[ARM64] Initial commit for arm64 backend

Based entirely off existing xbyak x86 implementation and available
tests. Still needs a lot of optimization and testing on non-Windows
platforms.

So far passes all tests and boots at least some games on Windows.

src/xenia/cpu/backend/a64/a64_tracers.h

@@ -0,0 +1,77 @@
+/**
+ ******************************************************************************
+ * Xenia : Xbox 360 Emulator Research Project                                 *
+ ******************************************************************************
+ * Copyright 2026 Ben Vanik. All rights reserved.                             *
+ * Released under the BSD license - see LICENSE in the root for more details. *
+ ******************************************************************************
+ */
+
+#ifndef XENIA_CPU_BACKEND_A64_A64_TRACERS_H_
+#define XENIA_CPU_BACKEND_A64_A64_TRACERS_H_
+
+#include <cstdint>
+
+namespace xe {
+namespace cpu {
+namespace backend {
+namespace a64 {
+
+class A64Emitter;
+
+enum TracingMode {
+  TRACING_INSTR = (1 << 1),
+  TRACING_DATA = (1 << 2),
+};
+
+uint32_t GetTracingMode();
+inline bool IsTracingInstr() { return (GetTracingMode() & TRACING_INSTR) != 0; }
+inline bool IsTracingData() { return (GetTracingMode() & TRACING_DATA) != 0; }
+
+void TraceString(void* raw_context, const char* str);
+
+void TraceContextLoadI8(void* raw_context, uint64_t offset, uint8_t value);
+void TraceContextLoadI16(void* raw_context, uint64_t offset, uint16_t value);
+void TraceContextLoadI32(void* raw_context, uint64_t offset, uint32_t value);
+void TraceContextLoadI64(void* raw_context, uint64_t offset, uint64_t value);
+void TraceContextLoadF32(void* raw_context, uint64_t offset, float value);
+void TraceContextLoadF64(void* raw_context, uint64_t offset, double value);
+void TraceContextLoadV128(void* raw_context, uint64_t offset,
+                          const uint8_t* value);
+
+void TraceContextStoreI8(void* raw_context, uint64_t offset, uint8_t value);
+void TraceContextStoreI16(void* raw_context, uint64_t offset, uint16_t value);
+void TraceContextStoreI32(void* raw_context, uint64_t offset, uint32_t value);
+void TraceContextStoreI64(void* raw_context, uint64_t offset, uint64_t value);
+void TraceContextStoreF32(void* raw_context, uint64_t offset, float value);
+void TraceContextStoreF64(void* raw_context, uint64_t offset, double value);
+void TraceContextStoreV128(void* raw_context, uint64_t offset,
+                           const uint8_t* value);
+
+void TraceMemoryLoadI8(void* raw_context, uint32_t address, uint8_t value);
+void TraceMemoryLoadI16(void* raw_context, uint32_t address, uint16_t value);
+void TraceMemoryLoadI32(void* raw_context, uint32_t address, uint32_t value);
+void TraceMemoryLoadI64(void* raw_context, uint32_t address, uint64_t value);
+void TraceMemoryLoadF32(void* raw_context, uint32_t address, float value);
+void TraceMemoryLoadF64(void* raw_context, uint32_t address, double value);
+void TraceMemoryLoadV128(void* raw_context, uint32_t address,
+                         const uint8_t* value);
+
+void TraceMemoryStoreI8(void* raw_context, uint32_t address, uint8_t value);
+void TraceMemoryStoreI16(void* raw_context, uint32_t address, uint16_t value);
+void TraceMemoryStoreI32(void* raw_context, uint32_t address, uint32_t value);
+void TraceMemoryStoreI64(void* raw_context, uint32_t address, uint64_t value);
+void TraceMemoryStoreF32(void* raw_context, uint32_t address, float value);
+void TraceMemoryStoreF64(void* raw_context, uint32_t address, double value);
+void TraceMemoryStoreV128(void* raw_context, uint32_t address,
+                          const uint8_t* value);
+
+void TraceMemset(void* raw_context, uint32_t address, uint8_t value,
+                 uint32_t length);
+
+}  // namespace a64
+}  // namespace backend
+}  // namespace cpu
+}  // namespace xe
+
+#endif  // XENIA_CPU_BACKEND_A64_A64_TRACERS_H_