Bart <bartjun...@gmail.com> schrieb am Fr., 27. Apr. 2018, 13:42:
> On Wed, Apr 25, 2018 at 11:04 AM, <i...@wolfgang-ehrhardt.de> wrote:
>
> > If you compile and run this 64-bit program on Win 64 you get a crash
>
> And AFAICS your analysis of the cause (see bugtracker) is correct as well.
>
> function fpc_frac_real(d: ValReal) : ValReal;compilerproc; assembler;
> nostackframe;
> asm
> cvttsd2si %xmm0,%rax
> { Windows defines %xmm4 and %xmm5 as first non-parameter volatile
> registers;
> on SYSV systems all are considered as such, so use %xmm4 }
> cvtsi2sd %rax,%xmm4
> subsd %xmm4,%xmm0
> end;
>
> CVTTSD2SI — Convert with Truncation Scalar Double-Precision
> Floating-Point Value to Signed Integer
> This should not be used to get a ValReal result.
>
The code essentially does the following (instruction by instruction):
=== code begin ===
tmpi := int64(d - trunc(d));
tmpd := double(tmpi);
Result := d - tmpd;
=== code end ===
Though why it fails with the given value is a different topic...
Regards,
Sven
>
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