[cfe-dev] Way to compare two Function bodies.

[Pavan Pattanada]

Thats pretty cool :) I will check what could be done. Thanks a lot!!

~Pavan


On Wed, Jul 17, 2013 at 5:44 PM, Richard Smith <richard at metafoo.co.uk>wrote:

> On Wed, Jul 17, 2013 at 5:20 PM, Pavan Pattanada <pattanad at uci.edu> wrote:
>
>> Yes, What you have mentioned is exactly what I want. So does it mean that
>> Stmt::Profile would generate unique ID (llvm::FoldingSetNodeID)
>> irrespective of it being a compound statement or not? If so, could I use it
>> to compare the two functions using the IDs that are generated using
>> FunctionDecl::getBody()::profile() ?
>>
>
> Yes, you can Stmt::Profile to compare two function bodies. But as noted
> below, it won't quite do what you want, because it doesn't consider
> variables declared within the statement to be "the same". You could fix
> this by teaching StmtProfiler to map declarations to some kind of
> declaration index if they are declared within the statement being profiled.
> You'd need similar treatment for LabelDecls. I don't see a good reason why
> we wouldn't accept such a patch for upstream Clang.
>
>
>> Thanks,
>> Pavan
>>
>>
>> On Wed, Jul 17, 2013 at 5:01 PM, Richard Smith <richard at metafoo.co.uk>wrote:
>>
>>> On Wed, Jul 17, 2013 at 4:18 PM, Pavan Pattanada <pattanad at uci.edu>wrote:
>>>
>>>> By "same", I mean, their ASTs to be the same to start with. I am
>>>> working on a tool,  which is used to syntactic/semantic similarity between
>>>> two versions of the code base. So far, I have been able to get the
>>>> FunctionDecls of both versions of a function into memory. But I am not sure
>>>> how to compare them.
>>>>
>>>
>>> This is still a little imprecise. Should functions compare equal if
>>> variables have been renamed between them? What if an expression has been
>>> rewritten into a trivially equivalent form (for instance, parentheses were
>>> added or removed, or p->x was changed to (*p).x)?
>>>
>>> Stmt::Profile does nearly what you want (it's the mechanism we use to
>>> determine if two dependent expressions are equivalent for the purposes of
>>> template redeclaration matching), but it will treat
>>>
>>>   void f() { int n; }
>>>   void g() { int n; }
>>>
>>> as having different bodies, because they do not declare the same
>>> variable. That's probably not very hard to fix.
>>>
>>>
>>>> ~Pavan
>>>>
>>>>
>>>> On Wed, Jul 17, 2013 at 3:42 PM, Richard Smith <richard at metafoo.co.uk>wrote:
>>>>
>>>>> On Wed, Jul 17, 2013 at 10:10 AM, Pavan Pattanada <pattanad at uci.edu>wrote:
>>>>>
>>>>>> Hi,
>>>>>> I need to compare two versions of the same clang::FunctionDecl
>>>>>> function body(a function in C). I would need to compare them statement by
>>>>>> statement and say if the two versions are the same. Is there a neat way to
>>>>>> do this in the clang framework?
>>>>>>
>>>>>
>>>>> This question is too vague to answer: what do you mean by "the same"?
>>>>> Same source text, same tokens, same tokens other than variable naming,
>>>>> something else?
>>>>>
>>>>
>>>>
>>>
>>
>
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