flat assembler - 64bit - proc or invoke problem?

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madmatt

Joined: 07 Oct 2003
Posts: 1045
Location: Michigan, USA

madmatt 03 Jan 2012, 02:02

Been working in 64bit windows for a while and did a dis-assembly of one of my executables and noticed that there some instructions in either the proc or invoke that I don't think are needed.

a sample is here (The instructions I'm talking about have a ?- in front of them):

Code:

        push    rbp                                     ; 00402000 _ 55
        mov     rbp, rsp                                ; 00402001 _ 48: 89. E5
        sub     rsp, 416                                ; 00402004 _ 48: 81. EC, 000001A0
        sub     rsp, 32                                 ; 0040200B _ 48: 83. EC, 20
        lea     rcx, [rbp-1A0H]                         ; 0040200F _ 48: 8D. 8D, FFFFFE60
        mov     rdx, 0                                  ; 00402016 _ 48: C7. C2, 00000000
        mov     r8, 80                                  ; 0040201D _ 49: C7. C0, 00000050
        call    near [rel imp_memset]                   ; 00402024 _ FF. 15, 000020E6(rel)
        ?-add     rsp, 32                                 ; 0040202A _ 48: 83. C4, 20
        ?-sub     rsp, 32                                 ; 0040202E _ 48: 83. EC, 20
        mov     rcx, ?_003                              ; 00402032 _ 48: C7. C1, 0040105C(d)
        call    near [rel imp_InitCommonControlsEx]     ; 00402039 _ FF. 15, 00002371(rel)
        ?-add     rsp, 32                                 ; 0040203F _ 48: 83. C4, 20
        ?-sub     rsp, 32                                 ; 00402043 _ 48: 83. EC, 20
        mov     rcx, 0                                  ; 00402047 _ 48: C7. C1, 00000000
        call    near [rel imp_GetModuleHandleA]         ; 0040204E _ FF. 15, 0000210C(rel)
        ?-add     rsp, 32                                 ; 00402054 _ 48: 83. C4, 20
        mov     qword [rbp-188H], rax                   ; 00402058 _ 48: 89. 85, FFFFFE78
        mov     qword [rel ?_002], rax                  ; 0040205F _ 48: 89. 05, FFFFEFD2(rel)
        mov     dword [rbp-1A0H], 80                    ; 00402066 _ C7. 85, FFFFFE60, 00000050
        mov     qword [rbp-180H], 0                     ; 00402070 _ 48: C7. 85, FFFFFE80, 00000000
        mov     qword [rbp-158H], 0                     ; 0040207B _ 48: C7. 85, FFFFFEA8, 00000000
        ?-sub     rsp, 32                                 ; 00402086 _ 48: 83. EC, 20
        mov     rcx, 0                                  ; 0040208A _ 48: C7. C1, 00000000
        mov     rdx, 32512                              ; 00402091 _ 48: C7. C2, 00007F00
        call    near [rel imp_LoadCursorA]              ; 00402098 _ FF. 15, 0000218A(rel)
        add     rsp, 32                                 ; 0040209E _ 48: 83. C4, 20

_________________
Gimme a sledge hammer! I'LL FIX IT!

03 Jan 2012, 02:02

Tomasz Grysztar

Joined: 16 Jun 2003
Posts: 8351
Location: Kraków, Poland

Tomasz Grysztar 03 Jan 2012, 10:26

Use "frame" macro to get rid of them. See documentation of 64-bit procedure macroinstructions.

03 Jan 2012, 10:26

madmatt

Joined: 07 Oct 2003
Posts: 1045
Location: Michigan, USA

madmatt 03 Jan 2012, 14:38

Tomasz Grysztar wrote:

Use "frame" macro to get rid of them. See documentation of 64-bit procedure macroinstructions.

Yeh, that worked, thanks.
But, why isn't this feature automatic?

_________________
Gimme a sledge hammer! I'LL FIX IT!

03 Jan 2012, 14:38

Tomasz Grysztar

Joined: 16 Jun 2003
Posts: 8351
Location: Kraków, Poland

Tomasz Grysztar 03 Jan 2012, 15:13

Documentation wrote:

They should be used to enclose a block, inside which the RSP register is not altered between the procedure calls (...)

These macros have to be used knowingly.

PS Also see the part about "static_rsp_prologue" family of macros, you may find them useful.

03 Jan 2012, 15:13

madmatt

Joined: 07 Oct 2003
Posts: 1045
Location: Michigan, USA

madmatt 03 Jan 2012, 21:10

Quote:

PS Also see them part about "static_rsp_prologue" family of macros, you may find them useful.

Yeh, putting these three lines (below) at the end of the proc64.inc file removes the added instructions and doesn't require the frame/endf macros. Thanks a lot, I feel better about the code output now. Very Happy

Code:

  prologue@proc equ static_rsp_prologue
  epilogue@proc equ static_rsp_epilogue
  close@proc equ static_rsp_close

03 Jan 2012, 21:10

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