A64: Add enable_optimizations configuration option

Allow library users to disable optimizations for debugging reasons.

include/dynarmic/A64/config.h

@@ -116,6 +116,14 @@ struct UserConfig {
     size_t processor_id = 0;
     ExclusiveMonitor* global_monitor = nullptr;
 
+    /// When set to false, this disables all optimizations than can't otherwise be disabled
+    /// by setting other configuration options. This includes:
+    /// - IR optimizations
+    /// - Block linking optimizations
+    /// - RSB optimizations
+    /// This is intended to be used for debugging.
+    bool enable_optimizations = true;
+
     /// When set to true, UserCallbacks::DataCacheOperationRaised will be called when any
     /// data cache instruction is executed. Notably DC ZVA will not implicitly do anything.
     /// When set to false, UserCallbacks::DataCacheOperationRaised will never be called.

src/backend/x64/a64_emit_x64.cpp

@@ -350,6 +350,14 @@ void A64EmitX64::GenTerminalHandlers() {
     }
 }
 
+void A64EmitX64::EmitPushRSB(EmitContext& ctx, IR::Inst* inst) {
+    if (!conf.enable_optimizations) {
+        return;
+    }
+
+    EmitX64::EmitPushRSB(ctx, inst);
+}
+
 void A64EmitX64::EmitA64SetCheckBit(A64EmitContext& ctx, IR::Inst* inst) {
     auto args = ctx.reg_alloc.GetArgumentInfo(inst);
     const Xbyak::Reg8 to_store = ctx.reg_alloc.UseGpr(args[0]).cvt8();
@@ -1156,6 +1164,13 @@ void A64EmitX64::EmitTerminalImpl(IR::Term::ReturnToDispatch, IR::LocationDescri
 }
 
 void A64EmitX64::EmitTerminalImpl(IR::Term::LinkBlock terminal, IR::LocationDescriptor) {
+    if (!conf.enable_optimizations) {
+        code.mov(rax, A64::LocationDescriptor{terminal.next}.PC());
+        code.mov(qword[r15 + offsetof(A64JitState, pc)], rax);
+        code.ReturnFromRunCode();
+        return;
+    }
+
     code.cmp(qword[r15 + offsetof(A64JitState, cycles_remaining)], 0);
 
     patch_information[terminal.next].jg.emplace_back(code.getCurr());
@@ -1170,6 +1185,13 @@ void A64EmitX64::EmitTerminalImpl(IR::Term::LinkBlock terminal, IR::LocationDesc
 }
 
 void A64EmitX64::EmitTerminalImpl(IR::Term::LinkBlockFast terminal, IR::LocationDescriptor) {
+    if (!conf.enable_optimizations) {
+        code.mov(rax, A64::LocationDescriptor{terminal.next}.PC());
+        code.mov(qword[r15 + offsetof(A64JitState, pc)], rax);
+        code.ReturnFromRunCode();
+        return;
+    }
+
     patch_information[terminal.next].jmp.emplace_back(code.getCurr());
     if (auto next_bb = GetBasicBlock(terminal.next)) {
         EmitPatchJmp(terminal.next, next_bb->entrypoint);
@@ -1179,6 +1201,11 @@ void A64EmitX64::EmitTerminalImpl(IR::Term::LinkBlockFast terminal, IR::Location
 }
 
 void A64EmitX64::EmitTerminalImpl(IR::Term::PopRSBHint, IR::LocationDescriptor) {
+    if (!conf.enable_optimizations) {
+        code.ReturnFromRunCode();
+        return;
+    }
+
     code.jmp(terminal_handler_pop_rsb_hint);
 }
 

src/backend/x64/a64_emit_x64.h

@@ -79,6 +79,7 @@ protected:
     void EmitExclusiveWrite(A64EmitContext& ctx, IR::Inst* inst, size_t bitsize);
 
     // Microinstruction emitters
+    void EmitPushRSB(EmitContext& ctx, IR::Inst* inst);
 #define OPCODE(...)
 #define A32OPC(...)
 #define A64OPC(name, type, ...) void EmitA64##name(A64EmitContext& ctx, IR::Inst* inst);

src/backend/x64/a64_interface.cpp

@@ -231,10 +231,12 @@ private:
         const auto get_code = [this](u64 vaddr) { return conf.callbacks->MemoryReadCode(vaddr); };
         IR::Block ir_block = A64::Translate(A64::LocationDescriptor{current_location}, get_code, {conf.define_unpredictable_behaviour});
         Optimization::A64CallbackConfigPass(ir_block, conf);
+        if (conf.enable_optimizations) {
             Optimization::A64GetSetElimination(ir_block);
             Optimization::ConstantPropagation(ir_block);
             Optimization::DeadCodeElimination(ir_block);
             Optimization::A64MergeInterpretBlocksPass(ir_block, conf.callbacks);
+        }
         // printf("%s\n", IR::DumpBlock(ir_block).c_str());
         Optimization::VerificationPass(ir_block);
         return emitter.Emit(ir_block).entrypoint;