[clang] [clang-tools-extra] Remove `StringLiteral` in favor of `StringRef` (PR #122366)

[David Blaikie via cfe-commits]

dwblaikie wrote:

> > > Anyway, my main point was that there are people who care about performance on Windows, so please don't treat it as a second-class citizen.
> > 
> > 
> > Yeah, I don't want to treat folks on Windows as second class citizens by any means - but I wouldn't mind/hope we can treat folks who care about performance but don't build their performance-critical binaries with clang, on platforms clang supports, as a lower priority.
> 
> Consider testing as a counter example. We don't seriously expect anyone to do a bootstrap build each time they want to run their tests and folks do still run tests locally on their machine, and may run those tests frequently.

Not each time - and I'm not suggesting performance should be horrendous when building with the platform's toolchain. Just that the last bit of performance may not be available with the platform's toolchain, and you might need to use clang.
I'd generally recommend folks use clang for developing with LLVM anyway, for diagnostic parity, etc - doesn't require a bootstrap every time, take a recent release, or when you setup on a new machine, build clang then use that for your development.
Yes, every now and then you might miss out on some perf improvement and rebuilding your clang toolchain used for building may help a bit - but nothing drastic.

https://github.com/llvm/llvm-project/pull/122366