[LLVMdev] Re: "pure" functions"

[Vladimir Prus]

Chris Lattner wrote:

> On Sun, 4 Jun 2006, Vladimir Prus wrote:
>> say I've a LLVM module with a call instruction. The called function is
>> "pure", that is it has no side-effects at all. How can I communicate this
>> to LLVM, so that the function call can be removed if the return value is
>> never used?
> 
> There isn't a way to do this from the source code yet.  However, if this
> is a standard library function, you can add it to the end of
> lib/Analysis/BasicAliasAnalysis.cpp.  Search of "isspace".

No, it's not a library function. Besides, what is "library" function? Do you
mean libc as of specific revision ;-) 

It would be nicer to have a method to declare function as pure without
modifying the code.

- Volodya