x86: Also check if -fcf-protection works

When defaulting CET run-time support to auto, check if -fcf-protection
works.  Even if the stage1 GCC doesn't support -fcf-protection, since
the final GCC does, CET run-time support will be enabled by default if
binutils support CET.

config/

	PR bootstrap/95147
	* cet.m4 (GCC_CET_FLAGS): Also check if -fcf-protection works
	when defaulting to auto.

libatomic/

	PR bootstrap/95147
	* configure: Regenerated.

libbacktrace/

	PR bootstrap/95147
	* configure: Regenerated.

libgcc/

	PR bootstrap/95147
	* configure: Regenerated.

libgfortran/

	PR bootstrap/95147
	* configure: Regenerated.

libgomp/

	PR bootstrap/95147
	* configure: Regenerated.

libitm/

	PR bootstrap/95147
	* configure: Regenerated.

libobjc/

	PR bootstrap/95147
	* configure: Regenerated.

libphobos/

	PR bootstrap/95147
	* configure: Regenerated.

libquadmath/

	PR bootstrap/95147
	* configure: Regenerated.

libsanitizer/

	PR bootstrap/95147
	* configure: Regenerated.

libssp/

	PR bootstrap/95147
	* configure: Regenerated.

libstdc++-v3/

	PR bootstrap/95147
	* configure: Regenerated.

libvtv/

	PR bootstrap/95147
	* configure: Regenerated.

zlib/

	PR bootstrap/95147
	* configure: Regenerated.

2 files changed, 9 insertions, 0 deletions

diff --git a/config/ChangeLog b/config/ChangeLog
index d36c5bb4976..a4d54749669 100644
--- a/config/ChangeLog
+++ b/config/ChangeLog
@@ -1,3 +1,9 @@
+2020-05-15  H.J. Lu  <hongjiu.lu@intel.com>
+
+        PR bootstrap/95147
+        * cet.m4 (GCC_CET_FLAGS): Also check if -fcf-protection works
+        when defaulting to auto.
+
 2020-05-14  H.J. Lu  <hongjiu.lu@intel.com>
 
         * cet.m4 (GCC_CET_FLAGS): Change default to auto.
diff --git a/config/cet.m4 b/config/cet.m4
index 63c6ea9ee02..2bb2c8a95ac 100644
--- a/config/cet.m4
+++ b/config/cet.m4
@@ -13,6 +13,8 @@ case "$host" in
       auto)
         # Check if target supports multi-byte NOPs
         # and if assembler supports CET insn.
+        save_CFLAGS="$CFLAGS"
+        CFLAGS="$CFLAGS -fcf-protection"
         AC_COMPILE_IFELSE(
          [AC_LANG_PROGRAM(
           [],
@@ -25,6 +27,7 @@ asm ("setssbsy");
           ])],
          [enable_cet=yes],
          [enable_cet=no])
+        CFLAGS="$save_CFLAGS"
         ;;
       yes)
         # Check if assembler supports CET.