[llvm-bugs] [Bug 31803] Canonicalization of rbit for ARMv8 64 bit fails

[via llvm-bugs]

https://llvm.org/bugs/show_bug.cgi?id=31803

Gonzalo BG <gonzalobg88 at gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|---                         |INVALID

--- Comment #4 from Gonzalo BG <gonzalobg88 at gmail.com> ---
So i've failed to reproduce this with clang trunk on aarch64:

https://godbolt.org/g/DHS2xz

clang 4.0 lowers __builtin_bitreverse to rbit properly.

On x86 the 32 and 64 bit versions of bitreverse look very good, but the
generated code for the 8-bit version looks worse than the naive implementation:

https://godbolt.org/g/kAlOC7

I'm closing this and filling a new issue for the bitreverse.i8 instruction.

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