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authorH.J. Lu <hjl.tools@gmail.com>2018-10-17 15:16:38 -0700
committerH.J. Lu <hjl.tools@gmail.com>2018-10-17 15:16:45 -0700
commit72771e53753647111d31c5c4bf43d8901e6baf7e (patch)
tree66c4a0605d4624372f8e6742bf0c417ceaba8d43 /sysdeps/x86
parentc2b7ccad93d6361eba91755e8f0c92e97c76e854 (diff)
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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>.
Diffstat (limited to 'sysdeps/x86')
-rw-r--r--sysdeps/x86/hp-timing.h52
-rw-r--r--sysdeps/x86/init-arch.h1
2 files changed, 53 insertions, 0 deletions
diff --git a/sysdeps/x86/hp-timing.h b/sysdeps/x86/hp-timing.h
new file mode 100644
index 0000000000..1c20e9d828
--- /dev/null
+++ b/sysdeps/x86/hp-timing.h
@@ -0,0 +1,52 @@
+/* High precision, low overhead timing functions.  x86 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 _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)
+
+/* 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;
+
+/* That's quite simple.  Use the `rdtsc' instruction.  Note that the value
+   might not be 100% accurate since there might be some more instructions
+   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)	((Var) = _rdtsc ())
+
+# 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 */
diff --git a/sysdeps/x86/init-arch.h b/sysdeps/x86/init-arch.h
index a81ca8a4eb..bc860fcd69 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