Remove the replaced backend's interpreter-fallback glue

The yaps2 recompilers compile every EE opcode natively, so the
per-instruction interpreter fallback the previous arm64 backend relied
on is dead code: drop intExecuteOneInst (Interpreter.cpp/R5900.h) and
the AndroidEEOpHist fallback-opcode histogram. EEDiffVerify stays — its
per-op hooks are worth re-emitting from the new recompiler later.

Also hoist the Qt metatype declarations shared by moc'd headers into
QtMetaTypes.h: with the debugger sources now optional the autogen bucket
layout shifted, exposing a specialization-after-instantiation error when
moc_MainWindow preceded moc_QtHost in mocs_compilation.

pcsx2-qt/CMakeLists.txt

@@ -38,6 +38,7 @@ target_sources(pcsx2-qt PRIVATE
 	Translations.cpp
 	QtHost.cpp
 	QtHost.h
+	QtMetaTypes.h
 	QtKeyCodes.cpp
 	QtProgressCallback.cpp
 	QtProgressCallback.h

pcsx2-qt/MainWindow.h

@@ -36,6 +36,8 @@ namespace Achievements
 	enum class LoginRequestReason;
 }
 
+#include "QtMetaTypes.h"
+
 namespace GameList
 {
 	struct Entry;

pcsx2-qt/QtHost.h

@@ -38,12 +38,7 @@ namespace Achievements
 	enum class LoginRequestReason;
 }
 
-Q_DECLARE_METATYPE(std::shared_ptr<VMBootParameters>);
-Q_DECLARE_METATYPE(std::optional<bool>);
-Q_DECLARE_METATYPE(GSRendererType);
-Q_DECLARE_METATYPE(InputBindingKey);
-Q_DECLARE_METATYPE(CDVD_SourceType);
-Q_DECLARE_METATYPE(Achievements::LoginRequestReason);
+#include "QtMetaTypes.h"
 
 class EmuThread : public QThread
 {

pcsx2-qt/QtMetaTypes.h

@@ -0,0 +1,36 @@
+// SPDX-FileCopyrightText: 2002-2026 PCSX2 Dev Team
+// SPDX-License-Identifier: GPL-3.0+
+
+#pragma once
+
+// Q_DECLARE_METATYPE specializations shared by every moc'd header that mentions
+// these types in a signal/slot. They must appear in a common header (not just
+// QtHost.h): AUTOMOC compiles all moc_*.cpp files into one mocs_compilation.cpp
+// TU, and a moc that instantiates QMetaTypeId<T> before another header's
+// specialization is an "explicit specialization after instantiation" error —
+// which moc comes first depends on the autogen bucket layout, so it can flip
+// whenever the source list changes.
+
+#include <memory>
+#include <optional>
+
+#include <QtCore/QMetaType>
+
+#include "pcsx2/Config.h"
+#include "pcsx2/Input/InputManager.h"
+
+struct VMBootParameters;
+
+enum class CDVD_SourceType : uint8_t;
+
+namespace Achievements
+{
+	enum class LoginRequestReason;
+}
+
+Q_DECLARE_METATYPE(std::shared_ptr<VMBootParameters>);
+Q_DECLARE_METATYPE(std::optional<bool>);
+Q_DECLARE_METATYPE(GSRendererType);
+Q_DECLARE_METATYPE(InputBindingKey);
+Q_DECLARE_METATYPE(CDVD_SourceType);
+Q_DECLARE_METATYPE(Achievements::LoginRequestReason);

pcsx2/AndroidEEOpHist.h

@@ -1,29 +0,0 @@
-// SPDX-License-Identifier: GPL-3.0+
-#pragma once
-
-#include "common/Pcsx2Types.h"
-
-// Gated EE opcode histogram for diagnosing interpreter-fallback hotspots on the mac
-// ARM64 backend. Counts how often each opcode runs through the two fallback paths:
-//   - STEP   : block-terminating single-step (intExecuteOneInst) — the expensive one
-//   - INLINE : in-block interpreter call      (recEmitInterpInline)
-// Every ~8M recorded fallback ops the EE thread prints "@@ANDROID_EE_OPHIST@@" lines
-// listing the hottest primary opcodes + SPECIAL/REGIMM/COP2/MMI sub-ops, then resets.
-// EE-thread-only (no atomics). Default 0 = zero overhead; flip to 1 for a diag build.
-#ifndef ARMSX2_ANDROID_EE_OPHIST
-#define ARMSX2_ANDROID_EE_OPHIST 0
-#endif
-
-#if ARMSX2_ANDROID_EE_OPHIST
-namespace AndroidEEOpHist
-{
-	// path: 0 = STEP (single-step), 1 = INLINE (in-block interp).
-	void Record(int path, u32 op);
-	// Emit-time tally of natively-compiled trap ops (proves the trap codegen engaged).
-	void NoteTrapCompiled();
-}
-
-// Counting thunk emitted by recEmitInterpInline in place of the raw interp handler
-// when the histogram is on: records cpuRegs.code on the INLINE path, then dispatches.
-void recOphistInlineThunk();
-#endif

pcsx2/CMakeLists.txt

@@ -1183,7 +1183,6 @@ if(ANDROID)
 	list(APPEND pcsx2Headers
 		VU1Fingerprint.h
 		EEDiffVerify.h
-		AndroidEEOpHist.h
 		AndroidPerfBuckets.h
 		PS1DrvTrace.h)
 	# Oboe is the Android audio backend consumed by Host/OboeAudioStream.cpp.

pcsx2/Interpreter.cpp

@@ -307,38 +307,6 @@ void intDoBranch(u32 target)
 	}
 }
 
-// Interpret exactly one guest instruction at cpuRegs.pc using the interpreter,
-// then return. This is the recompiler's per-instruction fallback: the ARM64 EE
-// rec dispatcher calls it for opcodes it cannot yet compile (likely branches,
-// coprocessor ops, syscalls, traps, ...). It mirrors execI; for branch opcodes
-// the interpreter's own branch functions handle the delay slot and PC redirect.
-// We must flush the accrued cycle count here for EVERY op, branches included:
-// intDoBranch/_doBranch_shared gate their flush on Cpu == &intCpu, so in rec
-// context a taken branch flushes nothing — a guest poll loop made of just a
-// branch (e.g. Burnout's `BC0F .; nop` CPCOND0 wait) would freeze cpuRegs.cycle
-// and the pending event (DMAC completion) would never come due.
-// It must NOT do the interpreter's fastjmp exit (intJmpBuf is not
-// set up in rec context); the rec drives exits through its own event test.
-void intExecuteOneInst()
-{
-	const u32 thispc = cpuRegs.pc;
-	// Pre-increment PC: exception handlers and branch target math expect cpuRegs.pc
-	// to already point at the delay slot (matches execI).
-	cpuRegs.pc += 4;
-	cpuRegs.code = memRead32(thispc);
-
-	const OPCODE& opcode = GetCurrentInstruction();
-	cpuBlockCycles += opcode.cycles * (2 - ((cpuRegs.CP0.n.Config >> 18) & 0x1));
-
-	opcode.interpret();
-
-	// Unconditional: in rec context the interpreter's branch helpers skip their
-	// flush (intDoBranch is gated on Cpu == &intCpu), so this is the only place
-	// the accrued cycles reach cpuRegs.cycle. Always advances cycle by >= 1,
-	// guaranteeing forward progress for branch-only guest wait loops.
-	intUpdateCPUCycles();
-}
-
 void intSetBranch()
 {
 	branch2 = /*cpuRegs.branch =*/ 1;

pcsx2/R5900.h

@@ -323,7 +323,6 @@ void intDoBranch(u32 target);
 
 // Interpret a single instruction at cpuRegs.pc (recompiler per-opcode fallback).
 // See the implementation in Interpreter.cpp for the contract.
-void intExecuteOneInst();
 
 // modules loaded at hardcoded addresses by the kernel
 const u32 EEKERNEL_START	= 0;