[fpc-pascal] intel vs att asm (fstp instruction) (osx/clang features)

[Ched]

Hello,

I have something like this which seems to work very nicely

Cheers, Ched'



PROCEDURE SINCOS(CONST X: DOUBLE; VAR S, C: DOUBLE);
BEGIN
    {$IFDEF NOASM}
       S:=SIN(X);
       C:=COS(X);
    {$ELSE}
       {$IFDEF VER70}
          IF TEST8087=3 THEN
             ASM
                FLD   X
                DB    $D9,$FB
                LES   DI,C
                FSTP  DOUBLE(ES:[DI])
                LES   DI,S
                FSTP  DOUBLE(ES:[DI])
             END
          ELSE
             BEGIN
                S:=SYSTEM.SIN(X);
                C:=SYSTEM.COS(X);
             END;
       {$ELSE}
           ASM
              FLD X
              FSINCOS
              MOV  ECX,C
              FSTP DOUBLE([ECX])
              MOV  ECX,S
              FSTP DOUBLE([ECX])
           END
       {$ENDIF}
    {$ENDIF}
END;



Le 04.05.2016 à 10:14, Pierre Free Pascal a écrit :
> I think the correct solution for you is to use explicit size information:
>
>
>
>   FSTP SINGLE PTR [EDX]
>
>   FSTP SINGLE PTR [EAX]
>
>
>
> but
>
>   FSTP [s]
>
> and
>
>   FSTP [c]
>
> would be even better, I don’t know if this syntax is Delphi compatible or not.
>
>
>
>   It seems that indeed Free Pascal does not set the size of those instruction,
>
> but seems to use single as default size for internal code generation…
>
>   When generating assembler file for GNU assembler or NASM,
>
> it does not seem to print out this “assumed” size, which indeed
>
> leads to a failure using –Anasm option on trunk compiler with i386-win32 target.
>
>
>
>   My GNU as version 2.26 does not seem to need an explicit size,
>
> but I don’t know what Xcode uses, isn’t it also a GNU assembler?
>
> Could you tell us which assembler is used?
>
>
>
>
>
> Pierre
>
>
>
>
>
> *De :*fpc-pascal-bounces at lists.freepascal.org [mailto:fpc-pascal-bounces at lists.freepascal.org] *De la
> part de* Dmitry Boyarintsev
> *Envoyé :* mercredi 4 mai 2016 02:28
> *À :* FPC-Pascal users discussions
> *Objet :* [fpc-pascal] intel vs att asm (fstp instruction) (osx/clang features)
>
>
>
> Hello,
>
>
>
> I'm dealing with the following code (from ZenGL library), targeting OSX
>
> ---------------
>
> {$mode delphi}
>
>
>
> procedure m_SinCos( Angle : Single; out s, c : Single ); assembler;
>
> asm
>
>   FLD Angle
>
>   FSINCOS
>
>   FSTP [EDX]
>
>   FSTP [EAX]
>
> end;
>
>
>
> var
>
>   s,c: single;
>
> begin
>
>   m_SinCos(0,s,c);
>
> end.
>
> ---------------
>
>
>
> The latest Xcode 7.0 tools does recognize the generated assembler (fpc trunk):
>
> ---------
>
> # [5] FLD Angle
>
>           flds      8(%ebp)
>
> # [6] FSINCOS
>
>           fsincos
>
> # [7] FSTP [EDX]
>
>           fstp      (%edx)
>
> # [8] FSTP [EAX]
>
>           fstp      (%eax)
>
> ---------
>
>
>
> as a problem:
>
>
>
> Assembling program
>
> test.s:21:2: error: ambiguous instructions require an explicit suffix (could be 'fstps', 'fstpl', or 'fstpt')
>
>         fstp    (%edx)
>
>         ^
>
> test.s:23:2: error: ambiguous instructions require an explicit suffix (could be 'fstps', 'fstpl', or 'fstpt')
>
>         fstp    (%eax)
>
>
>
> One interested could search the internet for the problem encountered with other platforms, and find out
> that the newer clang is somewhat backward incompatible.
>
>
>
> My first attempt was to replace to put the suggested FSTPS instruction in place:
>
> FSTPS [EDX]
>
> However, the compiler stopped me, complaining about "FSTPS" is not a recognized instruction.
>
>
>
> The next approach was to rewrite the function into at&t syntax. (The actual implementation could be found
> at sincos() of RTL math unit).
>
>
>
> Is it a yet to be developed feature for FPC to satisfy demands of external tools relies on?
>
>
>
> I presume since the compiler parses intel asm and translates it into at&t asm, it should take into
> consideration requirements of the latest osx building tools.
>
> Or is it already supported and I'm just missing a compiler switch?
>
>
>
> thanks,
>
> Dmitry
>
>
>
>
>
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