[llvm] Port Swift's merge function pass to llvm: merging functions that differ in constants (PR #68235)

[Manman Ren via llvm-commits]

manman-ren wrote:

> You likely need to start a new one, I don't think GitHub allows reopening merged PRs.
> 
> A couple obvious issues from scrolling through the code:
> 
> * Typed pointer support sprinkled about, including use of deprecated APIs. Needs to be removed. Also applies to tests.
> * Incomplete pointer authentication support sprinkled about. Unless there is full upstream support for this, it needs to be removed from this patch completely.
> * Drop `llvm::` prefixes. Not needed/used in LLVM.
> 
> TBH this PR doesn't really look in a reviewable state yet.

@nikic Thanks for pointing out the issues. I will be happy to make changes. This is ported from Swift repo, so it inherited some of the issues.

TBH, I don't think the final comment is necessary. I don't think it helps me in improving the patch.


https://github.com/llvm/llvm-project/pull/68235