[PATCH] D67661: [RISCV] Headers: Add Bitmanip extension Clang header files and rvintrin.h

[Roman Lebedev via Phabricator via cfe-commits]

lebedev.ri added a comment.

In D67661#1673993 <https://reviews.llvm.org/D67661#1673993>, @lebedev.ri wrote:

> In D67661#1673918 <https://reviews.llvm.org/D67661#1673918>, @s.egerton wrote:
>
> > Sorry I misread your original comment.
>
>
> (which one?)
>
> > These functions exist so that we can guarantee that these particular instructions will be emitted;
>
> Sure, that makes sense.
>
> > the other option was LLVM IR intrinsics and Clang builtins, this was the other patch (https://reviews.llvm.org/D66479).
> >  We are planning on abandoning that patch in favour of this one after the discussions on the patch and the mailing list.
>
> I sure did comment that both of these approaches (emitting inline asm, or having arch-specific intrinsics)
>  are worse than emitting plain IR (as there is no 'real' incentive to enhance backend pattern-matching),
>  but arch-specific intrinsics are certainly better than inline asm.
>  Sorry if that thought got convoluted.


Err, my main point against arch-specific intrinsics was about NOT producing them in middle-end,
since nothing will know about them, and thus the IR would become more opaque if you produce them in middle-end.


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