[cfe-commits] r41258 - in /cfe/trunk: AST/CFG.cpp include/clang/AST/CFG.h

[Chris Lattner]

On Aug 22, 2007, at 8:36 AM, Ted Kremenek wrote:

>
> On Aug 21, 2007, at 10:43 PM, Chris Lattner wrote:
>
>>>
>>> +      // Backpatch the gotos whose label -> block mappings we  
>>> didn't know
>>> +      // when we encountered them.
>>> +      for (BackpatchBlocksTy::iterator I = BackpatchBlocks.begin(),
>>> +           E = BackpatchBlocks.end(); I != E; ++I ) {
>>> +
>>> +        CFGBlock* B = *I;
>>> +        GotoStmt* G = cast<GotoStmt>(B->getTerminator());
>>> +        LabelMapTy::iterator LI = LabelMap.find(G->getLabel());
>>> +
>>> +        if (LI == LabelMap.end())
>>> +          return NULL; // No matching label.  Bad CFG.
>>
>> This should be an assert.  The CFG should only be built for valid  
>> ASTs.
>
> The current design thought was to allow the construction of CFGs  
> for arbitrary subtrees of valid ASTs (that represent a function body).
>
> However, a subtree of an AST may contain gotos that reference  
> labels in other subtrees of the AST (and thus the subtree is  
> "invalid" from the perspective of constructing a CFG).  If we allow  
> CFGs to be constructed from arbitrary subtrees of valid ASTs, then  
> I don't see how this cannot be a run-time check.

Interesting point.  In that case, instead of 'return NULL' you should  
have 'continue'.

-Chris