XPost: comp.theory, comp.lang.c, comp.lang.c++   
   From: NoOne@nospicedham.NoWhere.com   
      
   On 4/17/2021 9:15 AM, olcott wrote:   
   > If a function X() is called by function Y() twice in sequence from the   
   > same machine address of Y() with the same parameters to X() and the   
   > execution trace shows no conditional branch instructions in Y() or   
   > function call returns in X() then the function call from Y() to X() is   
   > infinitely recursive unless X() stops it.   
   >   
   > The referenced execution trace is on x86 machine language, disassembled   
   > for human consumption.   
   >   
      
   When Halts() uses an x86 emulator to simulate its input and maintains an   
   execution trace of this emulation then it can examine this execution   
   trace according to the above criteria and correctly decide that Y() is   
   invoking X() in infinite recursion. On this basis it can stop simulating   
   Y() and report that Y() would not halt unless its execution was aborted   
   by Halts().   
      
   void Y(u32 P)   
      Halts(P, P);   
   }   
      
      
   int main()   
   {   
      Halts((u32)Y, (u32)Y);   
   }   
      
      
   _Y()   
   [000009ac](01)  55                      push ebp   
   [000009ad](02)  8bec                    mov ebp,esp   
   [000009af](03)  8b4508                  mov eax,[ebp+08]   
   [000009b2](01)  50                      push eax   
   [000009b3](03)  8b4d08                  mov ecx,[ebp+08]   
   [000009b6](01)  51                      push ecx   
   [000009b7](05)  e840feffff              call 000007fc   
   [000009bc](03)  83c408                  add esp,+08   
   [000009bf](01)  5d                      pop ebp   
   [000009c0](01)  c3                      ret   
   Size in bytes:(0021) [000009c0]   
      
   _main()   
   [000009cc](01)  55                      push ebp   
   [000009cd](02)  8bec                    mov ebp,esp   
   [000009cf](05)  68ac090000              push 000009ac   
   [000009d4](05)  68ac090000              push 000009ac   
   [000009d9](05)  e81efeffff              call 000007fc   
   [000009de](03)  83c408                  add esp,+08   
   [000009e1](02)  33c0                    xor eax,eax   
   [000009e3](01)  5d                      pop ebp   
   [000009e4](01)  c3                      ret   
   Size in bytes:(0025) [000009e4]   
      
   ===============================   
   ....[000009cc][00011278][00000000](01)  55                      push ebp   
   ....[000009cd][00011278][00000000](02)  8bec                    mov ebp,esp   
   ....[000009cf][00011274][000009ac](05)  68ac090000              push 000009ac   
   ....[000009d4][00011270][000009ac](05)  68ac090000              push 000009ac   
   ....[000009d9][0001126c][000009de](05)  e81efeffff              call 000007fc   
   Begin Local Halt Decider Simulation at Machine Address:9ac   
   ....[000009ac][00031318][0003131c](01)  55                      push ebp   
   ....[000009ad][00031318][0003131c](02)  8bec                    mov ebp,esp   
   ....[000009af][00031318][0003131c](03)  8b4508                  mov   
   eax,[ebp+08]   
   ....[000009b2][00031314][000009ac](01)  50                      push eax   
   ....[000009b3][00031314][000009ac](03)  8b4d08                  mov   
   ecx,[ebp+08]   
   ....[000009b6][00031310][000009ac](01)  51                      push ecx   
   ....[000009b7][0003130c][000009bc](05)  e840feffff              call 000007fc   
   ....[000009ac][0007bd40][0007bd44](01)  55                      push ebp   
   ....[000009ad][0007bd40][0007bd44](02)  8bec                    mov ebp,esp   
   ....[000009af][0007bd40][0007bd44](03)  8b4508                  mov   
   eax,[ebp+08]   
   ....[000009b2][0007bd3c][000009ac](01)  50                      push eax   
   ....[000009b3][0007bd3c][000009ac](03)  8b4d08                  mov   
   ecx,[ebp+08]   
   ....[000009b6][0007bd38][000009ac](01)  51                      push ecx   
   ....[000009b7][0007bd34][000009bc](05)  e840feffff              call 000007fc   
   Local Halt Decider: Infinite Recursion Detected Simulation Stopped   
   ....[000009de][00011278][00000000](03)  83c408                  add esp,+08   
   ....[000009e1][00011278][00000000](02)  33c0                    xor eax,eax   
   ....[000009e3][0001127c][00010000](01)  5d                      pop ebp   
   ....[000009e4][00011280][00000058](01)  c3                      ret   
   Number_of_User_Instructions(23)   
   Number of Instructions Executed(16920)   
   sizeof(Decoded_Line_Of_Code)(24)   
      
   --   
   Copyright 2021 Pete Olcott   
      
   "Great spirits have always encountered violent opposition from mediocre   
   minds." Einstein   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)