unused var

Signed-off-by: lizzie <lizzie@eden-emu.dev>

src/core/arm/nce/arm_nce.cpp

@@ -160,16 +160,34 @@ bool ArmNce::HandleGuestAlignmentFault(GuestContext* guest_ctx, void* raw_info,
 bool ArmNce::HandleGuestAccessFault(GuestContext* guest_ctx, void* raw_info, void* raw_context) {
     auto* info = static_cast<siginfo_t*>(raw_info);
 
-    // Try to handle an invalid access.
-    // TODO: handle accesses which split a page?
-    const Common::ProcessAddress addr =
-        (reinterpret_cast<u64>(info->si_addr) & ~Memory::YUZU_PAGEMASK);
     auto& memory = guest_ctx->parent->m_running_thread->GetOwnerProcess()->GetMemory();
-    if (memory.InvalidateNCE(addr, Memory::YUZU_PAGESIZE)) {
-        // We handled the access successfully and are returning to guest code.
-        return true;
-    }
 
+    // Try to handle an invalid access.
+    // This computes the addr for the (first) page corresponding to the access
+    auto const acc_size = 16; // Max architectural access size
+    // Please note accesses can be wider than 16-bytes on some(which?) cases
+    // but this should handle **most** of the fragant issues with cases like 128-bit vector
+    // load/stores or GPU writes.
+    auto const addr_c1 = Common::ProcessAddress(u64(info->si_addr) & ~Memory::YUZU_PAGEMASK);
+    if (!(acc_size > 1 && (addr_c1 & Memory::YUZU_PAGEMASK) + acc_size > Memory::YUZU_PAGESIZE)) {
+        if (memory.InvalidateNCE(addr_c1, Memory::YUZU_PAGESIZE))
+            return true;
+    } else {
+        // Corresponds to the 2nd page, this means the access is split between two pages
+        auto const addr_c2 = (addr_c1 & ~Memory::YUZU_PAGEMASK) + Memory::YUZU_PAGESIZE;
+        // Heres the stupid part, how the fuck do we decide if either the first
+        // or second pages should be the ones to propagate the fault?
+        if (memory.InvalidateNCE(addr_c1, Memory::YUZU_PAGESIZE))
+            return true;
+        // ... well my solution is stupid, but basically we just ignore the second page
+        // IS THIS A REASONABLE SOLUTION? Absolutely. If we were to cross page boundaries
+        // we would need to fetch our stuff from **somewhere**, by then it would
+        // likely be too late to handle the "invalidate case".
+        //
+        // Or simply put, the architecture might expect us to invalidate the unaligned access
+        // this should especially reflect on any game that had unaligned issues with JIT before.
+        memory.InvalidateNCE(addr_c2, Memory::YUZU_PAGESIZE);
+    }
     // We couldn't handle the access.
     return HandleFailedGuestFault(guest_ctx, raw_info, raw_context);
 }

src/dynarmic/src/dynarmic/backend/arm64/emit_arm64_a32.cpp

@@ -34,8 +34,7 @@ oaknut::Label EmitA32Cond(oaknut::CodeGenerator& code, EmitContext&, IR::Cond co
     return pass;
 }
 
-void EmitA32LeafTerminal(oaknut::CodeGenerator& code, EmitContext& ctx, IR::Term::LeafTerminal const& terminal, IR::LocationDescriptor initial_location, bool is_single_step);
-void EmitA32Terminal(oaknut::CodeGenerator& code, EmitContext& ctx, IR::Term::Terminal const& terminal, IR::LocationDescriptor initial_location, bool is_single_step);
+void EmitA32Terminal(oaknut::CodeGenerator& code, EmitContext& ctx, IR::Term::Terminal terminal, IR::LocationDescriptor initial_location, bool is_single_step);
 
 void EmitA32Terminal(oaknut::CodeGenerator& code, EmitContext& ctx, IR::Term::ReturnToDispatch, IR::LocationDescriptor, bool) {
     EmitRelocation(code, ctx, LinkTarget::ReturnToDispatcher);
@@ -126,53 +125,31 @@ void EmitA32Terminal(oaknut::CodeGenerator& code, EmitContext& ctx, IR::Term::Fa
 
 void EmitA32Terminal(oaknut::CodeGenerator& code, EmitContext& ctx, IR::Term::If terminal, IR::LocationDescriptor initial_location, bool is_single_step) {
     oaknut::Label pass = EmitA32Cond(code, ctx, terminal.if_);
-    EmitA32LeafTerminal(code, ctx, terminal.else_, initial_location, is_single_step);
+    EmitA32Terminal(code, ctx, terminal.else_, initial_location, is_single_step);
     code.l(pass);
-    EmitA32LeafTerminal(code, ctx, terminal.then_, initial_location, is_single_step);
+    EmitA32Terminal(code, ctx, terminal.then_, initial_location, is_single_step);
 }
 
 void EmitA32Terminal(oaknut::CodeGenerator& code, EmitContext& ctx, IR::Term::CheckBit terminal, IR::LocationDescriptor initial_location, bool is_single_step) {
     oaknut::Label fail;
     code.LDRB(Wscratch0, SP, offsetof(StackLayout, check_bit));
     code.CBZ(Wscratch0, fail);
-    EmitA32LeafTerminal(code, ctx, terminal.then_, initial_location, is_single_step);
+    EmitA32Terminal(code, ctx, terminal.then_, initial_location, is_single_step);
     code.l(fail);
-    EmitA32LeafTerminal(code, ctx, terminal.else_, initial_location, is_single_step);
+    EmitA32Terminal(code, ctx, terminal.else_, initial_location, is_single_step);
 }
 
 void EmitA32Terminal(oaknut::CodeGenerator& code, EmitContext& ctx, IR::Term::CheckHalt terminal, IR::LocationDescriptor initial_location, bool is_single_step) {
     oaknut::Label fail;
     code.LDAR(Wscratch0, Xhalt);
     code.CBNZ(Wscratch0, fail);
-    EmitA32LeafTerminal(code, ctx, terminal.else_, initial_location, is_single_step);
+    EmitA32Terminal(code, ctx, terminal.else_, initial_location, is_single_step);
     code.l(fail);
     EmitRelocation(code, ctx, LinkTarget::ReturnToDispatcher);
 }
 
-void EmitA32LeafTerminal(oaknut::CodeGenerator& code, EmitContext& ctx, IR::Term::LeafTerminal const& terminal, IR::LocationDescriptor initial_location, bool is_single_step) {
-    if (auto const x = std::get_if<IR::Term::ReturnToDispatch>(&terminal))
-        return EmitA32Terminal(code, ctx, *x, initial_location, is_single_step);
-    if (auto const x = std::get_if<IR::Term::LinkBlock>(&terminal))
-        return EmitA32Terminal(code, ctx, *x, initial_location, is_single_step);
-    if (auto const x = std::get_if<IR::Term::LinkBlockFast>(&terminal))
-        return EmitA32Terminal(code, ctx, *x, initial_location, is_single_step);
-    if (auto const x = std::get_if<IR::Term::PopRSBHint>(&terminal))
-        return EmitA32Terminal(code, ctx, *x, initial_location, is_single_step);
-    if (auto const x = std::get_if<IR::Term::FastDispatchHint>(&terminal))
-        return EmitA32Terminal(code, ctx, *x, initial_location, is_single_step);
-    UNREACHABLE();
-}
-
-void EmitA32Terminal(oaknut::CodeGenerator& code, EmitContext& ctx, IR::Term::Terminal const& terminal, IR::LocationDescriptor initial_location, bool is_single_step) {
-    if (auto const x = std::get_if<IR::Term::LeafTerminal>(&terminal))
-        return EmitA32LeafTerminal(code, ctx, *x, initial_location, is_single_step);
-    if (auto const x = std::get_if<IR::Term::If>(&terminal))
-        return EmitA32Terminal(code, ctx, *x, initial_location, is_single_step);
-    if (auto const x = std::get_if<IR::Term::CheckBit>(&terminal))
-        return EmitA32Terminal(code, ctx, *x, initial_location, is_single_step);
-    if (auto const x = std::get_if<IR::Term::CheckHalt>(&terminal))
-        return EmitA32Terminal(code, ctx, *x, initial_location, is_single_step);
-    UNREACHABLE();
+void EmitA32Terminal(oaknut::CodeGenerator& code, EmitContext& ctx, IR::Term::Terminal terminal, IR::LocationDescriptor initial_location, bool is_single_step) {
+    boost::apply_visitor([&](const auto& t) { EmitA32Terminal(code, ctx, t, initial_location, is_single_step); }, terminal);
 }
 
 void EmitA32Terminal(oaknut::CodeGenerator& code, EmitContext& ctx) {

src/dynarmic/src/dynarmic/backend/arm64/emit_arm64_a64.cpp

@@ -33,8 +33,7 @@ oaknut::Label EmitA64Cond(oaknut::CodeGenerator& code, EmitContext&, IR::Cond co
     return pass;
 }
 
-void EmitA64LeafTerminal(oaknut::CodeGenerator& code, EmitContext& ctx, IR::Term::LeafTerminal const& terminal, IR::LocationDescriptor initial_location, bool is_single_step);
-void EmitA64Terminal(oaknut::CodeGenerator& code, EmitContext& ctx, IR::Term::Terminal const& terminal, IR::LocationDescriptor initial_location, bool is_single_step);
+void EmitA64Terminal(oaknut::CodeGenerator& code, EmitContext& ctx, IR::Term::Terminal terminal, IR::LocationDescriptor initial_location, bool is_single_step);
 
 void EmitA64Terminal(oaknut::CodeGenerator& code, EmitContext& ctx, IR::Term::ReturnToDispatch, IR::LocationDescriptor, bool) {
     EmitRelocation(code, ctx, LinkTarget::ReturnToDispatcher);
@@ -109,53 +108,31 @@ void EmitA64Terminal(oaknut::CodeGenerator& code, EmitContext& ctx, IR::Term::Fa
 
 void EmitA64Terminal(oaknut::CodeGenerator& code, EmitContext& ctx, IR::Term::If terminal, IR::LocationDescriptor initial_location, bool is_single_step) {
     oaknut::Label pass = EmitA64Cond(code, ctx, terminal.if_);
-    EmitA64LeafTerminal(code, ctx, terminal.else_, initial_location, is_single_step);
+    EmitA64Terminal(code, ctx, terminal.else_, initial_location, is_single_step);
     code.l(pass);
-    EmitA64LeafTerminal(code, ctx, terminal.then_, initial_location, is_single_step);
+    EmitA64Terminal(code, ctx, terminal.then_, initial_location, is_single_step);
 }
 
 void EmitA64Terminal(oaknut::CodeGenerator& code, EmitContext& ctx, IR::Term::CheckBit terminal, IR::LocationDescriptor initial_location, bool is_single_step) {
     oaknut::Label fail;
     code.LDRB(Wscratch0, SP, offsetof(StackLayout, check_bit));
     code.CBZ(Wscratch0, fail);
-    EmitA64LeafTerminal(code, ctx, terminal.then_, initial_location, is_single_step);
+    EmitA64Terminal(code, ctx, terminal.then_, initial_location, is_single_step);
     code.l(fail);
-    EmitA64LeafTerminal(code, ctx, terminal.else_, initial_location, is_single_step);
+    EmitA64Terminal(code, ctx, terminal.else_, initial_location, is_single_step);
 }
 
 void EmitA64Terminal(oaknut::CodeGenerator& code, EmitContext& ctx, IR::Term::CheckHalt terminal, IR::LocationDescriptor initial_location, bool is_single_step) {
     oaknut::Label fail;
     code.LDAR(Wscratch0, Xhalt);
     code.CBNZ(Wscratch0, fail);
-    EmitA64LeafTerminal(code, ctx, terminal.else_, initial_location, is_single_step);
+    EmitA64Terminal(code, ctx, terminal.else_, initial_location, is_single_step);
     code.l(fail);
     EmitRelocation(code, ctx, LinkTarget::ReturnToDispatcher);
 }
 
-void EmitA64LeafTerminal(oaknut::CodeGenerator& code, EmitContext& ctx, IR::Term::LeafTerminal const& terminal, IR::LocationDescriptor initial_location, bool is_single_step) {
-    if (auto const x = std::get_if<IR::Term::ReturnToDispatch>(&terminal))
-        return EmitA64Terminal(code, ctx, *x, initial_location, is_single_step);
-    if (auto const x = std::get_if<IR::Term::LinkBlock>(&terminal))
-        return EmitA64Terminal(code, ctx, *x, initial_location, is_single_step);
-    if (auto const x = std::get_if<IR::Term::LinkBlockFast>(&terminal))
-        return EmitA64Terminal(code, ctx, *x, initial_location, is_single_step);
-    if (auto const x = std::get_if<IR::Term::PopRSBHint>(&terminal))
-        return EmitA64Terminal(code, ctx, *x, initial_location, is_single_step);
-    if (auto const x = std::get_if<IR::Term::FastDispatchHint>(&terminal))
-        return EmitA64Terminal(code, ctx, *x, initial_location, is_single_step);
-    UNREACHABLE();
-}
-
-void EmitA64Terminal(oaknut::CodeGenerator& code, EmitContext& ctx, IR::Term::Terminal const& terminal, IR::LocationDescriptor initial_location, bool is_single_step) {
-    if (auto const x = std::get_if<IR::Term::LeafTerminal>(&terminal))
-        return EmitA64LeafTerminal(code, ctx, *x, initial_location, is_single_step);
-    if (auto const x = std::get_if<IR::Term::If>(&terminal))
-        return EmitA64Terminal(code, ctx, *x, initial_location, is_single_step);
-    if (auto const x = std::get_if<IR::Term::CheckBit>(&terminal))
-        return EmitA64Terminal(code, ctx, *x, initial_location, is_single_step);
-    if (auto const x = std::get_if<IR::Term::CheckHalt>(&terminal))
-        return EmitA64Terminal(code, ctx, *x, initial_location, is_single_step);
-    UNREACHABLE();
+void EmitA64Terminal(oaknut::CodeGenerator& code, EmitContext& ctx, IR::Term::Terminal terminal, IR::LocationDescriptor initial_location, bool is_single_step) {
+    boost::apply_visitor([&](const auto& t) { EmitA64Terminal(code, ctx, t, initial_location, is_single_step); }, terminal);
 }
 
 void EmitA64Terminal(oaknut::CodeGenerator& code, EmitContext& ctx) {

src/dynarmic/src/dynarmic/backend/riscv64/emit_riscv64_a32.cpp

@@ -112,7 +112,6 @@ void EmitA32Cond(biscuit::Assembler& as, EmitContext&, IR::Cond cond, biscuit::L
     }
 }
 
-void EmitA32LeafTerminal(biscuit::Assembler& as, EmitContext& ctx, IR::Term::LeafTerminal terminal, IR::LocationDescriptor initial_location, bool is_single_step);
 void EmitA32Terminal(biscuit::Assembler& as, EmitContext& ctx, IR::Term::Terminal terminal, IR::LocationDescriptor initial_location, bool is_single_step);
 
 void EmitA32Terminal(biscuit::Assembler& as, EmitContext& ctx, IR::Term::ReturnToDispatch, IR::LocationDescriptor, bool) {
@@ -171,18 +170,18 @@ void EmitA32Terminal(biscuit::Assembler& as, EmitContext& ctx, IR::Term::FastDis
 void EmitA32Terminal(biscuit::Assembler& as, EmitContext& ctx, IR::Term::If terminal, IR::LocationDescriptor initial_location, bool is_single_step) {
     biscuit::Label pass;
     EmitA32Cond(as, ctx, terminal.if_, &pass);
-    EmitA32LeafTerminal(as, ctx, terminal.else_, initial_location, is_single_step);
+    EmitA32Terminal(as, ctx, terminal.else_, initial_location, is_single_step);
     as.Bind(&pass);
-    EmitA32LeafTerminal(as, ctx, terminal.then_, initial_location, is_single_step);
+    EmitA32Terminal(as, ctx, terminal.then_, initial_location, is_single_step);
 }
 
 void EmitA32Terminal(biscuit::Assembler& as, EmitContext& ctx, IR::Term::CheckBit terminal, IR::LocationDescriptor initial_location, bool is_single_step) {
     biscuit::Label fail;
     as.LBU(Xscratch0, offsetof(StackLayout, check_bit), Xstate);
     as.BEQZ(Xscratch0, &fail);
-    EmitA32LeafTerminal(as, ctx, terminal.then_, initial_location, is_single_step);
+    EmitA32Terminal(as, ctx, terminal.then_, initial_location, is_single_step);
     as.Bind(&fail);
-    EmitA32LeafTerminal(as, ctx, terminal.else_, initial_location, is_single_step);
+    EmitA32Terminal(as, ctx, terminal.else_, initial_location, is_single_step);
 }
 
 void EmitA32Terminal(biscuit::Assembler& as, EmitContext& ctx, IR::Term::CheckHalt terminal, IR::LocationDescriptor initial_location, bool is_single_step) {
@@ -190,35 +189,13 @@ void EmitA32Terminal(biscuit::Assembler& as, EmitContext& ctx, IR::Term::CheckHa
     as.LWU(Xscratch0, 0, Xhalt);
     as.FENCE(biscuit::FenceOrder::RW, biscuit::FenceOrder::RW);
     as.BNEZ(Xscratch0, &fail);
-    EmitA32LeafTerminal(as, ctx, terminal.else_, initial_location, is_single_step);
+    EmitA32Terminal(as, ctx, terminal.else_, initial_location, is_single_step);
     as.Bind(&fail);
     EmitRelocation(as, ctx, LinkTarget::ReturnFromRunCode);
 }
 
-void EmitA32LeafTerminal(biscuit::Assembler& as, EmitContext& ctx, IR::Term::LeafTerminal terminal, IR::LocationDescriptor initial_location, bool is_single_step) {
-    if (auto const x = std::get_if<IR::Term::ReturnToDispatch>(&terminal))
-        return EmitA32LeafTerminal(as, ctx, *x, initial_location, is_single_step);
-    if (auto const x = std::get_if<IR::Term::LinkBlock>(&terminal))
-        return EmitA32LeafTerminal(as, ctx, *x, initial_location, is_single_step);
-    if (auto const x = std::get_if<IR::Term::LinkBlockFast>(&terminal))
-        return EmitA32LeafTerminal(as, ctx, *x, initial_location, is_single_step);
-    if (auto const x = std::get_if<IR::Term::PopRSBHint>(&terminal))
-        return EmitA32LeafTerminal(as, ctx, *x, initial_location, is_single_step);
-    if (auto const x = std::get_if<IR::Term::FastDispatchHint>(&terminal))
-        return EmitA32LeafTerminal(as, ctx, *x, initial_location, is_single_step);
-    UNREACHABLE();
-}
-
 void EmitA32Terminal(biscuit::Assembler& as, EmitContext& ctx, IR::Term::Terminal terminal, IR::LocationDescriptor initial_location, bool is_single_step) {
-    if (auto const x = std::get_if<IR::Term::LeafTerminal>(&terminal))
-        return EmitA32LeafTerminal(as, ctx, *x, initial_location, is_single_step);
-    if (auto const x = std::get_if<IR::Term::If>(&terminal))
-        return EmitA32Terminal(as, ctx, *x, initial_location, is_single_step);
-    if (auto const x = std::get_if<IR::Term::CheckBit>(&terminal))
-        return EmitA32Terminal(as, ctx, *x, initial_location, is_single_step);
-    if (auto const x = std::get_if<IR::Term::CheckHalt>(&terminal))
-        return EmitA32Terminal(as, ctx, *x, initial_location, is_single_step);
-    UNREACHABLE();
+    boost::apply_visitor([&](const auto& t) { EmitA32Terminal(as, ctx, t, initial_location, is_single_step); }, terminal);
 }
 
 void EmitA32Terminal(biscuit::Assembler& as, EmitContext& ctx) {

src/dynarmic/src/dynarmic/backend/x64/a32_emit_x64.cpp

@@ -175,7 +175,7 @@ finish_this_inst:
     if (conf.enable_cycle_counting)
         EmitAddCycles(block.CycleCount());
     code.mov(rbp, code.qword[rsp + ABI_SHADOW_SPACE + offsetof(StackLayout, abi_base_pointer)]);
-    EmitTerminal(block.terminal, ctx.Location().SetSingleStepping(false), ctx.IsSingleStep());
+    EmitTerminal(block.GetTerminal(), ctx.Location().SetSingleStepping(false), ctx.IsSingleStep());
     code.int3();
 
     for (auto& deferred_emit : ctx.deferred_emits)
@@ -219,7 +219,7 @@ void A32EmitX64::EmitCondPrelude(const A32EmitContext& ctx) {
     if (conf.enable_cycle_counting) {
         EmitAddCycles(ctx.block.ConditionFailedCycleCount());
     }
-    EmitLeafTerminal(IR::Term::LinkBlock{ctx.block.ConditionFailedLocation()}, ctx.Location().SetSingleStepping(false), ctx.IsSingleStep());
+    EmitTerminal(IR::Term::LinkBlock{ctx.block.ConditionFailedLocation()}, ctx.Location().SetSingleStepping(false), ctx.IsSingleStep());
     code.L(pass);
 }
 
@@ -1155,12 +1155,11 @@ void A32EmitX64::EmitSetUpperLocationDescriptor(IR::LocationDescriptor new_locat
 }
 
 namespace {
-bool EmitTerminalImpl(A32EmitX64& e, IR::Term::ReturnToDispatch, IR::LocationDescriptor, bool) {
+void EmitTerminalImpl(A32EmitX64& e, IR::Term::ReturnToDispatch, IR::LocationDescriptor, bool) {
     e.code.ReturnFromRunCode();
-    return true;
 }
 
-bool EmitTerminalImpl(A32EmitX64& e, IR::Term::LinkBlock terminal, IR::LocationDescriptor initial_location, bool is_single_step) {
+void EmitTerminalImpl(A32EmitX64& e, IR::Term::LinkBlock terminal, IR::LocationDescriptor initial_location, bool is_single_step) {
     e.EmitSetUpperLocationDescriptor(terminal.next, initial_location);
     if (!e.conf.HasOptimization(OptimizationFlag::BlockLinking) || is_single_step) {
         e.code.mov(MJitStateReg(A32::Reg::PC), A32::LocationDescriptor{terminal.next}.PC());
@@ -1187,10 +1186,9 @@ bool EmitTerminalImpl(A32EmitX64& e, IR::Term::LinkBlock terminal, IR::LocationD
         e.PushRSBHelper(rax, rbx, terminal.next);
         e.code.ForceReturnFromRunCode();
     }
-    return true;
 }
 
-bool EmitTerminalImpl(A32EmitX64& e, IR::Term::LinkBlockFast terminal, IR::LocationDescriptor initial_location, bool is_single_step) {
+void EmitTerminalImpl(A32EmitX64& e, IR::Term::LinkBlockFast terminal, IR::LocationDescriptor initial_location, bool is_single_step) {
     e.EmitSetUpperLocationDescriptor(terminal.next, initial_location);
     if (!e.conf.HasOptimization(OptimizationFlag::BlockLinking) || is_single_step) {
         e.code.mov(MJitStateReg(A32::Reg::PC), A32::LocationDescriptor{terminal.next}.PC());
@@ -1203,78 +1201,55 @@ bool EmitTerminalImpl(A32EmitX64& e, IR::Term::LinkBlockFast terminal, IR::Locat
             e.EmitPatchJmp(terminal.next);
         }
     }
-    return true;
 }
 
-bool EmitTerminalImpl(A32EmitX64& e, IR::Term::PopRSBHint, IR::LocationDescriptor, bool is_single_step) {
+void EmitTerminalImpl(A32EmitX64& e, IR::Term::PopRSBHint, IR::LocationDescriptor, bool is_single_step) {
     if (!e.conf.HasOptimization(OptimizationFlag::ReturnStackBuffer) || is_single_step) {
         e.code.ReturnFromRunCode();
     } else {
         e.code.jmp(e.terminal_handler_pop_rsb_hint);
     }
-    return true;
 }
 
-bool EmitTerminalImpl(A32EmitX64& e, IR::Term::FastDispatchHint, IR::LocationDescriptor, bool is_single_step) {
+void EmitTerminalImpl(A32EmitX64& e, IR::Term::FastDispatchHint, IR::LocationDescriptor, bool is_single_step) {
     if (!e.conf.HasOptimization(OptimizationFlag::FastDispatch) || is_single_step) {
         e.code.ReturnFromRunCode();
     } else {
         e.code.jmp(e.terminal_handler_fast_dispatch_hint);
     }
-    return true;
 }
 
-bool EmitTerminalImpl(A32EmitX64& e, IR::Term::If terminal, IR::LocationDescriptor initial_location, bool is_single_step) {
+void EmitTerminalImpl(A32EmitX64& e, IR::Term::If terminal, IR::LocationDescriptor initial_location, bool is_single_step) {
     Xbyak::Label pass = e.EmitCond(terminal.if_);
-    e.EmitLeafTerminal(terminal.else_, initial_location, is_single_step);
+    e.EmitTerminal(terminal.else_, initial_location, is_single_step);
     e.code.L(pass);
-    e.EmitLeafTerminal(terminal.then_, initial_location, is_single_step);
-    return true;
+    e.EmitTerminal(terminal.then_, initial_location, is_single_step);
 }
 
-bool EmitTerminalImpl(A32EmitX64& e, IR::Term::CheckBit terminal, IR::LocationDescriptor initial_location, bool is_single_step) {
+void EmitTerminalImpl(A32EmitX64& e, IR::Term::CheckBit terminal, IR::LocationDescriptor initial_location, bool is_single_step) {
     Xbyak::Label fail;
     e.code.cmp(e.code.byte[rsp + ABI_SHADOW_SPACE + offsetof(StackLayout, check_bit)], u8(0));
     e.code.jz(fail);
-    e.EmitLeafTerminal(terminal.then_, initial_location, is_single_step);
+    e.EmitTerminal(terminal.then_, initial_location, is_single_step);
     e.code.L(fail);
-    e.EmitLeafTerminal(terminal.else_, initial_location, is_single_step);
-    return true;
+    e.EmitTerminal(terminal.else_, initial_location, is_single_step);
 }
 
-bool EmitTerminalImpl(A32EmitX64& e, IR::Term::CheckHalt terminal, IR::LocationDescriptor initial_location, bool is_single_step) {
+void EmitTerminalImpl(A32EmitX64& e, IR::Term::CheckHalt terminal, IR::LocationDescriptor initial_location, bool is_single_step) {
     e.code.cmp(dword[e.code.ABI_JIT_PTR + offsetof(A32JitState, halt_reason)], 0);
     e.code.jne(e.code.GetForceReturnFromRunCodeAddress());
-    e.EmitLeafTerminal(terminal.else_, initial_location, is_single_step);
-    return true;
+    e.EmitTerminal(terminal.else_, initial_location, is_single_step);
 }
 
-}
-
-bool A32EmitX64::EmitLeafTerminal(IR::Term::LeafTerminal const& terminal, IR::LocationDescriptor initial_location, bool is_single_step) noexcept {
-    if (auto const x = std::get_if<IR::Term::ReturnToDispatch>(&terminal))
-        return EmitTerminalImpl(*this, *x, initial_location, is_single_step);
-    if (auto const x = std::get_if<IR::Term::LinkBlock>(&terminal))
-        return EmitTerminalImpl(*this, *x, initial_location, is_single_step);
-    if (auto const x = std::get_if<IR::Term::LinkBlockFast>(&terminal))
-        return EmitTerminalImpl(*this, *x, initial_location, is_single_step);
-    if (auto const x = std::get_if<IR::Term::PopRSBHint>(&terminal))
-        return EmitTerminalImpl(*this, *x, initial_location, is_single_step);
-    if (auto const x = std::get_if<IR::Term::FastDispatchHint>(&terminal))
-        return EmitTerminalImpl(*this, *x, initial_location, is_single_step);
+void EmitTerminalImpl(A32EmitX64&, IR::Term::Invalid, IR::LocationDescriptor, bool) {
     UNREACHABLE();
 }
+}
 
-bool A32EmitX64::EmitTerminal(IR::Term::Terminal const& terminal, IR::LocationDescriptor initial_location, bool is_single_step) noexcept {
-    if (auto const e = std::get_if<IR::Term::LeafTerminal>(&terminal))
-        return EmitLeafTerminal(*e, initial_location, is_single_step);
-    if (auto const x = std::get_if<IR::Term::If>(&terminal))
-        return EmitTerminalImpl(*this, *x, initial_location, is_single_step);
-    if (auto const x = std::get_if<IR::Term::CheckBit>(&terminal))
-        return EmitTerminalImpl(*this, *x, initial_location, is_single_step);
-    if (auto const x = std::get_if<IR::Term::CheckHalt>(&terminal))
-        return EmitTerminalImpl(*this, *x, initial_location, is_single_step);
-    UNREACHABLE();
+void A32EmitX64::EmitTerminal(IR::Terminal terminal, IR::LocationDescriptor initial_location, bool is_single_step) noexcept {
+    boost::apply_visitor([this, initial_location, is_single_step](auto x) {
+        EmitTerminalImpl(*this, x, initial_location, is_single_step);
+    }, terminal);
 }
 
 void A32EmitX64::EmitPatchJg(const IR::LocationDescriptor& target_desc, CodePtr target_code_ptr) {

src/dynarmic/src/dynarmic/backend/x64/a32_emit_x64.h

@@ -112,8 +112,7 @@ public:
 
     // Terminal instruction emitters
     void EmitSetUpperLocationDescriptor(IR::LocationDescriptor new_location, IR::LocationDescriptor old_location);
-    bool EmitLeafTerminal(IR::Term::LeafTerminal const& terminal, IR::LocationDescriptor initial_location, bool is_single_step) noexcept override;
-    bool EmitTerminal(IR::Term::Terminal const& terminal, IR::LocationDescriptor initial_location, bool is_single_step) noexcept override;
+    void EmitTerminal(IR::Terminal terminal, IR::LocationDescriptor initial_location, bool is_single_step) noexcept override;
 
     // Patching
     void Unpatch(const IR::LocationDescriptor& target_desc) override;

src/dynarmic/src/dynarmic/backend/x64/a64_emit_x64.cpp

@@ -12,7 +12,6 @@
 #include <fmt/ostream.h>
 #include "common/assert.h"
 #include "common/common_types.h"
-#include "dynarmic/ir/terminal.h"
 #include "dynarmic/mcl/integer_of_size.hpp"
 #include <boost/container/static_vector.hpp>
 
@@ -148,7 +147,7 @@ finish_this_inst:
     if (conf.enable_cycle_counting)
         EmitAddCycles(block.CycleCount());
     code.mov(rbp, code.qword[rsp + ABI_SHADOW_SPACE + offsetof(StackLayout, abi_base_pointer)]);
-    EmitTerminal(block.terminal, ctx.Location().SetSingleStepping(false), ctx.IsSingleStep());
+    EmitTerminal(block.GetTerminal(), ctx.Location().SetSingleStepping(false), ctx.IsSingleStep());
     code.int3();
     for (auto& deferred_emit : ctx.deferred_emits)
         deferred_emit();
@@ -618,12 +617,11 @@ std::string A64EmitX64::LocationDescriptorToFriendlyName(const IR::LocationDescr
 }
 
 namespace {
-bool EmitTerminalImpl(A64EmitX64& e, IR::Term::ReturnToDispatch, IR::LocationDescriptor, bool) {
+void EmitTerminalImpl(A64EmitX64& e, IR::Term::ReturnToDispatch, IR::LocationDescriptor, bool) {
     e.code.ReturnFromRunCode();
-    return true;
 }
 
-bool EmitTerminalImpl(A64EmitX64& e, IR::Term::LinkBlock terminal, IR::LocationDescriptor, bool is_single_step) {
+void EmitTerminalImpl(A64EmitX64& e, IR::Term::LinkBlock terminal, IR::LocationDescriptor, bool is_single_step) {
     // Used for patches and linking
     if (e.conf.HasOptimization(OptimizationFlag::BlockLinking) && !is_single_step) {
         if (e.conf.enable_cycle_counting) {
@@ -651,10 +649,9 @@ bool EmitTerminalImpl(A64EmitX64& e, IR::Term::LinkBlock terminal, IR::LocationD
         e.code.mov(qword[e.code.ABI_JIT_PTR + offsetof(A64JitState, pc)], rax);
         e.code.ReturnFromRunCode();
     }
-    return true;
 }
 
-bool EmitTerminalImpl(A64EmitX64& e, IR::Term::LinkBlockFast terminal, IR::LocationDescriptor, bool is_single_step) {
+void EmitTerminalImpl(A64EmitX64& e, IR::Term::LinkBlockFast terminal, IR::LocationDescriptor, bool is_single_step) {
     if (e.conf.HasOptimization(OptimizationFlag::BlockLinking) && !is_single_step) {
         e.patch_information[terminal.next].jmp.push_back(e.code.getCurr());
         if (auto next_bb = e.GetBasicBlock(terminal.next)) {
@@ -667,86 +664,63 @@ bool EmitTerminalImpl(A64EmitX64& e, IR::Term::LinkBlockFast terminal, IR::Locat
         e.code.mov(qword[e.code.ABI_JIT_PTR + offsetof(A64JitState, pc)], rax);
         e.code.ReturnFromRunCode();
     }
-    return true;
 }
 
-bool EmitTerminalImpl(A64EmitX64& e, IR::Term::PopRSBHint, IR::LocationDescriptor, bool is_single_step) {
+void EmitTerminalImpl(A64EmitX64& e, IR::Term::PopRSBHint, IR::LocationDescriptor, bool is_single_step) {
     if (e.conf.HasOptimization(OptimizationFlag::ReturnStackBuffer) && !is_single_step) {
         e.code.jmp(e.terminal_handler_pop_rsb_hint);
     } else {
         e.code.ReturnFromRunCode();
     }
-    return true;
 }
 
-bool EmitTerminalImpl(A64EmitX64& e, IR::Term::FastDispatchHint, IR::LocationDescriptor, bool is_single_step) {
+void EmitTerminalImpl(A64EmitX64& e, IR::Term::FastDispatchHint, IR::LocationDescriptor, bool is_single_step) {
     if (!e.conf.HasOptimization(OptimizationFlag::FastDispatch) || is_single_step) {
         e.code.ReturnFromRunCode();
     } else {
         e.code.jmp(e.terminal_handler_fast_dispatch_hint);
     }
-    return true;
 }
 
-bool EmitTerminalImpl(A64EmitX64& e, IR::Term::If terminal, IR::LocationDescriptor initial_location, bool is_single_step) {
+void EmitTerminalImpl(A64EmitX64& e, IR::Term::If terminal, IR::LocationDescriptor initial_location, bool is_single_step) {
     switch (terminal.if_) {
     case IR::Cond::AL:
     case IR::Cond::NV:
-        e.EmitLeafTerminal(terminal.then_, initial_location, is_single_step);
+        e.EmitTerminal(terminal.then_, initial_location, is_single_step);
         break;
     default:
         Xbyak::Label pass = e.EmitCond(terminal.if_);
-        e.EmitLeafTerminal(terminal.else_, initial_location, is_single_step);
+        e.EmitTerminal(terminal.else_, initial_location, is_single_step);
         e.code.L(pass);
-        e.EmitLeafTerminal(terminal.then_, initial_location, is_single_step);
+        e.EmitTerminal(terminal.then_, initial_location, is_single_step);
         break;
     }
-    return true;
 }
 
-bool EmitTerminalImpl(A64EmitX64& e, IR::Term::CheckBit terminal, IR::LocationDescriptor initial_location, bool is_single_step) {
+void EmitTerminalImpl(A64EmitX64& e, IR::Term::CheckBit terminal, IR::LocationDescriptor initial_location, bool is_single_step) {
     Xbyak::Label fail;
     e.code.cmp(e.code.byte[rsp + ABI_SHADOW_SPACE + offsetof(StackLayout, check_bit)], u8(0));
     e.code.jz(fail);
-    e.EmitLeafTerminal(terminal.then_, initial_location, is_single_step);
+    e.EmitTerminal(terminal.then_, initial_location, is_single_step);
     e.code.L(fail);
-    e.EmitLeafTerminal(terminal.else_, initial_location, is_single_step);
-    return true;
+    e.EmitTerminal(terminal.else_, initial_location, is_single_step);
 }
 
-bool EmitTerminalImpl(A64EmitX64& e, IR::Term::CheckHalt terminal, IR::LocationDescriptor initial_location, bool is_single_step) {
+void EmitTerminalImpl(A64EmitX64& e, IR::Term::CheckHalt terminal, IR::LocationDescriptor initial_location, bool is_single_step) {
     e.code.cmp(dword[e.code.ABI_JIT_PTR + offsetof(A64JitState, halt_reason)], 0);
     e.code.jne(e.code.GetForceReturnFromRunCodeAddress());
-    e.EmitLeafTerminal(terminal.else_, initial_location, is_single_step);
-    return true;
+    e.EmitTerminal(terminal.else_, initial_location, is_single_step);
 }
 
-}
-
-bool A64EmitX64::EmitLeafTerminal(IR::Term::LeafTerminal const& terminal, IR::LocationDescriptor initial_location, bool is_single_step) noexcept {
-    if (auto const x = std::get_if<IR::Term::ReturnToDispatch>(&terminal))
-        return EmitTerminalImpl(*this, *x, initial_location, is_single_step);
-    if (auto const x = std::get_if<IR::Term::LinkBlock>(&terminal))
-        return EmitTerminalImpl(*this, *x, initial_location, is_single_step);
-    if (auto const x = std::get_if<IR::Term::LinkBlockFast>(&terminal))
-        return EmitTerminalImpl(*this, *x, initial_location, is_single_step);
-    if (auto const x = std::get_if<IR::Term::PopRSBHint>(&terminal))
-        return EmitTerminalImpl(*this, *x, initial_location, is_single_step);
-    if (auto const x = std::get_if<IR::Term::FastDispatchHint>(&terminal))
-        return EmitTerminalImpl(*this, *x, initial_location, is_single_step);
+void EmitTerminalImpl(A64EmitX64&, IR::Term::Invalid, IR::LocationDescriptor, bool) {
     UNREACHABLE();
 }
+}
 
-bool A64EmitX64::EmitTerminal(IR::Term::Terminal const& terminal, IR::LocationDescriptor initial_location, bool is_single_step) noexcept {
-    if (auto const x = std::get_if<IR::Term::LeafTerminal>(&terminal))
-        return EmitLeafTerminal(*x, initial_location, is_single_step);
-    if (auto const x = std::get_if<IR::Term::If>(&terminal))
-        return EmitTerminalImpl(*this, *x, initial_location, is_single_step);
-    if (auto const x = std::get_if<IR::Term::CheckBit>(&terminal))
-        return EmitTerminalImpl(*this, *x, initial_location, is_single_step);
-    if (auto const x = std::get_if<IR::Term::CheckHalt>(&terminal))
-        return EmitTerminalImpl(*this, *x, initial_location, is_single_step);
-    UNREACHABLE();
+void A64EmitX64::EmitTerminal(IR::Terminal terminal, IR::LocationDescriptor initial_location, bool is_single_step) noexcept {
+    boost::apply_visitor([this, initial_location, is_single_step](auto x) {
+        EmitTerminalImpl(*this, x, initial_location, is_single_step);
+    }, terminal);
 }
 
 void A64EmitX64::EmitPatchJg(const IR::LocationDescriptor& target_desc, CodePtr target_code_ptr) {

src/dynarmic/src/dynarmic/backend/x64/a64_emit_x64.h

@@ -107,8 +107,7 @@ public:
     void EmitExclusiveWriteMemoryInline(A64EmitContext& ctx, IR::Inst* inst);
 
     // Terminal instruction emitters
-    bool EmitLeafTerminal(IR::Term::LeafTerminal const& terminal, IR::LocationDescriptor initial_location, bool is_single_step) noexcept override;
-    bool EmitTerminal(IR::Term::Terminal const& terminal, IR::LocationDescriptor initial_location, bool is_single_step) noexcept override;
+    void EmitTerminal(IR::Terminal terminal, IR::LocationDescriptor initial_location, bool is_single_step) noexcept override;
 
     // Patching
     void Unpatch(const IR::LocationDescriptor& target_desc) override;

src/dynarmic/src/dynarmic/backend/x64/emit_x64.h

@@ -111,8 +111,7 @@ public:
 #ifndef NDEBUG
     void EmitVerboseDebuggingOutput(RegAlloc& reg_alloc);
 #endif
-    virtual bool EmitLeafTerminal(IR::Term::LeafTerminal const& terminal, IR::LocationDescriptor initial_location, bool is_single_step) noexcept = 0;
-    virtual bool EmitTerminal(IR::Term::Terminal const& terminal, IR::LocationDescriptor initial_location, bool is_single_step) noexcept = 0;
+    virtual void EmitTerminal(IR::Terminal terminal, IR::LocationDescriptor initial_location, bool is_single_step) noexcept = 0;
 
     // Patching
     struct PatchInformation {

src/dynarmic/src/dynarmic/ir/basic_block.cpp

@@ -66,44 +66,43 @@ void Block::Reset(LocationDescriptor location_) noexcept {
     location = location_;
     end_location = location_;
     cond = Cond::AL;
-    terminal = std::monostate{};
+    terminal = Term::Invalid{};
     cond_failed_cycle_count = 0;
     cycle_count = 0;
     ASSERT(instructions.size() == 0);
 }
 
-static std::string TerminalToString(const Term::Terminal& terminal_variant) noexcept {
-    // struct : boost::static_visitor<std::string> {
-    //     std::string operator()(const std::monostate&) const {
-    //         return "<invalid>";
-    //     }
-    //     std::string operator()(const Term::ReturnToDispatch&) const {
-    //         return "ReturnToDispatch{}";
-    //     }
-    //     std::string operator()(const Term::LinkBlock& terminal) const {
-    //         return fmt::format("LinkBlock{{{}}}", terminal.next);
-    //     }
-    //     std::string operator()(const Term::LinkBlockFast& terminal) const {
-    //         return fmt::format("LinkBlockFast{{{}}}", terminal.next);
-    //     }
-    //     std::string operator()(const Term::PopRSBHint&) const {
-    //         return "PopRSBHint{}";
-    //     }
-    //     std::string operator()(const Term::FastDispatchHint&) const {
-    //         return "FastDispatchHint{}";
-    //     }
-    //     std::string operator()(const Term::If& terminal) const {
-    //         return fmt::format("If{{{}, {}, {}}}", A64::CondToString(terminal.if_), TerminalToString(terminal.then_), TerminalToString(terminal.else_));
-    //     }
-    //     std::string operator()(const Term::CheckBit& terminal) const {
-    //         return fmt::format("CheckBit{{{}, {}}}", TerminalToString(terminal.then_), TerminalToString(terminal.else_));
-    //     }
-    //     std::string operator()(const Term::CheckHalt& terminal) const {
-    //         return fmt::format("CheckHalt{{{}}}", TerminalToString(terminal.else_));
-    //     }
-    // } visitor;
-    // return boost::apply_visitor(visitor, terminal_variant);
-    return "";
+static std::string TerminalToString(const Terminal& terminal_variant) noexcept {
+    struct : boost::static_visitor<std::string> {
+        std::string operator()(const Term::Invalid&) const {
+            return "<invalid terminal>";
+        }
+        std::string operator()(const Term::ReturnToDispatch&) const {
+            return "ReturnToDispatch{}";
+        }
+        std::string operator()(const Term::LinkBlock& terminal) const {
+            return fmt::format("LinkBlock{{{}}}", terminal.next);
+        }
+        std::string operator()(const Term::LinkBlockFast& terminal) const {
+            return fmt::format("LinkBlockFast{{{}}}", terminal.next);
+        }
+        std::string operator()(const Term::PopRSBHint&) const {
+            return "PopRSBHint{}";
+        }
+        std::string operator()(const Term::FastDispatchHint&) const {
+            return "FastDispatchHint{}";
+        }
+        std::string operator()(const Term::If& terminal) const {
+            return fmt::format("If{{{}, {}, {}}}", A64::CondToString(terminal.if_), TerminalToString(terminal.then_), TerminalToString(terminal.else_));
+        }
+        std::string operator()(const Term::CheckBit& terminal) const {
+            return fmt::format("CheckBit{{{}, {}}}", TerminalToString(terminal.then_), TerminalToString(terminal.else_));
+        }
+        std::string operator()(const Term::CheckHalt& terminal) const {
+            return fmt::format("CheckHalt{{{}}}", TerminalToString(terminal.else_));
+        }
+    } visitor;
+    return boost::apply_visitor(visitor, terminal_variant);
 }
 
 std::string DumpBlock(const IR::Block& block) noexcept {

src/dynarmic/src/dynarmic/ir/basic_block.h

@@ -114,22 +114,22 @@ public:
     }
 
     /// Gets the terminal instruction for this basic block.
-    inline Term::Terminal GetTerminal() const noexcept {
+    inline Terminal GetTerminal() const noexcept {
         return terminal;
     }
     /// Sets the terminal instruction for this basic block.
-    inline void SetTerminal(Term::Terminal term) noexcept {
+    inline void SetTerminal(Terminal term) noexcept {
         ASSERT(!HasTerminal() && "Terminal has already been set.");
         terminal = std::move(term);
     }
     /// Replaces the terminal instruction for this basic block.
-    inline void ReplaceTerminal(Term::Terminal term) noexcept {
+    inline void ReplaceTerminal(Terminal term) noexcept {
         ASSERT(HasTerminal() && "Terminal has not been set.");
         terminal = std::move(term);
     }
     /// Determines whether or not this basic block has a terminal instruction.
     inline bool HasTerminal() const noexcept {
-        return !std::holds_alternative<std::monostate>(terminal);
+        return terminal.which() != 0;
     }
 
     /// Gets a mutable reference to the cycle count for this basic block.
@@ -156,7 +156,7 @@ public:
     /// Conditional to pass in order to execute this block
     Cond cond = Cond::AL;
     /// Terminal instruction of this block.
-    Term::Terminal terminal = std::monostate{};
+    Terminal terminal = Term::Invalid{};
     /// Number of cycles this block takes to execute if the conditional fails.
     size_t cond_failed_cycle_count = 0;
     /// Number of cycles this block takes to execute.

src/dynarmic/src/dynarmic/ir/ir_emitter.h

@@ -2943,7 +2943,7 @@ public:
         Inst(Opcode::CallHostFunction, Imm64(std::bit_cast<u64>(fn)), arg1, arg2, arg3);
     }
 
-    void SetTerm(const Term::Terminal& terminal) {
+    void SetTerm(const Terminal& terminal) {
         block.SetTerminal(terminal);
     }
 

src/dynarmic/src/dynarmic/ir/terminal.h

@@ -8,7 +8,7 @@
 
 #pragma once
 
-#include <variant>
+#include <boost/variant.hpp>
 #include "common/common_types.h"
 
 #include "dynarmic/ir/cond.h"
@@ -17,89 +17,106 @@
 namespace Dynarmic::IR {
 namespace Term {
 
-/// This terminal instruction returns control to the dispatcher.
-/// The dispatcher will use the current cpu state to determine what comes next.
+struct Invalid {};
+
+/**
+ * This terminal instruction returns control to the dispatcher.
+ * The dispatcher will use the current cpu state to determine what comes next.
+ */
 struct ReturnToDispatch {};
 
-/// This terminal instruction jumps to the basic block described by `next` if we have enough
-/// cycles remaining. If we do not have enough cycles remaining, we return to the
-/// dispatcher, which will return control to the host.
+/**
+ * This terminal instruction jumps to the basic block described by `next` if we have enough
+ * cycles remaining. If we do not have enough cycles remaining, we return to the
+ * dispatcher, which will return control to the host.
+ */
 struct LinkBlock {
-    explicit LinkBlock(const LocationDescriptor& next_) : next(next_) {}
+    explicit LinkBlock(const LocationDescriptor& next_)
+            : next(next_) {}
     LocationDescriptor next;  ///< Location descriptor for next block.
 };
 
-/// This terminal instruction jumps to the basic block described by `next` unconditionally.
-/// This is an optimization and MUST only be emitted when this is guaranteed not to result
-/// in hanging, even in the face of other optimizations. (In practice, this means that only
-/// forward jumps to short-ish blocks would use this instruction.)
-/// A backend that doesn't support this optimization may choose to implement this exactly
-/// as LinkBlock.
+/**
+ * This terminal instruction jumps to the basic block described by `next` unconditionally.
+ * This is an optimization and MUST only be emitted when this is guaranteed not to result
+ * in hanging, even in the face of other optimizations. (In practice, this means that only
+ * forward jumps to short-ish blocks would use this instruction.)
+ * A backend that doesn't support this optimization may choose to implement this exactly
+ * as LinkBlock.
+ */
 struct LinkBlockFast {
-    explicit LinkBlockFast(const LocationDescriptor& next_) : next(next_) {}
+    explicit LinkBlockFast(const LocationDescriptor& next_)
+            : next(next_) {}
     LocationDescriptor next;  ///< Location descriptor for next block.
 };
 
-/// This terminal instruction checks the top of the Return Stack Buffer against the current
-/// location descriptor. If RSB lookup fails, control is returned to the dispatcher.
-/// This is an optimization for faster function calls. A backend that doesn't support
-/// this optimization or doesn't have a RSB may choose to implement this exactly as
-/// ReturnToDispatch.
+/**
+ * This terminal instruction checks the top of the Return Stack Buffer against the current
+ * location descriptor. If RSB lookup fails, control is returned to the dispatcher.
+ * This is an optimization for faster function calls. A backend that doesn't support
+ * this optimization or doesn't have a RSB may choose to implement this exactly as
+ * ReturnToDispatch.
+ */
 struct PopRSBHint {};
 
-/// This terminal instruction performs a lookup of the current location descriptor in the
-/// fast dispatch lookup table. A backend that doesn't support this optimization may choose
-/// to implement this exactly as ReturnToDispatch.
+/**
+ * This terminal instruction performs a lookup of the current location descriptor in the
+ * fast dispatch lookup table. A backend that doesn't support this optimization may choose
+ * to implement this exactly as ReturnToDispatch.
+ */
 struct FastDispatchHint {};
 
 struct If;
 struct CheckBit;
 struct CheckHalt;
-
-/// Non recursive kind of terminal
-using LeafTerminal = std::variant<
-    std::monostate,
+/// A Terminal is the terminal instruction in a MicroBlock.
+using Terminal = boost::variant<
+    Invalid,
     ReturnToDispatch,
     LinkBlock,
     LinkBlockFast,
     PopRSBHint,
-    FastDispatchHint
->;
+    FastDispatchHint,
+    boost::recursive_wrapper<If>,
+    boost::recursive_wrapper<CheckBit>,
+    boost::recursive_wrapper<CheckHalt>>;
 
-/// A Terminal is the terminal instruction in a MicroBlock.
-using Terminal = std::variant<
-    std::monostate,
-    LeafTerminal,
-    If,
-    CheckBit,
-    CheckHalt
->;
-
-/// This terminal instruction conditionally executes one terminal or another depending
-/// on the run-time state of the ARM flags.
+/**
+ * This terminal instruction conditionally executes one terminal or another depending
+ * on the run-time state of the ARM flags.
+ */
 struct If {
-    explicit If(Cond if_, LeafTerminal then_, LeafTerminal else_) : if_(if_), then_(std::move(then_)), else_(std::move(else_)) {}
+    If(Cond if_, Terminal then_, Terminal else_)
+            : if_(if_), then_(std::move(then_)), else_(std::move(else_)) {}
     Cond if_;
-    LeafTerminal then_;
-    LeafTerminal else_;
+    Terminal then_;
+    Terminal else_;
 };
 
-/// This terminal instruction conditionally executes one terminal or another depending
-/// on the run-time state of the check bit.
-/// then_ is executed if the check bit is non-zero, otherwise else_ is executed.
+/**
+ * This terminal instruction conditionally executes one terminal or another depending
+ * on the run-time state of the check bit.
+ * then_ is executed if the check bit is non-zero, otherwise else_ is executed.
+ */
 struct CheckBit {
-    explicit CheckBit(LeafTerminal then_, LeafTerminal else_) : then_(std::move(then_)), else_(std::move(else_)) {}
-    LeafTerminal then_;
-    LeafTerminal else_;
+    CheckBit(Terminal then_, Terminal else_)
+            : then_(std::move(then_)), else_(std::move(else_)) {}
+    Terminal then_;
+    Terminal else_;
 };
 
-/// This terminal instruction checks if a halt was requested. If it wasn't, else_ is
-/// executed.
+/**
+ * This terminal instruction checks if a halt was requested. If it wasn't, else_ is
+ * executed.
+ */
 struct CheckHalt {
-    explicit CheckHalt(LeafTerminal else_) : else_(std::move(else_)) {}
-    LeafTerminal else_;
+    explicit CheckHalt(Terminal else_)
+            : else_(std::move(else_)) {}
+    Terminal else_;
 };
 
 }  // namespace Term
 
+using Term::Terminal;
+
 }  // namespace Dynarmic::IR

src/dynarmic/tests/A32/fuzz_arm.cpp

@@ -43,20 +43,32 @@ namespace {
 using namespace Dynarmic;
 
 template<typename Fn>
-bool AnyLocationDescriptorForTerminalHas(IR::Term::Terminal terminal, Fn fn) {
-    if (auto const e = std::get_if<IR::Term::LeafTerminal>(&terminal)) {
-        if (auto const x = std::get_if<IR::Term::LinkBlock>(e))
-            return fn(x->next);
-        if (auto const x = std::get_if<IR::Term::LinkBlockFast>(e))
-            return fn(x->next);
-    }
-    if (auto const x = std::get_if<IR::Term::If>(&terminal))
-        return AnyLocationDescriptorForTerminalHas(x->then_, fn) || AnyLocationDescriptorForTerminalHas(x->else_, fn);
-    if (auto const x = std::get_if<IR::Term::CheckBit>(&terminal))
-        return AnyLocationDescriptorForTerminalHas(x->then_, fn) || AnyLocationDescriptorForTerminalHas(x->else_, fn);
-    if (auto const x = std::get_if<IR::Term::CheckHalt>(&terminal))
-        return AnyLocationDescriptorForTerminalHas(x->else_, fn);
-    return false;
+bool AnyLocationDescriptorForTerminalHas(IR::Terminal terminal, Fn fn) {
+    return boost::apply_visitor([&](auto t) -> bool {
+        using T = std::decay_t<decltype(t)>;
+        if constexpr (std::is_same_v<T, IR::Term::Invalid>) {
+            return false;
+        } else if constexpr (std::is_same_v<T, IR::Term::ReturnToDispatch>) {
+            return false;
+        } else if constexpr (std::is_same_v<T, IR::Term::LinkBlock>) {
+            return fn(t.next);
+        } else if constexpr (std::is_same_v<T, IR::Term::LinkBlockFast>) {
+            return fn(t.next);
+        } else if constexpr (std::is_same_v<T, IR::Term::PopRSBHint>) {
+            return false;
+        } else if constexpr (std::is_same_v<T, IR::Term::FastDispatchHint>) {
+            return false;
+        } else if constexpr (std::is_same_v<T, IR::Term::If>) {
+            return AnyLocationDescriptorForTerminalHas(t.then_, fn) || AnyLocationDescriptorForTerminalHas(t.else_, fn);
+        } else if constexpr (std::is_same_v<T, IR::Term::CheckBit>) {
+            return AnyLocationDescriptorForTerminalHas(t.then_, fn) || AnyLocationDescriptorForTerminalHas(t.else_, fn);
+        } else if constexpr (std::is_same_v<T, IR::Term::CheckHalt>) {
+            return AnyLocationDescriptorForTerminalHas(t.else_, fn);
+        } else {
+            ASSERT(false && "Invalid terminal type");
+            return false;
+        }
+    }, terminal);
 }
 
 bool ShouldTestInst(u32 instruction, u32 pc, bool is_thumb, bool is_last_inst, A32::ITState it_state = {}) {