[MLIR][LLVM] Extend DIScopeForLLVMFuncOp to handle cross-file operatio… (#167844)
The current `DIScopeForLLVMFuncOp` pass handles debug information for
inlined code by processing `CallSiteLoc` attributes. However, some
compilation scenarios compose code from multiple source files directly
into a single function without generating `CallSiteLoc`.
**Scenario:**
```python
# a.py
def kernel_a(tensor):
print("a: {}", tensor) # a.py:3
jit_func_b(tensor) # Calls b.py code
# b.py
def func_b(tensor):
print("b: {}", tensor) # b.py:7
```
The scenario executes Python at compile-time and directly inserts
operations from `b.py` into the kernel function, resulting in MLIR like:
```mlir
@kernel_a(...) {
print("a: {}", %arg0) loc(#loc_a) // a.py:3
print("b: {}", %arg0) loc(#loc_b) // b.py:7 <- FileLineColLoc, not CallSiteLoc
} loc(#loc_kernel) // a.py:1
#loc1 = loc("a.py":3:.)
#loc2 = loc("b.py":7:.)
#loc_a = loc("print"(#loc1))
#loc_b = loc("print"(#loc2))
```
```llvm
!6 = !DIFile(filename: "a.py", directory: "...")
!9 = distinct !DISubprogram(name: "...", linkageName: "...", scope: !6, file: !6, line: 13, ...)
!10 = !DILocation(line: 7, column: ., scope: !9) // Points to kernel's DISubprogram, not correct
```
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