> Am 28.09.2024 um 09:24 schrieb Pierre Muller via fpc-devel
> <fpc-devel@lists.freepascal.org>:
>
> I think that the big endian version (see grep below)
> would suffer if you would use packed
> because the high field of size 2,
> would put the low field of size 8 at offset 2,
> which would trigger unaligned access to this field.
>
> For the little endian definition,
> it doesn't change anything, does it?
Yes, the record wouldn’t be aligned anymore like a real extended and on some
platforms it would be accessed only bytewise.
>
> Pierre
>
> See this grep result:
>
> muller@cfarm187:~/pas/trunk/fpcsrc/rtl/inc$ grep -inA9 "floatx80 *=" *
> softfpu.pp:139: floatx80 = record
> softfpu.pp-140- case byte of
> softfpu.pp-141- // force the record to be aligned like a double
> softfpu.pp-142- // else *_to_double will fail for cpus like sparc
> softfpu.pp-143- // and avoid expensive unpacking/packing operations
> softfpu.pp-144- 1: (dummy : extended);
> softfpu.pp-145- 2: (low : qword;high : word);
> softfpu.pp-146- end;
> softfpu.pp-147-
> softfpu.pp-148- float128 = record
> --
> softfpu.pp:167: floatx80 = record
> softfpu.pp-168- case byte of
> softfpu.pp-169- // force the record to be aligned like a double
> softfpu.pp-170- // else *_to_double will fail for cpus like sparc
> softfpu.pp-171- // and avoid expensive unpacking/packing operations
> softfpu.pp-172- 1: (dummy : qword);
> softfpu.pp-173- 2: (high : word;low : qword);
> softfpu.pp-174- end;
> softfpu.pp-175-
> softfpu.pp-176- float128 = record
> --
> ufloatx80.pp:32: floatx80 = {$IFDEF
> FPC_DOTTEDUNITS}System.SoftFpuX80{$ELSE}sfpux80{$ENDIF}.floatx80;
> ufloatx80.pp-33-
>
>
>> Le 27/09/2024 à 20:00, Martin Frb via fpc-devel a écrit :
>> Is there any indention in
>> floatx80 = record
>> case byte of
>> 1: (low : qword;high : word);
>> // force the record to be aligned like a double
>> // else *_to_double will fail for cpus like sparc
>> // and avoid expensive unpacking/packing operations
>> 2: (dummy : extended);
>> end;
>> NOT being a packed record?
>> If it was packed, it should have the same size as an actual extended: 80
>> bits / 10 bytes.
>> Possible similar issues for other softfloat types
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