We have a longstanding issue in debug info that use statement is not
fully respected. The problem has been described in
https://github.com/llvm/llvm-project/issues/160923. This is first part
of the effort to address this issue. This PR adds infrastructure to emit
`use` statement information in FIR, which will be used by subsequent
patches to generate DWARF debug information.
The information about use statement is collected during semantic
analysis and stored in `PreservedUseStmt` objects. During lowering,
`fir.use_stmt` operations are emitted for each `PreservedUseStmt`
object. The `fir.use_stmt` operation captures the module name, `only`
list symbols, and any renames specified in the use statement. The
`fir.use_stmt` is removed during `CodeGen`.
FrontendActions.cpp is currently one of the biggest compilation units in
all of flang. Measuring its compilation gives the following metrics:
User time (seconds): 139.21
System time (seconds): 4.65
Maximum resident set size (kbytes): 5891440 (5.61 GB)
This commit separates out explicit invocations of the parser into a
separate compilation unit - ParserActions.cpp - through helper functions
in order to decrease the maximum compilation time and memory usage of a
single unit.
After the split, the measurements of FrontendActions.cpp are as follows:
User time (seconds): 70.08
System time (seconds): 3.16
Maximum resident set size (kbytes): 3961492 (3.7 GB)
While the ones for the newly created ParserActions.cpp as follows:
User time (seconds): 104.33
System time (seconds): 3.37
Maximum resident set size (kbytes): 4185600 (3.99 GB)
---------
Signed-off-by: Kajetan Puchalski <kajetan.puchalski@arm.com>
