x86: Use _rdtsc intrinsic for HP_TIMING_NOW

Since _rdtsc intrinsic is supported in GCC 4.9, we can use it for
HP_TIMING_NOW.  This patch

1. Create x86 hp-timing.h to replace i686 and x86_64 hp-timing.h.
2. Move MINIMUM_ISA from init-arch.h to isa.h so that x86 hp-timing.h
can check minimum x86 ISA to decide if _rdtsc can be used.

NB: Checking if __i686__ isn't sufficient since __i686__ may not be
defined when building for i686 class processors.

	* sysdeps/i386/init-arch.h: Removed.
	* sysdeps/i386/i586/init-arch.h: Likewise.
	* sysdeps/i386/i686/init-arch.h: Likewise.
	* sysdeps/i386/i686/hp-timing.h: Likewise.
	* sysdeps/x86_64/hp-timing.h: Likewise.
	* sysdeps/i386/isa.h: New file.
	* sysdeps/i386/i586/isa.h: Likewise.
	* sysdeps/i386/i686/isa.h: Likewise.
	* sysdeps/x86_64/isa.h: Likewise.
	* sysdeps/x86/hp-timing.h: New file.
	* sysdeps/x86/init-arch.h: Include <isa.h>.

7 files changed, 65 insertions, 55 deletions

diff --git a/sysdeps/i386/i586/init-arch.h b/sysdeps/i386/i586/isa.h
index 72fb46c..79481ce 100644
--- a/sysdeps/i386/i586/init-arch.h
+++ b/sysdeps/i386/i586/isa.h
@@ -1,4 +1,5 @@
-/* Copyright (C) 2015-2018 Free Software Foundation, Inc.
+/* x86 ISA info.  i586 version.
+   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
@@ -15,5 +16,9 @@
    License along with the GNU C Library; if not, see
    <http://www.gnu.org/licenses/>.  */
 
+#ifndef _ISA_H
+#define _ISA_H
+
 #define MINIMUM_ISA 586
-#include <sysdeps/x86/init-arch.h>
+
+#endif
diff --git a/sysdeps/i386/i686/init-arch.h b/sysdeps/i386/i686/isa.h
index ab99392..584e26b 100644
--- a/sysdeps/i386/i686/init-arch.h
+++ b/sysdeps/i386/i686/isa.h
@@ -1,4 +1,5 @@
-/* Copyright (C) 2015-2018 Free Software Foundation, Inc.
+/* x86 ISA info.  i686 version.
+   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
@@ -15,5 +16,9 @@
    License along with the GNU C Library; if not, see
    <http://www.gnu.org/licenses/>.  */
 
+#ifndef _ISA_H
+#define _ISA_H
+
 #define MINIMUM_ISA 686
-#include <sysdeps/x86/init-arch.h>
+
+#endif
diff --git a/sysdeps/i386/init-arch.h b/sysdeps/i386/isa.h
index 043089c..e0a1e9c 100644
--- a/sysdeps/i386/init-arch.h
+++ b/sysdeps/i386/isa.h
@@ -1,4 +1,5 @@
-/* Copyright (C) 2015-2018 Free Software Foundation, Inc.
+/* x86 ISA info.  i486 version.
+   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
@@ -15,5 +16,9 @@
    License along with the GNU C Library; if not, see
    <http://www.gnu.org/licenses/>.  */
 
+#ifndef _ISA_H
+#define _ISA_H
+
 #define MINIMUM_ISA 486
-#include <sysdeps/x86/init-arch.h>
+
+#endif
diff --git a/sysdeps/i386/i686/hp-timing.h b/sysdeps/x86/hp-timing.h
index 59af526..1c20e9d 100644
--- a/sysdeps/i386/i686/hp-timing.h
+++ b/sysdeps/x86/hp-timing.h
@@ -1,7 +1,6 @@
-/* High precision, low overhead timing functions.  i686 version.
-   Copyright (C) 1998-2018 Free Software Foundation, Inc.
+/* High precision, low overhead timing functions.  x86 version.
+   Copyright (C) 2018 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
-   Contributed by Ulrich Drepper <drepper@cygnus.com>, 1998.
 
    The GNU C Library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Lesser General Public
@@ -20,12 +19,17 @@
 #ifndef _HP_TIMING_H
 #define _HP_TIMING_H	1
 
+#include <isa.h>
+
+#if MINIMUM_ISA == 686 || MINIMUM_ISA == 8664
+# include <x86intrin.h>
+
 /* We always assume having the timestamp register.  */
-#define HP_TIMING_AVAIL		(1)
-#define HP_SMALL_TIMING_AVAIL	(1)
+# define HP_TIMING_AVAIL	(1)
+# define HP_SMALL_TIMING_AVAIL	(1)
 
 /* We indeed have inlined functions.  */
-#define HP_TIMING_INLINE	(1)
+# define HP_TIMING_INLINE	(1)
 
 /* We use 64bit values for the times.  */
 typedef unsigned long long int hp_timing_t;
@@ -35,8 +39,14 @@ typedef unsigned long long int hp_timing_t;
    running in this moment.  This could be changed by using a barrier like
    'cpuid' right before the `rdtsc' instruciton.  But we are not interested
    in accurate clock cycles here so we don't do this.  */
-#define HP_TIMING_NOW(Var)	__asm__ __volatile__ ("rdtsc" : "=A" (Var))
+# define HP_TIMING_NOW(Var)	((Var) = _rdtsc ())
 
-#include <hp-timing-common.h>
+# include <hp-timing-common.h>
+#else
+/* NB: Undefine _HP_TIMING_H so that <sysdeps/generic/hp-timing.h> will
+   be included.  */
+# undef _HP_TIMING_H
+# include <sysdeps/generic/hp-timing.h>
+#endif
 
-#endif	/* hp-timing.h */
+#endif /* hp-timing.h */
diff --git a/sysdeps/x86/init-arch.h b/sysdeps/x86/init-arch.h
index a81ca8a..bc860fc 100644
--- a/sysdeps/x86/init-arch.h
+++ b/sysdeps/x86/init-arch.h
@@ -21,6 +21,7 @@
 # include <ldsodefs.h>
 #endif
 #include <ifunc-init.h>
+#include <isa.h>
 
 #ifndef __x86_64__
 /* Due to the reordering and the other nifty extensions in i686, it is
diff --git a/sysdeps/x86_64/hp-timing.h b/sysdeps/x86_64/hp-timing.h
deleted file mode 100644
index ec543be..0000000
--- a/sysdeps/x86_64/hp-timing.h
+++ /dev/null
@@ -1,40 +0,0 @@
-/* High precision, low overhead timing functions.  x86-64 version.
-   Copyright (C) 2002-2018 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/>.  */
-
-#ifndef _HP_TIMING_H
-#define _HP_TIMING_H	1
-
-/* We always assume having the timestamp register.  */
-#define HP_TIMING_AVAIL		(1)
-#define HP_SMALL_TIMING_AVAIL	(1)
-
-/* We indeed have inlined functions.  */
-#define HP_TIMING_INLINE	(1)
-
-/* We use 64bit values for the times.  */
-typedef unsigned long long int hp_timing_t;
-
-/* The "=A" constraint used in 32-bit mode does not work in 64-bit mode.  */
-#define HP_TIMING_NOW(Var) \
-  ({ unsigned int _hi, _lo; \
-     asm volatile ("rdtsc" : "=a" (_lo), "=d" (_hi)); \
-     (Var) = ((unsigned long long int) _hi << 32) | _lo; })
-
-#include <hp-timing-common.h>
-
-#endif /* hp-timing.h */
diff --git a/sysdeps/x86_64/isa.h b/sysdeps/x86_64/isa.h
new file mode 100644
index 0000000..452bce7
--- /dev/null
+++ b/sysdeps/x86_64/isa.h
@@ -0,0 +1,24 @@
+/* x86 ISA info.  x86-64 version.
+   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/>.  */
+
+#ifndef _ISA_H
+#define _ISA_H
+
+#define MINIMUM_ISA 8664
+
+#endif