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authorJoseph Myers <joseph@codesourcery.com>2012-07-01 13:06:41 +0000
committerJoseph Myers <joseph@codesourcery.com>2012-07-01 13:06:41 +0000
commite64ac02c24b43659048622714afdc92fedf561fa (patch)
tree37162878b72d302de351788bec4c9360c9d55f1d /ports/sysdeps/ia64/hp-timing.h
parenta20c2b3c87aebc7d4b090c622d36480263b80042 (diff)
downloadglibc-e64ac02c24b43659048622714afdc92fedf561fa.tar.gz
Move all files into ports/ subdirectory in preparation for merge with glibcglibc-2.16-ports-before-merge
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+/* High precision, low overhead timing functions. IA-64 version.
+ Copyright (C) 2001-2012 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+ Contributed by Ulrich Drepper <drepper@cygnus.com>, 2001.
+
+ 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 <string.h>
+#include <sys/param.h>
+#include <_itoa.h>
+#include <ia64intrin.h>
+
+/* The macros defined here use the timestamp counter in IA-64. They
+ provide a very accurate way to measure the time with very little
+ overhead. The time values themself have no real meaning, only
+ differences are interesting.
+
+ The list of macros we need includes the following:
+
+ - HP_TIMING_AVAIL: test for availability.
+
+ - HP_TIMING_INLINE: this macro is non-zero if the functionality is not
+ implemented using function calls but instead uses some inlined code
+ which might simply consist of a few assembler instructions. We have to
+ know this since we might want to use the macros here in places where we
+ cannot make function calls.
+
+ - hp_timing_t: This is the type for variables used to store the time
+ values.
+
+ - HP_TIMING_ZERO: clear `hp_timing_t' object.
+
+ - HP_TIMING_NOW: place timestamp for current time in variable given as
+ parameter.
+
+ - HP_TIMING_DIFF_INIT: do whatever is necessary to be able to use the
+ HP_TIMING_DIFF macro.
+
+ - HP_TIMING_DIFF: compute difference between two times and store it
+ in a third. Source and destination might overlap.
+
+ - HP_TIMING_ACCUM: add time difference to another variable. This might
+ be a bit more complicated to implement for some platforms as the
+ operation should be thread-safe and 64bit arithmetic on 32bit platforms
+ is not.
+
+ - HP_TIMING_ACCUM_NT: this is the variant for situations where we know
+ there are no threads involved.
+
+ - HP_TIMING_PRINT: write decimal representation of the timing value into
+ the given string. This operation need not be inline even though
+ HP_TIMING_INLINE is specified.
+
+*/
+
+/* We always assume having the timestamp register. */
+#define HP_TIMING_AVAIL (1)
+
+/* We indeed have inlined functions. */
+#define HP_TIMING_INLINE (1)
+
+/* We use 64bit values for the times. */
+typedef unsigned long int hp_timing_t;
+
+/* Set timestamp value to zero. */
+#define HP_TIMING_ZERO(Var) (Var) = (0)
+
+
+/* The Itanium/Merced has a bug where the ar.itc register value read
+ is not correct in some situations. The solution is to read again.
+ For now we always do this until we know how to recognize a fixed
+ processor implementation. */
+#define REPEAT_READ(val) __builtin_expect ((long int) val == -1, 0)
+
+/* That's quite simple. Use the `ar.itc' instruction. */
+#define HP_TIMING_NOW(Var) \
+ ({ unsigned long int __itc; \
+ do \
+ asm volatile ("mov %0=ar.itc" : "=r" (__itc) : : "memory"); \
+ while (REPEAT_READ (__itc)); \
+ Var = __itc; })
+
+/* Use two 'ar.itc' instructions in a row to find out how long it takes. */
+#define HP_TIMING_DIFF_INIT() \
+ do { \
+ int __cnt = 5; \
+ GLRO(dl_hp_timing_overhead) = ~0ul; \
+ do \
+ { \
+ hp_timing_t __t1, __t2; \
+ HP_TIMING_NOW (__t1); \
+ HP_TIMING_NOW (__t2); \
+ if (__t2 - __t1 < GLRO(dl_hp_timing_overhead)) \
+ GLRO(dl_hp_timing_overhead) = __t2 - __t1; \
+ } \
+ while (--__cnt > 0); \
+ } while (0)
+
+/* It's simple arithmetic for us. */
+#define HP_TIMING_DIFF(Diff, Start, End) (Diff) = ((End) - (Start))
+
+/* We have to jump through hoops to get this correctly implemented. */
+#define HP_TIMING_ACCUM(Sum, Diff) \
+ do { \
+ hp_timing_t __oldval; \
+ hp_timing_t __diff = (Diff) - GLRO(dl_hp_timing_overhead); \
+ hp_timing_t __newval; \
+ do \
+ { \
+ __oldval = (Sum); \
+ __newval = __oldval + __diff; \
+ } \
+ while (! __sync_bool_compare_and_swap (&Sum, __oldvar, __newval)); \
+ } while (0)
+
+/* No threads, no extra work. */
+#define HP_TIMING_ACCUM_NT(Sum, Diff) (Sum) += (Diff)
+
+/* Print the time value. */
+#define HP_TIMING_PRINT(Buf, Len, Val) \
+ do { \
+ char __buf[20]; \
+ char *__cp = _itoa_word (Val, __buf + sizeof (__buf), 10, 0); \
+ int __len = (Len); \
+ char *__dest = (Buf); \
+ while (__len-- > 0 && __cp < __buf + sizeof (__buf)) \
+ *__dest++ = *__cp++; \
+ memcpy (__dest, " clock cycles", MIN (__len, \
+ (int) sizeof (" clock cycles"))); \
+ } while (0)
+
+#endif /* hp-timing.h */