diff --git a/sapfor/experts/Sapfor_2017/_src/CFGraph/DataFlow/backward_data_flow.h b/sapfor/experts/Sapfor_2017/_src/CFGraph/DataFlow/backward_data_flow.h
index 7f81751..556af90 100644
--- a/sapfor/experts/Sapfor_2017/_src/CFGraph/DataFlow/backward_data_flow.h
+++ b/sapfor/experts/Sapfor_2017/_src/CFGraph/DataFlow/backward_data_flow.h
@@ -10,7 +10,8 @@
 #include "../IR.h"
 
 template <class NodeType>
-class BackwardDataFlowAnalysis : public DataFlowAnalysis<NodeType> {
+class BackwardDataFlowAnalysis : public DataFlowAnalysis<NodeType>
+{
     std::vector<SAPFOR::BasicBlock*> reorderSequence(const std::vector<SAPFOR::BasicBlock*>& blocks,
                                                      const std::set<SAPFOR::BasicBlock*> back_edge_sources);
 public:
diff --git a/sapfor/experts/Sapfor_2017/_src/CFGraph/DataFlow/data_flow.h b/sapfor/experts/Sapfor_2017/_src/CFGraph/DataFlow/data_flow.h
index 8067bd7..561d1b3 100644
--- a/sapfor/experts/Sapfor_2017/_src/CFGraph/DataFlow/data_flow.h
+++ b/sapfor/experts/Sapfor_2017/_src/CFGraph/DataFlow/data_flow.h
@@ -29,6 +29,7 @@ public:
     virtual bool addIn(const DataType& data) = 0;
     virtual bool addOut(const DataType& data) = 0;
 
+    virtual bool updateState() { return false; }
     virtual bool forwardData(const DataType& data) = 0;
 
     bool newerThan(const DataFlowAnalysisNode<DataType>* block) const { return out_cnt > block->in_cnt; }
diff --git a/sapfor/experts/Sapfor_2017/_src/CFGraph/DataFlow/data_flow_impl.h b/sapfor/experts/Sapfor_2017/_src/CFGraph/DataFlow/data_flow_impl.h
index 5e74e29..db33e73 100644
--- a/sapfor/experts/Sapfor_2017/_src/CFGraph/DataFlow/data_flow_impl.h
+++ b/sapfor/experts/Sapfor_2017/_src/CFGraph/DataFlow/data_flow_impl.h
@@ -27,6 +27,8 @@ template <class DataType>
 void DataFlowAnalysisNode<DataType>::doStep()
 {
     int in_max_cnt = CNT_NOTINIT, out_max_cnt = CNT_NOTINIT;
+    
+    bool uniq_change = updateState();
     for (auto next : prev_blocks)
     {
         if (in_cnt < next->out_cnt)
@@ -49,7 +51,7 @@ void DataFlowAnalysisNode<DataType>::doStep()
         }
     }
 
-    bool was_notinit = (out_cnt == CNT_NOTINIT);
+    uniq_change |= (out_cnt == CNT_NOTINIT);
 
     if (out_max_cnt != CNT_NOTINIT)
         out_cnt = out_max_cnt;
@@ -58,7 +60,7 @@ void DataFlowAnalysisNode<DataType>::doStep()
         in_cnt = in_max_cnt;
 
     // TODO: fix counter overflow
-    if (was_notinit)
+    if (uniq_change)
     {
         out_cnt++;
         in_cnt++;
@@ -68,7 +70,8 @@ void DataFlowAnalysisNode<DataType>::doStep()
 /* definitions for DataFlowAnalysis class */
 
 template <class NodeType>
-void DataFlowAnalysis<NodeType>::analyze() {
+void DataFlowAnalysis<NodeType>::analyze()
+{
     auto curr = 0;
     auto stop = nodes.size();
 
diff --git a/sapfor/experts/Sapfor_2017/_src/Transformations/dead_code.cpp b/sapfor/experts/Sapfor_2017/_src/Transformations/dead_code.cpp
index f7493d2..52f0458 100644
--- a/sapfor/experts/Sapfor_2017/_src/Transformations/dead_code.cpp
+++ b/sapfor/experts/Sapfor_2017/_src/Transformations/dead_code.cpp
@@ -14,6 +14,40 @@ using std::set;
 using std::remove_if;
 
 #define PRINT_USELESS_STATEMENTS 1
+#define DEBUG_IR 0
+
+// detect wich registers are used at more than one block
+// such registers should participate in live analysis to spread information about useful instructions
+// such registers appears at loops
+static void fillSharedRegs(const map<FuncInfo*, vector<SAPFOR::BasicBlock*>>& cfg, set<SAPFOR::Argument*>& shared_regs)
+{
+    map<SAPFOR::Argument*, SAPFOR::BasicBlock*> used_at;
+
+    for (const auto& byFunc : cfg)
+    {
+        for (const auto& byBlock : byFunc.second)
+        {
+            for (const auto& byIrBlock : byBlock->getInstructions())
+            {
+                auto instr = byIrBlock->getInstruction();
+
+                set<SAPFOR::Argument*> used = { instr->getResult(), instr->getArg1(), instr->getArg2() };
+                for (auto arg : used)
+                {
+                    if(arg && arg->getType() == SAPFOR::CFG_ARG_TYPE::REG)
+                    {
+                        auto it = used_at.find(arg);
+
+                        if (it == used_at.end())
+                            used_at[arg] = byBlock;
+                        else if(it->second != byBlock)
+                            shared_regs.insert(arg);
+                    }
+                }
+            }
+        }
+    }
+}
 
 static void updateUseDefForInstruction(SAPFOR::BasicBlock* block, SAPFOR::Instruction* instr,
                                        set<SAPFOR::Argument*>& use, set<SAPFOR::Argument*>& def,
@@ -39,7 +73,9 @@ static void updateUseDefForInstruction(SAPFOR::BasicBlock* block, SAPFOR::Instru
     {
         for (SAPFOR::Argument* r : res)
         {
-            if (use.find(r) != use.end() || r->getMemType() != SAPFOR::CFG_MEM_TYPE::LOCAL_)
+            if (use.find(r) != use.end() || 
+                r->getMemType() != SAPFOR::CFG_MEM_TYPE::LOCAL_ || 
+                !(r->getType() == SAPFOR::CFG_ARG_TYPE::VAR || r->getType() == SAPFOR::CFG_ARG_TYPE::REG))
             {
                 useful = true;
                 break;
@@ -88,8 +124,8 @@ static void updateUseDefForInstruction(SAPFOR::BasicBlock* block, SAPFOR::Instru
             use.insert(e);
             def.erase(e);
         }
-
-        insertIfVar(args.begin(), args.end(), usedByThisBlock);
+        
+        usedByThisBlock.insert(args.begin(), args.end());
     }
 
     if ((instr->getOperation() == SAPFOR::CFG_OP::F_CALL || instr->getOperation() == SAPFOR::CFG_OP::PARAM) && fName == "")
@@ -128,12 +164,13 @@ static void buildUseDef(SAPFOR::BasicBlock* block, set<SAPFOR::Argument*>& use,
         useful[i] = u;
     }
 
-    insertIfVar(use_with_regs.begin(), use_with_regs.end(), use);
-    insertIfVar(def_with_regs.begin(), def_with_regs.end(), def);
+    use.insert(use_with_regs.begin(), use_with_regs.end());
+    def.insert(def_with_regs.begin(), def_with_regs.end());
 }
 
 
-class DeadCodeAnalysisNode : public DataFlowAnalysisNode<map<SAPFOR::Argument*, vector<SAPFOR::BasicBlock*>>> {
+class DeadCodeAnalysisNode : public DataFlowAnalysisNode<map<SAPFOR::Argument*, vector<SAPFOR::BasicBlock*>>>
+{
 private:
     vector<bool> useful;
     bool useful_block = false;
@@ -142,6 +179,7 @@ private:
 
     vector<SAPFOR::Argument*>& formal_parameters;
     const map<string, FuncInfo*>& funcByName;
+    const set<SAPFOR::Argument*>& shared_regs;
 public:
     bool updateJumpStatus()
     {
@@ -196,30 +234,41 @@ public:
         return updated;
     }
 
-    map<SAPFOR::Argument*, vector<SAPFOR::BasicBlock*>> getIn() {
+    map<SAPFOR::Argument*, vector<SAPFOR::BasicBlock*>> getIn()
+    {
         return getBlock()->getLiveOut();
     }
 
-    map<SAPFOR::Argument*, vector<SAPFOR::BasicBlock*>> getOut() {
+    map<SAPFOR::Argument*, vector<SAPFOR::BasicBlock*>> getOut()
+    {
         return getBlock()->getLiveIn();
     }
 
-    bool addIn(const map<SAPFOR::Argument*, vector<SAPFOR::BasicBlock*>>& data) {
-        bool inserted = getBlock()->addLiveOut(data);
-
-        if (!useful_block)
-            inserted |= updateNextNotEmpty();
-
-        inserted |= updateJumpStatus();
-
-        return inserted;
+    bool addIn(const map<SAPFOR::Argument*, vector<SAPFOR::BasicBlock*>>& data)
+    {
+        return getBlock()->addLiveOut(data);
     }
 
-    bool addOut(const map<SAPFOR::Argument*, vector<SAPFOR::BasicBlock*>>& data) {
+    bool addOut(const map<SAPFOR::Argument*, vector<SAPFOR::BasicBlock*>>& data)
+    {
         return getBlock()->addLiveIn(data);
     }
 
-    bool forwardData(const map<SAPFOR::Argument*, vector<SAPFOR::BasicBlock*>>& data) {
+    bool updateState()
+    {
+        bool updated = false;
+
+        if (!useful_block)
+            updated |= updateNextNotEmpty();
+
+        updated |= updateJumpStatus();
+        updated |= this->forwardData({ });
+
+        return updated;
+    }
+
+    bool forwardData(const map<SAPFOR::Argument*, vector<SAPFOR::BasicBlock*>>& data)
+    {
         bool inserted = false;
         SAPFOR::BasicBlock* bb= getBlock();
 
@@ -235,30 +284,34 @@ public:
 
         for (SAPFOR::Argument* arg : use)
         {
-            bool this_block = usedByThisBlock.find(arg) != usedByThisBlock.end();
-
-            if (!this_block)
+            if(arg && (arg->getType() == SAPFOR::CFG_ARG_TYPE::VAR ||
+              (arg->getType() == SAPFOR::CFG_ARG_TYPE::REG && shared_regs.find(arg) != shared_regs.end())))
             {
-                auto data_it = data.find(arg);
+                bool this_block = usedByThisBlock.find(arg) != usedByThisBlock.end();
 
-                if (data_it == data.end())
-                    printInternalError(convertFileName(__FILE__).c_str(), __LINE__);
-
-                inserted |= bb->addLiveIn({ *data_it });
-            }
-            else
-            {
-                auto in_it = in.find(arg);
-                bool skip = false;
-                if (in_it != in.end())
+                if (!this_block)
                 {
-                    if (in_it->second.size() == 1 && *(in_it->second.begin()) == bb) 
-                        skip = true; // nothing to do, inserted = false
-                    else
-                        bb->removeLiveIn(arg);
+                    auto data_it = data.find(arg);
+
+                    if (data_it == data.end())
+                        printInternalError(convertFileName(__FILE__).c_str(), __LINE__);
+
+                    inserted |= bb->addLiveIn({ *data_it });
+                }
+                else
+                {
+                    auto in_it = in.find(arg);
+                    bool skip = false;
+                    if (in_it != in.end())
+                    {
+                        if (in_it->second.size() == 1 && *(in_it->second.begin()) == bb) 
+                            skip = true; // nothing to do, inserted = false
+                        else
+                            bb->removeLiveIn(arg);
+                    }
+                    if(!skip)
+                        inserted |= bb->addLiveIn({ { arg, { bb } } });
                 }
-                if(!skip)
-                    inserted |= bb->addLiveIn({ { arg, { bb } } });
             }
         }
 
@@ -291,38 +344,39 @@ public:
 
     DeadCodeAnalysisNode(SAPFOR::BasicBlock* block,
                          vector<SAPFOR::Argument*>& formal_parameters,
-                         const map<string, FuncInfo*>& funcByName)
+                         const map<string, FuncInfo*>& funcByName,
+                         const set<SAPFOR::Argument*>& shared_regs)
     :
         formal_parameters(formal_parameters),
-        funcByName(funcByName)
+        funcByName(funcByName),
+        shared_regs(shared_regs)
     {
         setBlock(block);
         useful.resize(block->getInstructions().size(), false);
-        set<SAPFOR::Argument*> use, def;
-        set<SAPFOR::Argument*> usedByThisBlock;
-
-        buildUseDef(getBlock(), use, def, this->formal_parameters, useful, usedByThisBlock, funcByName);
-        
-        for (SAPFOR::Argument* arg : use)
-            getBlock()->addLiveIn({ { arg, { getBlock() } } });
     }
     
     const vector<bool>& getResult() { return useful; }
 };
 
-class DeadCodeAnalysis : public BackwardDataFlowAnalysis<DeadCodeAnalysisNode> {
+class DeadCodeAnalysis : public BackwardDataFlowAnalysis<DeadCodeAnalysisNode>
+{
 protected:
     vector<SAPFOR::Argument*>& formal_parameters;
     const map<string, FuncInfo*>& funcByName;
+    const set<SAPFOR::Argument*>& shared_regs;
 
-    DeadCodeAnalysisNode* createNode(SAPFOR::BasicBlock* block) override {
-        return new DeadCodeAnalysisNode(block, formal_parameters, funcByName);
+    DeadCodeAnalysisNode* createNode(SAPFOR::BasicBlock* block) override
+    {
+        return new DeadCodeAnalysisNode(block, formal_parameters, funcByName, shared_regs);
     }
 public:
-    DeadCodeAnalysis(vector<SAPFOR::Argument*>& formal_parameters, const map<string, FuncInfo*>& funcByName)
+    DeadCodeAnalysis(vector<SAPFOR::Argument*>& formal_parameters, 
+                     const map<string, FuncInfo*>& funcByName,
+                     const set<SAPFOR::Argument*>& shared_regs)
     :
         formal_parameters(formal_parameters),
-        funcByName(funcByName)
+        funcByName(funcByName),
+        shared_regs(shared_regs)
     { }
 };
 
@@ -394,8 +448,10 @@ void removeDeadCode(SgStatement* func,
 
     cfg_pair.second.erase(remove_unreachable_it, cfg_pair.second.end());
 
+#if DEBUG_IR
+    dumpCFG({ cfg_pair }, false);
+#endif
     // detect useless code
-
     vector<SAPFOR::Argument*> func_parameters(cfg_pair.first->funcParams.countOfPars, NULL);
 
     map<string, FuncInfo*> funcByName;
@@ -403,8 +459,11 @@ void removeDeadCode(SgStatement* func,
     for (auto& byFile : allFuncs)
         for (auto byFunc : byFile.second)
             funcByName[byFunc->funcName] = byFunc;
+    
+    set<SAPFOR::Argument*> shared_regs;
+    fillSharedRegs({ cfg_pair }, shared_regs);
 
-    DeadCodeAnalysis analysis_object(func_parameters, funcByName);
+    DeadCodeAnalysis analysis_object(func_parameters, funcByName, shared_regs);
 
     analysis_object.fit(cfg_pair.second);
     analysis_object.analyze();
diff --git a/sapfor/experts/Sapfor_2017/_src/Utils/PassManager.h b/sapfor/experts/Sapfor_2017/_src/Utils/PassManager.h
index 0e07092..0f2e0fe 100644
--- a/sapfor/experts/Sapfor_2017/_src/Utils/PassManager.h
+++ b/sapfor/experts/Sapfor_2017/_src/Utils/PassManager.h
@@ -307,8 +307,8 @@ void InitPassesDependencies(map<passes, vector<passes>> &passDepsIn, set<passes>
 
     Pass(REMOVE_OMP_DIRS) <= Pass(REMOVE_OMP_DIRS_TRANSFORM);
 
-    Pass(CALL_GRAPH2) <= Pass(REMOVE_DEAD_CODE);
-    list({ REMOVE_DEAD_CODE, REVERT_SUBST_EXPR_RD, CONVERT_LOOP_TO_ASSIGN, RESTORE_LOOP_FROM_ASSIGN }) <= Pass(REMOVE_DEAD_CODE_AND_UNPARSE);
+    list({ CALL_GRAPH2, REVERT_SUBST_EXPR_RD }) <= Pass(REMOVE_DEAD_CODE);
+    list({ REMOVE_DEAD_CODE, CONVERT_LOOP_TO_ASSIGN, RESTORE_LOOP_FROM_ASSIGN }) <= Pass(REMOVE_DEAD_CODE_AND_UNPARSE);
 
     passesIgnoreStateDone.insert({ CREATE_PARALLEL_DIRS, INSERT_PARALLEL_DIRS, INSERT_SHADOW_DIRS, EXTRACT_PARALLEL_DIRS, 
                                    EXTRACT_SHADOW_DIRS, CREATE_REMOTES, UNPARSE_FILE, REMOVE_AND_CALC_SHADOW,