[fpc-devel] The new XMM intrinsics

[J. Gareth Moreton]

As a minor additional note, I think some of the mm types are declared 
incorrectly in compiler/psystem.pas - e.g. line 411:

tarraydef(x86_m128itype).elementdef:=s32floattype;

Shouldn't that be s32inttype or some other Integer type?  m128i is for 
when you're storing integers in the XMM registers.

Gareth aka. Kit


On 16/01/2020 22:22, J. Gareth Moreton wrote:
> Hey everyone,
>
> Maybe I'm being a bit pedantic with this, but must we abide by C/C++ 
> standards and go by the name __m128 etc. for the 128-bit data type?  
> Being as how Pascal tended to go for more readable and BASIC-inspired 
> names like Integer and Single, might it be better to name them TM128 
> instead?  If not that, then is it possible to add a union-like record 
> type to the System unit or the inc files that contain all of the 
> intrinsics?
>
> My vectorcall tests (e.g. tests\test\cg\tvectorcall1.pp) have 
> something like this:
>
> {$PUSH}
> {$CODEALIGN RECORDMIN=16}
> {$PACKRECORDS C}
> type
>   TM128 = record
>     case Byte of
>       0: (M128_F32: array[0..3] of Single);
>       1: (M128_F64: array[0..1] of Double);
>   end;
> {$POP}
>
> Granted, given that __m128 will be automatically aligned, all of the 
> codealign directives may not be necessary - for example:
>
> type
>   TM128 = record
>     case Byte of
>       0: (M128_F32: array[0..3] of Single);
>       2: (M128_F64: array[0..1] of Double);
>       3: (M128_Internal: __m128);
>   end;
>
> The main thing I'm thinking about is that it's actually rather 
> difficult to modify the elements of a variable of type __m128 directly 
> in C/C++ because of the type being opaque and difficult to typecast 
> sometimes (some compilers will treat it as an array, others will treat 
> it as a record type like the above (Visual C++ does this), while 
> others may not allow access to its elements at all).  Often, I might 
> want to map a 4-component vector with Single-type fields x, y, z and w 
> to an aligned __m128 type, or Double-type fields Re and Im when 
> dealing with complex numbers. That way, I can read from and write to 
> them outside of intrinsic calls.
>
> I suppose I'm suggesting we introduce something more usable than what 
> C has so people can actually use intrinsics more easily.
>
> Gareth aka. Kit
>
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