Attempt to implement changes necessary for JIT on Apple Silicon

as described on https://developer.apple.com/documentation/apple-silicon/porting-just-in-time-compilers-to-apple-silicon

src/backend/A64/block_of_code.cpp

@@ -20,6 +20,10 @@
     #include <sys/mman.h>
 #endif
 
+#ifdef __APPLE__
+#include <pthread.h>
+#endif
+
 namespace Dynarmic::BackendA64 {
 
 const Arm64Gen::ARM64Reg BlockOfCode::ABI_RETURN  = Arm64Gen::ARM64Reg::X0;
@@ -86,12 +90,18 @@ void BlockOfCode::EnableWriting() {
 #ifdef DYNARMIC_ENABLE_NO_EXECUTE_SUPPORT
     ProtectMemory(GetCodePtr(), TOTAL_CODE_SIZE, false);
 #endif
+#ifdef __APPLE__
+    pthread_jit_write_protect_np(false);
+#endif
 }
 
 void BlockOfCode::DisableWriting() {
 #ifdef DYNARMIC_ENABLE_NO_EXECUTE_SUPPORT
     ProtectMemory(GetCodePtr(), TOTAL_CODE_SIZE, true);
 #endif
+#ifdef __APPLE__
+    pthread_jit_write_protect_np(true);
+#endif
 }
 
 void BlockOfCode::ClearCache() {

src/backend/A64/emitter/a64_emitter.cpp

@@ -8,6 +8,10 @@
 #include <cstring>
 #include <vector>
 
+#if defined(__APPLE__)
+#include <libkern/OSCacheControl.h>
+#endif
+
 #include "a64_emitter.h"
 #include "common/assert.h"
 #include "common/bit_util.h"
@@ -366,6 +370,8 @@ void ARM64XEmitter::FlushIcacheSection(const u8* start, const u8* end) {
     // Header file says this is equivalent to: sys_icache_invalidate(start, end -
     // start);
     sys_cache_control(kCacheFunctionPrepareForExecution, start, end - start);
+#elif defined(__APPLE__)
+    sys_icache_invalidate(const_cast<u8*>(start), end - start);
 #else
     // Don't rely on GCC's __clear_cache implementation, as it caches
     // icache/dcache cache line sizes, that can vary between cores on

src/backend/A64/emitter/code_block.h

@@ -56,8 +56,12 @@ public:
         total_region_size = size;
 #if defined(_WIN32)
         void* ptr = VirtualAlloc(nullptr, size, MEM_COMMIT, PAGE_EXECUTE_READWRITE);
+#else
+#if defined(__APPLE__)
+        void* ptr = mmap(nullptr, size, PROT_READ | PROT_WRITE | PROT_EXEC, MAP_ANON | MAP_PRIVATE | MAP_JIT, -1, 0);
 #else
         void* ptr = mmap(nullptr, size, PROT_READ | PROT_WRITE | PROT_EXEC, MAP_ANON | MAP_PRIVATE, -1, 0);
+#endif
 
         if (ptr == MAP_FAILED)
             ptr = nullptr;