[fpc-pascal] fpc-2.1.4.x86_64-win64.exe: default switch generates intel asm, ironic ? Can free pascal reverse engineer executables and dll's ?

[Skybuck Flying]

Hello,

I like free pascal compiler to generate an assembler listing of 
HelloWorld.pas and fortunately it can do that which is really cool !

I simply type:

ppcrossx64 HelloWorld.pas -default

It then generates a HelloWorld.S file:

Here is a snipper from it ;)

<Begin of Snippet>

; Begin asmlist al_procedures

_TEXT SEGMENT
 ALIGN 16
 PUBLIC PASCALMAIN
PASCALMAIN:
 PUBLIC main
main:
  push rbp
  mov rbp,rsp
  sub rsp,96
  mov qword ptr [rbp-8],rbx
  call FPC_INITIALIZEUNITS
  call fpc_get_output
  mov rbx,rax
  mov al,1
  mov r9,24
  mov r8,offset _$HELLOWORLD$_Ld1
  mov rdx,rbx
  mov ecx,0
  mov byte ptr [rsp+32],al
  call fpc_write_text_pchar_as_array
  call FPC_IOCHECK
  mov rcx,rbx
  call fpc_writeln_end
  call FPC_IOCHECK
  mov eax,10
  mov qword ptr [U_P$HELLOWORLD_TEST],eax
  call fpc_get_output
  mov rbx,rax
  mov al,1
  mov r9,5
  mov r8,offset _$HELLOWORLD$_Ld2
  mov rdx,rbx
  mov ecx,0
  mov byte ptr [rsp+32],al
  call fpc_write_text_pchar_as_array
  call FPC_IOCHECK
  mov r8,qword ptr [U_P$HELLOWORLD_TEST]
  mov rdx,rbx
  mov ecx,0
  call fpc_write_text_sint
  call FPC_IOCHECK
  mov rcx,rbx
  call fpc_writeln_end
  call FPC_IOCHECK
  mov eax,100
  mov qword ptr [U_P$HELLOWORLD_TEST],eax
  call fpc_get_output
  mov rbx,rax
  mov al,1
  mov r9,5
  mov r8,offset _$HELLOWORLD$_Ld2
  mov rdx,rbx
  mov ecx,0
  mov byte ptr [rsp+32],al
  call fpc_write_text_pchar_as_array
  call FPC_IOCHECK
  mov r8,qword ptr [U_P$HELLOWORLD_TEST]
  mov rdx,rbx
  mov ecx,0
  call fpc_write_text_sint
  call FPC_IOCHECK
  mov rcx,rbx
  call fpc_writeln_end
  call FPC_IOCHECK
  mov rax,-1
  mov qword ptr [U_P$HELLOWORLD_TEST],rax
  call fpc_get_output
  mov rbx,rax
  mov al,1
  mov r9,5
  mov r8,offset _$HELLOWORLD$_Ld2
  mov rdx,rbx
  mov ecx,0
  mov byte ptr [rsp+32],al
  call fpc_write_text_pchar_as_array
  call FPC_IOCHECK
  mov r8,qword ptr [U_P$HELLOWORLD_TEST]
  mov rdx,rbx
  mov ecx,0
  call fpc_write_text_sint
  call FPC_IOCHECK
  mov rcx,rbx
  call fpc_writeln_end
  call FPC_IOCHECK
  mov dword ptr [U_P$HELLOWORLD_TEST],-1
  mov dword ptr [U_P$HELLOWORLD_TEST+4],2147483647
  call fpc_get_output
  mov rbx,rax
  mov al,1
  mov r9,5
  mov r8,offset _$HELLOWORLD$_Ld2
  mov rdx,rbx
  mov ecx,0
  mov byte ptr [rsp+32],al
  call fpc_write_text_pchar_as_array
  call FPC_IOCHECK
  mov r8,qword ptr [U_P$HELLOWORLD_TEST]
  mov rdx,rbx
  mov ecx,0
  call fpc_write_text_sint
  call FPC_IOCHECK
  mov rcx,rbx
  call fpc_writeln_end
  call FPC_IOCHECK
  call fpc_get_input
  mov rbx,rax
  mov rcx,rbx
  call fpc_readln_end
  call FPC_IOCHECK
  call FPC_DO_EXIT
  mov rbx,qword ptr [rbp-8]
  leave
  ret
; End asmlist al_procedures
; Begin asmlist al_globals

<End of Snippet>

Pretty cool.

Kinda ironic how it can generate it, but not interpret it ? ;)

For me it doesn't matter that much, I would like to give AT&T asm a try... 
though it might not be smart because Visual Studio 2005, Intel, probably AMD 
too, and Delphi 2007 all use intel syntax.

So for future compatibility using AT&T asm syntax might not be too smart.

But maybe I will like AT&T syntax... I never liked intel syntax that much... 
kinda stupid and crazy but ok ;) :)

I wonder what free pascal can do more ?

Can it reverse engineer executables and dll's and produce asm listings ?

Bye,
  Skybuck.

----- Original Message ----- 
From: "Jonas Maebe" <jonas.maebe at elis.ugent.be>
To: "FPC-Pascal users discussions" <fpc-pascal at lists.freepascal.org>
Sent: Thursday, July 26, 2007 10:51 AM
Subject: Re: [fpc-pascal] fpc-2.1.4.x86_64-win64.exe: -Mdelphi not working ?


>
> On 26 Jul 2007, at 10:44, Skybuck Flying wrote:
>
>> I just reinstalled fpc-2.1.4.x86_64-win64.exe:
>>
>> And this time I used the -Mdelphi compiler switch but it still  gives 
>> problems:
>>
>> Y:\Free Pascal\Tests\Hello World>ppcrossx64 HelloWorld.pas -Mdelphi
>> HelloWorld.pas(9,10) Error: Unknown identifier "EAX"
>> HelloWorld.pas(9,12) Error: Unknown identifier "ECX"
>> HelloWorld.pas(9,12) Error: Asm: [mov ???,???] invalid combination  of 
>> opcode and
>> operands
>> HelloWorld.pas(16,4) Fatal: There were 3 errors compiling module, 
>> stopping
>> Fatal: Compilation aborted
>
> I guess the Intel assembler syntax is simply not supported for  x86-64. 
> You will have to use AT&T syntax instead. Here are some  google links to 
> tutorials and overview documents:
> http://www.google.com/search?rls=en&q=at%26t+assembler+syntax
>
>
> Jonas
> _______________________________________________
> fpc-pascal maillist  -  fpc-pascal at lists.freepascal.org
> http://lists.freepascal.org/mailman/listinfo/fpc-pascal
>