # Check whether -fcf-protection=none -Wl,-z,ibt,-z,shstk work.
+  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+int
+main ()
+{
+return 0;
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_link "$LINENO"; then :
+  may_have_cet=yes
+else
+  may_have_cet=no
+fi
+rm -f core conftest.err conftest.$ac_objext \
+    conftest$ac_exeext conftest.$ac_ext
+fi
+
+if test x$may_have_cet = xyes; then
+  if test x$cross_compiling = xno; then
+    if test "$cross_compiling" = yes; then :
   { { $as_echo "$as_me:${as_lineno-$LINENO}: error: in \`$ac_pwd':" >&5
 $as_echo "$as_me: error: in \`$ac_pwd':" >&2;}
 as_fn_error $? "cannot run test program while cross compiling
@@ -5180,10 +5251,14 @@ rm -f core *.core core.conftest.* gmon.out bb.out conftest$ac_exeext \
   conftest.$ac_objext conftest.beam conftest.$ac_ext
 fi
 
-  LDFLAGS="$save_LDFLAGS"
-  if test x$enable_cet = xno -a x$have_cet = xyes; then
-    as_fn_error $? "Intel CET must be enabled on Intel CET enabled host" "$LINENO" 5
+    if test x$enable_cet = xno -a x$have_cet = xyes; then
+      as_fn_error $? "Intel CET must be enabled on Intel CET enabled host" "$LINENO" 5
+    fi
   fi
+else
+  # Enable CET in cross compiler if possible so that it will run on both
+  # CET and non-CET hosts.
+  have_cet=yes
 fi
 if test x$enable_cet = xyes; then
   CET_HOST_FLAGS="-fcf-protection"
@@ -5193,6 +5268,8 @@ else
   { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
 $as_echo "no" >&6; }
 fi
+CFLAGS="$save_CFLAGS"
+LDFLAGS="$save_LDFLAGS"
 
 case x$enable_languages in
 *jit*)