third_party/tcmalloc/chromium/src/base/cycleclock.h

   1 // Copyright (c) 2004, Google Inc.
   2 // All rights reserved.
   3 //
   4 // Redistribution and use in source and binary forms, with or without
   5 // modification, are permitted provided that the following conditions are
   6 // met:
   7 //
   8 //     * Redistributions of source code must retain the above copyright
   9 // notice, this list of conditions and the following disclaimer.
  10 //     * Redistributions in binary form must reproduce the above
  11 // copyright notice, this list of conditions and the following disclaimer
  12 // in the documentation and/or other materials provided with the
  13 // distribution.
  14 //     * Neither the name of Google Inc. nor the names of its
  15 // contributors may be used to endorse or promote products derived from
  16 // this software without specific prior written permission.
  17 //
  18 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  19 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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  21 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  22 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  23 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  24 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  25 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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  27 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  28 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  29
  30 // ----------------------------------------------------------------------
  31 // CycleClock
  32 //    A CycleClock tells you the current time in Cycles.  The "time"
  33 //    is actually time since power-on.  This is like time() but doesn't
  34 //    involve a system call and is much more precise.
  35 //
  36 // NOTE: Not all cpu/platform/kernel combinations guarantee that this
  37 // clock increments at a constant rate or is synchronized across all logical
  38 // cpus in a system.
  39 //
  40 // Also, in some out of order CPU implementations, the CycleClock is not
  41 // serializing. So if you're trying to count at cycles granularity, your
  42 // data might be inaccurate due to out of order instruction execution.
  43 // ----------------------------------------------------------------------
  44
  45 #ifndef GOOGLE_BASE_CYCLECLOCK_H_
  46 #define GOOGLE_BASE_CYCLECLOCK_H_
  47
  48 #include "base/basictypes.h"   // make sure we get the def for int64
  49 #include "base/arm_instruction_set_select.h"
  50 // base/sysinfo.h is really big and we don't want to include it unless
  51 // it is necessary.
  52 #if defined(__arm__) || defined(__mips__)
  53 # include "base/sysinfo.h"
  54 #endif
  55 #if defined(__MACH__) && defined(__APPLE__)
  56 # include <mach/mach_time.h>
  57 #endif
  58 // For MSVC, we want to use '_asm rdtsc' when possible (since it works
  59 // with even ancient MSVC compilers), and when not possible the
  60 // __rdtsc intrinsic, declared in <intrin.h>.  Unfortunately, in some
  61 // environments, <windows.h> and <intrin.h> have conflicting
  62 // declarations of some other intrinsics, breaking compilation.
  63 // Therefore, we simply declare __rdtsc ourselves. See also
  64 // http://connect.microsoft.com/VisualStudio/feedback/details/262047
  65 #if defined(_MSC_VER) && !defined(_M_IX86)
  66 extern "C" uint64 __rdtsc();
  67 #pragma intrinsic(__rdtsc)
  68 #endif
  69 #if defined(ARMV3) || defined(__mips__)
  70 #ifdef HAVE_SYS_TIME_H
  71 #include <sys/time.h>
  72 #endif
  73 #endif
  74
  75 // NOTE: only i386 and x86_64 have been well tested.
  76 // PPC, sparc, alpha, and ia64 are based on
  77 //    http://peter.kuscsik.com/wordpress/?p=14
  78 // with modifications by m3b.  See also
  79 //    https://setisvn.ssl.berkeley.edu/svn/lib/fftw-3.0.1/kernel/cycle.h
  80 struct CycleClock {
  81   // This should return the number of cycles since power-on.  Thread-safe.
  82   static inline int64 Now() {
  83 #if defined(__MACH__) && defined(__APPLE__)
  84     // this goes at the top because we need ALL Macs, regardless of
  85     // architecture, to return the number of "mach time units" that
  86     // have passed since startup.  See sysinfo.cc where
  87     // InitializeSystemInfo() sets the supposed cpu clock frequency of
  88     // macs to the number of mach time units per second, not actual
  89     // CPU clock frequency (which can change in the face of CPU
  90     // frequency scaling).  Also note that when the Mac sleeps, this
  91     // counter pauses; it does not continue counting, nor does it
  92     // reset to zero.
  93     return mach_absolute_time();
  94 #elif defined(__i386__)
  95     int64 ret;
  96     __asm__ volatile ("rdtsc" : "=A" (ret) );
  97     return ret;
  98 #elif defined(__x86_64__) || defined(__amd64__)
  99     uint64 low, high;
 100     __asm__ volatile ("rdtsc" : "=a" (low), "=d" (high));
 101     return (high << 32) | low;
 102 #elif defined(__powerpc__) || defined(__ppc__)
 103     // This returns a time-base, which is not always precisely a cycle-count.
 104     int64 tbl, tbu0, tbu1;
 105     asm("mftbu %0" : "=r" (tbu0));
 106     asm("mftb  %0" : "=r" (tbl));
 107     asm("mftbu %0" : "=r" (tbu1));
 108     tbl &= -static_cast<int64>(tbu0 == tbu1);
 109     // high 32 bits in tbu1; low 32 bits in tbl  (tbu0 is garbage)
 110     return (tbu1 << 32) | tbl;
 111 #elif defined(__sparc__)
 112     int64 tick;
 113     asm(".byte 0x83, 0x41, 0x00, 0x00");
 114     asm("mov   %%g1, %0" : "=r" (tick));
 115     return tick;
 116 #elif defined(__ia64__)
 117     int64 itc;
 118     asm("mov %0 = ar.itc" : "=r" (itc));
 119     return itc;
 120 #elif defined(_MSC_VER) && defined(_M_IX86)
 121     // Older MSVC compilers (like 7.x) don't seem to support the
 122     // __rdtsc intrinsic properly, so I prefer to use _asm instead
 123     // when I know it will work.  Otherwise, I'll use __rdtsc and hope
 124     // the code is being compiled with a non-ancient compiler.
 125     _asm rdtsc
 126 #elif defined(_MSC_VER)
 127     return __rdtsc();
 128 #elif defined(ARMV3)
 129 #if defined(ARMV6)  // V6 is the earliest arch that has a standard cyclecount
 130     uint32 pmccntr;
 131     uint32 pmuseren;
 132     uint32 pmcntenset;
 133     // Read the user mode perf monitor counter access permissions.
 134     asm volatile ("mrc p15, 0, %0, c9, c14, 0" : "=r" (pmuseren));
 135     if (pmuseren & 1) {  // Allows reading perfmon counters for user mode code.
 136       asm volatile ("mrc p15, 0, %0, c9, c12, 1" : "=r" (pmcntenset));
 137       if (pmcntenset & 0x80000000ul) {  // Is it counting?
 138         asm volatile ("mrc p15, 0, %0, c9, c13, 0" : "=r" (pmccntr));
 139         // The counter is set up to count every 64th cycle
 140         return static_cast<int64>(pmccntr) * 64;  // Should optimize to << 6
 141       }
 142     }
 143 #endif
 144     struct timeval tv;
 145     gettimeofday(&tv, NULL);
 146     return static_cast<int64>((tv.tv_sec + tv.tv_usec * 0.000001)
 147                               * CyclesPerSecond());
 148 #elif defined(__mips__)
 149     // mips apparently only allows rdtsc for superusers, so we fall
 150     // back to gettimeofday.  It's possible clock_gettime would be better.
 151     struct timeval tv;
 152     gettimeofday(&tv, NULL);
 153     return static_cast<int64>((tv.tv_sec + tv.tv_usec * 0.000001)
 154                               * CyclesPerSecond());
 155 #else
 156 // The soft failover to a generic implementation is automatic only for ARM.
 157 // For other platforms the developer is expected to make an attempt to create
 158 // a fast implementation and use generic version if nothing better is available.
 159 #error You need to define CycleTimer for your O/S and CPU
 160 #endif
 161   }
 162 };
 163
 164
 165 #endif  // GOOGLE_BASE_CYCLECLOCK_H_