aarch64 built-in SIMD types

[Kyrylo Tkachov]

Hi Tom,

> On 24 Feb 2025, at 20:40, Tom Kacvinsky via Gcc <gcc@gcc.gnu.org> wrote:
> 
> Hi all,
> 
> I am trying to find where the aarch64 SIMD built in types are defined in
> GCC.
> For instance, __Int8x8_t.  I see some code in gcc/config/aarch64 for these,
> but
> then it goes deeper into internals of gcc that I don't quite follow.
> 
> Any help pointing to where I should look would be appreciated.
> 

The logic for defining them is in aarch64-builtins.cc . The information about them is tracked in aarch64_simd_type_info structs.
There’s some preprocessor machinery at work so it may not be obvious how it works from a first read.
There are user-level typedefs in arm_private_neon_types.h that is later included standard ACLE headers like arm_neon.h and arm_sve.h
What particular information are you looking for?

Thanks,
Kyrill


> Thanks,
> 
> Tom