[LLVMdev] Pure external functions

[Duncan Sands]

> How do you do the equivalent from the JIT?

In the IR, give tanh the readnone attribute.
If you want it to pay attention to the floating
point rounding mode, give it the readonly attribute.

Best performance, ignores rounding mode:
  declare double @tanh(double) nounwind readnone

Pays attention to rounding mode; optimizers can still do something though:
  declare double @tanh(double) nounwind readonly

Ciao,

Duncan.