llvm dev - May 2006 - [LLVMdev] InstVisitor: RetType

Hi, 
the docs for InstVisitor say that if RetType != void, one has to override
visitInstruction. What is the reason for that? It's valid to define
visitInstruction like that:

   RetTy visitInstruction(Instruction &I) { return RetTy(); } 

so assuming RetTy has a sensible default constructor, user won't need to
override visitInstruction. Note that the above will work when RetTy =void, as
checked by gcc and como, and confirmed by C++ standard.

Of course, RetTy() might not be a reasonable value for all cases, but that
can be left to user. Am I missing something?

- Volodya

On Wed, 31 May 2006, Vladimir Prus wrote:
> the docs for InstVisitor say that if RetType != void, one has to override
> visitInstruction. What is the reason for that? It's valid to define
> visitInstruction like that:
>
>   RetTy visitInstruction(Instruction &I) { return RetTy(); }
>
> so assuming RetTy has a sensible default constructor, user won't need
to
> override visitInstruction. Note that the above will work when RetTy =>
void, as checked by gcc and como, and confirmed by C++ standard.
>
> Of course, RetTy() might not be a reasonable value for all cases, but that
> can be left to user. Am I missing something?
If that works, go for it.  Beware that it may break hp's acc or some other 
compiler, but if noone complains about it, ok :)

-Chris

-- 
http://nondot.org/sabre/
http://llvm.org/