[clang] [llvm] [mlir] [NVPTX] Unify and extend barrier{.cta} intrinsic support (PR #140615)

[Alex MacLean via cfe-commits]

AlexMaclean wrote:

> This merge broke our builds on Halide.
> 
> ```
> Unhandled exception: Error: Could not find PTX barrier intrinsic (llvm.nvvm.barrier0)
> ```
> 
> We have [an `.ll` file](https://github.com/halide/Halide/blob/main/src/runtime/ptx_dev.ll) declaring these intrinsics:
> 
> ```llvm
> declare void @llvm.nvvm.barrier0()
> ```
> 
> So, it seems the auto-upgrade mechanism doesn't work. Any ideas?

@mcourteaux it looks to me like the error you're seeing is coming from here: 

https://github.com/halide/Halide/blob/85a3b07fab4ce07a9747d645dd1274c3f1c29b44/src/CodeGen_PTX_Dev.cpp#L265-L267

I reverted this change, but I plan to reland soon. Once I do you'll need to update this code to reference the new intrinsic. 

https://github.com/llvm/llvm-project/pull/140615