As described in #98883, we have to qualify a module variable name in
debugger to get its value. This PR tries to remove this limitation.
LLVM provides `DIImportedEntity` to handle such cases but the PR is made
more complicated due to the following 2 issues.
1. The MLIR attributes are readonly and we have a circular dependency
here. This has to be handled using the recursive interface provided by
the MLIR. This requires us to first create a place holder
`DISubprogramAttr` which is used in creating `DIImportedEntityAttr`.
Later another `DISubprogramAttr` is created which replaces the place
holder.
2. The flang IR does not provide any information about the 'used' module
so this has to be extracted by doing a pass over the
`DeclareOp` in the function. This presents certain limitation as 'only'
and module variable renaming may not be handled properly.
Due to the change in `DISubprogramAttr`, some tests also needed to be
adjusted.
Fixes#98883.
This PR add debug info for module variables. The module variables are
added as global variables but their scope is set to module instead of
compile unit. The scope of function declared inside a module is also set
accordingly.
After this patch, a module variable could be evaluated in the GDB as `p
helper::gli` where helper is name of the module and gli is the name of
the variable. A future patch will add the import module functionality
which will remove the need to prefix the name with helper::.
The line number where is module is declared is a best guess at the
moment as this information is not part of the GlobalOp.
