[LLVMdev] Virtual methods (was: LLVMBuilder vs LLVMFoldingBuilder)

Joachim Durchholz jo at durchholz.org
Fri Apr 4 01:29:59 PDT 2008

Am Donnerstag, den 03.04.2008, 19:29 -0700 schrieb Chris Lattner:
> On Apr 2, 2008, at 9:54 AM, Dominic Hamon wrote:
> > Would it be reasonable for me to submit a patch whereby [...] the
> > LLVMFoldingBuilder methods become virtual overrides of the base
> > class methods?
> No, please don't do this.  The idea of llvmbuilder is that it is a  
> "free" wrapper around the other existing API calls.  Making the  
> methods virtual would make them much more expensive.

Wouldn't the class of the objects be known at compile time in most
cases? This is essentially just a case of precomputing constants, so I
think this should be possible.

If yes, the compiler can predetermine the type, hence the virtual method
table that will be used, and can replace the virtual call with a static

Does such an approach make sense with LLVM?
(I'd want to do such things for my personal language project, so the
answer would be affecting compilation strategy.)


More information about the llvm-dev mailing list