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

[Scott Egerton via Phabricator via cfe-commits]

s.egerton added a comment.

We have a patch to add codegen pattern matching (https://reviews.llvm.org/D67348). Unfortunately we have found that we will not be able to rely on pattern matching here to guarantee that these instructions are emitted in all situations due to differences in optimisation levels and the complexity of some instructions.
The approach of using arch-specific intrinsics in the middle end (https://reviews.llvm.org/D66479) was an alternative way to bridge the gap between the C level builtins and the Bitmanip instructions.

Thinking about it more, this could be approved and eventually have the inline asm parts replaced after the arch-specific intrinsics patch is approved.


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https://reviews.llvm.org/D67661