darwin: removed unused Platform_calculateNanosecondsPerMachTick function

darwin/Platform.c

@@ -148,14 +148,11 @@ const MeterClass* const Platform_meterTypes[] = {
    NULL
 };
 
-static double Platform_nanosecondsPerMachTick = 1.0;
-
 static double Platform_nanosecondsPerSchedulerTick = -1;
 
 static mach_port_t iokit_port; // the mach port used to initiate communication with IOKit
 
 bool Platform_init(void) {
-   Platform_nanosecondsPerMachTick = Platform_calculateNanosecondsPerMachTick();
 
    // Determine the number of scheduler clock ticks per second
    errno = 0;

darwin/PlatformHelpers.c

@@ -86,37 +86,3 @@ bool Platform_isRunningTranslated(void) {
    }
    return ret;
 }
-
-double Platform_calculateNanosecondsPerMachTick(void) {
-   // Check if we can determine the timebase used on this system.
-   // If the API is unavailable assume we get our timebase in nanoseconds.
-#ifndef HAVE_MACH_TIMEBASE_INFO
-   return 1.0;
-#else
-   mach_timebase_info_data_t info;
-
-   /* WORKAROUND for `mach_timebase_info` giving incorrect values on M1 under Rosetta 2.
-    *    rdar://FB9546856 https://openradar.appspot.com/radar?id=5055988478509056
-    *
-    *    We don't know exactly what feature/attribute of the M1 chip causes this mistake under Rosetta 2.
-    *    Until we have more Apple ARM chips to compare against, the best we can do is special-case
-    *    the "Apple M1" chip specifically when running under Rosetta 2.
-    */
-
-   bool isRunningUnderRosetta2 = Platform_isRunningTranslated();
-
-   // Kernel version 20.0.0 is macOS 11.0 (Big Sur)
-   bool isBuggedVersion = Platform_KernelVersionIsBetween((KernelVersion) {20, 0, 0}, (KernelVersion) {999, 999, 999});
-
-   if (isRunningUnderRosetta2 && isBuggedVersion) {
-      // In this case `mach_timebase_info` provides the wrong value, so we hard-code the correct factor,
-      // as determined from `mach_timebase_info` when the process running natively.
-      info = (mach_timebase_info_data_t) { .numer = 125, .denom = 3 };
-   } else {
-      // No workarounds needed, use the OS-provided value.
-      mach_timebase_info(&info);
-   }
-
-   return (double)info.numer / (double)info.denom;
-#endif
-}

darwin/PlatformHelpers.h

@@ -29,12 +29,8 @@ int Platform_CompareKernelVersion(KernelVersion v);
 // lowerBound <= currentVersion < upperBound
 bool Platform_KernelVersionIsBetween(KernelVersion lowerBound, KernelVersion upperBound);
 
-double Platform_calculateNanosecondsPerMachTick(void);
-
 void Platform_getCPUBrandString(char* cpuBrandString, size_t cpuBrandStringSize);
 
 bool Platform_isRunningTranslated(void);
 
-double Platform_calculateNanosecondsPerMachTick(void);
-
 #endif