push rbp

[habran]

Hi Japheth,
I would like to write some functions without "push rbp" because they are unnecessary in some cases EG:

xmemcpy:
;000000014004DA78  push        rbp  
;000000014004DA79  mov         rbp,rsp 
000000014004DA7C  mov         rax,rcx 
000000014004DA7F  cmp         rcx,rdx 
000000014004DA82  je          xmemcpy+25h (14004DA9Dh) 
000000014004DA84  test        r8,r8 
000000014004DA87  je          xmemcpy+25h (14004DA9Dh) 
000000014004DA89  mov         r9b,byte ptr [rdx] 
000000014004DA8C  mov         byte ptr [rcx],r9b 
000000014004DA8F  add         rcx,1 
000000014004DA93  add         rdx,1 
000000014004DA97  sub         r8,1 
000000014004DA9B  jne         xmemcpy+11h (14004DA89h) 
;000000014004DA9D  leave 
           
000000014004DA9E  ret

Is it possible to do that?

[japheth]

> Is it possible to do that?

I hope so - the directives OPTION PROLOGUE/EPILOGUE are still implemented in 64-bit mode.

[habran]

thanks Japheth
after little bit of struggle I found the way to use it here is example:

;//--------------------------------------------------
option win64:0
OPTION PROLOGUE:NONE 
OPTION EPILOGUE:NONE
xmemcpy PROC dest:QWORD,src :QWORD, count:UINT_PTR
        mov     rax, rcx
        cmp     rcx, rdx
        jz      aexit
        test    r8, r8
        jz      short aexit
@@:     mov     r9b, [rdx]
        mov     [rcx], r9b
        add     rcx, 1
        add     rdx, 1
        sub     r8, 1
        jnz     @b
aexit:  ret
xmemcpy ENDP
OPTION PROLOGUE:PrologueDef
OPTION EPILOGUE:EpilogueDef
;//--------------------------------------------------
option win64:3
option frame:auto

and this is what I get commpiled:

xmemcpy:
000000014004DA78  mov         rax,rcx 
000000014004DA7B  cmp         rcx,rdx 
000000014004DA7E  je          xmemcpy+21h (14004DA99h) 
000000014004DA80  test        r8,r8 
000000014004DA83  je          xmemcpy+21h (14004DA99h) 
000000014004DA85  mov         r9b,byte ptr [rdx] 
000000014004DA88  mov         byte ptr [rcx],r9b 
000000014004DA8B  add         rcx,1 
000000014004DA8F  add         rdx,1 
000000014004DA93  sub         r8,1 
000000014004DA97  jne         xmemcpy+0Dh (14004DA85h) 
000000014004DA99  ret