[llvm] [DataLayout] Add byte specification (PR #106536)

[Hongjia Cao via llvm-commits]

hongjia wrote:

> This patch adds byte specification to data layout string. The specification is `b:<size>`, where `<size>` is the size of a byte in bits (later referred to as "byte width").

Great work. Just a minor question: why not use character 'B' instead of 'b' for byte?



https://github.com/llvm/llvm-project/pull/106536