[te][llvm] Generate arithmetic vs logical right shift as appropriate (#51749)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/51749
Following in the mode of C++, we probably want to distinguish when
it's appropriate to do arithmetic vs. logical right shift.
> For negative a, the value of a >> b is implementation-defined (in most
> implementations, this performs arithmetic right shift, so that the result
> remains negative).
If you look at what clang does, if `a` is unsigned, a logical shift is
generated; if signed, an arithmetic shift. Let's do the same here. This turns
out to be useful for, e.g., implementing transcendental function
approximations.
ghstack-source-id: 121366317
Test Plan:
Added Byte (unsigned) and Char (signed) right-shift tests to
test_llvm.
Reviewed By: asuhan
Differential Revision: D26245856
fbshipit-source-id: 260ee9bf4b032b9ce216f89acbc273cde0ed688c
