User Config: Add option to specify wall clock CNTPCT.

include/dynarmic/A64/config.h

@@ -200,6 +200,10 @@ struct UserConfig {
     /// definite behaviour for some unpredictable instructions.
     bool define_unpredictable_behaviour = false;
 
+    /// This tells the translator a wall clock will be used, thus allowing it
+    /// to avoid writting certain unnecessary code only needed for cycle timers.
+    bool wall_clock_cntpct = false;
+
     /// This enables the fast dispatcher.
     bool enable_fast_dispatch = true;
 

src/backend/x64/a64_emit_x64.cpp

@@ -651,7 +651,9 @@ void A64EmitX64::EmitA64GetCNTFRQ(A64EmitContext& ctx, IR::Inst* inst) {
 
 void A64EmitX64::EmitA64GetCNTPCT(A64EmitContext& ctx, IR::Inst* inst) {
     ctx.reg_alloc.HostCall(inst);
-    code.UpdateTicks();
+    if (!conf.wall_clock_cntpct) {
+        code.UpdateTicks();
+    }
     Devirtualize<&A64::UserCallbacks::GetCNTPCT>(conf.callbacks).EmitCall(code);
 }
 

src/backend/x64/a64_interface.cpp

@@ -233,7 +233,8 @@ private:
 
         // JIT Compile
         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});
+        IR::Block ir_block = A64::Translate(A64::LocationDescriptor{current_location}, get_code,
+                                                {conf.define_unpredictable_behaviour, conf.wall_clock_cntpct});
         Optimization::A64CallbackConfigPass(ir_block, conf);
         if (conf.enable_optimizations) {
             Optimization::A64GetSetElimination(ir_block);

src/frontend/A64/translate/impl/system.cpp

@@ -120,7 +120,7 @@ bool TranslatorVisitor::MRS(Imm<1> o0, Imm<3> op1, Imm<4> CRn, Imm<4> CRm, Imm<3
         return true;
     case SystemRegisterEncoding::CNTPCT_EL0:
         // HACK: Ensure that this is the first instruction in the block it's emitted in, so the cycle count is most up-to-date.
-        if (!ir.block.empty()) {
+        if (!ir.block.empty() && !options.wall_clock_cntpct) {
             ir.block.CycleCount()--;
             ir.SetTerm(IR::Term::LinkBlock{*ir.current_location});
             return false;

src/frontend/A64/translate/translate.h

@@ -26,6 +26,10 @@ struct TranslationOptions {
     /// If this is true, we define some behaviour for some instructions.
     bool define_unpredictable_behaviour = false;
 
+    /// This tells the translator a wall clock will be used, thus allowing it
+    /// to avoid writting certain unnecessary code only needed for cycle timers.
+    bool wall_clock_cntpct = false;
+
     /// This changes what IR we emit when we translate a hint instruction.
     /// If this is false, we treat the instruction as a NOP.
     /// If this is true, we emit an ExceptionRaised instruction.