diff --git a/sapfor/experts/Sapfor_2017/_src/CFGraph/RD_subst.cpp b/sapfor/experts/Sapfor_2017/_src/CFGraph/RD_subst.cpp
index a99bf77..387b142 100644
--- a/sapfor/experts/Sapfor_2017/_src/CFGraph/RD_subst.cpp
+++ b/sapfor/experts/Sapfor_2017/_src/CFGraph/RD_subst.cpp
@@ -321,38 +321,6 @@ static bool getDependencies(SAPFOR::Argument* var, SAPFOR::Instruction* instr, c
     return true;
 }
 
-static bool ifVariableValid(SAPFOR::Argument* var, const set<pair<SAPFOR::Instruction*, SAPFOR::BasicBlock*>>& defs,
-                            SAPFOR::Argument* processed_var, const pair<SAPFOR::Instruction*, SAPFOR::BasicBlock*>& def_of_processed_var)
-{
-    const auto& BB_of_def_of_processed_var = def_of_processed_var.second;
-
-    if (defs.size() == 1)
-    {
-        const auto& def = *defs.begin();
-        if (def.second == BB_of_def_of_processed_var && def.first->getNumber() < def_of_processed_var.first->getNumber())
-            return true;
-    }
-
-    const auto& RD_In_BB_of_def_of_processed_var = BB_of_def_of_processed_var->getRD_In();
-    auto RD_of_var_from_BB_with_processed_var = RD_In_BB_of_def_of_processed_var.find(var);
-
-    if (RD_of_var_from_BB_with_processed_var != RD_In_BB_of_def_of_processed_var.end()
-        && RD_of_var_from_BB_with_processed_var->second.size() == defs.size())
-    {
-        for (const auto& def : defs)
-        {
-            int number_of_istruction_with_decl = def.first ? def.first->getNumber() : CFG_VAL::UNINIT;
-
-            if (RD_of_var_from_BB_with_processed_var->second.count(number_of_istruction_with_decl) == 0)
-                return false;
-        }
-
-        return true;
-    }
-
-    return false;
-}
-
 static const set<SAPFOR::Argument*>& func_affects(const FuncInfo* func, const vector<SAPFOR::BasicBlock*>& blocks)
 {
     static map<const FuncInfo*, set<SAPFOR::Argument*>> affects;
@@ -1150,7 +1118,7 @@ vector<SAPFOR::BasicBlock*> sortCfgNodes(const vector<SAPFOR::BasicBlock*>& bloc
         if (!nodes_added && processing_stack.size() != 0) {
             //there is some blocks in the stack but no one can be processed
             //this code should be unreachable
-#ifdef DEBUG_CHECKS
+#if DEBUG_CHECKS
             printInternalError(convertFileName(__FILE__).c_str(), __LINE__);
 #endif // DEBUG_CHECKS
             auto block = processing_stack.back();
@@ -1167,7 +1135,7 @@ vector<SAPFOR::BasicBlock*> sortCfgNodes(const vector<SAPFOR::BasicBlock*>& bloc
         }
     }
     
-#ifdef DEBUG_CHECKS
+#if DEBUG_CHECKS
     set<SAPFOR::BasicBlock*> verify_unique;
     verify_unique.insert(result.begin(), result.end());
 
@@ -1176,7 +1144,7 @@ vector<SAPFOR::BasicBlock*> sortCfgNodes(const vector<SAPFOR::BasicBlock*>& bloc
     verify_unique.clear();
 #endif // DEBUG_CHECKS
 
-#ifdef DEBUG_CHECKS
+#if DEBUG_CHECKS
     set<SAPFOR::BasicBlock*> all_blocks, res_blocks;
 
     all_blocks.insert(blocks.begin(), blocks.end());
@@ -1267,7 +1235,7 @@ bool isArgReaches(int decl_instr, SAPFOR::BasicBlock* decl_bb,
     if (RDs_for_arg.size() == 1)
     {
         const int rd = *RDs_for_arg.begin();
-        if (rd >= decl_bb->getInstructions().front()->getNumber() && rd <= decl_instr)
+        if (rd >= decl_bb->getInstructions().front()->getNumber() && rd < decl_instr)
             return true;
     }
 
@@ -1275,7 +1243,67 @@ bool isArgReaches(int decl_instr, SAPFOR::BasicBlock* decl_bb,
     if (arg_in_from_decl_it == decl_bb->getRD_In().end())
         return false;
 
-    return arg_in_from_decl_it->second == RDs_for_arg;
+    if(arg_in_from_decl_it->second != RDs_for_arg)
+        return false;
+
+    set<SAPFOR::BasicBlock*> reachable = { decl_bb };
+    set<int> banned_instructions;
+    for (int instr_def : arg_in_from_decl_it->second)
+        if (instr_def >= decl_instr || instr_def < decl_bb->getInstructions().front()->getNumber())
+            //try to find way [decl_bb] -> [dest_bb] with redefining of var (that means that var value from decl_bb could be overwrited)
+            banned_instructions.insert(instr_def);
+
+    set<SAPFOR::BasicBlock*> worklist = reachable, banned_blocks;
+    bool way_found = false;
+    while (worklist.size() != 0 && banned_instructions.size() != 0)
+    {
+        for (SAPFOR::BasicBlock* wl : worklist)
+        {
+            int start = wl->getInstructions().front()->getNumber(), end = wl->getInstructions().back()->getNumber();
+
+            for (auto banned_it = banned_instructions.begin(); banned_it != banned_instructions.end();)
+            {
+                if(start <= *banned_it && *banned_it <= end)
+                {
+                    banned_it = banned_instructions.erase(banned_it);
+                    banned_blocks.insert(wl);
+                }
+                else
+                {
+                    banned_it++;
+                }
+            }
+        }
+        
+        set<SAPFOR::BasicBlock*> to_insert;
+
+        for (auto b : worklist)
+            for (auto next : b->getNext())
+                if (reachable.insert(next).second)
+                    to_insert.insert(next);
+
+        worklist = to_insert;
+    }
+
+    reachable = banned_blocks;
+    worklist = reachable;
+    while (worklist.size() != 0 || banned_instructions.size() == 0)
+    {
+        if(worklist.find(dest_bb) != worklist.end())
+            return false;
+
+        set<SAPFOR::BasicBlock*> to_insert;
+
+        for (auto b : worklist)
+            for (auto next : b->getNext())
+                if(next != decl_bb)
+                    if (reachable.insert(next).second)
+                        to_insert.insert(next);
+
+        worklist = to_insert;
+    }
+
+    return true;
 }
 
 // return arg's definition if it really reaches dest_bb
@@ -1597,28 +1625,7 @@ void buildSubstitutions(const map<FuncInfo*, vector<SAPFOR::BasicBlock*>>& CFGra
 
                             for (SAPFOR::Argument* dep : dependencies_of_var->second)
                             {
-                                if (dep->getType() != CFG_ARG_TYPE::VAR)
-                                {
-                                    can_use = false;
-                                    break;
-                                }
-
-                                const auto& RD_In_of_curr_BB = cur_BB->getRD_In();
-                                auto dep_from_curr_RD_In = RD_In_of_curr_BB.find(dep);  
-
-                                if (dep_from_curr_RD_In == RD_In_of_curr_BB.end())
-                                {
-                                    can_use = false;
-                                    break;
-                                }
-
-                                const auto& RDs_for_dep = dep_from_curr_RD_In->second;
-
-                                set<pair<SAPFOR::Instruction*, SAPFOR::BasicBlock*>> defs_of_dep;
-                                for (int def_instruction_num : RDs_for_dep)
-                                    defs_of_dep.insert(getInstructionAndBlockByNumber(CFGraph_for_project, def_instruction_num));
-
-                                if (!ifVariableValid(dep, defs_of_dep, in_val.first, instr_and_bb))
+                                if (!isArgReaches(instr_num, instr_and_bb.second, dep, cur_BB))
                                 {
                                     can_use = false;
                                     break;