[Patch, AArch64] Restructure arm_neon.h vector types' implementation.

[Tejas Belagod]

On 28/06/14 11:25, Marc Glisse wrote:
> On Mon, 23 Jun 2014, Tejas Belagod wrote:
>
>> Here is a patch that restructures neon builtins to use vector types based on
>> standard base types. We previously defined arm_neon.h's neon vector
>> types(int8x8_t) using gcc's front-end vector extensions. We now move away
>> from that and use types built internally(e.g. __Int8x8_t). These internal
>> types names are defined by the AAPCS64 and we build arm_neon.h's public
>> vector types over these internal types. e.g.
>>
>>   typedef __Int8x8_t int8x8_t;
>>
>> as opposed to
>>
>>   typedef __builtin_aarch64_simd_qi int8x8_t
>>     __attribute__ ((__vector_size__ (8)));
>>
>> Impact on mangling:
>>
>> This patch does away with these builtin scalar types that the vector types
>> were based on. These were previously used to look up mangling names. We now
>> use the internal vector type names(e.g. __Int8x8_t) to lookup mangling for
>> the arm_neon.h-exported vector types. There are a few internal scalar
>> types(__builtin_aarch64_simd_oi etc.) that is needed to efficiently implement
>> some NEON Intrinsics. These will be declared in the back-end and registered
>> in the front-end and aarch64-specific builtin types, but are not
>> user-visible. These, along with a few scalar __builtin types that aren't
>> user-visible will have implementation-defined mangling. Because we don't have
>> strong-typing across all builtins yet, we still have to maintain the old
>> builtin scalar types - they will be removed once we move over to a
>> strongly-typed builtin system implemented by the qualifier infrastructure.
>>
>> Marc Glisse's patch in this thread exposed this issue
>> https://gcc.gnu.org/ml/gcc-patches/2014-04/msg00618.html. I've tested my
>> patch with the change that his patch introduced, and it seems to work fine -
>> specifically these two lines:
>>
>> +  for (tree t = registered_builtin_types; t; t = TREE_CHAIN (t))
>> +    emit_support_tinfo_1 (TREE_VALUE (t));
>
> If you still have that build somewhere, could you try:
> nm -C libsupc++.a | grep typeinfo
> and check how much your builtins appear there? With my patch you may have
> half-floats in addition to what you get without the patch (I think that's
> a good thing), but I hope not too much more...
>
> Thanks for working on this,
>

Marc,

Revisiting this old thread - sorry for the delay in getting back.

When I do this, I see no aarch64 builtin types listed with my patch and 
the above two lines from your patch. Is this expected?

Thanks,
Tejas.