[libc-commits] [libc] [libc][stdfix] Implement fixed point bitsfx functions in llvm libc (PR #128413)

[Krishna Pandey via libc-commits]

krishna2803 wrote:

@PiJoules @lntue @nickdesaulniers 

Tests for `int_hr_t` (`short fract`) don't seem to work as it's just a `typedef` for `signed char`, and we don't have defined tests for that (and also `signed char` != `char`), I’ve excluded the tests for this type from `libc/test/CMakeLists.txt` for now. Apart from that, I built on the implementations of the already existing `fxbits` and `countlsfx` functions for this patch.

A side note: I noticed that the documentation for the fxbits functions is not updated in libc/docs/headers/math/stdfix.rst, even though we have an implementation for those. This also means that the "checks" are missing from the [llvm website](https://libc.llvm.org/headers/math/stdfix.html).

https://github.com/llvm/llvm-project/pull/128413