[cfe-dev] Getting the location or scope of variable from a DeclRefExpr

[Ahmed Badran]

Hi,

I have a Stmt that belongs in a CFG that I built and in that Stmt is a
DeclRefExpr that points to a variable, I was wondering what's the advisable
and most appropriate way to get to the location where this variable is
defined (source location, scope) starting from the DeclRefExpr.

In my case, this variable is in a Stmt, that's in a CFGBlock, that belongs
to a CFG that I created, I've looked at the code and I could come up with a
couple of ideas, I'm not sure these are the correct ways though:
1. Visit the CFG using a visitor that notes the source locations of variable
definitions, variable names and types then use the LiveVariables (not sure
of the exact name of the class) to run on the different CFGBlocks in the CFG
and manually interrogate the class for the liveness of every variable at the
end of a CFGBlock, taking into account the correct path and reachability
through the CFG starting from the entry block.

2. Possibly create an AnalysisContext and from there possibly find a way to
get the Scopes.


As per my limited experience with Clang and just looking at the code, it
seems that 1 is quite tedious but probably more straightforward, and I'm
sure that it is already being done in Clang/LLVM to resolve the variable
references to the proper variables already, it's just that I haven't figured
out where is it being done to reuse it without having to reimplement it
again.

2 seemed to be way more complicated, involving creating the
AnalysisContextManager and a whole lot more support objects.

I was wondering which of the 2 is more appropriate and if there's yet
another way to do it that's simpler than these two potential solutions.

Regards,
Ahmed
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