diff --git a/byterun/dune b/byterun/dune
index c3f6eae02..27fd457f0 100644
--- a/byterun/dune
+++ b/byterun/dune
@@ -9,6 +9,20 @@
   (:runtime ../runtime/runtime.a))
  (mode
   (promote (until-clean)))
+ (action
+  (run g++ -std=c++20 -DWITH_CHECK -Iinclude/ %{main} %{parser} %{analyzer} %{runtime} %{obj} -o %{target})))
+
+(rule
+ (target old_byterun.exe)
+ (deps
+  (:include (source_tree include))
+  (:main src/cli.cpp)
+  (:parser src/parser.cpp)
+  (:analyzer src/analyzer.cpp)
+  (:obj old_types.o old_parser.o old_interpreter.o)
+  (:runtime ../runtime/runtime.a))
+ (mode
+  (promote (until-clean)))
  (action
   (run g++ -std=c++20 -Iinclude/ %{main} %{parser} %{analyzer} %{runtime} %{obj} -o %{target})))
 
@@ -21,7 +35,7 @@
  (mode
   (promote (until-clean)))
  (action
-  (run gcc -Iinclude/ -c %{src} -o %{target})))
+  (run gcc -Iinclude/ -DWITH_CHECK -c %{src} -o %{target})))
 
 (rule
  (target parser.o)
@@ -32,10 +46,43 @@
  (mode
   (promote (until-clean)))
  (action
-  (run gcc -Iinclude/ -c %{src} -o %{target})))
+  (run gcc -Iinclude/ -DWITH_CHECK -c %{src} -o %{target})))
 
 (rule
  (target interpreter.o)
+ (deps
+  (:include (source_tree include))
+  (:src src/interpreter.c)
+  (:runtime ../runtime/runtime.a))
+ (mode
+  (promote (until-clean)))
+ (action
+  (run gcc -Iinclude/ -DWITH_CHECK -c %{src} -o %{target})))
+
+(rule
+ (target old_types.o)
+ (deps
+  (:include (source_tree include))
+  (:src src/types.c)
+  (:runtime ../runtime/runtime.a))
+ (mode
+  (promote (until-clean)))
+ (action
+  (run gcc -Iinclude/ -c %{src} -o %{target})))
+
+(rule
+ (target old_parser.o)
+ (deps
+  (:include (source_tree include))
+  (:src src/parser.c)
+  (:runtime ../runtime/runtime.a))
+ (mode
+  (promote (until-clean)))
+ (action
+  (run gcc -Iinclude/ -c %{src} -o %{target})))
+
+(rule
+ (target old_interpreter.o)
  (deps
   (:include (source_tree include))
   (:src src/interpreter.c)
diff --git a/byterun/include/parser.hpp b/byterun/include/parser.hpp
index f8288ef07..db1c7d7d2 100644
--- a/byterun/include/parser.hpp
+++ b/byterun/include/parser.hpp
@@ -70,3 +70,5 @@ static inline const char *ip_read_string(char **ip, const Bytefile &bf) {
 std::pair<Cmd, uint8_t> parse_command(char **ip, const Bytefile &bf);
 std::pair<Cmd, uint8_t> parse_command(char **ip, const Bytefile &bf,
                                       std::ostream &out);
+
+void print_file(const Bytefile &bf, std::ostream &out);
diff --git a/byterun/include/stack.h b/byterun/include/stack.h
index b7f616683..e865a6d16 100644
--- a/byterun/include/stack.h
+++ b/byterun/include/stack.h
@@ -24,23 +24,27 @@ static inline bool s_is_empty() {
 }
 
 static inline void **s_nth(size_t n) {
+#ifndef WITH_CHECK
   if ((void **)__gc_stack_top + n >= s_top()) {
     s_failure(&s, "not enough elements in stack");
   }
   if (s.fp != NULL && (void **)__gc_stack_top + n >= f_locals(s.fp)) {
     s_failure(&s, "not enough elements in function stack");
   }
+#endif
 
   return (void **)__gc_stack_top + n;
 }
 
 static inline void **s_peek() {
+#ifndef WITH_CHECK
   if ((void **)__gc_stack_top == s_top()) {
     s_failure(&s, "empty stack");
   }
   if (s.fp != NULL && (void **)__gc_stack_top == f_locals(s.fp)) {
     s_failure(&s, "empty function stack");
   }
+#endif
 
   return (void **)__gc_stack_top;
 }
@@ -48,9 +52,11 @@ static inline void **s_peek() {
 static inline aint *s_peek_i() { return (aint *)s_peek(); }
 
 static inline void s_push(void *val) {
+#ifndef WITH_CHECK
   if ((void **)__gc_stack_top == s.stack) {
     s_failure(&s, "stack overflow");
   }
+#endif
 #ifdef DEBUG_VERSION
   printf("--> push\n");
 #endif
@@ -63,9 +69,11 @@ static inline void s_push_i(aint val) { s_push((void *)val); }
 static inline void s_push_nil() { s_push(NULL); }
 
 static inline void s_pushn_nil(size_t n) {
+#ifndef WITH_CHECK
   if ((void **)__gc_stack_top + (aint)n - 1 <= s.stack) {
     s_failure(&s, "stack overflow");
   }
+#endif
   for (size_t i = 0; i < n; ++i) {
     __gc_stack_top -= sizeof(void *);
     *(void **)__gc_stack_top = NULL;
@@ -73,12 +81,14 @@ static inline void s_pushn_nil(size_t n) {
 }
 
 static inline void *s_pop() {
+#ifndef WITH_CHECK
   if ((void **)__gc_stack_top == s_top()) {
     s_failure(&s, "empty stack");
   }
   if (s.fp != NULL && (void **)__gc_stack_top == f_locals(s.fp)) {
     s_failure(&s, "empty function stack");
   }
+#endif
 #ifdef DEBUG_VERSION
   printf("--> pop\n");
 #endif
@@ -102,12 +112,14 @@ static inline void s_popn(size_t n) {
 // behaviour
 static inline void s_put_nth(size_t n, void *val) {
   s_push_nil();
+#ifndef WITH_CHECK
   if ((void **)__gc_stack_top + n >= s_top()) {
     s_failure(&s, "not enough elements in stack");
   }
   if (s.fp != NULL && (void **)__gc_stack_top + n >= f_locals(s.fp)) {
     s_failure(&s, "not enough elements in function stack");
   }
+#endif
 
   for (size_t i = 0; i < n; ++i) {
     ((void **)__gc_stack_top)[i] = ((void **)__gc_stack_top)[i + 1];
@@ -117,12 +129,14 @@ static inline void s_put_nth(size_t n, void *val) {
 
 static inline void s_rotate_n(size_t n) {
   s_push_nil();
+#ifndef WITH_CHECK
   if ((void **)__gc_stack_top + (aint)n - 1 >= s_top()) {
     s_failure(&s, "not enough elements in stack");
   }
   if (s.fp != NULL && (void **)__gc_stack_top + (aint)n - 1 >= f_locals(s.fp)) {
     s_failure(&s, "not enough elements in function stack");
   }
+#endif
 
   void *buf = NULL;
   for (size_t i = 0; 2 * i < n; ++i) {
@@ -147,6 +161,7 @@ static inline void s_enter_f(char *rp, bool is_closure_call, auint args_sz,
   printf("-> %i locals sz\n", locals_sz);
 #endif
 
+  // TODO: move checks to BEGIN/CBEGIN
   // check that params count is valid
   if ((void **)__gc_stack_top + (aint)args_sz - (is_closure_call ? 0 : 1) >=
       s_top()) {
@@ -223,14 +238,17 @@ static inline void **var_by_category(enum VarCategory category, size_t id) {
   void **var = NULL;
   switch (category) {
   case VAR_GLOBAL:
+#ifndef WITH_CHECK
     if (s.bf->global_area_size <= id) {
       s_failure(&s,
                 "can't read global: too big id"); //, %i >= %ul", id,
                                                   // s.bf->global_area_size);
     }
+#endif
     var = s.stack + STACK_SIZE - 1 - id;
     break;
   case VAR_LOCAL:
+#ifndef WITH_CHECK
     if (s.fp == NULL) {
       s_failure(&s, "can't read local outside of function");
     }
@@ -238,12 +256,14 @@ static inline void **var_by_category(enum VarCategory category, size_t id) {
       s_failure(&s, "can't read local: too big id"); //, %i >= %ul", id,
                                                      // f_locals_sz(s.fp));
     }
+#endif
     // printf("id is %i, local is %i, %i\n", id,
     // UNBOX((auint)*((void**)f_locals(s.fp) + id)), f_locals(s.fp) - (void
     // **)__gc_stack_top);
     var = f_locals(s.fp) + (f_locals_sz(s.fp) - id - 1);
     break;
   case VAR_ARGUMENT:
+#ifndef WITH_CHECK
     if (s.fp == NULL) {
       s_failure(&s, "can't read argument outside of function");
     }
@@ -251,9 +271,10 @@ static inline void **var_by_category(enum VarCategory category, size_t id) {
       s_failure(&s, "can't read arguments: too big id"); //, %i >= %ul", id,
                                                          // f_args_sz(s.fp));
     }
+#endif
     var = f_args(s.fp) + (f_args_sz(s.fp) - id - 1);
     break;
-  case VAR_CLOSURE:
+  case VAR_CLOSURE: // TODO: check that clojure vars are used only in clojures
     if (s.fp == NULL) {
       s_failure(&s, "can't read closure parameter outside of function");
     }
diff --git a/byterun/include/types.h b/byterun/include/types.h
index cd8f8279d..0ff7c63e2 100644
--- a/byterun/include/types.h
+++ b/byterun/include/types.h
@@ -73,6 +73,14 @@ static inline void s_failure(struct State *s, const char *msg) {
                s->instr_ip - s->bf->code_ptr, msg);
 }
 
+static inline void ip_failure(char *ip, Bytefile *bf, const char *msg) {
+  exec_failure(read_cmd(ip), 0, ip - bf->code_ptr, msg);
+}
+
+static inline void ip_safe_failure(char *ip, Bytefile *bf, const char *msg) {
+  exec_failure("_UNDEF_", 0, ip - bf->code_ptr, msg);
+}
+
 // ------ VarCategory ------
 
 enum VarCategory {
diff --git a/byterun/old-byterun.exe b/byterun/old-byterun.exe
new file mode 100755
index 000000000..4ce4edcef
Binary files /dev/null and b/byterun/old-byterun.exe differ
diff --git a/byterun/old_byterun.exe b/byterun/old_byterun.exe
new file mode 100755
index 000000000..4ce4edcef
Binary files /dev/null and b/byterun/old_byterun.exe differ
diff --git a/byterun/performance_check.sh b/byterun/performance_check.sh
index 7e8a0f0c9..7175360f4 100755
--- a/byterun/performance_check.sh
+++ b/byterun/performance_check.sh
@@ -11,7 +11,12 @@ time echo '0' | lamac -s ../performance/Sort.lama > /dev/null
 
 lamac -b  ../performance/Sort.lama > /dev/null
 
+# ./byterun.exe -p Sort.bc
+
+echo "Old Byterun:"
+time ./old_byterun.exe -i Sort.bc > /dev/null
+
 echo "Byterun:"
-time ./byterun.exe Sort.bc > /dev/null
+time ./byterun.exe -vi Sort.bc > /dev/null
 
 rm Sort.*
diff --git a/byterun/src/analyzer.cpp b/byterun/src/analyzer.cpp
index a4a5d5dd9..202eb7879 100644
--- a/byterun/src/analyzer.cpp
+++ b/byterun/src/analyzer.cpp
@@ -1,5 +1,6 @@
 #include "analyzer.hpp"
 #include "parser.hpp"
+#include <iostream>
 
 extern "C" {
 #include "types.h"
@@ -21,43 +22,65 @@ void analyze(Bytefile *bf) {
   uint current_args_count = 0;
   uint16_t *current_begin_counter = nullptr;
 
-  auto const to_visit_push = [&visited, &current_stack_depth](size_t offset,
-                                                              auto &to_visit) {
+  char *ip = bf->code_ptr;
+  char *current_ip = ip;
+  char *saved_current_ip = current_ip;
+
+  auto const jmp_to_visit_push = [&saved_current_ip, &bf, &visited,
+                                  &current_stack_depth,
+                                  &to_visit_jmp](size_t offset) {
     if (visited[offset] == NOT_VISITED) {
-      visited[offset] = true;
-      to_visit.push_back(offset);
+      visited[offset] = current_stack_depth;
+      to_visit_jmp.push_back(offset);
     } else if (visited[offset] != current_stack_depth) {
       // TODO: is this condition same for calls?
-      failure("different stack depth on same point is not allowed");
+      ip_failure(saved_current_ip, bf,
+                 "different stack depth on same point is not allowed");
     }
   };
 
-  auto const control_push = [&to_visit_push, &control_flow_in](size_t offset,
-                                                               auto &to_visit) {
-    control_flow_in[offset] = true;
-    to_visit_push(offset, to_visit);
+  auto const func_to_visit_push = [&saved_current_ip, &bf, &visited,
+                                   &current_stack_depth,
+                                   &to_visit_func](size_t offset) {
+    if (visited[offset] == NOT_VISITED) {
+      to_visit_func.push_back(offset);
+    }
+    visited[offset] = 0;
   };
 
-  auto const check_correct_var = [&globals_count, &current_locals_count,
+  auto const jmp_control_push = [&jmp_to_visit_push,
+                                 &control_flow_in](size_t offset) {
+    control_flow_in[offset] = true;
+    jmp_to_visit_push(offset);
+  };
+
+  auto const func_control_push = [&func_to_visit_push,
+                                  &control_flow_in](size_t offset) {
+    control_flow_in[offset] = true;
+    func_to_visit_push(offset);
+  };
+
+  auto const check_correct_var = [&saved_current_ip, &bf, &globals_count,
+                                  &current_locals_count,
                                   &current_args_count](uint8_t l, uint id) {
     if (l > 3) {
-      failure("unexpected variable category");
+      ip_failure(saved_current_ip, bf, "unexpected variable category");
     }
     VarCategory category = to_var_category(l);
     switch (category) {
     case VAR_GLOBAL:
       if (id >= globals_count) {
-        failure("global var index is out of range");
+        ip_failure(saved_current_ip, bf, "global var index is out of range");
       }
       break;
     case VAR_LOCAL:
       if (id >= current_locals_count) {
-        failure("local var index is out of range");
+        ip_failure(saved_current_ip, bf, "local var index is out of range");
       }
       break;
     case VAR_ARGUMENT:
       if (id >= current_args_count) {
-        failure("argument var index is out of range");
+        ip_failure(saved_current_ip, bf, "argument var index is out of range");
       }
       break;
     case VAR_CLOSURE:
@@ -69,7 +92,7 @@ void analyze(Bytefile *bf) {
   // add publics
   to_visit_func.reserve(bf->public_symbols_number);
   for (size_t i = 0; i < bf->public_symbols_number; ++i) {
-    control_push(get_public_offset(bf, i), to_visit_func);
+    func_control_push(get_public_offset(bf, i));
   }
 
   if (to_visit_func.size() == 0) {
@@ -77,7 +100,7 @@ void analyze(Bytefile *bf) {
   }
 
   while (true) {
-    char *ip = bf->code_ptr;
+    ip = bf->code_ptr;
     if (current_begin_counter == nullptr) {
       if (to_visit_func.empty()) {
         break;
@@ -95,36 +118,47 @@ void analyze(Bytefile *bf) {
     }
 
     if (ip >= bf->code_ptr + bf->code_size) {
-      failure("instruction pointer is out of range (>= size)");
+      ip_safe_failure(ip, bf, "instruction pointer is out of range (>= size)");
     }
 
     if (ip < bf->code_ptr) {
-      failure("instruction pointer is out of range (< 0)");
+      ip_safe_failure(ip, bf, "instruction pointer is out of range (< 0)");
     }
 
-    char *current_ip = ip;
+    current_ip = ip;
+    saved_current_ip = current_ip;
 
 #ifdef DEBUG_VERSION
-    printf("0x%.8lx \n", current_ip - bf->code_ptr - 1);
-#endif
-
+    const auto [cmd, l] = parse_command(&ip, *bf, std::cout);
+#else
     const auto [cmd, l] = parse_command(&ip, *bf);
+#endif
 
     if (current_begin_counter == nullptr && cmd != Cmd::BEGIN &&
         cmd != Cmd::CBEGIN) {
-      failure("function does not start with begin");
+      ip_failure(saved_current_ip, bf, "function does not start with begin");
     }
 
-    visited[current_ip - bf->code_ptr] = current_stack_depth;
+    if (visited[current_ip - bf->code_ptr] == NOT_VISITED) {
+      ip_failure(saved_current_ip, bf, "not visited command");
+    }
+    current_stack_depth = visited[current_ip - bf->code_ptr];
+
+#ifdef DEBUG_VERSION
+    std::cout << " -- [" << current_stack_depth << ']' << '\n';
+#endif
 
     ++current_ip; // skip command byte
-    char *const saved_current_ip = current_ip;
 
     size_t extra_stack_during_opr = 0;
     // change stack depth
     switch (cmd) {
     case Cmd::BINOP:
       current_stack_depth -= 2;
+      if (current_stack_depth < 0) {
+        ip_failure(saved_current_ip, bf, "not enough elements in stack");
+      }
+      ++current_stack_depth;
       break;
     case Cmd::CONST:
       ++current_stack_depth;
@@ -135,18 +169,22 @@ void analyze(Bytefile *bf) {
     case Cmd::SEXP:
       ip_read_string(&current_ip, *bf);
       current_stack_depth -= ip_read_int(&current_ip, *bf);
+      if (current_stack_depth < 0) {
+        ip_failure(saved_current_ip, bf, "not enough elements in stack");
+      }
+      ++current_stack_depth;
       break;
     case Cmd::STI:
       current_stack_depth -= 2;
       if (current_stack_depth < 0) {
-        failure("not enough elements in stack");
+        ip_failure(saved_current_ip, bf, "not enough elements in stack");
       }
       ++current_stack_depth;
       break;
     case Cmd::STA:
       current_stack_depth -= 3;
       if (current_stack_depth < 0) {
-        failure("not enough elements in stack");
+        ip_failure(saved_current_ip, bf, "not enough elements in stack");
       }
       ++current_stack_depth;
       break;
@@ -166,13 +204,13 @@ void analyze(Bytefile *bf) {
       break;
     case Cmd::SWAP:
       if (current_stack_depth < 2) {
-        failure("not enough elements in stack");
+        ip_failure(saved_current_ip, bf, "not enough elements in stack");
       }
       break;
     case Cmd::ELEM:
       current_stack_depth -= 2;
       if (current_stack_depth < 0) {
-        failure("not enough elements in stack");
+        ip_failure(saved_current_ip, bf, "not enough elements in stack");
       }
       ++current_stack_depth;
       break;
@@ -187,7 +225,7 @@ void analyze(Bytefile *bf) {
     case Cmd::ST:
       check_correct_var(l, ip_read_int(&current_ip, *bf));
       if (current_stack_depth < 1) {
-        failure("not enough elements in stack");
+        ip_failure(saved_current_ip, bf, "not enough elements in stack");
       }
       break;
     case Cmd::CJMPz:
@@ -197,7 +235,7 @@ void analyze(Bytefile *bf) {
     case Cmd::BEGIN:
     case Cmd::CBEGIN:
       if (current_begin_counter != nullptr) {
-        failure("unexpected function beginning");
+        ip_failure(saved_current_ip, bf, "unexpected function beginning");
       }
       current_args_count = ip_read_int(&current_ip, *bf);
       current_begin_counter = (uint16_t *)(current_ip + sizeof(uint16_t));
@@ -221,7 +259,7 @@ void analyze(Bytefile *bf) {
       uint args_count = ip_read_int(&current_ip, *bf);
       current_stack_depth -= args_count + 1; // + closure itself
       if (current_stack_depth < 0) {
-        failure("not enough elements in stack");
+        ip_failure(saved_current_ip, bf, "not enough elements in stack");
       }
       ++current_stack_depth;
       // NOTE: can't check args == cbegin args (?)
@@ -231,27 +269,27 @@ void analyze(Bytefile *bf) {
       uint args_count = ip_read_int(&current_ip, *bf);
       current_stack_depth -= args_count;
       if (current_stack_depth < 0) {
-        failure("not enough elements in stack");
+        ip_failure(saved_current_ip, bf, "not enough elements in stack");
       }
       ++current_stack_depth;
 
       // TODO: unify with next loop
       if (call_offset >= bf->code_size) {
-        failure("jump/call out of file");
+        ip_failure(saved_current_ip, bf, "jump/call out of file");
       }
 
       if (args_count != *(uint *)(bf->code_ptr + call_offset + 1)) {
-        failure("wrong call argument count");
+        ip_failure(saved_current_ip, bf, "wrong call argument count");
       }
     } break;
     case Cmd::TAG:
       if (current_stack_depth < 1) {
-        failure("not enough elements in stack");
+        ip_failure(saved_current_ip, bf, "not enough elements in stack");
       }
       break;
     case Cmd::ARRAY:
       if (current_stack_depth < 1) {
-        failure("not enough elements in stack");
+        ip_failure(saved_current_ip, bf, "not enough elements in stack");
       }
       break;
     case Cmd::FAIL:
@@ -265,7 +303,7 @@ void analyze(Bytefile *bf) {
         --current_stack_depth;
       }
       if (current_stack_depth < 0) {
-        failure("not enough elements in stack");
+        ip_failure(saved_current_ip, bf, "not enough elements in stack");
       }
       ++current_stack_depth;
       break;
@@ -276,30 +314,31 @@ void analyze(Bytefile *bf) {
     case Cmd::Llength:
     case Cmd::Lstring:
       if (current_stack_depth < 1) {
-        failure("not enough elements in stack");
+        ip_failure(saved_current_ip, bf, "not enough elements in stack");
       }
       break;
     case Cmd::Barray:
-      current_stack_depth -= ip_read_int(&current_ip, *bf);
+      current_stack_depth -= ip_read_int(&current_ip, *bf); // elem count
       if (current_stack_depth < 0) {
-        failure("not enough elements in stack");
+        ip_failure(saved_current_ip, bf, "not enough elements in stack");
       }
       ++current_stack_depth;
       break;
     case Cmd::EXIT:
-      failure("exit should be unreachable"); // NOTE: not sure
+      ip_failure(saved_current_ip, bf,
+                 "exit should be unreachable"); // NOTE: not sure
       break;
     case Cmd::_UNDEF_:
-      failure("undefined command");
+      ip_failure(saved_current_ip, bf, "undefined command");
       break;
     }
 
     if (current_begin_counter == nullptr) {
-      failure("function does not start with begin");
+      ip_failure(saved_current_ip, bf, "function does not start with begin");
     }
 
     if (current_stack_depth < 0) {
-      failure("not enough elements in stack");
+      ip_failure(saved_current_ip, bf, "not enough elements in stack");
     }
 
     *current_begin_counter =
@@ -307,6 +346,7 @@ void analyze(Bytefile *bf) {
                  (uint16_t)(current_stack_depth + extra_stack_during_opr));
 
     current_ip = saved_current_ip;
+    ++current_ip; // skip command byte
     // do jumps
     switch (cmd) {
     case Cmd::EXIT:
@@ -318,25 +358,29 @@ void analyze(Bytefile *bf) {
     case Cmd::CJMPnz:
     case Cmd::CLOSURE:
     case Cmd::CALL:
-      to_visit_push(ip - bf->code_ptr, to_visit_jmp);
+      jmp_to_visit_push(ip - bf->code_ptr);
     case Cmd::JMP: {
       bool is_call = (cmd == Cmd::CLOSURE || cmd == Cmd::CALL);
 
       uint jmp_p = ip_read_int(&current_ip, *bf);
       if (jmp_p >= bf->code_size) {
         // NOTE: maybe also should check that > begin (?)
-        failure("jump/call out of file");
+        ip_failure(saved_current_ip, bf, "jump/call out of file");
+      }
+      if (is_call) {
+        func_control_push(jmp_p);
+      } else {
+        jmp_control_push(jmp_p);
       }
-      control_push(jmp_p, is_call ? to_visit_func : to_visit_jmp);
       break;
     }
 
     case Cmd::_UNDEF_:
-      failure("undefined command");
+      ip_failure(saved_current_ip, bf, "undefined command");
       break;
 
     default:
-      to_visit_push(ip - bf->code_ptr, to_visit_jmp);
+      jmp_to_visit_push(ip - bf->code_ptr);
       break;
     }
   }
diff --git a/byterun/src/cli.cpp b/byterun/src/cli.cpp
index 4160c609d..2f625becf 100644
--- a/byterun/src/cli.cpp
+++ b/byterun/src/cli.cpp
@@ -1,3 +1,8 @@
+#include <iostream>
+
+#include "analyzer.hpp"
+#include "parser.hpp"
+
 extern "C" {
 #include "../../runtime/runtime.h"
 #include "interpreter.h"
@@ -5,8 +10,6 @@ extern "C" {
 #include "utils.h"
 }
 
-#include "analyzer.hpp"
-
 int main(int argc, char **argv) {
   if (argc < 2) {
     failure("no execution option");
@@ -14,6 +17,7 @@ int main(int argc, char **argv) {
 
   bool do_verification = false;
   bool do_interpretation = false;
+  bool do_print = false;
   if (strcmp(argv[1], "-vi") == 0) {
     do_verification = true;
     do_interpretation = true;
@@ -21,6 +25,8 @@ int main(int argc, char **argv) {
     do_interpretation = true;
   } else if (strcmp(argv[1], "-v") == 0) {
     do_verification = true;
+  } else if (strcmp(argv[1], "-p") == 0) {
+    do_print = true;
   } else {
     failure("wrong execution option (acceptable options - '-i', '-v', '-vi')");
   }
@@ -33,6 +39,9 @@ int main(int argc, char **argv) {
   // #ifdef DEBUG_VERSION
   //   dump_file (stdout, f);
   // #endif
+  if (do_print) {
+    print_file(*f, std::cout);
+  }
   if (do_verification) {
     analyze(f);
   }
diff --git a/byterun/src/interpreter.c b/byterun/src/interpreter.c
index faf8a096a..57ed63f3b 100644
--- a/byterun/src/interpreter.c
+++ b/byterun/src/interpreter.c
@@ -17,25 +17,31 @@
 struct State s;
 
 static inline uint16_t ip_read_half_int(char **ip) {
+#ifndef WITH_CHECK
   if (*ip + sizeof(uint16_t) > s.bf->code_ptr + s.bf->code_size) {
     failure("last command is invalid, int parameter can not be read\n");
   }
+#endif
   *ip += sizeof(uint16_t);
   return *(uint16_t *)((*ip) - sizeof(uint16_t));
 }
 
 static inline int ip_read_int(char **ip) {
+#ifndef WITH_CHECK
   if (*ip + sizeof(int) > s.bf->code_ptr + s.bf->code_size) {
     failure("last command is invalid, int parameter can not be read\n");
   }
+#endif
   *ip += sizeof(int);
   return *(int *)((*ip) - sizeof(int));
 }
 
 static inline uint8_t ip_read_byte(char **ip) {
+#ifndef WITH_CHECK
   if (*ip + sizeof(char) > s.bf->code_ptr + s.bf->code_size) {
     failure("last command is invalid, byte parameter can not be read\n");
   }
+#endif
   return *(*ip)++;
 }
 
@@ -73,6 +79,7 @@ void run(Bytefile *bf, int argc, char **argv) {
   do {
     bool call_happened = false;
 
+#ifndef WITH_CHECK
     if (s.ip >= bf->code_ptr + bf->code_size) {
       s_failure(&s, "instruction pointer is out of range (>= size)");
     }
@@ -80,6 +87,7 @@ void run(Bytefile *bf, int argc, char **argv) {
     if (s.ip < bf->code_ptr) {
       s_failure(&s, "instruction pointer is out of range (< 0)");
     }
+#endif
 
     s.instr_ip = s.ip;
     uint8_t x = ip_read_byte(&s.ip), h = (x & 0xF0) >> 4, l = x & 0x0F;
@@ -179,9 +187,11 @@ void run(Bytefile *bf, int argc, char **argv) {
       case CMD_BASIC_JMP: { // JMP 0x%.8x
         uint jmp_p = ip_read_int(&s.ip);
 
+#ifndef WITH_CHECK
         if (jmp_p >= bf->code_size) {
           s_failure(&s, "jump out of file");
         }
+#endif
         s.ip = bf->code_ptr + jmp_p;
         break;
       }
@@ -254,9 +264,11 @@ void run(Bytefile *bf, int argc, char **argv) {
       case CMD_CTRL_CJMPz: { // CJMPz 0x%.8x
         uint jmp_p = ip_read_int(&s.ip);
 
+#ifndef WITH_CHECK
         if (jmp_p >= bf->code_size) {
           s_failure(&s, "jump out of file");
         }
+#endif
         if (UNBOX(s_pop_i()) == 0) {
           s.ip = bf->code_ptr + jmp_p;
         }
@@ -266,9 +278,11 @@ void run(Bytefile *bf, int argc, char **argv) {
       case CMD_CTRL_CJMPnz: { // CJMPnz  0x%.8x
         uint jmp_p = ip_read_int(&s.ip);
 
+#ifndef WITH_CHECK
         if (jmp_p >= bf->code_size) {
           s_failure(&s, "jump out of file");
         }
+#endif
         if (UNBOX(s_pop_i()) != 0) {
           s.ip = bf->code_ptr + jmp_p;
         }
@@ -277,34 +291,50 @@ void run(Bytefile *bf, int argc, char **argv) {
 
       case CMD_CTRL_BEGIN: { // BEGIN %d %d // function begin
         uint args_sz = ip_read_int(&s.ip);
+// #ifdef WITH_CHECK
         uint locals_sz = ip_read_half_int(&s.ip);
         uint max_additional_stack_sz = ip_read_half_int(&s.ip);
+// #else
+//         uint locals_sz = ip_read_int(&s.ip);
+// #endif
+#ifdef WITH_CHECK
         if (s.fp != NULL && s.call_ip == NULL) {
           s_failure(&s, "begin should only be called after call");
         }
+#endif
         s_enter_f(s.call_ip /*ip from call*/, s.is_closure_call, args_sz,
                   locals_sz);
-        // TODO: add ifdef
+#ifndef WITH_CHECK
+        // TODO
         if ((void **)__gc_stack_top + (aint)max_additional_stack_sz - 1 <= s.stack) {
           s_failure(&s, "stack owerflow");
         }
+#endif
         break;
       }
 
       case CMD_CTRL_CBEGIN: { // CBEGIN %d %d
         // NOTE: example not found, no checks done
         uint args_sz = ip_read_int(&s.ip);
-        uint max_additional_stack_sz = ip_read_half_int(&s.ip);
+// #ifdef WITH_CHECK
         uint locals_sz = ip_read_half_int(&s.ip);
+        uint max_additional_stack_sz = ip_read_half_int(&s.ip);
+// #else
+        // uint locals_sz = ip_read_int(&s.ip);
+// #endif
+#ifndef WITH_CHECK
         if (s.fp != NULL && s.call_ip == NULL) {
           s_failure(&s, "begin should only be called after call");
         }
+#endif
         s_enter_f(s.call_ip /*ip from call*/, s.is_closure_call, args_sz,
                   locals_sz);
         // TODO: add ifdef
+#ifdef WITH_CHECK
         if ((void **)__gc_stack_top + (aint)max_additional_stack_sz - 1 <= s.stack) {
           s_failure(&s, "stack owerflow");
         }
+#endif
         break;
       }
 
@@ -320,9 +350,11 @@ void run(Bytefile *bf, int argc, char **argv) {
               var_by_category(to_var_category(arg_type), arg_id);
           s_push(*var_ptr);
         }
+#ifndef WITH_CHECK
         if (call_offset >= bf->code_size) {
           s_failure(&s, "jump out of file");
         }
+#endif
         s_push(bf->code_ptr + call_offset);
 
         void *closure = Bclosure((aint *)__gc_stack_top, args_count);
@@ -351,9 +383,11 @@ void run(Bytefile *bf, int argc, char **argv) {
         s.is_closure_call = false;
         s.call_ip = s.ip;
 
+#ifndef WITH_CHECK
         if (call_p >= bf->code_size) {
           s_failure(&s, "jump out of file");
         }
+#endif
         s.ip = bf->code_ptr + call_p;
         break;
       }
diff --git a/byterun/src/parser.cpp b/byterun/src/parser.cpp
index 3a449ce8b..949084ebf 100644
--- a/byterun/src/parser.cpp
+++ b/byterun/src/parser.cpp
@@ -1,5 +1,6 @@
 #include <cassert>
 #include <errno.h>
+#include <iomanip>
 #include <iostream>
 #include <malloc.h>
 #include <string.h>
@@ -574,3 +575,18 @@ std::pair<Cmd, uint8_t> parse_command(char **ip, const Bytefile &bf,
                                       std::ostream &out) {
   return parse_command_impl<true>(ip, bf, out);
 }
+
+void print_file(const Bytefile &bf, std::ostream &out) {
+  char *ip = bf.code_ptr;
+
+  while (true) {
+    out << std::setfill('0') << std::setw(8) << std::hex << ip - bf.code_ptr
+        << ": ";
+    const auto [cmd, l] = parse_command(&ip, bf, out);
+    out << '\n';
+
+    if (cmd == Cmd::EXIT) {
+      break;
+    }
+  }
+}