[LLVMdev] [RFC] NoBuiltin Attribute

[Chris Lattner]

On Feb 19, 2013, at 10:50 AM, Krzysztof Parzyszek <kparzysz at codeaurora.org> wrote:

> On 2/19/2013 12:23 PM, Chris Lattner wrote:
>> 
>> I think that there is general confusion here about what -fno-builtin does.  It is *not* an attribute that affects the definition of builtin functions, it is a statement that the code being compiled in the current translation unit should change behavior.
> 
> Here are the cases that I see:
> (1) Nobuiltin attribute on printf, telling the compiler that the printf that can appear in a call may not be the printf from libc, meaning that the compiler cannot do anything to any such call that would take advantage of knowing what printf would normally do.

What is the use case of this?  This makes no sense for LTO, and minimal sense for the non-LTO case.  What problem are you trying to solve here?

-Chris