On Fri, 14 Oct 2011, Richard Earnshaw wrote:
> One way we might address this is to redefine our 128-bit vector types as
> structs of low/high Dwords. Each Dword remains a vector (apart from
> 64-bit lane types), but the Dword order then matches the ABI
> specification correctly. For example, the definition of uint8x16_t becomes
>
> typedef struct { uint8x8_t _val[2]; } uint8x16_t;
Those types have different ABIs for argument passing and return, so you'd
need some magic for special handling of the uint8x16_t type as defined in
the header....
> Secondly, all vector loads/stores should really be changed to use
> vld1.64 (with {d<n>, d<n+1>} as the register list for 128-bit accesses)
> rather than vldm; this then sorts out any issues with unaligned accesses
> without changing the memory format.
vld1 runs into problems for big-endian of not being able to do core
register loads / stores / transfers between core and NEON registers that
way, and needing to convert to the other format for argument passing /
return.
--
Joseph S. Myers
[email protected]
