Patchwork [revisedx4] Fix PR bootstrap/54419

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Submitter Jack Howarth
Date Sept. 7, 2012, 2:02 p.m.
Message ID <20120907140241.GA4912@bromo.med.uc.edu>
Download mbox | patch
Permalink /patch/182382/
State New
Headers show

Comments

Jack Howarth - Sept. 7, 2012, 2:02 p.m.
The attached patch eliminates the bootstrap failures in libstdc++-v3
of PR 54419 by adding a define to acinclude.m4, GLIBCXX_CHECK_X86_RDRAND, that
checks for assembler support of the new rdrnd opcode, using this new define
in configure.ac and also defining _GLIBCXX_X86_RDRAND in config.h if supported.
Tested on x86_64-apple-darwin12 against the assembler from Xcode 4.4.1.
Modified to utilize AC_MSG_CHECKING, AC_CACHE_VAL and AC_MSG_RESULT in acinclude.m4.
Okay for gcc trunk?
             Jack
ps Corrected Dominique's email address in the ChangeLog.

libstdc++-v3/


2012-09-07  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.
Paolo Carlini - Sept. 7, 2012, 8:13 p.m.
Hi,

On 09/07/2012 04:02 PM, Jack Howarth wrote:
>     The attached patch eliminates the bootstrap failures in libstdc++-v3
> of PR 54419 by adding a define to acinclude.m4, GLIBCXX_CHECK_X86_RDRAND, that
> checks for assembler support of the new rdrnd opcode, using this new define
> in configure.ac and also defining _GLIBCXX_X86_RDRAND in config.h if supported.
> Tested on x86_64-apple-darwin12 against the assembler from Xcode 4.4.1.
> Modified to utilize AC_MSG_CHECKING, AC_CACHE_VAL and AC_MSG_RESULT in acinclude.m4.
> Okay for gcc trunk?
 From the library configury point of view the patch looks Ok to me, but 
I didn't really follow the whole discussion. Jakub is it OK with you?

Thanks,
Paolo.

Patch

Index: libstdc++-v3/src/c++11/random.cc
===================================================================
--- libstdc++-v3/src/c++11/random.cc	(revision 191071)
+++ libstdc++-v3/src/c++11/random.cc	(working copy)
@@ -50,7 +50,7 @@  namespace std _GLIBCXX_VISIBILITY(defaul
       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(defaul
 
     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(defaul
   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
Index: libstdc++-v3/configure.ac
===================================================================
--- libstdc++-v3/configure.ac	(revision 191071)
+++ libstdc++-v3/configure.ac	(working copy)
@@ -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
 
Index: libstdc++-v3/acinclude.m4
===================================================================
--- libstdc++-v3/acinclude.m4	(revision 191071)
+++ libstdc++-v3/acinclude.m4	(working copy)
@@ -3360,6 +3360,26 @@  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
 AC_DEFUN([GLIBCXX_CHECK_GET_NPROCS], [