Is there a list of deprecated x86 instructions?

Question

I\'m taking an x86 assembly language programming class and know that certain instructions shouldn\'t be used anymore -- because they\'re slow on modern processors; for example,

Answer 1

All CPU instructions are 100% functional to reach compatibility with older CPUs. So why to avoid some instruction? There is no realy deprecated x86 instructions! But we can say:

1)All string istructions like rep movsb are slower.

2) xlat is slow and very rare in use.

3)Also the use of stack frame functions ENTER and LEAVE is slow.

4)Uder Windows (XP, vista...) the deprecated instructions are IN and OUT, but only under CPU ring 2 (aplication level), also the int nn is deprecated, except int3 (debugger trap).

EDIT: added simple speed test to check strings instruction rep cmp on different versions of CPUs.

Test is made under Delphi IDE but the asm part is very easy to translate in any other IDE.

program ProjectTest;

{$APPTYPE CONSOLE}

uses SysUtils, windows;

const
  ArraySize = 50000;

var
  StartTicks    :int64;
  EndTicks      :int64;
  arA           :array [0..ArraySize - 1]of byte;
  arB           :array [0..ArraySize - 1]of byte;

begin
  FillChar(ArA, SizeOf(ArA), 255);          //Set all bytes to 0xFF
  FillChar(ArB, SizeOf(ArB), 255);          //Set all bytes to 0xFF

repeat
  Sleep(100);       //Calm down
  asm
//Save  StartTicks
    rdtsc
    mov         dword ptr [StartTicks], eax
    mov         dword ptr [StartTicks + 4], edx
//Test LOOP
    push        edi
    mov         ecx, -ArraySize
    mov         edi, offset arA + ArraySize
    mov         esi, offset arB + ArraySize
@loop:
    mov         al,[esi + ecx]
    cmp         [edi + ecx], al
    jnz         @exit
    inc         ecx
    jnz         @loop
@exit:
    pop         edi
//Save  EndTicks
    rdtsc
    mov         dword ptr [EndTicks], eax
    mov         dword ptr [EndTicks + 4], edx
  end;

  WriteLn('Loop ticks : ' + IntToStr(EndTicks - StartTicks));

  Sleep(100);       //Calm down
  asm
//Save  StartTicks
    rdtsc
    mov         dword ptr [StartTicks], eax
    mov         dword ptr [StartTicks + 4], edx
//Test REP
    push        edi
    cld
    mov         ecx, ArraySize
    mov         edi, offset arA
    mov         esi, offset arB
    repe        cmpsb
    pop         edi
//Save  EndTicks
    rdtsc
    mov         dword ptr [EndTicks], eax
    mov         dword ptr [EndTicks + 4], edx
  end;

  WriteLn('Rep ticks  : ' + IntToStr(EndTicks - StartTicks));

  ReadLn                    //Wait keyboard
until false;

end.

TESTs for ArraySize = 50000

Average results...

1)My Intel single core CPU Pentium 4 results: Loop ticks : 232000; Rep ticks : 233000

2)My Intel Core 2 Quad CPU results: Loop ticks : 158000; Rep ticks : 375000