ports/sysdeps/ia64/hp-timing.h

   1 /* High precision, low overhead timing functions.  IA-64 version.
   2    Copyright (C) 2001-2014 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4    Contributed by Ulrich Drepper <drepper@cygnus.com>, 2001.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Lesser General Public
   8    License as published by the Free Software Foundation; either
   9    version 2.1 of the License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library; if not, see
  18    <http://www.gnu.org/licenses/>.  */
  19
  20 #ifndef _HP_TIMING_H
  21 #define _HP_TIMING_H    1
  22
  23 #include <string.h>
  24 #include <sys/param.h>
  25 #include <_itoa.h>
  26 #include <ia64intrin.h>
  27
  28 /* The macros defined here use the timestamp counter in IA-64.  They
  29    provide a very accurate way to measure the time with very little
  30    overhead.  The time values themself have no real meaning, only
  31    differences are interesting.
  32
  33    The list of macros we need includes the following:
  34
  35    - HP_TIMING_AVAIL: test for availability.
  36
  37    - HP_TIMING_INLINE: this macro is non-zero if the functionality is not
  38      implemented using function calls but instead uses some inlined code
  39      which might simply consist of a few assembler instructions.  We have to
  40      know this since we might want to use the macros here in places where we
  41      cannot make function calls.
  42
  43    - hp_timing_t: This is the type for variables used to store the time
  44      values.
  45
  46    - HP_TIMING_ZERO: clear `hp_timing_t' object.
  47
  48    - HP_TIMING_NOW: place timestamp for current time in variable given as
  49      parameter.
  50
  51    - HP_TIMING_DIFF_INIT: do whatever is necessary to be able to use the
  52      HP_TIMING_DIFF macro.
  53
  54    - HP_TIMING_DIFF: compute difference between two times and store it
  55      in a third.  Source and destination might overlap.
  56
  57    - HP_TIMING_ACCUM: add time difference to another variable.  This might
  58      be a bit more complicated to implement for some platforms as the
  59      operation should be thread-safe and 64bit arithmetic on 32bit platforms
  60      is not.
  61
  62    - HP_TIMING_ACCUM_NT: this is the variant for situations where we know
  63      there are no threads involved.
  64
  65    - HP_TIMING_PRINT: write decimal representation of the timing value into
  66      the given string.  This operation need not be inline even though
  67      HP_TIMING_INLINE is specified.
  68
  69 */
  70
  71 /* We always assume having the timestamp register.  */
  72 #define HP_TIMING_AVAIL         (1)
  73
  74 /* We indeed have inlined functions.  */
  75 #define HP_TIMING_INLINE        (1)
  76
  77 /* We use 64bit values for the times.  */
  78 typedef unsigned long int hp_timing_t;
  79
  80 /* Set timestamp value to zero.  */
  81 #define HP_TIMING_ZERO(Var)     (Var) = (0)
  82
  83
  84 /* The Itanium/Merced has a bug where the ar.itc register value read
  85    is not correct in some situations.  The solution is to read again.
  86    For now we always do this until we know how to recognize a fixed
  87    processor implementation.  */
  88 #define REPEAT_READ(val) __builtin_expect ((long int) val == -1, 0)
  89
  90 /* That's quite simple.  Use the `ar.itc' instruction.  */
  91 #define HP_TIMING_NOW(Var) \
  92   ({ unsigned long int __itc;                                                 \
  93      do                                                                       \
  94        asm volatile ("mov %0=ar.itc" : "=r" (__itc) : : "memory");            \
  95      while (REPEAT_READ (__itc));                                             \
  96      Var = __itc; })
  97
  98 /* Use two 'ar.itc' instructions in a row to find out how long it takes.  */
  99 #define HP_TIMING_DIFF_INIT() \
 100   do {                                                                        \
 101     int __cnt = 5;                                                            \
 102     GLRO(dl_hp_timing_overhead) = ~0ul;                                       \
 103     do                                                                        \
 104       {                                                                       \
 105         hp_timing_t __t1, __t2;                                               \
 106         HP_TIMING_NOW (__t1);                                                 \
 107         HP_TIMING_NOW (__t2);                                                 \
 108         if (__t2 - __t1 < GLRO(dl_hp_timing_overhead))                        \
 109           GLRO(dl_hp_timing_overhead) = __t2 - __t1;                          \
 110       }                                                                       \
 111     while (--__cnt > 0);                                                      \
 112   } while (0)
 113
 114 /* It's simple arithmetic for us.  */
 115 #define HP_TIMING_DIFF(Diff, Start, End)        (Diff) = ((End) - (Start))
 116
 117 /* We have to jump through hoops to get this correctly implemented.  */
 118 #define HP_TIMING_ACCUM(Sum, Diff) \
 119   do {                                                                        \
 120     hp_timing_t __oldval;                                                     \
 121     hp_timing_t __diff = (Diff) - GLRO(dl_hp_timing_overhead);                \
 122     hp_timing_t __newval;                                                     \
 123     do                                                                        \
 124       {                                                                       \
 125         __oldval = (Sum);                                                     \
 126         __newval = __oldval + __diff;                                         \
 127       }                                                                       \
 128     while (! __sync_bool_compare_and_swap (&Sum, __oldvar, __newval));        \
 129   } while (0)
 130
 131 /* No threads, no extra work.  */
 132 #define HP_TIMING_ACCUM_NT(Sum, Diff)   (Sum) += (Diff)
 133
 134 /* Print the time value.  */
 135 #define HP_TIMING_PRINT(Buf, Len, Val) \
 136   do {                                                                        \
 137     char __buf[20];                                                           \
 138     char *__cp = _itoa_word (Val, __buf + sizeof (__buf), 10, 0);             \
 139     int __len = (Len);                                                        \
 140     char *__dest = (Buf);                                                     \
 141     while (__len-- > 0 && __cp < __buf + sizeof (__buf))                      \
 142       *__dest++ = *__cp++;                                                    \
 143     memcpy (__dest, " clock cycles", MIN (__len,                              \
 144                                           (int) sizeof (" clock cycles")));   \
 145   } while (0)
 146
 147 #endif  /* hp-timing.h */