[cfe-dev] Handling multiple translation units

[Simone Pellegrini]

Douglas Gregor wrote:
>
> On Oct 23, 2009, at 10:19 AM, Simone Pellegrini wrote:
>
>> Dear all,
>> I need to perform code transformations based on inter-procedural 
>> analysis done on multiple translation units.
>>
>> In order to do that I need to keep the AST generated for each 
>> translation unit in memory, do my analysis and then restart rewriting 
>> part of the AST I need to modify. Conceptually is not difficult my I 
>> am experiencing a weird behavior of Clang and maybe you can help me.
>>
>> basically that's what I am doing:
>>
>> vector<ASTContext*> ctxs;
>> for each input file{
>>     Preprocessor PP(...);
>>     InitializePreprocessor(PP);
>>     ctxs.push_back( new ASTContext(...., false, 0) );
>>     ParseAST(PP, *ctxs.back(),...);
>> }
>
> You will need to make sure that the SourceManager is also retained, 
> since the ASTContext stores a reference to its SourceManager. The same 
> is true for TargetInfo, IdentifierTable, SelectorTable, etc.
>
>> // Now do ANALYSIS (e.g. building a clang::CallGraph )
>> for each context in ctxs{
>>     DeclContext *DC=ctxs[i];
>>     for each decl{
>>         if decl is a func{
>>             FuncDecl* FD = ();
>>             cout << FD->getNameAsString() << endl; <--- ERROR
>>         }
>>     }
>> }
>>    
>> As you can see from the code, every time I try to access the 
>> information of the ASTContext it looks like everything is gone. why?
>
> Well, getNameAsString() is going to try to look at an IdentifierInfo 
> that may have been deallocated when the IdentifierTable is destroyed. 
> Your best bet would be to keep the whole Preprocessor alive for each 
> ASTContext.
Thanks Doug,
it works as expected now... no more strange error messages because of 
corrupted memory!
cheers bye
>
> - Doug