[LLVMdev] llvm-gcc cannot emit @llvm.pow.* ?

[Zhou Sheng]

2007/11/22, Duncan Sands <baldrick at free.fr>:
>
> Hi,
>
> > Current llvm-gcc cannot emit llvm intrinsic function like llvm.pow.* and
> > llvm.sin.*
> > For example:
> >
> > double foo(double x, double y) {
> >   return pow(x,y);
> > }
> >
> > will compiled into ll:
> >
> > define double @foo(double %x, double %y) {
> >    %tmp3 = tail call double @pow( double %x, double %y )
> >   ret double %tmp3
> > }
> >
> > This is not consistent with llvm language reference.
>
> first of all, this is logically wrong - the language reference
> doesn't say anywhere that you *have* to use llvm.pow.* rather than
> pow from the C library.


Sure. But now the question is the llvm-gcc will not emit llvm.pow.* anytime.

Also, don't forget that the llvm intrinsics
> don't set errno, so using them is only valid on systems/for languages
> for which errno is ignored.  That said, llvm.pow.* is for raising
> to an integer power, and here you raise to a double power.


I don't understand. why we  can't  use llvm.pow.f64 for double power?

Sheng.

Ciao,
>
> Duncan.
>
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