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

Wed Sep 18 08:20:42 PDT 2019

lebedev.ri added a comment.

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.

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https://reviews.llvm.org/D67661