Fix getting cpu frequency on apple silicon

Author: Rye

indra/llcommon/llprocessor.cpp

@@ -628,6 +628,8 @@ class LLProcessorInfoWindowsImpl : public LLProcessorInfoImpl
 
 #elif LL_DARWIN
 
+#include <CoreFoundation/CoreFoundation.h>
+#include <IOKit/IOKitLib.h>
 #include <mach/machine.h>
 #include <sys/sysctl.h>
 
@@ -638,6 +640,43 @@ class LLProcessorInfoDarwinImpl : public LLProcessorInfoImpl
     {
         getCPUIDInfo();
         uint64_t frequency = getSysctlInt64("hw.cpufrequency");
+        if(frequency == 0)
+        {
+            CFMutableDictionaryRef arm_io_matching = IOServiceMatching("AppleARMIODevice");
+            io_iterator_t  iter;
+            kern_return_t ret = IOServiceGetMatchingServices(kIOMasterPortDefault, arm_io_matching, &iter);
+            if(ret == KERN_SUCCESS)
+            {
+                io_object_t obj;
+                while ((obj = IOIteratorNext(iter)))
+                {
+                    io_name_t obj_class;
+                    ret = IOObjectGetClass(obj, obj_class);
+                    if(ret == KERN_SUCCESS)
+                    {
+                        io_name_t obj_name;
+                        ret = IORegistryEntryGetName(obj, obj_name);
+                        if(ret == KERN_SUCCESS)
+                        {
+                            if (strncmp(obj_name, "pmgr", sizeof(obj_name)) == 0)
+                            {
+                                CFTypeRef cfData = IORegistryEntryCreateCFProperty(obj, CFSTR("voltage-states5-sram"), kCFAllocatorDefault, 0); // pcore frequency
+                                if(cfData)
+                                {
+                                    CFIndex size = CFDataGetLength((CFDataRef)cfData);
+                                    std::vector<U8> databuf(size);
+                                    CFDataGetBytes((CFDataRef)cfData, CFRangeMake(0, size), databuf.data());
+
+                                    frequency = 0x00000000FFFFFFFF & ((databuf[size-5] << 24) | (databuf[size-6] << 16) | (databuf[size-7] << 8) | (databuf[size-8]));
+                                    CFRelease(cfData);
+                                }
+                                break;
+                            }
+                        }
+                    }
+                }
+            }
+        }
         setInfo(eFrequency, (F64)frequency  / (F64)1000000);
     }