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Merge pull request #176 from enh/cycle-timer-aarch64

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Add aarch64 support to src/cycleclock.h.
This commit is contained in:
Dominic Hamon 2016-02-13 13:05:16 -08:00
commit af489cd4a3
1 changed files with 8 additions and 0 deletions
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src/cycleclock.h
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@ -99,6 +99,14 @@ inline BENCHMARK_ALWAYS_INLINE int64_t Now() {
_asm rdtsc _asm rdtsc
#elif defined(COMPILER_MSVC) #elif defined(COMPILER_MSVC)
return __rdtsc(); return __rdtsc();
#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) #elif defined(__ARM_ARCH)
#if (__ARM_ARCH >= 6) // V6 is the earliest arch that has a standard cyclecount #if (__ARM_ARCH >= 6) // V6 is the earliest arch that has a standard cyclecount
uint32_t pmccntr; uint32_t pmccntr;