re PR bootstrap/54419 (Compiling libstdc++-v3/src/c++11/random.cc fails on platforms not knowing rdrand)

2012-09-09  Ulrich Drepper  <drepper@gmail.com>
	    Dominique d'Humieres  <dominiq@lps.ens.fr>
	    Jack Howarth  <howarth@bromo.med.uc.edu>

	PR bootstrap/54419
	* acinclude.m4: Define GLIBCXX_CHECK_X86_RDRAND.
	* configure.ac: Use GLIBCXX_CHECK_X86_RDRAND to test for rdrand
	support in assembler.
	* src/c++11/random.cc (__x86_rdrand): Depend on _GLIBCXX_X86_RDRAND.
	(random_device::_M_init): Likewise.
	(random_device::_M_getval): Likewise.
	* configure: Regenerated.
	* config.h.in: Regenerated.

Co-Authored-By: Dominique d'Humieres <dominiq@lps.ens.fr>
Co-Authored-By: Jack Howarth <howarth@bromo.med.uc.edu>

From-SVN: r191111

libstdc++-v3/ChangeLog

@@ -1,3 +1,17 @@
+2012-09-09  Ulrich Drepper  <drepper@gmail.com>
+	    Dominique d'Humieres  <dominiq@lps.ens.fr>
+	    Jack Howarth  <howarth@bromo.med.uc.edu>
+
+	PR bootstrap/54419
+	* acinclude.m4: Define GLIBCXX_CHECK_X86_RDRAND.
+	* configure.ac: Use GLIBCXX_CHECK_X86_RDRAND to test for rdrand
+	support in assembler.
+	* src/c++11/random.cc (__x86_rdrand): Depend on _GLIBCXX_X86_RDRAND.
+	(random_device::_M_init): Likewise.
+	(random_device::_M_getval): Likewise.
+	* configure: Regenerated.
+	* config.h.in: Regenerated.
+
 2012-09-09  Ulrich Drepper  <drepper@gmail.com>
 
 	* src/c++11/random.cc (random_device::_M_init): Use new macro

libstdc++-v3/acinclude.m4

@@ -3359,6 +3359,26 @@ AC_DEFUN([AC_LC_MESSAGES], [
   ])
 ])
 
+dnl
+dnl Check whether rdrand is supported in the assembler.
+AC_DEFUN([GLIBCXX_CHECK_X86_RDRAND], [
+  AC_MSG_CHECKING([for rdrand support in assembler])
+  AC_CACHE_VAL($ac_cv_x86_rdrand, [
+  ac_cv_x86_rdrand=no
+  case "$target" in
+    i?86-*-* | \
+    x86_64-*-*)
+    AC_TRY_COMPILE(, [asm("rdrand %eax");],
+		[ac_cv_x86_rdrand=yes], [ac_cv_x86_rdrand=no])
+  esac
+  ])
+  if test $ac_cv_x86_rdrand = yes; then
+    AC_DEFINE(_GLIBCXX_X86_RDRAND, 1,
+		[ Defined if as can handle rdrand. ])
+  fi
+  AC_MSG_RESULT($ac_cv_x86_rdrand)
+])
+
 dnl
 dnl Check whether get_nprocs is available in <sys/sysinfo.h>, and define _GLIBCXX_USE_GET_NPROCS.
 dnl

libstdc++-v3/config.h.in

@@ -845,6 +845,9 @@
 /* Define if code specialized for wchar_t should be used. */
 #undef _GLIBCXX_USE_WCHAR_T
 
+/* Defined if as can handle rdrand. */
+#undef _GLIBCXX_X86_RDRAND
+
 /* Define to 1 if mutex_timedlock is available. */
 #undef _GTHREAD_USE_MUTEX_TIMEDLOCK
 

libstdc++-v3/configure

@@ -70621,6 +70621,48 @@ $as_echo "#define _GLIBCXX_LONG_DOUBLE_COMPAT 1" >>confdefs.h
 esac
 
 
+# Check if assembler supports rdrand opcode.
+
+  { $as_echo "$as_me:${as_lineno-$LINENO}: checking for rdrand support in assembler" >&5
+$as_echo_n "checking for rdrand support in assembler... " >&6; }
+  if { as_var=$ac_cv_x86_rdrand; eval "test \"\${$as_var+set}\" = set"; }; then :
+  $as_echo_n "(cached) " >&6
+else
+
+  ac_cv_x86_rdrand=no
+  case "$target" in
+    i?86-*-* | \
+    x86_64-*-*)
+    cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+int
+main ()
+{
+asm("rdrand %eax");
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_compile "$LINENO"; then :
+  ac_cv_x86_rdrand=yes
+else
+  ac_cv_x86_rdrand=no
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+  esac
+
+fi
+
+  if test $ac_cv_x86_rdrand = yes; then
+
+$as_echo "#define _GLIBCXX_X86_RDRAND 1" >>confdefs.h
+
+  fi
+  { $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_x86_rdrand" >&5
+$as_echo "$ac_cv_x86_rdrand" >&6; }
+
+
 # This depends on GLIBCXX_ENABLE_SYMVERS and GLIBCXX_IS_NATIVE.
 
   if $GLIBCXX_IS_NATIVE ; then

libstdc++-v3/configure.ac

@@ -330,6 +330,9 @@ case "$target" in
 esac
 GLIBCXX_CONDITIONAL(GLIBCXX_LDBL_COMPAT, test $ac_ldbl_compat = yes)
 
+# Check if assembler supports rdrand opcode.
+GLIBCXX_CHECK_X86_RDRAND
+
 # This depends on GLIBCXX_ENABLE_SYMVERS and GLIBCXX_IS_NATIVE.
 GLIBCXX_CONFIGURE_TESTSUITE
 

libstdc++-v3/src/c++11/random.cc

@@ -50,7 +50,7 @@ namespace std _GLIBCXX_VISIBILITY(default)
       return __ret;
     }
 
-#if defined __i386__ || defined __x86_64__
+#if (defined __i386__ || defined __x86_64__) && defined _GLIBCXX_X86_RDRAND
     unsigned int
     __attribute__ ((target("rdrnd")))
     __x86_rdrand(void)
@@ -75,7 +75,7 @@ namespace std _GLIBCXX_VISIBILITY(default)
 
     if (token == "default")
       {
-#if defined __i386__ || defined __x86_64__
+#if (defined __i386__ || defined __x86_64__) && defined _GLIBCXX_X86_RDRAND
 	unsigned int eax, ebx, ecx, edx;
 	// Check availability of cpuid and, for now at least, also the
 	// CPU signature for Intel's
@@ -118,7 +118,7 @@ namespace std _GLIBCXX_VISIBILITY(default)
   random_device::result_type
   random_device::_M_getval()
   {
-#if (defined __i386__ || defined __x86_64__)
+#if (defined __i386__ || defined __x86_64__) && defined _GLIBCXX_X86_RDRAND
     if (! _M_file)
       return __x86_rdrand();
 #endif