[LLVMdev] JIT API example (fibonacci)

[Alkis Evlogimenos]

On Tue, 2004-08-17 at 17:47, Chris Lattner wrote:
> On Wed, 18 Aug 2004, Valery A.Khamenya wrote:
> 
> >   the example attached I have used to prove that JIT and some visible
> >   optimizations are really invoked.
> >
> >   Proved OK. I got 30% speed-up in comparison to gcc 3.3.3
> >   on my Athlon XP 1500.
> 
> Cool!  Hey Valery, before we add this to the CVS repo, can you take a look
> at some of the changes I made to your HowToUseJIT example and use them to
> simplify this example too?
> 
> For example, instead of code like this:
> 
>     // the type is 'int ()'
>     std::vector<const Type*> ArgT(1);
>     ArgT[0] = Type::IntTy;
> 
>     // now create full type of the "fib" function:
>     FunctionType *FibT = FunctionType::get(Type::IntTy, // type of result
>                                            ArgT,
>                                            /*not vararg*/false);
> 
>     // Now create the fib function entry and
>     // insert this entry into module M
>     // (By passing a module as the last parameter to the Functionconstructor,
>     // it automatically gets appended to the Module.)
>     FibF = new Function(FibT,
>                         Function::ExternalLinkage, // maybe too much
>                         "fib", M);
> 
> You can do this same thing with code like this:
> 
>   Function *FibF = M->getOrInsertFunction("fib", Type::IntTy, Type::IntTy, 0);

Also instead of this:

    SetCondInst* CondInst 
      = new SetCondInst( Instruction::SetLE, 
                         &ArgX, Two );

    BB->getInstList().push_back(CondInst);

you can write it as:

    SetCondInst* CondInst 
      = new SetCondInst( Instruction::SetLE, 
                         &ArgX, Two, "cond", BB);

Ditto for all other instructions.

-- 

Alkis