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Diffstat (limited to 'src/third_party/benchmark-1.3.0/benchmark/src/cycleclock.h')
| -rw-r--r-- | src/third_party/benchmark-1.3.0/benchmark/src/cycleclock.h | 177 |
1 files changed, 177 insertions, 0 deletions
diff --git a/src/third_party/benchmark-1.3.0/benchmark/src/cycleclock.h b/src/third_party/benchmark-1.3.0/benchmark/src/cycleclock.h new file mode 100644 index 00000000000..e8a5ae48862 --- /dev/null +++ b/src/third_party/benchmark-1.3.0/benchmark/src/cycleclock.h @@ -0,0 +1,177 @@ +// ---------------------------------------------------------------------- +// CycleClock +// A CycleClock tells you the current time in Cycles. The "time" +// is actually time since power-on. This is like time() but doesn't +// involve a system call and is much more precise. +// +// NOTE: Not all cpu/platform/kernel combinations guarantee that this +// clock increments at a constant rate or is synchronized across all logical +// cpus in a system. +// +// If you need the above guarantees, please consider using a different +// API. There are efforts to provide an interface which provides a millisecond +// granularity and implemented as a memory read. A memory read is generally +// cheaper than the CycleClock for many architectures. +// +// Also, in some out of order CPU implementations, the CycleClock is not +// serializing. So if you're trying to count at cycles granularity, your +// data might be inaccurate due to out of order instruction execution. +// ---------------------------------------------------------------------- + +#ifndef BENCHMARK_CYCLECLOCK_H_ +#define BENCHMARK_CYCLECLOCK_H_ + +#include <cstdint> + +#include "benchmark/benchmark.h" +#include "internal_macros.h" + +#if defined(BENCHMARK_OS_MACOSX) +#include <mach/mach_time.h> +#endif +// For MSVC, we want to use '_asm rdtsc' when possible (since it works +// with even ancient MSVC compilers), and when not possible the +// __rdtsc intrinsic, declared in <intrin.h>. Unfortunately, in some +// environments, <windows.h> and <intrin.h> have conflicting +// declarations of some other intrinsics, breaking compilation. +// Therefore, we simply declare __rdtsc ourselves. See also +// http://connect.microsoft.com/VisualStudio/feedback/details/262047 +#if defined(COMPILER_MSVC) && !defined(_M_IX86) +extern "C" uint64_t __rdtsc(); +#pragma intrinsic(__rdtsc) +#endif + +#ifndef BENCHMARK_OS_WINDOWS +#include <sys/time.h> +#include <time.h> +#endif + +#ifdef BENCHMARK_OS_EMSCRIPTEN +#include <emscripten.h> +#endif + +namespace benchmark { +// NOTE: only i386 and x86_64 have been well tested. +// PPC, sparc, alpha, and ia64 are based on +// http://peter.kuscsik.com/wordpress/?p=14 +// with modifications by m3b. See also +// https://setisvn.ssl.berkeley.edu/svn/lib/fftw-3.0.1/kernel/cycle.h +namespace cycleclock { +// This should return the number of cycles since power-on. Thread-safe. +inline BENCHMARK_ALWAYS_INLINE int64_t Now() { +#if defined(BENCHMARK_OS_MACOSX) + // this goes at the top because we need ALL Macs, regardless of + // architecture, to return the number of "mach time units" that + // have passed since startup. See sysinfo.cc where + // InitializeSystemInfo() sets the supposed cpu clock frequency of + // macs to the number of mach time units per second, not actual + // CPU clock frequency (which can change in the face of CPU + // frequency scaling). Also note that when the Mac sleeps, this + // counter pauses; it does not continue counting, nor does it + // reset to zero. + return mach_absolute_time(); +#elif defined(BENCHMARK_OS_EMSCRIPTEN) + // this goes above x86-specific code because old versions of Emscripten + // define __x86_64__, although they have nothing to do with it. + return static_cast<int64_t>(emscripten_get_now() * 1e+6); +#elif defined(__i386__) + int64_t ret; + __asm__ volatile("rdtsc" : "=A"(ret)); + return ret; +#elif defined(__x86_64__) || defined(__amd64__) + uint64_t low, high; + __asm__ volatile("rdtsc" : "=a"(low), "=d"(high)); + return (high << 32) | low; +#elif defined(__powerpc__) || defined(__ppc__) + // This returns a time-base, which is not always precisely a cycle-count. + int64_t tbl, tbu0, tbu1; + asm("mftbu %0" : "=r"(tbu0)); + asm("mftb %0" : "=r"(tbl)); + asm("mftbu %0" : "=r"(tbu1)); + tbl &= -static_cast<int64_t>(tbu0 == tbu1); + // high 32 bits in tbu1; low 32 bits in tbl (tbu0 is garbage) + return (tbu1 << 32) | tbl; +#elif defined(__sparc__) + int64_t tick; + asm(".byte 0x83, 0x41, 0x00, 0x00"); + asm("mov %%g1, %0" : "=r"(tick)); + return tick; +#elif defined(__ia64__) + int64_t itc; + asm("mov %0 = ar.itc" : "=r"(itc)); + return itc; +#elif defined(COMPILER_MSVC) && defined(_M_IX86) + // Older MSVC compilers (like 7.x) don't seem to support the + // __rdtsc intrinsic properly, so I prefer to use _asm instead + // when I know it will work. Otherwise, I'll use __rdtsc and hope + // the code is being compiled with a non-ancient compiler. + _asm rdtsc +#elif defined(COMPILER_MSVC) + return __rdtsc(); +#elif defined(BENCHMARK_OS_NACL) + // Native Client validator on x86/x86-64 allows RDTSC instructions, + // and this case is handled above. Native Client validator on ARM + // rejects MRC instructions (used in the ARM-specific sequence below), + // so we handle it here. Portable Native Client compiles to + // architecture-agnostic bytecode, which doesn't provide any + // cycle counter access mnemonics. + + // Native Client does not provide any API to access cycle counter. + // Use clock_gettime(CLOCK_MONOTONIC, ...) instead of gettimeofday + // because is provides nanosecond resolution (which is noticable at + // least for PNaCl modules running on x86 Mac & Linux). + // Initialize to always return 0 if clock_gettime fails. + struct timespec ts = { 0, 0 }; + clock_gettime(CLOCK_MONOTONIC, &ts); + return static_cast<int64_t>(ts.tv_sec) * 1000000000 + ts.tv_nsec; +#elif defined(__aarch64__) + // System timer of ARMv8 runs at a different frequency than the CPU's. + // The frequency is fixed, typically in the range 1-50MHz. It can be + // read at CNTFRQ special register. We assume the OS has set up + // the virtual timer properly. + int64_t virtual_timer_value; + asm volatile("mrs %0, cntvct_el0" : "=r"(virtual_timer_value)); + return virtual_timer_value; +#elif defined(__ARM_ARCH) + // V6 is the earliest arch that has a standard cyclecount + // Native Client validator doesn't allow MRC instructions. +#if (__ARM_ARCH >= 6) + uint32_t pmccntr; + uint32_t pmuseren; + uint32_t pmcntenset; + // Read the user mode perf monitor counter access permissions. + asm volatile("mrc p15, 0, %0, c9, c14, 0" : "=r"(pmuseren)); + if (pmuseren & 1) { // Allows reading perfmon counters for user mode code. + asm volatile("mrc p15, 0, %0, c9, c12, 1" : "=r"(pmcntenset)); + if (pmcntenset & 0x80000000ul) { // Is it counting? + asm volatile("mrc p15, 0, %0, c9, c13, 0" : "=r"(pmccntr)); + // The counter is set up to count every 64th cycle + return static_cast<int64_t>(pmccntr) * 64; // Should optimize to << 6 + } + } +#endif + struct timeval tv; + gettimeofday(&tv, nullptr); + return static_cast<int64_t>(tv.tv_sec) * 1000000 + tv.tv_usec; +#elif defined(__mips__) + // mips apparently only allows rdtsc for superusers, so we fall + // back to gettimeofday. It's possible clock_gettime would be better. + struct timeval tv; + gettimeofday(&tv, nullptr); + return static_cast<int64_t>(tv.tv_sec) * 1000000 + tv.tv_usec; +#elif defined(__s390__) + // MONGODB MODIFICATION: Return the CPU clock on s390x. + uint64_t tsc; + asm("\tstck\t%0\n" : "=Q" (tsc) : : "cc"); + return tsc; +#else +// The soft failover to a generic implementation is automatic only for ARM. +// For other platforms the developer is expected to make an attempt to create +// a fast implementation and use generic version if nothing better is available. +#error You need to define CycleTimer for your OS and CPU +#endif +} +} // end namespace cycleclock +} // end namespace benchmark + +#endif // BENCHMARK_CYCLECLOCK_H_ |