[PATCH] D123773: [clang][analyzer][ctu] Make CTU a two phase analysis

[Gábor Horváth via Phabricator via cfe-commits]

xazax.hun added inline comments.


================
Comment at: clang/lib/StaticAnalyzer/Core/ExprEngineCallAndReturn.cpp:446
+    }
+    const bool BState = State->contains<CTUDispatchBifurcationSet>(D);
+    if (!BState) { // This is the first time we see this foreign function.
----------------
martong wrote:
> xazax.hun wrote:
> > So if we see the same foreign function called in multiple contexts, we will only queue one of the contexts for the CTU. Is this the intended design? 
> > 
> > So if I see:
> > ```
> > foreign(true);
> > foreign(false);
> > ```
> > 
> > The new CTU will only evaluate `foreign(true)` but not `foreign(false)`. 
> This is intentional.
> ```
> foreign(true);
> foreign(false);
> ```
> The new CTU will evaluate the following paths in the exploded graph:
> ```
> foreign(true); // conservative evaluated
> foreign(false); // conservative evaluated
> foreign(true); // inlined
> foreign(false); // inlined
> ```
> The point is to keep bifurcation to a minimum and avoid the exponential blow up.
> So, we will never have a path like this:
> ```
> foreign(true); // conservative evaluated
> foreign(false); // inlined
> ```
> 
> Actually, this is the same strategy that we use during the dynamic dispatch of C++ virtual calls. See `DynamicDispatchBifurcationMap`.
> 
> The conservative evaluation happens in the first phase, the inlining in the second phase (assuming the phase1 inlining option is set to none).
> The new CTU will evaluate the following paths in the exploded graph:
> ```
> foreign(true); // conservative evaluated
> foreign(false); // conservative evaluated
> foreign(true); // inlined
> foreign(false); // inlined
> ```

When we encounter `foreign(true)`, we would add the decl to `CTUDispatchBifurcationSet`. So the second time we see a call to the function `foreign(false);`, we will just do the conservative evaluation and will not add the call to the CTU worklist. So how will `foreign(false);` be inlined in the second pass? Do I miss something? 



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