* Fix multi-threaded IRGen: store the DeclContext in a SILFunction explicitly instead of deriving it from the debug location. It's used in IRGen to decide into which module a function is emitted. With -gsil the debug location is changed and that should not change the module decision.
* Erase debug_value/debug_value_addr instructions when using -gsil. Those instructions are not needed anymore. They can also trigger a verifier error.
The fix is to set the DebugCompilationDir when -gsil is used.
Otherwise no debug info is generated if the source file name does not contain a path.
rdar://problem/49796695
This applies the same changes from Clang CFE r349065 to the Swift
frontend to unify how filenames, cmpilation directories and absolute
paths in filenames and path remappings are handled.
With the option -sil-print-debuginfo the printing of debug locations and scopes can be enabled.
I made the default for the option “false”, because in 99% of the time I don’t need the debug info in the printed SIL and I prefer better readability.
This change follows up on an idea from Michael (thanks!).
It enables debugging and profiling on SIL level, which is useful for compiler debugging.
There is a new frontend option -gsil which lets the compiler write a SIL file and generated debug info for it.
For details see docs/DebuggingTheCompiler.rst and the comments in SILDebugInfoGenerator.cpp.
