[fpc-devel] Problems with MM types (__m128 etc).

[J. Gareth Moreton]

On 08/04/2022 19:19, Jonas Maebe via fpc-devel wrote:
> On 08/04/2022 19:57, J. Gareth Moreton via fpc-devel wrote:
>> It looks like support for writing to arrays that are wholly stored in 
>> registers is a little limited and buggy
>
> Modifying individual elements of arrays stored in registers has never 
> been enabled nor supported in the compiler. That is why 
> tvecnode.pass_typecheck calls make_not_regable(left,[ra_addr_regable]);
>
> Enabling that will probably require quite a few changes in many 
> different places and possibly for several architectures all over the 
> compiler.
>
>
> Jonas
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>
That might explain a few things.  The problem is that under vectorcall 
and the System V ABI (the default x86_64 calling convention for Linux), 
vector types are supposed to be fully supported, like an aligned array 
of 4 Singles should be passed in a single XMM register.

I had a feeling that the compiler didn't support it, and you directing 
me to pass_typecheck for tvecnode is very helpful - thanks.

I'll have to think about this one a bit since, currently, this is a 
feature specific to x86_64.  I'll have to double-check if there's 
anything special for AArch64 since that has vector registers too.

https://gitlab.com/freepascal.org/fpc/source/-/issues/39657

Gareth aka. Kit


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