[PATCH] D27091: Add the way to extract SVals of arguments used in a call for a given StackFrameCtx

[Anna Zaks via Phabricator via cfe-commits]

zaks.anna added a comment.

Hi!

Looks like this this is used by the Infinite recursion checker. Specifically, the checker not only needs to get Smalls for arguments of the current CallEvent, but it also looks for arguments of other calls on the stack. The checker walks the LocationContext and uses this new API to look up the arguments passed to the calls on the stack.

The two concerns I have with this patch is that it is extending the overloaded ProgramState API and also that this does not fully cover all the call types we have in C/ObjC/C++. The good news is that the CallEvent API was created specifically to encapsulate this complexity and it already contains the needed API to look up the SVal of the argument. Have you considered creating CallEvent for the calls on the stack and using that existing API to find the Smalls of the arguments.

Here is some documentation from CallEvent.h:
`
 /// CallEvents are created through the factory methods of CallEventManager.
 ///
 /// CallEvents should always be cheap to create and destroy. In order for
 /// CallEventManager to be able to re-use CallEvent-sized memory blocks,
 /// subclasses of CallEvent may not add any data members to the base class.
 /// Use the "Data" and "Location" fields instead.

`

It looks like this code from BugReporterVisitors.cpp is doing something similar:

  ` // Don't automatically suppress a report if one of the arguments is
   // known to be a null pointer. Instead, start tracking /that/ null
   // value back to its origin.
   ProgramStateManager &StateMgr = BRC.getStateManager();
   CallEventManager &CallMgr = StateMgr.getCallEventManager();
  
   ProgramStateRef State = N->getState();
   CallEventRef<> Call = CallMgr.getCaller(StackFrame, State);
   for (unsigned I = 0, E = Call->getNumArgs(); I != E; ++I) {
     Optional<Loc> ArgV = Call->getArgSVal(I).getAs<Loc>();
     if (!ArgV)
       continue;

`

     

I hope this approach works and you could just add that code to your checker. (If not, we can investigate other options.)


https://reviews.llvm.org/D27091