From 72771e53753647111d31c5c4bf43d8901e6baf7e Mon Sep 17 00:00:00 2001 From: "H.J. Lu" Date: Wed, 17 Oct 2018 15:16:38 -0700 Subject: 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 . --- sysdeps/x86/hp-timing.h | 52 +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 52 insertions(+) create mode 100644 sysdeps/x86/hp-timing.h (limited to 'sysdeps/x86/hp-timing.h') 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 + . */ + +#ifndef _HP_TIMING_H +#define _HP_TIMING_H 1 + +#include + +#if MINIMUM_ISA == 686 || MINIMUM_ISA == 8664 +# include + +/* 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 +#else +/* NB: Undefine _HP_TIMING_H so that will + be included. */ +# undef _HP_TIMING_H +# include +#endif + +#endif /* hp-timing.h */ -- cgit v1.2.3