[PATCH v4 0/1] Add vector math function acos/acosf to libmvec

[Adhemerval Zanella]

On 16/12/2021 16:18, Joseph Myers wrote:
> I'd like to know more about where this assembly code came from.  Is it 
> manually written?  Generated by a compiler and then manually edited, as 
> suggested in previous discussions?  If it was generated by a compiler but 
> then sufficiently edited that the assembly version is now the preferred 
> form for subsequent modifications, it would still be helpful to see the 
> original input to that compiler (e.g. as a comment in the .S files), in 
> order to assess the relative merits of C and assembly sources for this 
> code and the possibilities of adapting to other architectures - and also 
> to see the original compiler output so we can judge the extent of the 
> editing and work out what is in fact the preferred form for modifications.
> 


Besides it I am curious why it can't be coded in C with proper builtins
plus some portability wrapper, as libraries like SLEEF does.  With some 
care we can make generic code that can ported to other vector ABIs, and 
add optimizations only its is really requires (as FMA for the newer math
functions).