a64_get_set_elimination_pass: Simplify algorithm

src/ir_opt/a64_get_set_elimination_pass.cpp

@@ -17,8 +17,15 @@ namespace Dynarmic::Optimization {
 
 void A64GetSetElimination(IR::Block& block) {
     using Iterator = IR::Block::iterator;
+
+    enum TrackingType {
+        W, X,
+        S, D, Q,
+        SP, NZCV,
+    };
     struct RegisterInfo {
         IR::Value register_value;
+        TrackingType tracking_type;
         bool set_instruction_present = false;
         Iterator last_set_instruction;
     };
@@ -27,108 +34,101 @@ void A64GetSetElimination(IR::Block& block) {
     RegisterInfo sp_info;
     RegisterInfo nzcv_info;
 
-    const auto do_set = [&block](RegisterInfo& info, IR::Value value, Iterator set_inst) {
+    const auto do_set = [&block](RegisterInfo& info, IR::Value value, Iterator set_inst, TrackingType tracking_type) {
         if (info.set_instruction_present) {
             info.last_set_instruction->Invalidate();
             block.Instructions().erase(info.last_set_instruction);
         }
 
         info.register_value = value;
+        info.tracking_type = tracking_type;
         info.set_instruction_present = true;
         info.last_set_instruction = set_inst;
     };
 
-    const auto do_get = [&block](RegisterInfo& info, Iterator get_inst) {
+    const auto do_get = [&block](RegisterInfo& info, Iterator get_inst, TrackingType tracking_type) {
-        if (info.register_value.IsEmpty()) {
+        const auto do_nothing = [&] {
+            info = {};
             info.register_value = IR::Value(&*get_inst);
-            return;
+            info.tracking_type = tracking_type;
-        }
-
-        if (!info.set_instruction_present) {
-            static const std::vector<IR::Opcode> ordering {
-                IR::Opcode::A64GetW,
-                IR::Opcode::A64GetX,
-                IR::Opcode::A64GetS,
-                IR::Opcode::A64GetD,
-                IR::Opcode::A64GetQ,
         };
-            const auto source_order = std::find(ordering.begin(), ordering.end(), info.register_value.GetInst()->GetOpcode());
+
-            const auto dest_order = std::find(ordering.begin(), ordering.end(), get_inst->GetOpcode());
+        if (info.register_value.IsEmpty()) {
-            if (source_order < dest_order) {
+            do_nothing();
-                // Zero extension of the value is not appropriate in this case.
-                // Replace currently known value with the new value.
-                info.register_value = IR::Value(&*get_inst);
             return;
         }
-        }
 
-        if (get_inst->GetType() == info.register_value.GetType()) {
+        if (info.tracking_type == tracking_type) {
             get_inst->ReplaceUsesWith(info.register_value);
             return;
         }
 
-        const IR::Value replacement = [&]() -> IR::Value {
+        do_nothing();
-            IR::IREmitter ir{block};
+        return;
-            ir.SetInsertionPoint(get_inst);
-
-            const IR::UAny value_to_convert{info.register_value};
-            switch (get_inst->GetType()) {
-            case IR::Type::U8:
-                return ir.LeastSignificantByte(ir.ZeroExtendToWord(value_to_convert));
-            case IR::Type::U16:
-                return ir.LeastSignificantHalf(ir.ZeroExtendToWord(value_to_convert));
-            case IR::Type::U32:
-                return ir.ZeroExtendToWord(value_to_convert);
-            case IR::Type::U64:
-                return ir.ZeroExtendToLong(value_to_convert);
-            case IR::Type::U128:
-                return ir.ZeroExtendToQuad(value_to_convert);
-            default:
-                UNREACHABLE();
-                return {};
-            }
-        }();
-        get_inst->ReplaceUsesWith(replacement);
     };
 
     for (auto inst = block.begin(); inst != block.end(); ++inst) {
         switch (inst->GetOpcode()) {
-        case IR::Opcode::A64GetW:
+        case IR::Opcode::A64GetW: {
-        case IR::Opcode::A64GetX: {
             const size_t index = A64::RegNumber(inst->GetArg(0).GetA64RegRef());
-            do_get(reg_info.at(index), inst);
+            do_get(reg_info.at(index), inst, TrackingType::W);
+            break;
+        }
+        case IR::Opcode::A64GetX: {
+            const size_t index = A64::RegNumber(inst->GetArg(0).GetA64RegRef());
+            do_get(reg_info.at(index), inst, TrackingType::X);
+            break;
+        }
+        case IR::Opcode::A64GetS: {
+            const size_t index = A64::VecNumber(inst->GetArg(0).GetA64VecRef());
+            do_get(vec_info.at(index), inst, TrackingType::S);
+            break;
+        }
+        case IR::Opcode::A64GetD: {
+            const size_t index = A64::VecNumber(inst->GetArg(0).GetA64VecRef());
+            do_get(vec_info.at(index), inst, TrackingType::D);
             break;
         }
-        case IR::Opcode::A64GetS:
-        case IR::Opcode::A64GetD:
         case IR::Opcode::A64GetQ: {
             const size_t index = A64::VecNumber(inst->GetArg(0).GetA64VecRef());
-            do_get(vec_info.at(index), inst);
+            do_get(vec_info.at(index), inst, TrackingType::Q);
             break;
         }
         case IR::Opcode::A64GetSP: {
-            do_get(sp_info, inst);
+            do_get(sp_info, inst, TrackingType::SP);
+            break;
+        }
+        case IR::Opcode::A64SetW: {
+            const size_t index = A64::RegNumber(inst->GetArg(0).GetA64RegRef());
+            do_set(reg_info.at(index), inst->GetArg(1), inst, TrackingType::W);
             break;
         }
-        case IR::Opcode::A64SetW:
         case IR::Opcode::A64SetX: {
             const size_t index = A64::RegNumber(inst->GetArg(0).GetA64RegRef());
-            do_set(reg_info.at(index), inst->GetArg(1), inst);
+            do_set(reg_info.at(index), inst->GetArg(1), inst, TrackingType::X);
+            break;
+        }
+        case IR::Opcode::A64SetS: {
+            const size_t index = A64::VecNumber(inst->GetArg(0).GetA64VecRef());
+            do_set(vec_info.at(index), inst->GetArg(1), inst, TrackingType::S);
+            break;
+        }
+        case IR::Opcode::A64SetD: {
+            const size_t index = A64::VecNumber(inst->GetArg(0).GetA64VecRef());
+            do_set(vec_info.at(index), inst->GetArg(1), inst, TrackingType::D);
             break;
         }
-        case IR::Opcode::A64SetS:
-        case IR::Opcode::A64SetD:
         case IR::Opcode::A64SetQ: {
             const size_t index = A64::VecNumber(inst->GetArg(0).GetA64VecRef());
-            do_set(vec_info.at(index), inst->GetArg(1), inst);
+            do_set(vec_info.at(index), inst->GetArg(1), inst, TrackingType::Q);
             break;
         }
         case IR::Opcode::A64SetSP: {
-            do_set(sp_info, inst->GetArg(0), inst);
+            do_set(sp_info, inst->GetArg(0), inst, TrackingType::SP);
             break;
         }
         case IR::Opcode::A64SetNZCV: {
-            do_set(nzcv_info, inst->GetArg(0), inst);
+            do_set(nzcv_info, inst->GetArg(0), inst, TrackingType::NZCV);
             break;
         }
         default: {