On 06/09/2012 22:18, Jonas Maebe wrote:
On 06 Sep 2012, at 23:00, Martin wrote:
Stopping in the disassemble view (using asm single stepping) the point in
classes had the below asm:
CLASSES_POINT$LONGINT$LONGINT$$TPOINT
0010BAF0 83ec0c sub $0xc,%esp
0010BAF3 890424 mov %eax,(%esp)
0010BAF6 89542404 mov %edx,0x4(%esp)
0010BAFA 8b0424 mov (%esp),%eax
0010BAFD 8b542404 mov 0x4(%esp),%edx
0010BB01 83c40c add $0xc,%esp
0010BB04 c3 ret
I don't have the exact copy of the asm for the case where the function was
compiled in a unit outside the RTL, but it used eax,ecx,edx. And eax would be
the pointer to the record (result:TPoint). Above the result is at -12(esp)
For now, my question is: What settings could get fpc to generate the above code?
It's the default setting on Darwin/i386 and iPhoneSim/i386, because that's how
its ABI prescribes that small records should be returned. Apparently there's a
check for cdecl/cppdecl/mwpascal missing in the parameter manager for that
platform, although until now nobody noticed.
All those custom calling conventions on i386 are a real pain, especially on
platforms where they have absolutely no use or right of existence other than
the fact that everyone and their uncle insists on writing inline assembler code
in when programming in FPC/Delphi/TP.
Ok.
Then my next question.
As indicated, compiling a copy and paste of this code, using the same
compiler, it produced asm using eax as pointer to the result.
Is that possible or allowed? If so how?
And if so then how would
type TPointProc = function(AX, AY: Integer): TPoint;
work?
If dereferenced any were in code
SomePointProc(1,1);
how would it know which calling convention (if there are 2 to choose from)
_______________________________________________
fpc-devel maillist - [email protected]
http://lists.freepascal.org/mailman/listinfo/fpc-devel
