[clang] [Clang][OpenCL][AMDGPU] Allow a kernel to call another kernel (PR #115821)

[Brock Wyma via cfe-commits]

bwyma wrote:

@t-tye Would you mind reviewing this patch from a debug perspective?

Potentially multiple subprograms with the same source name, same source correlation in different routines, missing artificial or trampoline attributes, stepping between functions works as expected, etc. Your input would be appreciated.

https://github.com/llvm/llvm-project/pull/115821