[llvm-dev] LLVM 3.9 RC2's SCCP pass removing calls to external functions?!

[Renato Golin via llvm-dev]

On 24 August 2016 at 15:51, Félix Cloutier <felixcca at yahoo.ca> wrote:
> Yes, there is no way for any pass to find out by itself whether that
> function has side effects, and I didn't tell it that it doesn't have any, so
> that seems overly aggressive.

Indeed.


> As far as finding and fixing the problem goes: I used to build LLVM and
> Clang from source, but I stopped because a full build takes around 3 hours
> on this machine and I don't get a lot out of it. I use LLVM on my spare time
> and I'm about as casual as a compiler back-end user can be. Sanjoy, I'd be
> happy if you looked into it.

I've just done it locally and it works on your example, but has some
test failures.

I've open a bug: https://llvm.org/bugs/show_bug.cgi?id=29120, and made
it block 3.9.0 for now.

cheers,
--renato