Windows have different separators for paths than Unix based OS. One of
the tests in debug-compilation-unit.ll didn't have Win supported '\\'
variant which broken test suite on that OS.
AsmPrinter always creates a symbol for the end of function if valid
debug info is present. However, this breaks SPIR-V target's output,
because SPIR-V specification allows label instructions only inside a
block, not after the function body (see
https://registry.khronos.org/SPIR-V/specs/unified1/SPIRV.html#OpLabel).
This PR proposes to disable emission of label instructions after the
function body if the target is SPIR-V.
This PR is a fix of the
https://github.com/llvm/llvm-project/issues/102732 issue.
The commit introduces support for fundamental DI instruction. Metadata
handlers required for this instruction is stored inside debug records
(https://llvm.org/docs/SourceLevelDebugging.html) parts of the module
which rises the necessity of it's traversal.
