DSP: Replace x64 JIT pointer with a pointer to an architecture-agnostic base

This adds a base class that is used to replace the concrete instance of
the x64 JIT pointer within DSPCore. This fully removes the direct use
(read: non-ifdefed) usage of x86-64-specifics within the main DSP code.

Said base can also be used for creating JITs for other architectures,
such as AArch64, etc.

Source/Core/Core/DSP/DSPCore.cpp

@@ -22,8 +22,7 @@
 #include "Core/DSP/DSPHost.h"
 #include "Core/DSP/Interpreter/DSPIntUtil.h"
 #include "Core/DSP/Interpreter/DSPInterpreter.h"
-#include "Core/DSP/Jit/x64/DSPEmitter.h"
-#include "Core/HW/DSP.h"
+#include "Core/DSP/Jit/DSPEmitterBase.h"
 
 namespace DSP
 {
@@ -31,7 +30,7 @@ SDSP g_dsp;
 DSPBreakpoints g_dsp_breakpoints;
 static State core_state = State::Stopped;
 bool g_init_hax = false;
-std::unique_ptr<JIT::x64::DSPEmitter> g_dsp_jit;
+std::unique_ptr<JIT::DSPEmitter> g_dsp_jit;
 std::unique_ptr<DSPCaptureLogger> g_dsp_cap;
 static Common::Event step_event;
 
@@ -172,7 +171,7 @@ bool DSPCore_Init(const DSPInitOptions& opts)
 
   // Initialize JIT, if necessary
   if (opts.core_type == DSPInitOptions::CoreType::JIT64)
-    g_dsp_jit = std::make_unique<JIT::x64::DSPEmitter>();
+    g_dsp_jit = JIT::CreateDSPEmitter();
 
   g_dsp_cap.reset(opts.capture_logger);
 

Source/Core/Core/DSP/DSPCore.h

@@ -20,11 +20,8 @@ class Accelerator;
 
 namespace JIT
 {
-namespace x64
-{
 class DSPEmitter;
 }
-}
 
 enum : u32
 {
@@ -317,7 +314,7 @@ struct SDSP
 extern SDSP g_dsp;
 extern DSPBreakpoints g_dsp_breakpoints;
 extern bool g_init_hax;
-extern std::unique_ptr<JIT::x64::DSPEmitter> g_dsp_jit;
+extern std::unique_ptr<JIT::DSPEmitter> g_dsp_jit;
 extern std::unique_ptr<DSPCaptureLogger> g_dsp_cap;
 
 struct DSPInitOptions

Source/Core/Core/DSP/Jit/DSPEmitterBase.cpp

@@ -0,0 +1,23 @@
+// Copyright 2018 Dolphin Emulator Project
+// Licensed under GPLv2+
+// Refer to the license.txt file included.
+
+#include "Core/DSP/Jit/DSPEmitterBase.h"
+
+#if defined(_M_X86) || defined(_M_X86_64)
+#include "Core/DSP/Jit/x64/DSPEmitter.h"
+#endif
+
+namespace DSP::JIT
+{
+DSPEmitter::~DSPEmitter() = default;
+
+std::unique_ptr<DSPEmitter> CreateDSPEmitter()
+{
+#if defined(_M_X86) || defined(_M_X86_64)
+  return std::make_unique<x64::DSPEmitter>();
+#else
+  return std::make_unique<DSPEmitterNull>();
+#endif
+}
+}  // namespace DSP::JIT

Source/Core/Core/DSP/Jit/DSPEmitterBase.h

@@ -0,0 +1,35 @@
+// Copyright 2018 Dolphin Emulator Project
+// Licensed under GPLv2+
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include <memory>
+
+#include "Common/CommonTypes.h"
+
+class PointerWrap;
+
+namespace DSP::JIT
+{
+class DSPEmitter
+{
+public:
+  virtual ~DSPEmitter();
+
+  virtual u16 RunCycles(u16 cycles) = 0;
+  virtual void ClearIRAM() = 0;
+
+  virtual void DoState(PointerWrap& p) = 0;
+};
+
+class DSPEmitterNull final : public DSPEmitter
+{
+public:
+  u16 RunCycles(u16) override { return 0; }
+  void ClearIRAM() override {}
+  void DoState(PointerWrap&) override {}
+};
+
+std::unique_ptr<DSPEmitter> CreateDSPEmitter();
+}  // namespace DSP::JIT

Source/Core/Core/DSP/Jit/x64/DSPEmitter.h

@@ -14,6 +14,7 @@
 #include "Common/x64Emitter.h"
 
 #include "Core/DSP/DSPCommon.h"
+#include "Core/DSP/Jit/DSPEmitterBase.h"
 #include "Core/DSP/Jit/x64/DSPJitRegCache.h"
 
 class PointerWrap;
@@ -24,7 +25,7 @@ enum class StackRegister;
 
 namespace JIT::x64
 {
-class DSPEmitter : public Gen::X64CodeBlock
+class DSPEmitter final : public JIT::DSPEmitter, public Gen::X64CodeBlock
 {
 public:
   using DSPCompiledCode = u32 (*)();
@@ -33,14 +34,13 @@ public:
   static constexpr size_t MAX_BLOCKS = 0x10000;
 
   DSPEmitter();
-  ~DSPEmitter();
+  ~DSPEmitter() override;
 
-  u16 RunCycles(u16 cycles);
-
-  void DoState(PointerWrap& p);
+  u16 RunCycles(u16 cycles) override;
+  void DoState(PointerWrap& p) override;
+  void ClearIRAM() override;
 
   void EmitInstruction(UDSPInstruction inst);
-  void ClearIRAM();
   void ClearIRAMandDSPJITCodespaceReset();
 
   void CompileDispatcher();